Abstract:
The invention provides a system and method of monitoring at least one operating characteristic of a hand power tool. In one embodiment, a hand power tool includes a housing, a motor within the housing and a tag mounted on the housing. The tag includes a first antenna for harvesting energy from an electromagnetic field associated with the motor, a microprocessor configured to operate using the harvested energy, a memory including stored commands which, when executed by the microprocessor, cause data associated with a sensed condition of the hand power tool to be stored within the memory, and a second antenna for coupling with a radio frequency identification (RFID) reader and for transmitting the data stored within the memory to the RFID reader.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a power hand tool and more particularly to a motorized power hand tool. 
       BACKGROUND 
       [0002]    Power tools including battery operated tools are well-known. These tools typically include an electric motor having an output shaft that is coupled to a spindle for holding a tool. The tool may be a drill bit, sanding disc, a de-burring implement, or the like. Electrical power is supplied to the electric motor from a power source. The power source may be provided to the power tool through a cord. Alternatively, the power source may be a battery source such as a Ni-Cad or other rechargeable battery that may be de-coupled from the tool to charge the battery and coupled to the tool to provide power. 
         [0003]    These power tools may be returned to a manufacturer or sent to a repair facility for a variety of reasons. Many of the reasons for returning a power tool are very benign. By way of example, some hand power tools may be returned for routine maintenance. Additionally, many retailers offer a limited time money back guarantee on products sold. Accordingly, many power hand tools are purchased, taken home and then returned simply because the purchaser has reconsidered the purchase. Other returns may be precipitated by the discovery of a minor cosmetic blemish on the power hand tool. Still other power tools may have been used as demonstration tools. Tools that have been returned to a manufacturer for reasons other than operational problems such as those described above can be rapidly refurbished and sold as a factory reconditioned unit without undue concern that the unit will fail. 
         [0004]    In some instances, however, a power tool is returned because an operational issue has arisen. By way of example, a hand drill may have been over-torqued, thereby damaging the power drill. If such damage occurs within the retailer guaranteed time frame, however, some customers may return the power tool without alerting the retailer of the damage to the power tool. Such damage may be difficult to discover. For example, a drill may only malfunction at certain speeds or at certain torques. Nonetheless, it is important that any such damage be discovered during the inspection and testing conducted by the factory to avoid mistakenly selling an inferior product. 
         [0005]    Other power tools are returned to a manufacturer under a warranty. Typically, at least some of the operational issues of such power tools are identified by the purchaser. Frequently, however, the manner in which the tool was being operated at the time the operational problem developed may not be accurately reported. The actual operating condition at the time of the failure, however, may implicate the manufacturer&#39;s obligations under a warranty program. Moreover, information as to how a tool has failed provides insight into potential design changes that can be made to preclude failures in updated versions of the tool. 
         [0006]    There is a need to obtain data indicative of the manner in which a tool has been operated. There is a further need to be able to obtain that data without the need to breech the housing of the tool. There is also a need for a system that could easily be retrofitted onto hand power tools. 
       SUMMARY 
       [0007]    Some of the limitations of previously known hand power tools may be overcome by a system and method of monitoring at least one operating characteristic of a hand power tool including harvesting energy from the motor of a hand power tool and storing data corresponding to a sensed condition of the hand power tool in a memory using the harvested energy. 
         [0008]    In one embodiment, a hand power tool includes a housing, a motor within the housing and a tag mounted on the housing. The tag includes a first antenna for harvesting energy from an electromagnetic field associated with the motor, a microprocessor configured to operate using the harvested energy, a memory including stored commands which, when executed by the microprocessor, cause data associated with a sensed condition of the hand power tool to be stored within the memory, and a second antenna for coupling with a radio frequency identification (RFID) reader and for transmitting the data stored within the memory to the RFID reader. 
         [0009]    One method of monitoring at least one operating characteristic of a hand power tool includes harvesting energy from the motor of a hand power tool and storing data corresponding to a sensed condition of the hand power tool in a memory using the harvested energy. 
         [0010]    In an alternative embodiment, a method of diagnosing a problem in a hand power tool includes harvesting energy from an electromagnetic field associated with the motor of the hand power tool with a tag, storing data corresponding to a sensed condition of the hand power tool within a memory located on the hand power tool using the harvested energy, obtaining the data corresponding to the sensed condition from the memory, comparing the obtained data to reference data, and determining that a problem exists with the hand power tool based upon the comparison. 
         [0011]    In a further embodiment, a method of monitoring the operating characteristics of a hand power tool includes attaching a radio frequency identification (RFID) film to the hand power tool, harvesting energy from the motor of the hand power tool with a first antenna located on the RFID film, powering components on the RFID film with the harvested energy, storing data corresponding to a sensed condition of the hand power tool within a memory located on the RFID film, transmitting the data corresponding to the sensed condition from the memory using a second antenna located on the RFID film and analyzing the transmitted data to determine an operating characteristic of the hand held power tool. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The present invention may take form in various system and method components and arrangement of system and method components. The drawings are only for purposes of illustrating exemplary embodiments and are not to be construed as limiting the invention. 
           [0013]      FIG. 1  shows a perspective view of a power assisted tag attached to an articulating drill incorporating features of the present invention; 
           [0014]      FIG. 2  shows a perspective view of the articulating drill of  FIG. 1  with the battery pack, a portion of the main housing cover, and a portion of the head housing removed and a bit in the bit holder; 
           [0015]      FIG. 3  shows a perspective view of the power assisted tag of  FIG. 1  with various layers of the power assisted tag partially peeled apart; 
           [0016]      FIG. 4  shows an electrical diagram/schematic of the power assisted tag of  FIG. 1  including a harvesting coil and a transmitter/receiver coil; 
           [0017]      FIG. 5  shows an electrical diagram/schematic of a reader that can be used to receive data stored in the memory of the power assisted tag of  FIG. 1 ; 
           [0018]      FIG. 6  shows a perspective view of a power assisted tag attached to a circular saw incorporating features of the present invention; and 
           [0019]      FIG. 7  shows an electrical diagram/schematic of the power assisted tag of  FIG. 6  including a harvesting coil and a transmitter/receiver coil. 
       
    
    
     DESCRIPTION 
       [0020]    A power tool generally designated  100  is shown in  FIG. 1 . In the embodiment of  FIG. 1 , the power tool  100  is a drill which includes a main housing portion  102  and a head portion  104 . The main housing portion  102  houses a motor and associated electronics for control of the drill  100 . The main housing portion  102  includes a battery receptacle for receiving a rechargeable battery pack  106  as is known in the art. In one embodiment, the rechargeable battery pack  106  comprises a lithium-ion battery. The battery pack  106  is removed by depression of the battery release tabs  108 . The drill  100  may alternatively be powered by an external power source such as an external battery or a power cord. 
         [0021]    A variable speed trigger switch  110  controls the speed at which the motor rotates. The direction of rotation of the motor is controlled by a reversing button  112  which slides within a finger platform  114 . Ventilation openings  116  allow for cooling air to be circulated around the motor inside of the main housing  102 . A power assisted tag  118  is located on the main housing portion  102  above the ventilation openings  116 . 
         [0022]    A clutch control  120  sets the maximum torque that may be generated when using the drill  100 . At the position shown in  FIG. 1 , the clutch control  120  is at the highest setting or drill mode. