Patent Publication Number: US-2022231502-A1

Title: Sensor device, management system, management server, acceptance inspecting device, method executed by sensor device, and nomenclature plate

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation under 35 U.S.C. § 120 of PCT/JP2020/036955, filed Sep. 29, 2020, which is incorporated herein by reference, and which claimed priority to Japanese Application No. 2019-182541, filed Oct. 2, 2019. The present application likewise claims priority under 35 U.S.C. § 119 to Japanese Application No. 2019-182541, filed Oct. 2, 2019, the entire content of which is also incorporated herein by reference. 
    
    
     1. FIELD OF THE INVENTION 
     The present invention relates to a data processing technology and particularly relates to a sensor device, a management system, a management server, an acceptance inspection device, a method executed by the sensor device, and a nomenclature plate. 
     2. DESCRIPTION OF THE RELATED ART 
     A technology has been proposed for storing characteristic values measured at the time of manufacturing a product in a storage medium provided in the product and performing control based on the stored characteristic values (see, for example, Patent Literature 1). 
     [Patent Literature 1] Japanese Patent Application Publication No. 2000-220508 
     The technology described in the above Patent Literature 1 is for acquiring the characteristic values of a product by using an inspection device at the time of manufacturing the product and does not allow for the acquisition of the situation during the transportation of the product. Therefore, if the characteristics of the product change from those at the time of manufacture due to transportation condition, it may be difficult to properly control the product. 
     SUMMARY OF THE INVENTION 
     In this background, one of the purposes of the present invention is to allow for the grasping of a condition related to a product under a situation where no external power source is supplied such as during the transportation of the product. 
     A sensor device according to one embodiment of the present invention includes: a sensor unit that measures a condition related to an object; a communication unit that outputs information that is based on the measurement result from the sensor unit; a storage unit that stores the measurement result from the sensor unit and the information output from the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. The sensor unit, the communication unit, the storage unit, the power storage unit, and the power generation unit are integrally provided, and at least two of the sensor unit, the communication unit, the storage unit, the power storage unit, and the power generation unit are arranged in an overlapping manner. 
     Another embodiment of the present invention also relates to a sensor device. This sensor device includes: a sensor unit that measures a condition related to an object; a communication unit that outputs information that is based on the measurement result from the sensor unit; a processing unit that generates information output from the communication unit based on the measurement result from the sensor unit; a storage unit that stores the measurement result from the sensor unit and the information output from the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit; and a power supply control unit that controls the supply or disconnection of electric power for at least one of the sensor unit, the communication unit, and the storage unit. The storage unit is capable of storing a plurality of measurement results from the sensor unit or a plurality of pieces of information output from the communication unit, the storage unit stores the plurality of measurement results or the plurality of pieces of information in association with a value that changes over time, and the sensor unit has a first sensor group composed of a plurality of sensors that measure different types of physical quantities and a second sensor group composed of a plurality of sensors that are arranged apart from one another and that measure the same type of physical quantity. The processing unit calculates the physical phenomenon inside the object based on the measurement result from the second sensor group and stores the calculation result in the storage unit, and the sensor unit, the communication unit, the processing unit, the storage unit, the power storage unit, the power generation unit, and the power supply control unit are integrally provided, and at least two of the sensor unit, the communication unit, the storage unit, the power storage unit, and the power generation unit are arranged in an overlapping manner. 
     Still another embodiment of the present invention relates to a management system. This management system includes: a sensor device that is attached to a part; a management server that manages information related to the part; and an acceptance inspection device that inspects whether or not the quality of the part meets the standard. The sensor device includes: a sensor unit that measures a condition related to the part; a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. The acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the sensor device received from the sensor device to the management server and also transmits the information received from the management server to the sensor device, and the management server obtains a correction value for the part based on the information that is based on the measurement result from the sensor unit of the sensor device transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     Still another embodiment of the present invention relates to a management server. This management server is a management server that manages information related to a part and includes: a deriving unit that obtains a correction value for the part based on the information related to the part transmitted from an acceptance inspection device that inspects whether or not the quality of the part meets the standard; and a providing unit that transmits the correction value derived by the deriving unit to the acceptance inspection device. The acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the sensor device received from the sensor device attached to the part to the management server and also transmits the correction value received from the management server to the sensor device, and the sensor device includes: a sensor unit that measures a condition related to the part; a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. 
     Yet another embodiment of the present invention relates to an acceptance inspection device. This device is an acceptance inspection device that inspects whether or not the quality of a part meets the standard and includes: a first acquisition unit that acquires information that is based on a measurement result from a sensor unit of a sensor device attached to the part from the sensor device; a second acquisition unit that transmits the information acquired by the first acquisition unit to a management server that manages information related to the part and also acquires a correction value for the part obtained based on the information by the management server from the management server; and an update unit that transmits the correction value acquired by the second acquisition unit to the sensor device. The sensor device includes: a sensor unit that measures a condition related to the part; a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. 
     Still another embodiment of the present invention relates to a management system for a speed reducer. This management system for a speed reducer includes: a speed reducer; a management server that manages information related to the speed reducer; and an acceptance inspection device that inspects whether or not the quality of the speed reducer meets the standard. The speed reducer includes: a speed reduction mechanism; a case that houses the speed reduction mechanism; a sensor unit that measures a condition related to the case; a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. The acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the speed reducer received from the speed reducer to the management server and also transmits the information received from the management server to the speed reducer, and the management server obtains a correction value for the speed reducer based on the information that is based on the measurement result from the sensor unit of the speed reducer transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     Still another embodiment of the present invention relates to a management system for a traveling unit for a crawler. This management system for a traveling unit for a crawler includes: a traveling unit for a crawler; a management server that manages information related to the traveling unit for a crawler; and an acceptance inspection device that inspects whether or not the quality of the traveling unit for a crawler meets the standard. The traveling unit for a crawler includes: a traveling control unit that controls the operation of the crawler; a case that houses the traveling control unit; a sensor unit that measures a condition related to the case; a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. The acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the traveling unit for a crawler received from the traveling unit for a crawler to the management server and also transmits the information received from the management server to the traveling unit for a crawler, and the management server obtains a correction value for the traveling unit for a crawler based on the information that is based on the measurement result from the sensor unit of the traveling unit for a crawler transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     Still another embodiment of the present invention relates to a management system for a fluid valve. This management system for a fluid valve includes: a fluid valve; a management server that manages information related to the fluid valve; and an acceptance inspection device that inspects whether or not the quality of the fluid valve meets the standard. The fluid valve includes: a valve unit that controls the flow of fluid; a case that houses the valve unit; a sensor unit that measures a condition related to the case; a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. The acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the fluid valve received from the fluid valve to the management server and also transmits the information received from the management server to the fluid valve, and the management server obtains a correction value for the fluid valve based on the information that is based on the measurement result from the sensor unit of the fluid valve transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     Still another embodiment of the present invention relates to a management system for a fluid cylinder. This management system for a fluid cylinder includes: a fluid cylinder; a management server that manages information related to the fluid cylinder; and an acceptance inspection device that inspects whether or not the quality of the fluid cylinder meets the standard. The fluid cylinder includes: a cylinder unit that houses fluid; a case that houses the cylinder unit; a sensor unit that measures a condition related to the case; a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. The acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the fluid cylinder received from the fluid cylinder to the management server and also transmits the information received from the management server to the fluid cylinder, and the management server obtains a correction value for the fluid cylinder based on the information that is based on the measurement result from the sensor unit of the fluid cylinder transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     Still another embodiment of the present invention relates to a management system for a fluid pump. This management system for a fluid pump includes: a fluid pump; a management server that manages information related to the fluid pump; and an acceptance inspection device that inspects whether or not the quality of the fluid pump meets the standard. The fluid pump includes: a pump unit that controls the flow of fluid; a case that houses the pump unit; a sensor unit that measures a condition related to the case; a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. The acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the fluid pump received from the fluid pump to the management server and also transmits the information received from the management server to the fluid pump, and the management server obtains a correction value for the fluid pump based on the information that is based on the measurement result from the sensor unit of the fluid pump transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     Still another embodiment of the present invention relates to a management system for a fluid compressor. This management system for a fluid compressor includes: a fluid compressor; a management server that manages information related to the fluid compressor; and an acceptance inspection device that inspects whether or not the quality of the fluid compressor meets the standard. The fluid compressor includes: a compression unit that applies pressure to fluid; a case that houses the compression unit; a sensor unit that measures a condition related to the case; a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. The acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the fluid compressor received from the fluid compressor to the management server and also transmits the information received from the management server to the fluid compressor, and the management server obtains a correction value for the fluid compressor based on the information that is based on the measurement result from the sensor unit of the fluid compressor transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     Still another embodiment of the present invention relates to a management system for an electric motor. This management system for an electric motor includes: an electric motor; a management server that manages information related to the electric motor; and an acceptance inspection device that inspects whether or not the quality of the electric motor meets the standard. The electric motor includes: a motor unit that converts electrical energy into mechanical energy; a case that houses the motor unit; a sensor unit that measures a condition related to the case; a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. The acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the electric motor received from the electric motor to the management server and also transmits the information received from the management server to the electric motor, and the management server obtains a correction value for the electric motor based on the information that is based on the measurement result from the sensor unit of the electric motor transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     Still another embodiment of the present invention relates to a management system for an electric actuator. This management system for an electric actuator includes: an electric actuator; a management server that manages information related to the electric actuator; and an acceptance inspection device that inspects whether or not the quality of the electric actuator meets the standard. The electric actuator includes: a drive unit that operates based on electrical energy; a case that houses the drive unit; a sensor unit that measures a condition related to the case; a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. The acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the electric actuator received from the electric actuator to the management server and also transmits the information received from the management server to the electric actuator, and the management server obtains a correction value for the electric actuator based on the information that is based on the measurement result from the sensor unit of the electric actuator transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     Still another embodiment of the present invention relates to a method. This method performed by a sensor device includes: detecting performed by measuring a condition related to an object; outputting information that is based on the measurement result in the detecting; storing the measurement result and the information in a storage unit; supplying electric power from a power storage unit as electric power for executing at least one of the respective processes of the detecting, the outputting, and the storing; and converting energy that exists in an external environment into electric power and charging the power storage unit. 
     Still another embodiment of the present invention relates to a nomenclature plate. This nomenclature plate that is attached to an article and on which information related to the article is displayed includes: a sensor unit that measures a condition related to the article; a communication unit that outputs information that is based on the measurement result from the sensor unit; a storage unit that stores the measurement result from the sensor unit and the information output from the communication unit; a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. 
     Optional combinations of the aforementioned constituting elements, and implementations of the invention in the form of apparatuses, systems, methods, computer programs, and recording media storing computer programs may also be practiced as additional modes of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will now be described, by way of example only, with reference to the accompanying drawings that are meant to be exemplary, not limiting, and wherein like elements are numbered alike in several figures, in which: 
         FIG. 1  is a block diagram showing functional blocks of a sensor device according to an exemplary embodiment; 
         FIG. 2  shows a circuit configuration example of the sensor device according to  FIG. 1 ; 
         FIG. 3  is a diagram showing the configuration of a sensor system including the sensor device according to  FIG. 1 ; 
         FIG. 4  is a flowchart showing an example of a sensing process performed by the sensor device; 
         FIG. 5  is a flowchart showing another example of a sensing process performed by the sensor device; 
         FIG. 6  is a flowchart showing an example of an information output process performed by the sensor device; 
         FIG. 7  is a flowchart showing another example of an information output process performed by the sensor device; 
         FIG. 8  is a flowchart showing another example of an information output process performed by the sensor device; 
         FIG. 9  is a flowchart showing an example of an initialization process performed by the sensor device; 
         FIG. 10A  is a diagram showing a first attachment example of the sensor device to a speed reducer; 
         FIG. 10B  is a diagram showing the first attachment example of the sensor device to the speed reducer; 
         FIG. 10C  is a diagram showing an example of functional blocks of the sensor device of  FIG. 10A  and  FIG. 10B ; 
         FIG. 11A  is a diagram showing the first attachment example of the sensor device to the speed reducer; 
         FIG. 11B  is a diagram showing the first attachment example of the sensor device to the speed reducer; 
         FIG. 11C  is a diagram showing an example of the functional blocks of the sensor device of  FIG. 11A  and  FIG. 11B ; 
         FIG. 12  is a diagram showing another example of the functional blocks of the sensor device of  FIG. 10A  and  FIG. 10B ; 
         FIG. 13  is a diagram showing another example of the functional blocks of the sensor device of  FIG. 10A  and  FIG. 10B ; 
         FIG. 14  is a diagram showing another example of the functional blocks of the sensor device of  FIG. 10A  and  FIG. 10B ; 
         FIG. 15  is a diagram showing another example of the functional blocks of the sensor device of  FIG. 10A  and  FIG. 10B ; 
         FIG. 16  is a diagram showing another example of the functional blocks of the sensor device of  FIG. 11A  and  FIG. 11B ; 
         FIG. 17A  is a diagram showing an attachment example of the sensor device to a traveling unit for a crawler; 
         FIG. 17B  is a diagram showing an attachment example of the sensor device to the traveling unit for a crawler; 
         FIG. 17C  is a diagram showing an example of functional blocks of the sensor device of  FIG. 17A  and  FIG. 17B ; 
         FIG. 18A  is a diagram showing an attachment example of the sensor device to a hydraulic valve; 
         FIG. 18B  is a diagram showing an attachment example of the sensor device to the hydraulic valve; 
         FIG. 18C  is a diagram showing an example of functional blocks of the sensor device of  FIG. 18A  and  FIG. 18B ; 
         FIG. 19A  is a diagram showing an attachment example of the sensor device to a pneumatic cylinder; 
         FIG. 19B  is a diagram showing an attachment example of the sensor device to the pneumatic cylinder; 
         FIG. 19C  is a diagram showing an example of functional blocks of the sensor device of  FIG. 19A  and  FIG. 19B ; 
         FIG. 20  is a diagram showing an example of cooperation between a plurality of sensor devices; 
         FIG. 21  is a diagram showing an example of cooperation between the plurality of sensor devices; 
         FIG. 22  is a diagram showing the configuration of a sensor system according to an exemplary variation; 
         FIG. 23  is a block diagram showing functional blocks of a sensor device according to the second exemplary embodiment; 
         FIG. 24  is a diagram showing the configuration of a management system including the sensor system according to  FIG. 23 ; 
         FIG. 25  is a diagram showing a distribution process of parts; 
         FIG. 26  is a flowchart showing an example of the process of a sensor device at the time of acceptance inspection of the parts; 
         FIG. 27  is a flowchart showing an example of the process of the sensor device at the time of acceptance inspection of the parts; 
         FIG. 28  is a flowchart showing an exemplary variation of the process of the sensor device at the time of acceptance inspection of the parts; and 
         FIG. 29  is a diagram showing the configuration of a management system according to the exemplary variation. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention will now be described by reference to the preferred embodiments. This does not intend to limit the scope of the present invention, but to exemplify the invention. 
     First Exemplary Embodiment 
     Japanese Patent Application Publication No. 2018-096451 suggests a technology for monitoring the state of a machine component by providing a sensor inside the machine component and transmitting the output of the sensor to an electric circuit outside the machine component by wire communication. The technology described in the above publication requires a place to arrange the sensor inside the mechanical component and further requires wiring for supplying power to the sensor. Therefore, the cost and period of time required for the manufacturing of the mechanical component may increase. 
     Therefore, in an exemplary embodiment, a nomenclature plate attached to the surface of a mechanical component (parts and the like) is used as a sensor device. The sensor device in the exemplary embodiment, in other words, the nomenclature plate attached to the machine component detects a condition related to the machine component before the actual use during the transportation or storage of the machine component, in other words, after the manufacturing of the machine component by using power generated by the sensor device itself. Then, information based on the detection result is output to the outside. 
     More specifically, the sensor device in the exemplary embodiment includes (1) a sensor unit that measures (can be said to detect) the condition of an attached mechanical component and the condition of the surrounding environment of the mechanical component, (2) an output unit that outputs information based on a measurement result (can be said to be a detection result) from the sensor unit, and (3) an energy harvesting unit that self-generates electricity for operating the sensor unit and the output unit using Wi-Fi (registered trademark) radio waves, etc. This eliminates the need to secure a location for the sensor to be placed inside the mechanical component and to provide new wiring for supplying electric power to the sensor. In other words, while making it possible to grasp the condition related to machine component, it is possible to suppress an increase in the cost and period of time required for manufacturing the machine component. 
       FIG. 1  is a block diagram showing functional blocks of a sensor device  10  according to an exemplary embodiment. The figure shows an example of functional blocks included in the sensor device  10  according to the exemplary embodiment. Each block shown in the block diagrams of the present specification is implemented in hardware such as elements, electronic circuits, or mechanical devices such as a processor, a CPU, and a memory of a computer, and in software such as a computer program. The figure depicts functional blocks implemented by the cooperation of the hardware and the software. Thus, a person skilled in the art should appreciate that there are many ways of accomplishing these functional blocks in various forms in accordance with the components of hardware, software, or the combination of both. 
     The sensor device  10  is attached to the surface of an article (hereinafter, also referred to as an “object”) having a predetermined physical structure as a nomenclature plate. The sensor device  10  includes a sensor unit  12 , a processing unit  14 , an output unit  16 , a storage unit  18 , a fingerprint sensor  20 , an energy harvesting unit  22 , and a power storage unit  24 . The sensor device  10  displays information regarding the object on the surface (outer surface) thereof as a nomenclature plate. Further, in the sensor device  10 , members corresponding to the functional blocks shown in  FIG. 1  are integrally provided in a sheet shape. The sheet shape means that the length of the sensor device  10  in the thickness direction is shorter than the length in the vertical direction and the length in the horizontal direction of the sensor device  10 . For example, when the length in the vertical direction and the length in the horizontal direction of the sensor device  10  are several centimeters, the length in the thickness direction of the sensor device  10  is 4 mm or less. Further, the length of the sensor device  10  in the thickness direction is desirably 1 mm or less. The length of the sensor device  10  in the thickness direction is more desirably 0.5 mm or less. Since the sensor device is attached to the surface of the object as a nomenclature plate, having a thin thickness is more desirable since the amount of protrusion from the object becomes small. The housing of the sensor device  10  may be formed of a material having high flexibility (plasticity) or may be formed of a material having low flexibility (plasticity). 
     The sensor unit  12  is provided so as to come into contact with (including being in proximity) to the object and measures the condition related to the object to which the sensor device  10  is attached. The object may be various types of electronic devices, electrical devices, mechanical devices, parts or finished products. The sensor unit  12  outputs a signal (hereinafter, also referred to as “detection signal”) based on the measurement result (detection result) to the processing unit  14 . 
     The condition related to the object measured by the sensor unit  12  may be either one or both of the state of the object itself (the state of either the inside or the surface of the object or both) and the state of the surroundings of the object (in other words, the environment surrounding the object). Further, the condition related to the object may be one type of physical state or physical quantity or may be a combination of a plurality of types of physical states or physical quantities. For example, the condition related to the object may be any one of vibration (in other words, 3-axis acceleration), temperature, humidity, sound, ultrasonic waves, distortion, atmospheric pressure, illuminance, global positioning system (GPS) (for example, position data measured using GPS), Bluetooth low energy (BLE) (“Bluetooth” is a registered trademark) beacon (e.g., position data measured using a BLE beacon), submersion degree, and wind power or any combination of these. Furthermore, the condition related to the object may include a chemical state. The chemical state may be, for example, the presence or absence of certain chemicals such as odor, acidity, neutrality, alkalinity, or allergens. 
     The processing unit  14  generates information (hereinafter, also referred to as “output information”) output from the output unit  16  based on a detection signal output from the sensor unit in the exemplary embodiment, which is the measurement result from the sensor unit  12 . The processing unit  14  may execute a predetermined arithmetic operation (for example, various filter processes, abnormality diagnosis processes by an artificial intelligence function, etc.) based on the detection signal output from the sensor unit  12  and generate output information including the arithmetic operation result. This allows the data amount of the output information to be reduced. 
     The output unit  16  outputs the output information generated by the processing unit  14  to the outside in the exemplary embodiment, which is information based on the measurement result from the sensor unit  12 . The storage unit  18  stores the measurement result from the sensor unit  12  (detection signal in the exemplary embodiment) or the information output from the output unit  16  (output information in the exemplary embodiment). In the exemplary embodiment, the storage unit  18  stores the output information generated by the processing unit  14  and further stores fingerprint data of an operator who is authorized to operate the sensor device  10  (in other words, an operator who has the authority to operate the sensor device  10 ). 
     The storage unit  18  may have storage capacity capable of storing a plurality of measurement results from the sensor unit  12  (for example, a plurality of detection signals output from the sensor unit  12 ) or a plurality of pieces of output information. The storage unit  18  may store the plurality of measurement results or the plurality of pieces of output information in association with a value that changes over time. The value that changes over time can be considered as a value that changes over the passage of time and may be a counter value or a time value that is counted up or countered down over time. This allows the plurality of measurement results or the plurality of pieces of output information to be held in chronological order. 
     For example, the processing unit  14  may store a plurality of pieces of output information generated based on the plurality of measurement results from the sensor unit  12  in the storage unit  18  in correspondence with a time value output from a real-time clock (or a GPS device). The processing unit  14  may aggregate or totalize the plurality of pieces of output information stored in the storage unit  18  based on the time value and generate new output information based on the aggregation result or the totalization result. In this case, the output unit  16  may output the new output information to the outside along with individual output information based on an individual measurement result or in place of the individual output information. 
     When the sensor unit  12  includes a plurality of sensors, the storage unit  18  may hold a detection signal from each sensor (or output information based on each detection signal) in association with each other based on the counter value, the time value, or the like. Alternatively, the storage unit  18  may separately hold the detection signal from each sensor (or output information based on each detection signal). 
     Further, the storage unit  18  may store the identification information (identification number) of the sensor unit  12  in correspondence with the detection signal or the output information. When the sensor unit  12  includes a plurality of sensors, the storage unit  18  may store a detection signal from each sensor or output information based on the signal in correspondence with the identification information of the sensor. Further, the storage unit  18  may further store the identification information (may be a product type) of the object. Further, the storage unit  18  may be provided independently of the processing unit  14  or may be configured to be removable from the sensor device  10 . 
     The output unit  16  may include electronic paper or a liquid crystal display as a display unit, and the output information generated by the processing unit  14  may be displayed on the electronic paper or the liquid crystal display. When the output unit  16  is formed using electronic paper or a liquid crystal display, the output unit  16  preferably includes a touch panel. In this case, in normal times, the output unit  16  may display information to be displayed on a nomenclature plate (which can also be called default information and includes, for example, product name and manufacturer information). On the other hand, when a predetermined operation is input via the touch panel, the output unit  16  (processing unit  14 ) may update screen display content so as to display the detection result from the sensor unit  12  and the output information stored in the storage unit  18 . 
     Further, the output unit  16  may include an antenna as a communication unit. In this case, the output unit  16  may transmit the output information generated by the processing unit  14  to an external device by using Wi-Fi, BLE, NFC, or the like. 
     The fingerprint sensor  20  is a sensor that reads a fingerprint from a finger of the operator of the sensor device  10 . The fingerprint sensor  20  may be integrated with the output unit  16  that includes electronic paper or a liquid crystal display. 
     The energy harvesting unit  22  converts energy existing in the environment (external environment) around the sensor device  10  into electric power (so-called energy harvesting) and supplies the electric power (the generated electric power) as the electric power for operating at least one of the sensor unit  12  and the output unit  16  (each unit in  FIG. 1  in the exemplary embodiment). For example, the sensor unit  12 , the processing unit  14 , the output unit  16 , the storage unit  18 , and the fingerprint sensor  20  in  FIG. 1  operate based on the electric power supplied from the energy harvesting unit  22 . The energy harvesting unit  22  may generate electric power based on at least one of energy: temperature; humidity; radio waves such as Wi-Fi; electromagnetic waves from the surroundings of the sensor device  10  (including radiation and cosmic rays and also includes electromagnetic noise emitted from an electric motor or the like); vibration; sound (including ultrasonic waves); light (including visible light, infrared light, and ultraviolet light); and flow of fluid or powder (wind, wave, etc.). 
     For example, the energy harvesting unit  22  may convert Wi-Fi radio waves into direct current by using the technology described in “http://gigazine.net/news/20190129-wifi-rectenna/”, “http://news.mit.edu/2019/converting-wi-fi-signals-electricity-0128”, or the like. Further, the energy harvesting unit  22  may supply electric power to each unit based on electromotive force generated by short-range wireless communication (NFC or the like). The energy harvesting unit  22  that includes such a communication function may execute data communication and power generation in a time-division manner, in other words, may execute data communication and power generation alternately. 
     The power storage unit  24  stores the electricity generated by the energy harvesting unit  22  and supplies the stored electric power to each unit in  FIG. 1 . 
     For example, the sensor unit  12 , the processing unit  14 , the output unit  16 , the storage unit  18 , and the fingerprint sensor  20  in  FIG. 1  can operate based on the electric power supplied from the energy harvesting unit  22  and can further operate using the electric power supplied from the power storage unit  24 . The power storage unit  24  may be a capacitor (including an electric double layer capacitor) or a secondary battery (for example, a lithium ion battery, a solid lithium ion battery, an air battery, etc.). 
     The processing unit  14  includes an authentication unit  30 , a power supply control unit  32 , an information generation unit  34 , and an update unit  36 . When the fingerprint data of an operator read by the fingerprint sensor  20  matches the fingerprint data of an authorized operator stored in advance in the storage unit  18 , the authentication unit  30  determines that the authentication of the operator has been successful. When the processing unit  14  determines that the authentication unit  30  has succeeded in authenticating the operator, the processing unit  14  causes output information to be output from the output unit  16  in accordance with operation by the operator. 
     The power supply control unit  32  controls the supply or disconnection of electric power for each unit in  FIG. 1 .  FIG. 2  shows a circuit configuration example of the sensor device according to  FIG. 1 . In the example in the figure, the energy harvesting unit  22  includes a first power generation unit  22   a  and a second power generation unit  22   b  as a plurality of power generation means. For example, the first power generation unit  22   a  may be a power generation means using a thermoelectric conversion element, and the second power generation unit  22   b  may be a power generation means using a photovoltaic cell. A voltage control unit  40   a  controls voltage supplied from the first power generation unit  22   a , and a voltage control unit  40   b  controls voltage supplied from the second power generation unit  22   b . For example, the voltage control unit  40   a  and the voltage control unit  40   b  transform voltage supplied from each power generation unit to a level within a predetermined range. 
     The sensor device  10  includes a plurality of switches for controlling the supply or disconnection of electric power for each unit in  FIG. 1 . These switches may be semiconductor switches or mechanical relays. Further, these switches are electrically connected to the processing unit  14 . The power supply control unit  32  of the processing unit  14  switches a switch  42   a  on when electricity generated by the first power generation unit  22   a  and electricity generated by the second power generation unit  22   b  are stored in the power storage unit  24 . Further, the power supply control unit  32  switches the switch  42   a  on when supplying electric power from the power storage unit  24  to the sensor unit  12 , the storage unit  18 , and the output unit  16 . 
     The power supply control unit  32  of the processing unit  14  switches a switch  42   b  on when supplying electric power to the sensor unit  12 , while the power supply control unit  32  switches the switch  42   b  off when disconnecting the power supply to the sensor unit  12 . Further, the power supply control unit  32  switches a switch  42   c  on when supplying electric power to the storage unit  18 , while the power supply control unit  32  switches the switch  42   c  off when disconnecting the power supply to the storage unit  18 . Further, the power supply control unit  32  switches a switch  42   d  on when supplying electric power to the output unit  16 , while the power supply control unit  32  switches the switch  42   d  off when disconnecting the power supply to the output unit  16 . 
     Referring back to  FIG. 1 , the information generation unit  34  generates output information output from the output unit  16  based on the detection signal output from the sensor unit  12 . As described above, the information generation unit  34  may execute an arithmetic operation such as various filter processes and abnormality diagnosis processes by an artificial intelligence function based on the detection signal and generate output information including the arithmetic operation result. Further, the information generation unit  34  may aggregate or totalize the plurality of detection signals or the plurality of pieces of output information stored in the storage unit  18  so as to generate new output information. 
     The update unit  36  updates the data stored in the storage unit  18 . For example, the update unit  36  stores the detection signal output from the sensor unit  12  or the output information generated by the information generation unit  34  in the storage unit  18 . Further, when a predetermined instruction for instructing the initialization of the storage unit  18  is input, the update unit  36  deletes (in other words, initializes) the data stored in the storage unit  18 . When the output unit  16  has a communication function, the above-mentioned predetermined instruction may be input from an external device via communication. Further, when the output unit  16  has a touch panel function, the predetermined instruction may be input through operation by the operator on the touch panel. 
     The processing unit  14  is a processor (for example, a micro control unit (MCU) or the like) whose arithmetic capacity increases as the number of operation clocks increases and may be realized by a processor capable of changing the number of operation clocks according to the processing details. In this case, a computer program in which a plurality of modules corresponding to the plurality of functional blocks in the processing unit  14  of  FIG. 1  are mounted may be stored in a storage area such as the storage unit  18 . Then, the function of each functional block may be exerted by the processor reading and executing the computer program. Further, the processor may execute a process for which low arithmetic capacity is sufficient (for example, the process of the power supply control unit  32 ) at a relatively low operation clock frequency and execute a process requiring high arithmetic capacity (for example, the process of the information generation unit  34 ) at a relatively high operation clock frequency. The high and low of the operation clock frequency of the processor may be specified by a computer program corresponding to each functional block. 
     As another aspect, the processing unit  14  may be realized by a processor having a plurality of cores with different power consumption per unit time. When the power supply from the energy harvesting unit  22  and the power storage unit  24  is less than a predetermined threshold value, the processing unit  14  may execute a data process (the process of each functional block) using a core with relatively low power consumption. On the other hand, when the power supply from the energy harvesting unit  22  and the power storage unit  24  is equal to or higher than the above threshold value, the processing unit  14  may execute the data process (the process of each functional block) using a core with relatively large power consumption. Thereby, the electric power supplied from the energy harvesting unit  22  and the power storage unit  24  can be efficiently used. 
     In the sensor device  10 , at least two of the sensor unit  12 , the output unit  16 , and the energy harvesting unit  22  are arranged in an overlapping manner. Thereby, the size of the sensor device  10  can be reduced, allowing for easy attachment of the sensor device  10  to an object. For example, when the output unit  16  is electronic paper, it is necessary to secure an area of a certain size (information display area) in the vertical direction and the horizontal direction as an area for the output unit  16 . In this case, the sensor unit  12  and the energy harvesting unit  22  may be arranged at a position directly below the output unit  16  in the thickness direction. 
     The processing unit  14 , the storage unit  18 , the fingerprint sensor  20 , and the power storage unit  24  in  FIG. 1  are not essential components. For example, when the measurement result from the sensor unit  12  is output from the output unit  16  without processing the measurement result, the processing unit  14  may be omitted. Further, when the measurement result from the sensor unit  12  is immediately output from the output unit  16 , the storage unit  18  may be omitted. Further, if the authentication of the operator is not necessary, the fingerprint sensor  20  and the authentication unit  30  of the processing unit  14  may be omitted. Further, if the storage of electricity generated by the energy harvesting unit  22  is not necessary, the power storage unit  24  may be omitted. 
     A typical example of the sensor device  10  will be described. The sensor unit  12  may include a plurality of sensors that measure a plurality of types of physical quantities (for example, temperature, humidity, and vibration) of an object or the surroundings of the object. The output unit  16  may output output information that is based on the measurement result from the sensor unit  12  to the outside by wireless communication such as Wi-Fi or NFC. The energy harvesting unit  22  may generate electric power based on Wi-Fi radio waves, NFC radio waves, or light (sunlight or illumination light) so as to supply electric power to at least one of the sensor unit  12  and the output unit  16 . 
       FIG. 3  shows the configuration of a sensor system  50  including the sensor device  10  according to  FIG. 1 . The sensor system  50  is an information processing system including the sensor device  10  and a terminal device  54 . The terminal device  54  may be any of a smartphone, a PC, a drone, and a stationary gate that reads the sensor device  10 . The sensor device  10  includes an antenna (in other words, a communication unit) as the output unit  16  and transmits output information to the terminal device  54 . The terminal device  54  acquires the output information transmitted from the sensor device  10  via an antenna  52 . The terminal device  54  may acquire the output information from a plurality of sensor devices  10  attached to a plurality of objects, associate each piece of output information with the output source sensor device  10 , and store the output information in a cloud (database on the cloud, etc.). 
     The operation of a sensor device  10  according to the above configuration will be described.  FIG. 4  is a flowchart showing an example of a sensing process performed by the sensor device  10 . When the time for detecting the condition related to the object is reached (Y in S 10 ), the power supply control unit  32  of the processing unit  14  supplies electric power to the sensor unit  12  (S 11 ). The processing unit  14  acquires a detection signal output from the sensor unit  12  (S 12 ). The update unit  36  of the processing unit  14  stores the detection signal in the storage unit  18  (S 13 ). The power supply control unit  32  of the processing unit  14  stops the power supply to the sensor unit  12  (S 14 ). If it is not the time for detecting the condition related to the object (N in S 10 ), processes in and after S 11  are skipped. The sensor device  10  repeatedly executes the sensing process in the present figure. The processing unit  14  may repeatedly execute the processes in and after S 11  without performing a determination process in S 10 . 
       FIG. 5  is a flowchart showing another example of the sensing process performed by the sensor device  10 . When the time for detecting the condition related to the object is reached (Y in S 20 ), the power supply control unit  32  of the processing unit  14  supplies electric power to the sensor unit  12  (S 21 ). The processing unit  14  acquires a detection signal output from the sensor unit  12  (S 22 ). The information generation unit  34  of the processing unit  14  executes a filter process or the like on the detection signal so as to generate output information (S 23 ). The update unit  36  of the processing unit  14  stores the output signal in the storage unit  18  (S 24 ). The power supply control unit  32  of the processing unit  14  stops the power supply to the sensor unit  12  (S 25 ). If it is not the time for detecting the condition related to the object (N in S 20 ), processes in and after S 21  are skipped. The sensor device  10  repeatedly executes the sensing process in the present figure. The processes in and after S 21  may be repeatedly executed without performing a determination process in S 20 . 
       FIG. 6  is a flowchart showing an example of an information output process performed by the sensor device  10 . The figure shows a process of updating the display content of electronic paper serving as the output unit  16 . It is assumed that the electronic paper in this case requires power supply in order to update the display content but does not require power supply in order to maintain the display content. The electronic paper may display default information such as a product name and a manufacturer name in normal times. 
     When a predetermined operation for instructing display switching is input to the touch panel integrated with the output unit  16  (Y in S 30 ), the power supply control unit  32  of the processing unit  14  supplies electric power to the electronic paper (S 31 ). The processing unit  14  acquires the output information stored in the storage unit  18  and passes the output information to the output unit  16  (S 32 ). The output unit  16  updates the display content of the electronic paper by applying a voltage to the electronic paper so as to display the output information passed from the processing unit  14  (S 33 ). If an operation for instructing display switching to the touch panel has not been input (N in S 30 ), the output unit  16  maintains the display content of the electronic paper without changing the display content (S 34 ). 
     The trigger for update of the display content of the electronic paper is not limited to an operation on the touch panel. For example, the display content of the electronic paper may be updated when the electric power is supplied from the energy harvesting unit  22  by NFC or the like. Further, the display content of the electronic paper may be updated when a display update instruction from an external device is received via communication. 
       FIG. 7  is a flowchart showing another example of an information output process performed by the sensor device  10 . In this case, it is assumed that the output unit  16  has an NFC function and includes a receiving circuit (including a power generation function) and a transmitting circuit. The receiving circuit of the output unit  16  functions as the energy harvesting unit  22 . Specifically, upon receiving a data transmission request transmitted from an external device (Y in S 40 ), the receiving circuit supplies electric power to the processing unit  14  based on the electromotive force generated by the communication. The power supply control unit  32  of the processing unit  14  supplies electric power to the transmitting circuit of the output unit  16  (S 41 ). The processing unit  14  acquires the output information stored in the storage unit  18  and passes the output information to the transmitting circuit of the output unit  16  (S 42 ). The transmitting circuit transmits the output information to the request source external device (S 43 ). The power supply control unit  32  of the processing unit  14  stops the power supply to the transmitting circuit of the output unit  16  (S 44 ). If the data transmission request has not been received (N in S 40 ), processes in and after S 41  are skipped. The processes in and after S 41  may be executed without performing a determination process in S 40 . 
       FIG. 8  is a flowchart showing another example of an information output process performed by the sensor device  10 . This figure corresponds to  FIG. 6 . However, the sensor device  10  in the figure does not include a storage unit  18  for storing detection signals or output information. When a predetermined operation for instructing display switching is input to the touch panel integrated with the output unit  16  (Y in S 50 ), the power supply control unit  32  of the processing unit  14  supplies electric power to the sensor unit  12  (S 51 ). According to the details of the operation input to the touch panel, the information generation unit  34  of the processing unit  14  acquires a detection signal from the sensor unit  12  and generates output information based on the detection signal (S 52 ). The output unit  16  updates the display content of the electronic paper by applying a voltage to the electronic paper so as to display the output information generated by the processing unit  14  (S 53 ). If an operation for instructing display switching to the touch panel has not been input (N in S 50 ), the output unit  16  maintains the display content of the electronic paper without changing the display content (S 54 ). 
       FIG. 9  is a flowchart showing an example of an initialization process performed by the sensor device  10 . When an initialization instruction (in other words, a signal instructing the deletion of storage data) is input via communication, or when an initialization instruction is input via an operation by an operator (Y in S 60 ), the update unit  36  of the processing unit  14  initializes the storage unit  18  by deleting data stored in the storage unit  18  (S 61 ). When the data deletion is completed, the update unit  36  passes a notification to the output unit  16  indicating that the data deletion (that is, initialization) is completed. The output unit  16  transmits the notification to the request source external device via communication or displays the notification on a display unit such as electronic paper (S 62 ). If the initialization instruction has not been input (N in S 60 ), processes in and after S 61  are skipped. 
     A attachment example of a sensor device  10  to various articles will be described. In a sensor device  10  in each of the following examples, a sensor unit  12 , an output unit  16 , and an energy harvesting unit  22  are integrally provided in a sheet shape as described above. Further, at least two of the sensor unit  12 , the output unit  16 , and the energy harvesting unit  22  are arranged in an overlapping manner. 
       FIG. 10A  and  FIG. 10B  show a first attachment example of a sensor device  10  to a speed reducer  100 . As shown in  FIG. 10A , the speed reducer  100  includes a speed reduction mechanism  102 , a casing  104  for housing the speed reduction mechanism  102 , and a sensor device  10 . As shown in  FIG. 10B , the sensor device  10  is attached so as to adhere to the surface of the casing  104 . 
       FIG. 10C  shows an example of functional blocks of the sensor device  10  of  FIG. 10A  and  FIG. 10B . The sensor device  10  includes a first sensor  12   a  and a second sensor  12   b  as a plurality of sensors. The first sensor  12   a  and the second sensor  12   b  are sensors that detect different types of physical quantities. The first sensor  12   a  may detect any one of temperature, humidity, sound, ultrasonic waves, distortion, atmospheric pressure, illuminance, GPS signals, BLE beacons, submersion degree, and wind power. Further, the second sensor  12   b  may detect a physical quantity of a type different from that by the first sensor  12   a  among the plurality of types of physical quantities. 
     The first sensor  12   a  and the second sensor  12   b  are arranged on the main unit side of the speed reducer  100 , in other words, on the casing  104  side and detect the condition related to the casing. For example, the first sensor  12   a  may be a vibration sensor that detects the vibration of the casing  104  of the speed reducer  100 . The second sensor  12   b  may be a temperature sensor that detects the temperature of the casing  104  of the speed reducer  100 . The power storage unit  24  may be a capacitor (including an electric double layer capacitor). A transparent antenna  60  may be used as an energy harvesting unit  22  that generates electricity based on Wi-Fi radio waves. 
     The processing unit  14  may derive the condition of the casing  104  based on a detection signal output from the first sensor  12   a  and a detection signal output from the second sensor  12   b  and further estimate the condition of the speed reduction mechanism  102  from the condition of the casing  104 . For example, the processing unit  14  may derive the vibration and temperature of the casing  104  based on a detection signal output from the vibration sensor and a detection signal output from the temperature sensor and further estimate the vibration and temperature of the speed reduction mechanism  102  from the vibration and temperature of the casing  104 . The processing unit  14  may generate output information obtained by aggregating the estimation results in chronological order and display the output information on the output unit  16  arranged on the outer surface side (for example, the front surface side of the nomenclature plate). 
       FIG. 11A  and  FIG. 11B  show a second attachment example of a sensor device  10  to a speed reducer  100 . The sensor device  10  in the figures includes a fastening part  62 , and the sensor device  10  is fixed to the surface of the casing  104  by inserting the fastening part  62  into the casing  104 . The fastening part  62  may be a screw, a pin, or a rivet and may be, for example, a metal screw. The housing of the sensor device  10  is desirably made of a flexible material (for example, a thin metal plate or the like) so as to be in close contact with the casing  104 . 
       FIG. 11C  shows an example of functional blocks of the sensor device  10  of  FIG. 11A  and  FIG. 11B . The sensor device  10  includes an ultrasonic sensor  66   a  and an ultrasonic sensor  66   b  as a plurality of sensors. The ultrasonic sensor  66   a  and the ultrasonic sensor  66   b  are connected to the fastening part  62 , in other words, are arranged so as to be in contact with the fastening part  62 . Thereby, the fastening part  62  also functions as a probe for accurately detecting the condition inside the main unit of the speed reducer  100 . In this way, by providing a plurality of sensors (the ultrasonic sensor  66   a  and the ultrasonic sensor  66   b  in this case) that detect the same type of physical quantity at positions away from each other, it is possible to estimate the location where an abnormality has occurred by using triangulation. 
     A plurality of ultrasonic sensors may be used instead of the plurality of ultrasonic sensors. Further, a strain gauge may be used along with the ultrasonic sensors or instead of the ultrasonic sensors. By arranging the sensor device  10  on the curved surface of the casing  104 , the amount of strain is increased, and the strain inside the main unit of the speed reducer  100  can be detected with high accuracy. 
     The power storage unit  24  may be a capacitor (including an electric double layer capacitor). A photovoltaic cell  64  (in other words, a solar cell) may be used as an energy harvesting unit  22  that generates electric power based on light from lighting or the like. The processing unit  14  may use the principle of triangulation based on a detection signal output from the ultrasonic sensor  66   a  and a detection signal output from the ultrasonic sensor  66   b  so as to generate output information that indicates the location of an abnormality inside the main unit of the speed reducer  100 . 
       FIG. 12  shows another example of functional blocks of the sensor device  10  of  FIG. 10A  and  FIG. 10B . Differences from the sensor device  10  of  FIG. 10C  will be described here. The sensor device  10  in this figure includes an antenna  68  (that is, a communication unit) instead of electronic paper (that is, a display unit) as an output unit  16 . The output unit  16  transmits a signal including output information generated by the processing unit  14  to an external device. Further, as an energy harvesting unit  22 , the antenna  68  also has a function of generating electricity by Wi-Fi radio waves or NFC and supplying electric power to each unit. A print surface of the sensor device  10  is a surface that can be visually recognized from the outside. Items to be listed on a nomenclature plate are printed on the print surface, and for example, the manufacturer name, the speed reducer model number, the date of manufacture, and the like are printed. 
       FIG. 13  also shows another example of the functional blocks of the sensor device  10  of  FIG. 10A  and  FIG. 10B . The sensor device  10  in the figure is different from the sensor device  10  in  FIG. 12  in that the sensor device  10  in the figure includes a plurality of types of antennas. A Wi-Fi antenna  72  generates electricity based on Wi-Fi radio waves as an energy harvesting unit  22 . On the other hand, a BLE antenna  70  communicates with an external device as an output unit  16 . By generating electric power using Wi-Fi with relatively large reception power, and transmitting and receiving electricity using a power-saving BLE, the efficiency of power generation and power consumption can be improved. 
       FIG. 14  also shows another example of the functional blocks of the sensor device  10  of  FIG. 10A  and  FIG. 10B . In the same way as in the sensor device  10  of  FIG. 12 , the antenna  68  functions not only as a communication unit but also as a first power generation unit. A thermoelectric conversion element  78  is an element that converts heat energy conducted from the inside of the speed reducer  100  into electric energy by utilizing the Seebeck effect, the Pertier effect, or the Thomson effect and functions as a second power generation unit. A humidity sensor  76  is provided on the outer surface side (that is, the print surface side) of the sensor device  10  and detects the humidity around the speed reducer  100 . 
     A strain gauge  74  dynamically measures the deformation of the main unit of the speed reducer  100  (casing  104 ). Therefore, at least a portion of the housing of the sensor device  10  where the strain gauge is arranged is desirably made of a stretchable material (can be also considered as a stretchable material, for example, a resin film or the like). Further, as shown in  FIG. 10B , the sensor device  10  of  FIG. 14  is fixed to the casing  104  of the speed reducer  100  by adhesion. 
     The strain gauge  74  also functions as a touch sensor for detecting stress generated by the touching or the like of the outer surface (print surface) of the sensor device  10  by the operator. When the strain gauge  74  detects a stress of a predetermined magnitude and direction, the processing unit  14  may determine that an output instruction for detection information has been input. The processing unit  14  may generate output information based on the humidity detected by the humidity sensor  76  and the strain detected by the strain gauge  74  and transmit the output information to an external device via the antenna  68 . 
       FIG. 15  also shows another example of the functional blocks of the sensor device  10  of  FIG. 10A  and  FIG. 10B . The photovoltaic cell  64  converts light energy of lighting or the like into electrical energy as a first power generation unit. As a second power generation unit, the antenna  79  receives electromagnetic noise propagated from the main unit side of the speed reducer  100  so as to generate power. Temperature difference power generation may be performed by using the thermoelectric conversion element  78  instead of the antenna  79 . As a secondary effect of providing the antenna  79 , the sensor device  10  can be used as an electromagnetic shield since the antenna  79  absorbs electromagnetic noise. 
     As shown in  FIGS. 14 and 15 , by providing a plurality of power generation units of different methods, the required electric power can be easily fulfilled as a whole even when the power generation amount of one of the power generation units becomes insufficient. Further, since the sensor device  10  of  FIG. 15  is not provided with the power storage unit  24  (capacitor or the like), the sensor device  10  can be miniaturized. 
       FIG. 16  shows another example of functional blocks of the sensor device  10  of  FIG. 11A  and  FIG. 11B . A submersion meter  82  is a sensor that detects the degree of submersion (presence or absence of submersion). By providing the submersion meter  82 , whether or not the main unit of the speed reducer  100  has been submerged can be checked. For example, when a plurality of speed reducers  100  are attached in a vertical direction to one robot, how high the robot has been submerged can be grasped by aggregating output information from the plurality of sensor devices  10  mounted on the plurality of speed reducers  100 . 
     An illuminance meter  80  is provided on the outer surface (outside side) of the speed reducer  100  and detects the illuminance around the speed reducer  100 . By including the illuminance around the speed reducer  100  based on the detection result from the illuminance meter  80  in the output information, whether or not a worker (inspection worker or the like) having a portable electric lamp has come nearby can be grasped. Further, whether or not the lighting near the speed reducer  100  is turned off can be grasped. 
       FIG. 17A  and  FIG. 17B  show an attachment example of the sensor device  10  to a traveling unit  110  for a crawler. As shown in  FIG. 17A , the traveling unit  110  for a crawler includes a traveling control unit  112  that controls the operation of the crawler, a casing  114  that houses the traveling control unit  112 , and a sensor device  10 . The casing  114  includes a hydraulic supply unit  116 . As shown in  FIG. 17B , the sensor device  10  includes a fastening part  62 . The sensor device  10  is fixed to the surface of the casing  114  (the hydraulic supply unit  116  in this case) by inserting the fastening part  62  into the casing  114  (the hydraulic supply unit  116  in this case). 
       FIG. 17C  shows an example of functional blocks of the sensor device  10  of  FIG. 17A  and  FIG. 17B . The thermoelectric conversion element  78  generates electricity by utilizing the temperature of hydraulic oil as an energy harvesting unit  22 . The power storage unit  24  is, for example, a capacitor. The antenna  86  functions as an output unit  16 . The antenna  86  wirelessly communicates with an external device by using the housing (metal body) of the traveling unit  110  for a crawler as an antenna. As an exemplary variation, the sensor device  10  may communicate with an external device using known human body communication technology, handshake communication technology, or electric field communication technology. 
     The processing unit  14  may derive the vibration amount of the casing  114  (the hydraulic supply unit  116  in this case) based on the detection signal output from the vibration sensor  84  and further estimate from the vibration amount the vibration amount of the traveling control unit  112  or the crawler. The processing unit  14  may transmit the estimation result from the antenna  86  to the external device. 
       FIG. 18A  and  FIG. 18B  show an attachment example of the sensor device  10  to a hydraulic valve  120 . As shown in  FIG. 18A , the hydraulic valve  120  includes a valve unit  122  that controls the flow of hydraulic oil (mineral oil or the like), a casing  124  that houses the valve unit  122 , and a sensor device  10 . As shown in  FIG. 18B , the sensor device  10  includes a fastening part  62 . The sensor device  10  is fixed to the surface of the casing  124  by inserting the fastening part  62  into the casing  124 . 
       FIG. 18C  shows an example of functional blocks of the sensor device  10  of  FIG. 18A  and  FIG. 18B . The thermoelectric conversion element  78  generates electricity by utilizing the temperature of hydraulic oil as an energy harvesting unit  22 . The power storage unit  24  is, for example, a capacitor. The sensor device  10  in this example includes electronic paper with a touch panel as an output unit  16 . As in the case of the sensor device  10  of  FIG. 17C , the housing (metal body) of the hydraulic valve  120  may be used as an antenna. 
     The processing unit  14  may derive the vibration amount of the casing  124  based on the detection signal output from the vibration sensor  84  and further estimate from the vibration amount the vibration amount of the valve unit  122 . The processing unit  14  may display the estimation result on the electronic paper of the output unit  16 . Needless to say, the sensor device  10  may be attached not only to the hydraulic valve  120  but also to various types of fluid valves (pneumatic valve, water pressure valve, etc.). 
       FIG. 19A  and  FIG. 19B  show an attachment example of the sensor device  10  to a pneumatic cylinder  130 . As shown in  FIG. 19A , the pneumatic cylinder  130  includes a cylinder unit  132  for accommodating air, a casing  134  for accommodating the cylinder unit  132 , and a sensor device  10 . As shown in  FIG. 19B , the sensor device  10  includes a fastening part  62 . The sensor device  10  is fixed to the surface of the casing  134  by inserting the fastening part  62  into the casing  134 . 
       FIG. 19C  shows an example of functional blocks of the sensor device  10  of  FIG. 19A  and  FIG. 19B . As an energy harvesting unit  22 , a sound power/vibration power generation unit  88  converts the energy of the exhaust sound or vibration of compressed air in the cylinder unit  132  into electrical energy. The power storage unit  24  is a secondary battery such as a lithium ion battery, a solid lithium ion battery, or an air battery in this case. The sensor device  10  in this example includes electronic paper with a touch panel as an output unit  16 . As in the case of the sensor device  10  of  FIG. 17C , the housing (metal body) of the pneumatic cylinder  130  may be used as an antenna. 
     The processing unit  14  may derive the vibration amount of the casing  134  based on the detection signal output from the vibration sensor  84  and further estimate from the vibration amount the vibration amount of the cylinder unit  132 . The processing unit  14  may display the estimation result on the electronic paper of the output unit  16 . Needless to say, the sensor device  10  may be attached not only to the pneumatic cylinder  130  but also to various types of fluid cylinders (hydraulic cylinder, water pressure cylinder, mechanical cylinder, etc.). 
     Next, an example of a sensor system including a plurality of sensor devices  10  will be described.  FIG. 20  shows an example of cooperation (in other words, collaboration) of the plurality of sensor devices  10 . In the example in  FIG. 20 , one sensor device  10  is attached to one speed reducer. More specifically, a first sensor device  10   a  is attached to a first speed reducer  100   a , a second sensor device  10   b  is attached to a second speed reducer  100   b , and a third sensor device  10   c  is attached to a third speed reducer  100   c . The respective output units  16  of the first sensor device  10   a , the second sensor device  10   b , and the third sensor device  10   c  include a communication unit that uses Wi-Fi or the like. The first sensor device  10   a , the second sensor device  10   b , and the third sensor device  10   c  are formed to be communicable with one another. 
     For example, when the communication unit of the first sensor device  10   a  receives an information provision request from the terminal device  54 , the communication unit may transmit the information provision request to the second sensor device  10   b  and the third sensor device  10   c . The communication unit of the second sensor device  10   b  may transmit output information (for example, temperature information of the second speed reducer  100   b ) generated by the processing unit  14  to the first sensor device  10   a . The communication unit of the third sensor device  10   c  may transmit output information (for example, temperature information of the third speed reducer  100   c ) generated by the processing unit  14  to the first sensor device  10   a . The communication unit of the first sensor device  10   a  may transmit output information generated by the own device (for example, temperature information of the first speed reducer  100   a ), output information transmitted from the second sensor device  10   b , and output information transmitted from the third sensor device  10   c  collectively to the terminal device  54 . According to this aspect, if the terminal device  54  makes a request to one sensor device  10 , the terminal device  54  can acquire a plurality of pieces of output information indicating conditions related to the plurality of speed reducers  100  generated by the plurality of sensor devices  10 . 
       FIG. 21  also shows an example of cooperation of a plurality of sensor devices  10 . In the example of  FIG. 21 , a plurality of sensor devices  10  (in this example, the first sensor device  10   a  and the second sensor device  10   b ) are attached to one speed reducer  100 . The output unit  16  of the first sensor device  10   a  and the output unit  16  of the second sensor device  10   b  include a communication unit that uses Wi-Fi or the like. The first sensor device  10   a  and the second sensor device  10   b  are formed to be communicable with each other. 
     For example, when the communication unit of the first sensor device  10   a  receives an information provision request from the terminal device  54 , the communication unit may transmit the information provision request to the second sensor device  10   b . The communication unit of the second sensor device  10   b  may transmit output information (for example, temperature information and/or vibration information of the second portion of the speed reducer  100 ) generated by the processing unit  14  to the first sensor device  10   a . The communication unit of the first sensor device  10   a  may transmit the output information generated by the own device (for example, the temperature information and/or vibration information of the first portion of the speed reducer  100 ) and the output information transmitted from the second sensor device  10   b  collectively to the terminal device  54 . According to this aspect, if terminal device  54  makes a request to one sensor device  10 , the terminal device  54  can acquire a plurality of pieces of output information indicating conditions related to a plurality of locations of one speed reducer  100  generated by the plurality of sensor devices  10 . For example, according to the vibration amount detected at a plurality of locations of one speed reducer  100 , the terminal device  54  can identify abnormal locations in the speed reducer  100  by using the principle of triangulation. 
     Described above is an explanation made based on an exemplary embodiment. The exemplary embodiment is intended to be illustrative only, and it will be obvious to those skilled in the art that various modifications to constituting elements and processes described in the exemplary embodiment could be developed and that such modifications are also within the scope of the present invention. 
     An exemplary variation will be described. A sensor device  10  can be attached to various articles not mentioned in the above exemplary embodiment. For example, the sensor device  10  may be attached as a nomenclature plate of a fluid pump (hydraulic pump, water pressure pump, air pump, etc.). This fluid pump may include a pump unit that controls the flow of fluid, a casing that houses the pump unit, and a sensor device  10 . The sensor device  10  may be attached to the casing. The sensor device  10  may estimate the condition related to the pump unit (for example, temperature, vibration, etc.) by detecting the condition related to the casing and output output information indicating the estimation result to the outside. 
     Further, for example, the sensor device  10  may be attached as a nomenclature plate of a fluid compressor (air compressor, gas compressor, etc.). This fluid compressor may include a compression unit that applies pressure to the fluid, a casing that houses the compression unit, and a sensor device  10 . The sensor device  10  may be attached to the casing. The sensor device  10  may estimate the condition related to the compression unit (for example, temperature, vibration, etc.) by detecting the condition related to the casing and output output information indicating the estimation result to the outside. 
     Further, for example, the sensor device  10  may be attached as a nomenclature plate of an electric motor. The electric motor may include a motor unit that converts electrical energy into mechanical energy, a casing that houses the motor unit, and a sensor device  10 . The sensor device  10  may be attached to the casing. The sensor device  10  may estimate the condition related to the motor unit (for example, temperature, vibration, etc.) by detecting the condition related to the casing and output output information indicating the estimation result to the outside. 
     Further, for example, the sensor device  10  may be attached as a nomenclature plate of an electric actuator. This electric actuator may include a drive unit that converts electrical energy into mechanical energy, a casing that houses the drive unit, and a sensor device  10 . The sensor device  10  may be attached to the casing. The sensor device  10  may estimate the condition related to the drive unit (for example, temperature, vibration, etc.) by detecting the condition related to the casing and output output information indicating the estimation result to the outside. 
     Further, for example, the sensor device  10  may be attached as a nomenclature plate of furniture, in other words, furniture to which the sensor device  10  is attached may be realized. The sensor device  10  may be attached to the housing (outer surface) of the furniture. The sensor device  10  may detect the condition related to the furniture (the housing of the furniture) and output output information indicating the detection result to the outside. 
     Further, for example, the sensor device  10  may be attached as a nomenclature plate of a tray used for the delivery of an article, in other words, a tray to which the sensor device  10  is attached may be realized. By detecting the condition related to the tray, the sensor device  10  may estimate the condition related to the article being delivered in the tray and output output information indicating the estimation result to the outside. 
     Further, for example, the sensor device  10  may be attached to the packaging material of the article, in other words, the packaging material to which the sensor device  10  is attached may be realized. The sensor device  10  may be attached to the outer surface of the packaging material. By detecting the condition related to the packaging material, the sensor device  10  may estimate the condition related to the article packaged by the packaging material and output output information indicating the estimation result to the outside. 
     Further, for example, the sensor device  10  may be attached as a nomenclature plate of tableware, in other words, the tableware to which the sensor device  10  is attached may be realized. The sensor device  10  may detect the condition related to the tableware and output output information indicating the detection result to the outside. 
     Further, for example, the sensor device  10  may be attached as a nomenclature plate of a home electric appliance, in other words, a home electric appliance to which the sensor device  10  is attached may be realized. The sensor device  10  may be attached to the housing (outer surface) of a home electric appliance. The sensor device  10  may estimate the condition related to the device portion (for example, temperature, vibration, etc.) by detecting the condition related to the housing of the home electric appliance and output output information indicating the detection result to the outside. 
     The sensor device  10  may be attached as a nomenclature plate to various constructions having predetermined physical structures. In this case, the sensor unit  12  of the sensor device  10  measures various conditions related to the physical structure of a construction. The construction may be the furniture, the tray, the packaging material, the tableware, or the household appliance described above, as well as building materials, automobile parts, railroad vehicle parts, aircraft parts, ship parts, industrial robot parts, or construction machine parts. 
     Another exemplary variation will be described. The sensor device  10  according to the present exemplary variation may include an output unit  16  (communication unit) capable of long-distance wireless communication with a wireless base station installed in a remote location.  FIG. 22  corresponds to  FIG. 3  and shows the configuration of a sensor system  50  including a sensor device  10  according to the exemplary variation. In the sensor system  50  according to the exemplary variation, the sensor device  10  directly transmits/receives data to/from a device on the cloud via a wireless base station installed in a remote location. For example, the sensor device  10  may directly transmit output information generated by the own device to a database server  56  on the cloud and store the output information in the database server  56 . 
     Yet another exemplary variation will be described. Elements (hardware and software) for enhancing security are desirably mounted on at least one of the sensor device  10  and a part or the like (hereinafter, also referred to as “mother device”) to which the sensor device  10  is attached. The security implementation may include, for example, password authentication and communication by public key cryptosystem. 
     An example of the security implementation will be described. 
     (1) Communication (wireless or wired) between the mother device and the sensor device  10  (nomenclature plate) has a possibility of having low security strength. 
     Therefore, a hole may be made in the attachment surface (nomenclature plate attachment surface) of the sensor device  10  in the mother device, and the sensor device  10  may be arranged in the hole. This makes it difficult for an external device to eavesdrop on the communication between the mother device and the sensor device  10 . As described, the reduction of the possibility of leakage of communication between the mother device and the sensor device  10  by the devising of the hardware allows for the operation of communication between the mother device and the sensor device  10  with low security. 
     (2) High security is required for communication (wireless) between the sensor device  10  and an external base station (cloud). 
     Since wireless communication systems such as 4G and 5G are so-called closed networks, no problem occurs. On the other hand, in the case of Wi-Fi or the like, at least password authentication is desirably implemented, and more preferably, communication by a public key cryptosystem is implemented. 
     Yet another exemplary variation will be described. The mother device and the sensor device  10  may be connected by wire, the mother device may supply electric power to the sensor device  10 , and the sensor device  10  may monitor the normality of the power source in the mother device based on the electric power (voltage) supplied from the mother device. When predetermined electric power (voltage) from the mother device is not supplied, the sensor device  10  may detect that and store output information indicating a power source abnormality of the mother device or output the output information to the outside. The mother device may supply electric power for operating the sensor device  10 . When electric power is not supplied from the mother device, the sensor device  10  may be operated by electric power provided from the energy harvesting unit  22  or the power storage unit  24 . 
     Second Exemplary Embodiment 
     The technology described in the above Patent Literature 1 (Japanese Patent Application Publication No. 2000-220508) is for acquiring the characteristic values of a product by using an inspection device at the time of manufacturing the product and does not allow for the acquisition of the situation during the transportation of the product. Therefore, if the characteristics of the product change from those at the time of manufacture due to transportation condition, it may be difficult to properly control the product. 
     Therefore, in the second exemplary embodiment, a nomenclature plate attached to the surface of a product (mechanical components, parts, and the like) is used as a sensor device as in the case of the first exemplary embodiment. The sensor device (nomenclature plate) in the exemplary embodiment uses the electric power generated by the sensor device itself so as to detect the condition related to a product during the transportation or storage of the product, in other words, the condition related to the product after the manufacturing of the product and before the actual use. Then, information based on the detection result is output to the outside. 
     More specifically, as in the case of the sensor device in the first exemplary embodiment, the sensor device in the second exemplary embodiment includes (1) a sensor unit that measures the condition of an attached mechanical component and the condition of the surrounding environment of the mechanical component, (2) an output unit that outputs information based on a measurement result from the sensor unit, and (3) an energy harvesting unit that self-generates electricity for operating the sensor unit and the output unit using Wi-Fi (registered trademark) radio waves, etc. This eliminates the need to secure a location for the sensor to be placed inside the mechanical component and to provide new wiring for supplying electric power to the sensor. In other words, while making it possible to grasp the condition related to machine component, it is possible to suppress an increase in the cost and period of time required for manufacturing the machine component. 
     Further, as an example of utilizing the sensor device proposed in the first exemplary embodiment, an information processing system is proposed that manages the characteristic values and control parameters of a product to which the sensor device is attached through the cooperation of the sensor device and an external device in the second exemplary embodiment. Hereinafter, elements that are the same as or correspond to those elements (functional blocks, etc.) described in the first exemplary embodiment shall be denoted by the same reference numerals. Repetitive description of features already described in the first exemplary embodiment will be omitted as appropriate. 
       FIG. 23  is a block diagram showing functional blocks of a sensor device  10  according to the second exemplary embodiment. The figure shows an example of functional blocks included in the sensor device  10  according to the second exemplary embodiment. The sensor device  10  includes a sensor unit  12 , a processing unit  14 , a storage unit  18 , an energy harvesting unit  22 , a power storage unit  24 , a communication unit  200 , and a display unit  202 . The configuration of the sensor device  10  shown in  FIG. 23  is an example, and various configurations of the sensor device  10  described in the first exemplary embodiment can be applied. 
     The sensor device  10  according to the second exemplary embodiment is also attached to the surface of an article (hereinafter, also referred to as an “object”) having a predetermined physical structure as a nomenclature plate. As in the case of the first exemplary embodiment, members corresponding to the functional blocks shown in  FIG. 23  are integrally provided in a sheet shape also in the sensor device  10  according to the second exemplary embodiment. Thereby, the size of the sensor device  10  can be reduced, allowing for easy attachment of the sensor device  10  to an object as a nomenclature plate. Further, as in the case of the first exemplary embodiment, at least two of the members corresponding to the functional blocks shown in  FIG. 23  are arranged in an overlapping manner also in the sensor device  10  according to the second exemplary embodiment. For example, in the sensor device  10  according to the second exemplary embodiment, at least two of the sensor unit  12 , the communication unit  200 , the storage unit  18 , the power storage unit  24 , and the energy harvesting unit  22  are arranged in an overlapping manner. Thereby, the size of the sensor device  10  can be reduced, allowing the sensor device  10  to be easily attached to an object as a nomenclature plate. As an exemplary variation, the sensor device  10  may be configured such that at least two of the sensor unit  12 , the communication unit  200 , the storage unit  18 , the power storage unit  24 , the energy harvesting unit  22 , the processing unit  14 , and the display unit  202  are arranged in an overlapping manner. 
     The sensor unit  12  measures the condition related to the object to which the sensor device  10  is attached. The processing unit  14  generates information output from the communication unit  200  (also referred to as “output information”) based on the measurement result from the sensor unit  12  or generates output information displayed on the display unit  202 . The processing unit  14  may output the output information that is based on the measurement result from the sensor unit  12  to the outside via the communication unit  200  or the display unit  202 . Further, the processing unit  14  may store time-series output information that is based on measurement results at a plurality of points of time from the sensor unit  12  in the storage unit  18 . 
     The processing unit  14  is operated by electric power supplied from the energy harvesting unit  22  or electric power supplied from the power storage unit  24 . Further, the processing unit  14  includes a power supply control unit  32  that controls the power supply to each unit as in the case of the first exemplary embodiment. The storage unit  18  stores the measurement result from the sensor unit  12  and the information output from the communication unit  200  (or the display unit  202 ). 
     The energy harvesting unit  22  generates electric power based on the energy of the external environment such as temperature, humidity, radio waves of Wi-Fi or the like, electromagnetic noise from the surroundings, vibration, sound, light, wind, etc., and supplies the electric power to each unit (for example, at least one of the sensor unit  12 , the storage unit  18 , and the communication unit  200 ). In the second exemplary embodiment, the energy harvesting unit  22  charges the power storage unit  24  with the generated electricity. 
     The power storage unit  24  stores the electricity generated by the energy harvesting unit  22  and supplies the electric power (stored electric power) as electric power for operating each unit (for example, at least one of the sensor unit  12 , the storage unit  18 , and the communication unit  200 ). The power storage unit  24  may be a capacitor (including an electric double layer capacitor), a primary battery of every kind, or a secondary battery of every kind. 
     The communication unit  200  and the display unit  202  correspond to the output unit  16  according to the first exemplary embodiment. The communication unit  200  performs known wired communication or known wireless communication with an external device. In the case of wired communication, serial communication of every kind may be used. In the case of wireless communication, BLE, Wi-Fi, low-power radio, specific power saving wireless or 5th generation mobile communication system (5G) may be used. The communication unit  200  outputs output information (for example, output information stored in the storage unit  18 ) that is based on the measurement result from the sensor unit  12  in response to a request from an external device. The communication unit  200  may spontaneously output the output information based on a specific operation on the sensor device  10  or a physical quantity (for example, a vibration amount) that can be measured by the sensor device  10 , regardless of a request from an external device. 
     The display unit  202  includes an electronic paper and a touch panel in the second exemplary embodiment. As an exemplary variation, the display unit  202  may use another display means such as a liquid crystal display. In normal times, the display unit  202  displays information (product name, manufacturer, serial number, etc.) about the object to be indicated on a nomenclature plate and displays the measurement result from the sensor unit  12  and the output information stored in the storage unit  18  when a predetermined operation is input to the touch panel. 
     The processing unit  14  and the display unit  202  in  FIG. 23  are not essential in the sensor device  10  according to the second exemplary embodiment. For example, when the measurement result from the sensor unit  12  is output from the communication unit  200  without processing the measurement result, the processing unit  14  may be omitted. Further, if it is not necessary to display information that is based on the measurement result from the sensor unit  12  on the surface of the sensor device  10  (a surface that can be visually recognized by an inspector or the like), the display unit  202  may be omitted. 
     As a typical example of the sensor device  10  according to the second exemplary embodiment, the sensor device  10  may include a sensor unit  12 , a communication unit  200 , a processing unit  14  (including a power supply control unit  32 ), a storage unit  18 , an energy harvesting unit  22 , and a power storage unit  24  out of the functional blocks shown in  FIG. 23 . The storage unit  18  has a capacity capable of storing a plurality of measurement results from the sensor unit  12  and a plurality of pieces of information output from the communication unit  200 . The storage unit  18  stores the plurality of measurement results or the plurality of pieces of information in association with a value that changes over time. 
     The sensor unit  12  has a first sensor group composed of a plurality of sensors that measure different types of physical quantities and a second sensor group composed of a plurality of sensors that are arranged apart from one another and that measure the same type of physical quantity. The first sensor group may include, for example, a strain gauge  74  and a humidity sensor  76  as described in relation to  FIG. 14 . The second sensor group may include, for example, an ultrasonic sensor  66   a  and an ultrasonic sensor  66   b  as described in relation to  FIG. 11C . The processing unit  14  calculates the physical phenomenon inside the object based on the measurement result from the second sensor group and stores the calculation result in the storage unit  18 . For example, the processing unit  14  may estimate the position inside the object in which the abnormality has occurred by using triangulation based on the detection result from each sensor included in the second sensor group. 
       FIG. 24  shows the configuration of a management system  210  including the sensor device  10  according to  FIG. 23 . The management system  210  includes a part  212 , an acceptance inspection device  214 , and a parts management server  216 . The management system  210  is an information processing system that manages or adjusts the characteristic values of the part  212 . These devices communicate by a known method and exchange data with one another. 
     The sensor device  10  is attached as a nomenclature plate of the part  212 , and various types of information to be written on the nomenclature plate is displayed on the surface (surface visible from the outside) thereof. As described in the first exemplary embodiment, the sensor device  10  can be attached to various articles, products, and mechanical components. For example, the part  212  may be the speed reducer, the traveling unit for a crawler, the fluid valve, the fluid cylinder, the fluid pump, the fluid compressor, the electric motor, or the electric actuator exemplified in the first exemplary embodiment. For example, when the part  212  is the speed reducer (in other words, when the sensor device  10  is attached to the speed reducer), the management system  210  of the speed reducer is realized. Further, the mode of attaching the sensor device  10  to these parts  212  and the functional block of the sensor device  10  may be the same as those in the first exemplary embodiment. 
     The communication unit  200  of the sensor device  10  transmits output information that is based on the measurement result from the sensor unit  12  to the acceptance inspection device  214 . Further, the communication unit  200  receives information (correction information in the second exemplary embodiment) transmitted from the acceptance inspection device  214 . 
     The storage unit  18  of the sensor device  10  stores the measurement result from the sensor unit  12  and the information (correction information in the second exemplary embodiment) received by the communication unit  200  from the acceptance inspection device  214 . Further, the part ID and the characteristic value of the part  212  are stored in the storage unit  18  of the sensor device  10  at the time of manufacturing or shipping the part  212 . The part ID is the ID of the part  212  to which the sensor device  10  is attached. The characteristic value of the part  212  is data referred to when the part  212  is put into operation and may be, for example, a control parameter suitable for the condition or property of the part  212  at the time of shipping inspection. 
     The acceptance inspection device  214  is an information processing device of a mother device manufacturer that manufactures a device (also referred to as a “mother device”) in which the part  212  is incorporated. The acceptance inspection device  214  inspects whether or not the quality of the part  212  meets a predetermined standard. The acceptance inspection device  214  includes a part information acquisition unit  220 , a correction information acquisition unit  222 , and an update unit  224 . The part information acquisition unit  220  acquires information (referred to as “part information”) related to the part  212  transmitted from the sensor device  10  attached to the part  212 . The part information includes the part ID, the characteristic value stored in advance in the storage unit  18  of the sensor device  10 , and detection information (corresponding to the above output information) based on the detection result from the sensor unit  12  of the sensor device  10 . 
     The correction information acquisition unit  222  transmits the part information acquired by the part information acquisition unit  220  to the parts management server  216 . The correction information acquisition unit  222  acquires correction information (typically including a correction value for the characteristic value) for the characteristic value of the part  212  transmitted from the parts management server  216 . The update unit  224  transmits the correction information acquired by the correction information acquisition unit  222  to the sensor device  10  so as to thereby store the correction value included in the correction information in the storage unit  18  of the sensor device  10 . 
     The parts management server  216  is an information processing device of a parts manufacturer that manufactured the part  212 . The parts management server  216  manages information related to the part  212  (conditions of the part and the environment, an initial characteristic value, a correction value, etc.). The parts management server  216  includes a correction information deriving unit  230  and a correction information providing unit  232 . The correction information deriving unit  230  derives correction information (typically including a correction value for the characteristic value) related to the characteristics of the part  212  based on the part information transmitted from the acceptance inspection device  214 . The correction information providing unit  232  transmits the correction information derived by the correction information deriving unit  230  to the acceptance inspection device  214 . 
     For example, the correction information deriving unit  230  may identify the existing characteristic value of the part  212  based on the part information and may identify the condition (temperature, vibration, etc.) related to the part  212  based on the part information. Further, the correction information deriving unit  230  may identify a correction value derivation algorithm, a parameter, or the like predetermined for the part  212  based on the part ID indicated by the part information. The correction information deriving unit  230  may derive a correction value so as to offset the influence of the condition related to the part  212  on the characteristic value of the part  212  in accordance with the identified algorithm, parameter, or the like. Further, the correction information deriving unit  230  may derive a new characteristic value of the part  212  as the correction value. 
     The correction information deriving unit  230  determines whether or not the condition related to the part  212  indicated by the part information deviates from a predetermined correctable range and determines that the correction value is not applicable if the condition related to the part  212  deviates from the correctable range (or falls in an abnormal range). The above normal range may be defined as a normal range of the temperature inside or outside the part  212  or may be defined as a normal range of the amount of vibration generated in the part  212 . When it is determined that the correction value cannot be applicable, the correction information deriving unit  230  generates correction information indicating that the correction is impossible. 
     The operation of the management system  210  will be described with reference to FIG.  24 . 
     (1) The part information acquisition unit  220  of the acceptance inspection device  214  transmits a request for transmitting part information to the sensor device  10 . 
     (2) The communication unit  200  of the sensor device  10  transmits the part information generated by the processing unit  14  based on data stored in the storage unit  18  to the acceptance inspection device  214 . 
     (3) The correction information acquisition unit  222  of the acceptance inspection device  214  transmits a request for transmitting correction information to the parts management server  216 . 
     This transmission request includes the part information acquired from the part  212 . 
     (4) The correction information deriving unit  230  of the parts management server  216  generates correction information based on the part information transmitted from the acceptance inspection device  214 . The correction information providing unit  232  transmits the correction information to the acceptance inspection device  214 . 
     (5) The update unit  224  of the acceptance inspection device  214  transmits the correction information transmitted from the parts management server  216  to the sensor device  10 . 
     (6) The communication unit  200  of the sensor device  10  acquires the correction information transmitted from the acceptance inspection device  214 , and the processing unit  14  (update unit  36 ) stores a correction value indicated by the correction information in the storage unit  18 . 
     In this way, according to the management system  210 , the correction value according to the condition (vibration, temperature, etc.) related to the part  212  during transportation or storage is stored in the part  212 . Thereby, the characteristic value (a control parameter, etc.) stored in advance in the part  212  can be corrected to a value in which the influence of the external environment is taken into account, allowing for the proper operation of the part  212  to be supported. Further, according to the configuration of the management system  210  shown in  FIG. 24 , the method of deriving the correction value, which is important for the manufacturer of the part, is not leaked to the manufacturer of the mother device, and the burden on the manufacturer of the mother device for setting a correction value for the part  212  can be minimized. 
       FIG. 25  shows the distribution process of the part  212 . After the shipping inspection of the part  212  is performed by the manufacturer of the part, the communication unit  200  of the sensor device  10  attached to the part  212  communicates with a device of the manufacturer of the part using the electricity generated by the energy harvesting unit  22 . The processing unit  14  of the sensor device  10  acquires the characteristic value of the part  212  transmitted from the device of the manufacturer of the part via the communication unit  200  and stores the characteristic value in the storage unit  18 . Further, during the shipping inspection or during a period before and after the shipping inspection, the power storage unit  24  of the sensor device  10  stores the electricity generated by the energy harvesting unit  22 . 
     During transportation and storage of the part  212 , the processing unit  14  (power supply control unit  32 ) of the sensor device  10  mainly supplies the electric power stored in the power storage unit  24  to the sensor unit  12  and the storage unit  18  on a regular basis. The processing unit  14  stores detection information (in other words, output information) that is based on the detection result from the sensor unit  12  in the storage unit  18 . The flow of the sensing process during transportation and storage of the part  212  is the same as the flow in  FIG. 4  described in the first exemplary embodiment. 
     When the part  212  arrives at the manufacturer of the mother device and the acceptance inspection is performed, the energy harvesting unit  22  of the sensor device  10  generates electric power based on illumination light, Wi-Fi radio wave, etc., at the manufacturer of the mother device, and the communication unit  200  of the sensor device  10  communicates with the acceptance inspection device  214  based on the electric power supplied from the energy harvesting unit  22 . As described in relation to  FIG. 24 , the processing unit  14  of the sensor device  10  acquires the correction information provided from the parts management server  216  and corrects the characteristic value of the part  212  stored in the storage unit  18  based on the correction value indicated by the correction information. When the correction information indicates that the correction is impossible, the processing unit  14  of the sensor device  10  displays that the part  212  is abnormal or out of order on the display unit  202 . 
       FIG. 26  is a flowchart showing an example of the process of the sensor device  10  at the time of acceptance inspection of the part  212 . When the communication unit  200  of the sensor device  10  receives an acceptance inspection signal transmitted from the acceptance inspection device  214  (Y of S 100 ), the processing unit  14  of the sensor device  10  acquires a data transmission request indicated by the acceptance inspection signal (S 101 ). The processing unit  14  of the sensor device  10  acquires detection information (output information) stored in the storage unit  18  according to the details of the data transmission request and generates part information including the detection information (S 102 ). The communication unit  200  of the sensor device  10  transmits the part information generated by the processing unit  14  to the acceptance inspection device  214  (S 103 ). If the acceptance inspection signal has not been received (N in S 100 ), processed in and after S 101  are skipped. The sensor device  10  repeatedly executes the processes shown in the figure. 
       FIG. 27  is a flowchart showing an example of the process of the sensor device  10  at the time of acceptance inspection of the part  212 . The figure shows processes that follow the processes in  FIG. 26 . When the communication unit  200  of the sensor device  10  receives correction information transmitted from the acceptance inspection device  214  (Y in S 110 ), the processing unit  14  of the sensor device  10  determines whether the correction information includes a correction value (or a new characteristic value) or the correction information indicates that the correction is impossible. When the correction information includes the correction value (Y in S 111 ), the processing unit  14  (update unit  36 ) of the sensor device  10  updates the characteristic value stored in advance in the storage unit  18  based on the correction value indicated by the correction information (S 112 ). When the correction information indicates that the correction is impossible (N in S 111 ), the processing unit  14  of the sensor device  10  displays that there is a failure (S 113 ) on the display unit  202 . 
     The processing unit  14  of the sensor device  10  transmits information indicating the completion of the update process based on the correction information to the acceptance inspection device  214  via the communication unit  200  (S 114 ). If the correction information has not been received (N in S 110 ), processes in and after S 111  are skipped. The sensor device  10  repeatedly executes the processes shown in the figure. 
     An exemplary variation will be described. The processing unit  14  of the sensor device  10  autonomously determines whether or not the condition related to the part  212  indicated by the detection information deviates from a predetermined normal range and may determine that the part  212  is abnormal if the condition related to the part  212  deviates from the normal range. When the processing unit  14  of the sensor device  10  determines that the part  212  is abnormal, the processing unit  14  may display that there is an abnormality or failure on the display unit  202 . The above normal range may be defined as a normal range of the internal or external temperature of the part  212  detected by the sensor unit  12  (temperature sensor) or may be defined as a normal range of the amount of vibration generated in the part  212  detected by the sensor unit  12  (vibration sensor). 
     Alternatively, the processing unit  14  of the sensor device  10  may autonomously determine that there is an abnormality when the condition related to the part  212  indicated by the detection information satisfies a predetermined abnormality condition and display that there is an abnormality or failure on the display unit  202 . For example, the abnormality condition may be that the temperature inside or outside the part  212  detected by the sensor unit  12  (temperature sensor) is equal to or higher than a predetermined value or may be that the amount of vibration that has occurred in the part  212  detected by the sensor unit  12  (vibration sensor) is equal to or higher than a predetermined value. 
       FIG. 28  is a flowchart showing an exemplary variation of the process of the sensor device  10  at the time of acceptance inspection of the part  212 . Since the processes in S 120 , S 121 , and S 122  in the figure are the same as the processes in S 100 , S 101 , and S 102  in  FIG. 26 , the description thereof will be omitted. If the condition related to the part  212  indicated by the detection information is within the normal range (Y in S 123 ), the processing unit  14  of the sensor device  10  transmits the part information including the detection information to the acceptance inspection device  214  (S 124 ). If the condition related to the part  212  indicated by the detection information deviates from the normal range (N in S 123 ), the processing unit  14  of the sensor device  10  displays that there is a failure on the display unit  202  (S 125 ). Although not shown, the processing unit  14  may transmit the part information indicating that there is an abnormality or failure in the part  212  to the acceptance inspection device  214  along with the process in S 125 . 
     Described above is an explanation on the present invention based on the second exemplary embodiment. The second exemplary embodiment is intended to be illustrative only, and it will be obvious to those skilled in the art that various modifications to constituting elements and processes described in the second exemplary embodiment could be developed and that such modifications are also within the scope of the present invention. 
     An exemplary variation will be described. A sensor device  10  according to the present exemplary variation may include a communication unit  200  capable of long-distance communication with a wireless base station installed in a remote location.  FIG. 29  corresponds to  FIG. 24  and shows the configuration of a management system  210  including the sensor device  10  according to the present exemplary variation. In the management system  210  according to the exemplary variation, the sensor device  10  directly transmits/receives data to/from a device on the cloud via a wireless base station installed in a remote location. For example, the sensor device  10  may transmit the output information generated by the own device to a parts management server  216  on the cloud and receive correction information transmitted from the parts management server  216 . 
     The parts management server  216  according to the present exemplary variation includes the function of the acceptance inspection device  214  according to the second exemplary embodiment and may include, for example, a part information acquisition unit  220 , a correction information deriving unit  230 , and an update unit  224 . Further, the parts management server  216  may include a storage unit (not shown) for accumulating output information uploaded from a plurality of sensor devices  10  attached to a plurality of parts  212 . The parts management server  216  may provide a screen (user interface) for displaying output information uploaded from the plurality of sensor devices  10  to a UI terminal  218  (PC, tablet terminal, etc.) provided in the factory of the manufacturer of the parts or the like. Thereby, parts management can be effectively supported. 
     The security implementation configuration and the configuration for monitoring the power supply of the mother device described above as the exemplary variation of the first exemplary embodiment are also useful as an exemplary variation of the second exemplary embodiment. 
     Optional combinations of the aforementioned exemplary embodiments and exemplary variations will also be within the scope of the present invention. New embodiments resulting from the combinations have combined effects of the exemplary embodiments and exemplary variations that are combined. It will be obvious to those skilled in the art that the function to be achieved by each constituent requirement described in the claims are achieved by each constituting element shown in the exemplary embodiments and in the exemplary variations or by a combination of the constituting elements. 
     The technologies according to the exemplary embodiments and the exemplary variations may be defined by the following aspects. 
     [Item 1] 
     A sensor device comprising: 
     a sensor unit that comes into contact with an object having a predetermined physical structure and measures a condition related to the object; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in the external environment into electric power and supplies the electric power as the electric power for operating at least one of the sensor unit and the output unit, wherein 
     the sensor unit, the output unit, and the power generation unit are integrally provided in a sheet shape, and at least two of the sensor unit, the output unit, and the power generation unit are arranged in an overlapping manner. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in an object such as a mechanical component. Thereby, while making it possible to grasp the condition related to an object, it is possible to suppress an increase in the cost and period of time required for manufacturing the object. Further, by arranging at least two of the sensor unit, the output unit, and the power generation unit in an overlapping manner, the size of the sensor device is reduced, allowing for easy attachment to the object. 
     [Item 2] 
     The sensor device according to Item 1, further comprising: 
     a processing unit that generates information output from the output unit based on the measurement result from the sensor unit. 
     This aspect allows for the processing of the measurement result from the sensor unit so as to output more useful information to the outside. Further, it is possible to generate information in which measurement results from the sensor unit are aggregated, allowing for the reduction in the amount of information to be output to the outside. 
     [Item 3] 
     The sensor device according to Item 1 or 2, further comprising: 
     a storage unit that stores the measurement result from the sensor unit or the information output from the output unit. 
     This aspect allows the measurement result from the sensor unit or the information output from the output unit to be stored and output at a proper time. 
     [Item 4] 
     The sensor device according to Item 3, wherein 
     the storage unit is capable of storing a plurality of measurement results from the sensor unit or a plurality of pieces of information output from the output unit, and 
     the storage unit stores the plurality of measurement results or the plurality of pieces of information in association with a value that changes over time. 
     This aspect allows the plurality of measurement results or the plurality of pieces of information to be held in chronological order and also allows for the analysis and aggregation in chronological order. 
     [Item 5] 
     The sensor device according to any one of Items 1 through 4, wherein 
     the output unit outputs the information to an external device by communication, and 
     the power generation unit supplies electric power based on electromotive force generated by the communication. 
     This aspect allows the power generation to be achieved along with communication by using NFC or the like. 
     [Item 6] 
     The sensor device according to any one of Items 1 through 5, further comprising: 
     a power supply control unit that controls the supply or disconnection of electric power for at least one of the sensor unit and the output unit. 
     This aspect allows for the efficient use of generated electric power. 
     [Item 7] 
     The sensor device according to Item 2, wherein 
     the processing unit has arithmetic capacity that increases as the number of operation clocks increases and is capable of changing the number of operation clocks according to processing details. 
     This aspect allows for the efficient use of generated electric power. 
     [Item 8] 
     The sensor device according to any one of Items 1 through 7, further comprising: 
     a power storage unit, wherein 
     at least one of the sensor unit and the output unit is operated by electric power supplied from the power generation unit and electric power supplied from the power storage unit. 
     This aspect allows the operation of the sensor unit and the operation of the output unit to continue even when the electric power supplied from the power generation unit is temporarily reduced. 
     [Item 9] 
     The sensor device according to any one of Items 1 through 8, wherein the sensor unit has a plurality of sensors that measure different types of physical quantities. 
     This aspect allows various types of information based on many types of physical quantities to be output. 
     [Item 10] 
     The sensor device according to Item 2, wherein 
     the sensor unit includes a plurality of sensors that are arranged apart from one another and has a plurality of sensors that measure the same type of physical quantity, and 
     the processing unit generates the information based on measurements results from the plurality of sensors. 
     This aspect allows various types of information related to an object to be output based on measurement results from a plurality of sensors. For example, when a sensor device is attached to the surface of an object (such as the case of a nomenclature plate or the like), the physical phenomenon inside the object can be accurately estimated based on the physical phenomenon on or near the surface of the object measured by a plurality of sensors. 
     [Item 11] 
     The sensor device according to any one of Items 1 through 10, wherein 
     the power generation unit has a plurality of power generation means. 
     According to this aspect, even when electric power obtained from one power generation means is reduced, the operation can be continued by electric power obtained from another power generation means. 
     [Item 12] 
     The sensor device according to any one of Items 1 through 11, wherein 
     the output unit includes electronic paper. 
     According to this aspect, information can be output to the outside while suppressing power consumption. 
     [Item 13] 
     The sensor device according to any one of Items 1 through 12, wherein 
     the output unit includes an antenna. 
     According to this aspect, information can be transmitted to an external device by communication. 
     [Item 14] 
     The sensor device according to any one of Items 1 through 13, further comprising: 
     a fastening part that is for fixing the sensor device to the object and that is inserted into the object, wherein 
     the sensor unit is connected to the fastening part. 
     According to this aspect, since the fastening part functions as a probe, the physical phenomenon inside the object can be acquired without providing a sensor unit inside the object. 
     [Item 15] 
     The sensor device according to any one of Items 1 through 14, wherein 
     the sensor unit includes a strain gauge, and 
     at least a part where the strain gauge is arranged is made of a stretchable material and is fixed to the object by adhesion. 
     According to this aspect, information on the distortion of the object can be obtained. 
     [Item 16] 
     A sensor device comprising: 
     a sensor unit that measures temperature, humidity, and vibration of an object or the surroundings of the object; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside by wireless communication; and 
     a power generation unit that generates electric power based on Wi-Fi (registered trademark) radio waves, near field communication (NFC) radio waves, or light so as to supply electric power for operating at least one of the sensor unit and the output unit. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in an object such as a mechanical component. Thereby, while making it possible to grasp the condition related to an object, it is possible to suppress an increase in the cost and period of time required for manufacturing the object. 
     [Item 17] 
     A speed reducer comprising: 
     a speed reduction mechanism; 
     a case that houses the speed reduction mechanism; 
     a sensor unit that measures a condition related to the case; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in an external environment into electric power and supplies the electric power as electric power for operating at least one of the sensor unit and the output unit. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in a speed reducer. Thereby, while making it possible to grasp the condition related to a speed reducer, it is possible to suppress an increase in the cost and period of time required for manufacturing the speed reducer. 
     [Item 18] 
     A traveling unit for a crawler, comprising: 
     a traveling control unit that controls the operation of the crawler; 
     a case that houses the traveling control unit; 
     a sensor unit that measures the condition related to the case; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in an external environment into electric power and supplies the electric power as electric power for operating at least one of the sensor unit and the output unit. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in a traveling unit for a crawler. Thereby, while making it possible to grasp the condition related to a traveling unit for a crawler, it is possible to suppress an increase in the cost and period of time required for manufacturing the traveling unit for a crawler. 
     [Item 19] 
     A fluid valve comprising: 
     a valve unit that controls the flow of fluid; 
     a case that houses the valve unit; 
     a sensor unit that measures a condition related to the case; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in an external environment into electric power and supplies the electric power as electric power for operating at least one of the sensor unit and the output unit. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in a fluid valve. Thereby, while making it possible to grasp the condition related to a fluid valve, it is possible to suppress an increase in the cost and period of time required for manufacturing the fluid valve. 
     [Item 20] 
     A fluid cylinder comprising: 
     a cylinder unit that houses fluid; 
     a case that houses the cylinder unit; 
     a sensor unit that measures a condition related to the case; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in an external environment into electric power and supplies the electric power as electric power for operating at least one of the sensor unit and the output unit. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in a fluid cylinder. Thereby, while making it possible to grasp the condition related to a fluid cylinder, it is possible to suppress an increase in the cost and period of time required for manufacturing the fluid cylinder. 
     [Item 21] 
     A fluid pump comprising: 
     a pump unit that controls the flow of fluid; 
     a case that houses the pump unit; 
     a sensor unit that measures a condition related to the case; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in an external environment into electric power and supplies the electric power as electric power for operating at least one of the sensor unit and the output unit. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in a fluid pump. Thereby, while making it possible to grasp the condition related to a fluid pump, it is possible to suppress an increase in the cost and period of time required for manufacturing the fluid pump. 
     [Item 22] 
     A fluid compressor comprising: 
     a compression unit that applies pressure to fluid; 
     a case that houses the compression unit; 
     a sensor unit that measures a condition related to the case; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in an external environment into electric power and supplies the electric power as electric power for operating at least one of the sensor unit and the output unit. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in a fluid compressor. Thereby, while making it possible to grasp the condition related to a fluid compressor, it is possible to suppress an increase in the cost and period of time required for manufacturing the fluid compressor. 
     [Item 23] 
     An electric motor comprising: 
     a motor unit that converts electrical energy into mechanical energy; 
     a case that houses the motor unit; 
     a sensor unit that measures a condition related to the case; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in an external environment into electric power and supplies the electric power as electric power for operating at least one of the sensor unit and the output unit. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in an electric motor. Thereby, while making it possible to grasp the condition related to an electric motor, it is possible to suppress an increase in the cost and period of time required for manufacturing the electric motor. 
     [Item 24] 
     An electric actuator comprising: 
     a drive unit that operates based on electrical energy; 
     a case that houses the drive unit; 
     a sensor unit that measures a condition related to the case; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in an external environment into electric power and supplies the electric power as electric power for operating at least one of the sensor unit and the output unit. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in an electric actuator. Thereby, while making it possible to grasp the condition related to an electric actuator, it is possible to suppress an increase in the cost and period of time required for manufacturing the electric actuator. 
     [Item 25] 
     A construction comprising: 
     a predetermined physical structure; 
     a sensor unit that measures a condition related to the physical structure; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in an external environment into electric power and supplies the electric power as electric power for operating at least one of the sensor unit and the output unit, wherein 
     the sensor unit, the output unit, and the power generation unit are integrally provided in a sheet shape, and at least two of the sensor unit, the output unit, and the power generation unit are arranged in an overlapping manner. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in furniture. Thereby, while making it possible to grasp the condition related to furniture, it is possible to suppress an increase in the cost and period of time required for manufacturing the furniture. Further, by arranging at least two of the sensor unit, the output unit, and the power generation unit in an overlapping manner, the size of the sensor device is reduced, allowing for easy attachment to an object. 
     [Item 26] 
     A method performed by a sensor device that comes into contact with an object having a predetermined physical structure, comprising: 
     detecting performed by measuring a condition related to the object; 
     outputting information that is based on the measurement result in the detecting to the outside; and 
     converting energy in an external environment into electric power and supplying the electric power as electric power for executing at least one of the respective processes of the detecting and the outputting. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in an object such as a mechanical component. Thereby, while making it possible to grasp the condition related to an object, it is possible to suppress an increase in the cost and period of time required for manufacturing the object. 
     [Item 27] 
     The method according to Item 26 performed by the sensor device, further comprising: storing the detection result in the detecting or the information output in the outputting in a storage unit; and 
     deleting data stored in the storage unit when a predetermined instruction is input. 
     According to this aspect, a sensor device can be reused by deleting data stored in a storage unit based on an instruction from the outside. For example, a sensor device used in one object can be attached to another object for use. 
     [Item 28] 
     A method performed by a sensor device attached to a part, comprising: 
     using electric power generated by the sensor device so as to detect a condition related to the part during the transportation or storage of the part; and 
     outputting information that is based on the detection result to the outside. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in an object such as a mechanical component. Thereby, while making it possible to grasp the condition related to an object, it is possible to suppress an increase in the cost and period of time required for manufacturing the object. 
     [Item 29] 
     A sensor system comprising: 
     an object having a predetermined physical structure; and 
     a sensor device attached to the object, wherein 
     the sensor device includes: 
     a sensor unit that measures a condition related to the object; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in an external environment into electric power and supplies the electric power as electric power for operating at least one of the sensor unit and the output unit, and 
     the sensor unit, the output unit, and the power generation unit are integrally provided in a sheet shape, and at least two of the sensor unit, the output unit, and the power generation unit are arranged in an overlapping manner. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in an object such as a mechanical component. Thereby, while making it possible to grasp the condition related to an object, it is possible to suppress an increase in the cost and period of time required for manufacturing the object. Further, by arranging at least two of the sensor unit, the output unit, and the power generation unit in an overlapping manner, the size of the sensor device is reduced, allowing for easy attachment to the object. 
     [Item 30] 
     A sensor system comprising: 
     an object having a predetermined physical structure; and 
     a plurality of sensor devices attached to the object, wherein 
     each of the plurality of sensor devices includes: 
     a sensor unit that measures a condition related to the object; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in an external environment into electric power and supplies the electric power as electric power for operating at least one of the sensor unit and the output unit, and 
     the sensor unit, the output unit, and the power generation unit are integrally provided in a sheet shape, and at least two of the sensor unit, the output unit, and the power generation unit are arranged in an overlapping manner. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in an object such as a mechanical component. Thereby, while making it possible to grasp the condition related to an object, it is possible to suppress an increase in the cost and period of time required for manufacturing the object. Further, by attaching a plurality of sensor devices to the object, the condition of the object at a plurality of locations can be grasped, and the condition of the object (internal condition, etc.) can be estimated more accurately according to the condition of the object at the plurality of locations. Furthermore, by arranging at least two of the sensor unit, the output unit, and the power generation unit in an overlapping manner, the size of the sensor device is reduced, allowing for easy attachment to the object. 
     [Item 31] 
     A nomenclature plate that is attached to an article having a predetermined physical structure and on which information related to the article is displayed, comprising: 
     a sensor unit that measures the condition of the article; 
     an output unit that outputs information that is based on the measurement result from the sensor unit to the outside; and 
     a power generation unit that converts energy in an external environment into electric power and supplies the electric power as electric power for operating at least one of the sensor unit and the output unit, wherein 
     at least two of the sensor unit, the output unit, and the power generation unit are arranged in an overlapping manner. 
     This aspect eliminates the need to newly provide wiring for supplying electric power to a sensor in an article such as a mechanical component. Further, it is not necessary to newly secure an area for storing a sensor on or in the housing of the article. Thereby, while making it possible to grasp the condition related to an article, it is possible to suppress an increase in the cost and period of time required for manufacturing the article. Further, by arranging at least two of the sensor unit, the output unit, and the power generation unit in an overlapping manner, the size of the nomenclature plate is reduced, allowing for easy attachment to the object. 
     [Item 2-1] 
     A sensor device comprising: 
     a sensor unit that measures a condition related to an object; 
     a communication unit that outputs information that is based on the measurement result from the sensor unit; 
     a storage unit that stores the measurement result from the sensor unit and the information output from the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit, wherein 
     the sensor unit, the communication unit, the storage unit, the power storage unit, and the power generation unit are integrally provided, and at least two of the sensor unit, the communication unit, the storage unit, the power storage unit, and the power generation unit are arranged in an overlapping manner. 
     This aspect can make it possible to grasp the condition related to an object under a situation where no external power source is supplied such as a case during the transportation of the object. For example, the condition related to the object can be grasped mainly based on electric power supplied from the power storage unit during the transportation or storage of the object (i.e., under a situation where no external power source is supplied). Further, when a relatively large amount of electric power is required, such as during the acceptance inspection using a communication unit, the electric power supplied from the power generation unit can be utilized. 
     [Item 2-2] 
     The sensor device according to Item 2-1, wherein 
     the storage unit is capable of storing a plurality of measurement results from the sensor unit or a plurality of pieces of information output from the communication unit, and 
     the storage unit stores the plurality of measurement results or the plurality of pieces of information in association with a value that changes over time. 
     This aspect allows the plurality of detection results or the plurality of pieces of information to be held in chronological order and also allows for the analysis and aggregation in chronological order. 
     [Item 2-3] 
     The sensor device according to Item 2-1 or 2-2, further comprising: 
     a power supply control unit that controls the supply or disconnection of electric power for at least one of the sensor unit, the communication unit, and the storage unit. 
     This aspect allows for the efficient use of generated electric power or stored electric power. 
     [Item 2-4] 
     The sensor device according to any one of Items 2-1 through 2-3, wherein 
     the power generation unit has a plurality of power generation means. 
     According to this aspect, even when electric power obtained from one power generation means is reduced, the operation can be continued by electric power obtained from another power generation means. 
     [Item 2-5] 
     The sensor device according to any one of Items 2-1 through 2-4, wherein 
     the sensor unit has a plurality of sensors that measure different types of physical quantities. 
     This aspect allows various types of information based on many types of physical quantities to be output. 
     [Item 2-6] 
     The sensor device according to any one of Items 2-1 through 2-5, further comprising: 
     a processing unit that generates information output from the communication unit based on the measurement result from the sensor unit. 
     This aspect allows for the processing of the detection result from the sensor unit so as to output more useful information to the outside. Further, it is possible to generate information in which detection results from the sensor unit are aggregated, allowing for the reduction in the amount of information to be output to the outside. 
     [Item 2-7] 
     The sensor device according to Item 2-6, wherein 
     the processing unit has arithmetic capacity that increases as the number of operation clocks increases and is capable of changing the number of operation clocks according to processing details. 
     This aspect allows for the efficient use of generated electric power. 
     [Item 2-8] 
     The sensor device according to Item 2-6 or 2-7, wherein 
     the sensor unit includes a plurality of sensors that are arranged apart from one another and has a plurality of sensors that measure the same type of physical quantity, and 
     the processing unit calculates the physical phenomenon inside the object based on the measurement result from the plurality of sensors and stores the calculation result in the storage unit. 
     This aspect allows various types of information related to an object to be output based on detection results from a plurality of sensors. For example, when a sensor device is attached to the surface of an object (such as the case of a nomenclature plate or the like), the physical phenomenon inside the object can be accurately estimated based on the physical phenomenon on or near the surface of the object detected by a plurality of sensors. 
     [Item 2-9] 
     The sensor device according to any one of Items 2-1 through 2-8, further comprising: 
     a display unit that includes electronic paper. 
     According to this aspect, information can be output to the outside while suppressing power consumption. 
     [Item 2-10] 
     A sensor device comprising: 
     a sensor unit that measures a condition related to an object; 
     a communication unit that outputs information that is based on the measurement result from the sensor unit; 
     a processing unit that generates information output from the communication unit based on the measurement result from the sensor unit; 
     a storage unit that stores the measurement result from the sensor unit and the information output from the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit; and 
     a power supply control unit that controls the supply or disconnection of electric power for at least one of the sensor unit, the communication unit, and the storage unit, wherein 
     the storage unit is capable of storing a plurality of measurement results from the sensor unit or a plurality of pieces of information output from the communication unit, 
     the storage unit stores the plurality of measurement results or the plurality of pieces of information in association with a value that changes over time, 
     the sensor unit has a first sensor group composed of a plurality of sensors that measure different types of physical quantities and a second sensor group composed of a plurality of sensors that are arranged apart from one another and that measure the same type of physical quantity, 
     the processing unit calculates the physical phenomenon inside the object based on the measurement result from the second sensor group and stores the calculation result in the storage unit, and 
     the sensor unit, the communication unit, the processing unit, the storage unit, the power storage unit, the power generation unit, and the power supply control unit are integrally provided, and at least two of the sensor unit, the communication unit, the storage unit, the power storage unit, and the power generation unit are arranged in an overlapping manner. 
     This aspect can make it possible to: (1) grasp the condition related to an object under a situation where no external power source is supplied such as a case during the transportation of the object. (2) The plurality of detection results or the plurality of pieces of information can be held in chronological order, and the analysis and aggregation in chronological order can be also possible. Also, (3) generated electric power or stored electric power can be efficiently used. Further, (4) the detection result from the sensor unit can be processed, allowing for more useful information to be output to the outside. Further, it is possible to generate information in which detection results from the sensor unit are aggregated, allowing for the reduction in the amount of information to be output to the outside. Further, (5) various types of information related to an object can be output based on detection results from the first sensor group and the second sensor group. 
     [Item 2-11] 
     A management system comprising: 
     a sensor device that is attached to a part; 
     a management server that manages information related to the part; and 
     an acceptance inspection device that inspects whether or not the quality of the part meets the standard, wherein 
     the sensor device includes: 
     a sensor unit that measures a condition related to the part; 
     a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; 
     a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit, wherein 
     the acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the sensor device received from the sensor device to the management server and also transmits the information received from the management server to the sensor device, and 
     the management server obtains a correction value for the part based on the information that is based on the measurement result from the sensor unit of the sensor device transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     This aspect can make it possible to grasp the condition of a part (for example, vibration received by the part, etc.) during the transportation or storage (typically under a situation where no external power source is supplied) and allows a correction value (for example, control parameters, etc.) according to the condition to be set for the part. 
     [Item 2-12] 
     A management server that manages information related to a part, comprising: 
     a deriving unit that obtains a correction value for the part based on the information related to the part transmitted from an acceptance inspection device that inspects whether or not the quality of the part meets the standard; and 
     a providing unit that transmits the correction value derived by the deriving unit to the acceptance inspection device, wherein 
     the acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the sensor device received from the sensor device attached to the part to the management server and also transmits the correction value received from the management server to the sensor device, and 
     the sensor device includes: 
     a sensor unit that measures a condition related to the part; 
     a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; 
     a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. 
     This aspect can make it possible to grasp the condition of a part (for example, vibration received by the part, etc.) during the transportation or storage (typically under a situation where no external power source is supplied) and allows a correction value (for example, control parameters, etc.) according to the condition to be set for the part. 
     [Item 2-13] 
     An acceptance inspection device that inspects whether or not the quality of a part meets the standard, comprising: 
     a first acquisition unit that acquires information that is based on a measurement result from a sensor unit of a sensor device attached to the part from the sensor device; 
     a second acquisition unit that transmits the information acquired by the first acquisition unit to a management server that manages information related to the part and also acquires a correction value for the part obtained based on the information by the management server from the management server; and 
     an update unit that transmits the correction value acquired by the second acquisition unit to the sensor device, wherein 
     the sensor device includes: 
     a sensor unit that measures a condition related to the part; 
     a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; 
     a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. 
     This aspect can make it possible to grasp the condition of a part (for example, vibration received by the part, etc.) during the transportation or storage (typically under a situation where no external power source is supplied) and allows a correction value (for example, control parameters, etc.) according to the condition to be set for the part. 
     [Item 2-14] 
     A management system for a speed reducer, comprising: 
     a speed reducer; 
     a management server that manages information related to the speed reducer; and 
     an acceptance inspection device that inspects whether or not the quality of the speed reducer meets the standard, wherein 
     the speed reducer includes: 
     a speed reduction mechanism; 
     a case that houses the speed reduction mechanism; 
     a sensor unit that measures a condition related to the case; 
     a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; 
     a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit, wherein 
     the acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the speed reducer received from the speed reducer to the management server and also transmits the information received from the management server to the speed reducer, and 
     the management server obtains a correction value for the speed reducer based on the information that is based on the measurement result from the sensor unit of the speed reducer transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     This aspect can make it possible to grasp the condition of a speed reducer (for example, vibration received by the speed reducer, etc.) during the transportation or storage (typically under a situation where no external power source is supplied) and allows a correction value (for example, control parameters, etc.) according to the condition to be set for the speed reducer. 
     [Item 2-15] 
     A management system for a traveling unit for a crawler, comprising: 
     a traveling unit for a crawler; 
     a management server that manages information related to the traveling unit for a crawler; and 
     an acceptance inspection device that inspects whether or not the quality of the traveling unit for a crawler meets the standard, wherein 
     the traveling unit for a crawler includes: 
     a traveling control unit that controls the operation of the crawler; 
     a case that houses the traveling control unit; 
     a sensor unit that measures a condition related to the case; 
     a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; 
     a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit, wherein 
     the acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the traveling unit for a crawler received from the traveling unit for a crawler to the management server and also transmits the information received from the management server to the traveling unit for a crawler, and 
     the management server obtains a correction value for the traveling unit for a crawler based on the information that is based on the measurement result from the sensor unit of the traveling unit for a crawler transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     This aspect can make it possible to grasp the condition of a traveling unit (for example, vibration received by the traveling unit for a crawler, etc.) for a crawler during the transportation or storage (typically under a situation where no external power source is supplied) and allows a correction value (for example, control parameters, etc.) according to the condition to be set for the traveling unit for a crawler. 
     [Item 2-16] 
     A management system for a fluid valve, comprising: 
     a fluid valve; 
     a management server that manages information related to the fluid valve; and 
     an acceptance inspection device that inspects whether or not the quality of the fluid valve meets the standard, wherein 
     the fluid valve includes: 
     a valve unit that controls the flow of fluid; 
     a case that houses the valve unit; 
     a sensor unit that measures a condition related to the case; 
     a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; 
     a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit, wherein 
     the acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the fluid valve received from the fluid valve to the management server and also transmits the information received from the management server to the fluid valve, and 
     the management server obtains a correction value for the fluid valve based on the information that is based on the measurement result from the sensor unit of the fluid valve transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     This aspect can make it possible to grasp the condition of a fluid valve (for example, vibration received by the fluid valve, etc.) during the transportation or storage (typically under a situation where no external power source is supplied) and allows a correction value (for example, control parameters, etc.) according to the condition to be set for the fluid valve. 
     [Item 2-17] 
     A management system for a fluid cylinder, comprising: 
     a fluid cylinder; 
     a management server that manages information related to the fluid cylinder; and 
     an acceptance inspection device that inspects whether or not the quality of the fluid cylinder meets the standard, wherein 
     the fluid cylinder includes: 
     a cylinder unit that houses fluid; 
     a case that houses the cylinder unit; 
     a sensor unit that measures a condition related to the case; 
     a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; 
     a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit, wherein 
     the acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the fluid cylinder received from the fluid cylinder to the management server and also transmits the information received from the management server to the fluid cylinder, and 
     the management server obtains a correction value for the fluid cylinder based on the information that is based on the measurement result from the sensor unit of the fluid cylinder transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     This aspect can make it possible to grasp the condition of a fluid cylinder (for example, vibration received by the fluid cylinder, etc.) during the transportation or storage (typically under a situation where no external power source is supplied) and allows a correction value (for example, control parameters, etc.) according to the condition to be set for the fluid cylinder. 
     [Item 2-18] 
     A management system for a fluid pump, comprising: 
     a fluid pump; 
     a management server that manages information related to the fluid pump; and 
     an acceptance inspection device that inspects whether or not the quality of the fluid pump meets the standard, wherein 
     the fluid pump includes: 
     a pump unit that controls the flow of fluid; 
     a case that houses the pump unit; 
     a sensor unit that measures a condition related to the case; 
     a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; 
     a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit, wherein 
     the acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the fluid pump received from the fluid pump to the management server and also transmits the information received from the management server to the fluid pump, and 
     the management server obtains a correction value for the fluid pump based on the information that is based on the measurement result from the sensor unit of the fluid pump transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     This aspect can make it possible to grasp the condition of a fluid pump (for example, vibration received by the fluid pump, etc.) during the transportation or storage (typically under a situation where no external power source is supplied) and allows a correction value (for example, control parameters, etc.) according to the condition to be set for the fluid pump. 
     [Item 2-19] 
     A management system for a fluid compressor, comprising: 
     a fluid compressor; 
     a management server that manages information related to the fluid compressor; and 
     an acceptance inspection device that inspects whether or not the quality of the fluid compressor meets the standard, wherein 
     the fluid compressor includes: 
     a compression unit that applies pressure to fluid; 
     a case that houses the compression unit; 
     a sensor unit that measures a condition related to the case; 
     a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; 
     a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit, wherein 
     the acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the fluid compressor received from the fluid compressor to the management server and also transmits the information received from the management server to the fluid compressor, and 
     the management server obtains a correction value for the fluid compressor based on the information that is based on the measurement result from the sensor unit of the fluid compressor transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     This aspect can make it possible to grasp the condition of a fluid compressor (for example, vibration received by the fluid compressor, etc.) during the transportation or storage (typically under a situation where no external power source is supplied) and allows a correction value (for example, control parameters, etc.) according to the condition to be set for the fluid compressor. 
     [Item 2-20] 
     A management system for an electric motor, comprising: 
     an electric motor; 
     a management server that manages information related to the electric motor; 
     an acceptance inspection device that inspects whether or not the quality of the electric motor meets the standard, wherein 
     the electric motor includes: 
     a motor unit that converts electrical energy into mechanical energy; 
     a case that houses the motor unit; 
     a sensor unit that measures a condition related to the case; 
     a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; 
     a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit, wherein 
     the acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the electric motor received from the electric motor to the management server and also transmits the information received from the management server to the electric motor, and 
     the management server obtains a correction value for the electric motor based on the information that is based on the measurement result from the sensor unit of the electric motor transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     This aspect can make it possible to grasp the condition of an electric motor (for example, vibration received by the electric motor, etc.) during the transportation or storage (typically under a situation where no external power source is supplied) and allows a correction value (for example, control parameters, etc.) according to the condition to be set for the electric motor. 
     [Item 2-12] 
     A management system for an electric actuator, comprising: 
     an electric actuator; 
     a management server that manages information related to the electric actuator; and 
     an acceptance inspection device that inspects whether or not the quality of the electric actuator meets the standard, wherein 
     the electric actuator includes: 
     a drive unit that operates based on electrical energy; 
     a case that houses the drive unit; 
     a sensor unit that measures a condition related to the case; 
     a communication unit that transmits information that is based on the measurement result from the sensor unit to the acceptance inspection device and also receives information transmitted from the acceptance inspection device; 
     a storage unit that stores the measurement result from the sensor unit and the information received by the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit, wherein 
     the acceptance inspection device transmits the information that is based on the measurement result from the sensor unit of the electric actuator received from the electric actuator to the management server and also transmits the information received from the management server to the electric actuator, and 
     the management server obtains a correction value for the electric actuator based on the information that is based on the measurement result from the sensor unit of the electric actuator transmitted from the acceptance inspection device and transmits the correction value to the acceptance inspection device. 
     This aspect can make it possible to grasp the condition of an electric actuator (for example, vibration received by the electric actuator, etc.) during the transportation or storage (typically under a situation where no external power source is supplied) and allows a correction value (for example, control parameters, etc.) according to the condition to be set for the electric actuator. 
     [Item 2-22] 
     A method performed by a sensor device, comprising: 
     detecting performed by measuring a condition related to an object; 
     outputting information that is based on the measurement result in the detecting; 
     storing the measurement result and the information in a storage unit; 
     supplying electric power from a power storage unit as electric power for executing at least one of the respective processes of the detecting, the outputting, and the storing; and 
     converting energy that exists in an external environment into electric power and charging the power storage unit. 
     This aspect can make it possible to grasp the condition related to an object under a situation where no external power source is supplied such as a case during the transportation of the object. For example, the condition related to the object can be grasped mainly based on stored electric power during the transportation or storage of the object (i.e., under a situation where no external power source is supplied). Further, when a relatively large amount of electric power is required, such as during the acceptance inspection that performs communication, the electric power generated based on energy in an external environment can be utilized. 
     [Item 2-23] 
     The method according to Item 2-22 performed by the sensor device, further comprising: 
     deleting data stored in the storage unit when a predetermined instruction is input. 
     According to this aspect, a sensor device can be reused by deleting data stored in a storage unit based on an instruction from the outside. For example, a sensor device used in one object can be attached to another object for use. 
     [Item 2-24] 
     A nomenclature plate that is attached to an article and on which information related to the article is displayed, comprising: 
     a sensor unit that measures a condition related to the article; 
     a communication unit that outputs information that is based on the measurement result from the sensor unit; 
     a storage unit that stores the measurement result from the sensor unit and the information output from the communication unit; 
     a power storage unit that supplies electric power for operating at least one of the sensor unit, the communication unit, and the storage unit; and 
     a power generation unit that converts energy that exists in an external environment into electric power and charges the power storage unit. 
     This aspect can make it possible to grasp the condition related to an article under a situation where no external power source is supplied such as a case during the transportation of the article such as a mechanical component. For example, the condition related to the article can be grasped mainly based on stored electric power during the transportation or storage of the article (i.e., under a situation where no external power source is supplied). Further, when a relatively large amount of electric power is required, such as during the acceptance inspection that performs communication, the electric power generated based on energy in an external environment can be utilized. Further, it is not necessary to newly secure an area for housing a sensor unit, a storage unit, and the like on or in the housing of the article. Thereby, while making it possible to grasp the condition related to an article, it is possible to suppress an increase in the cost and period of time required for manufacturing the article.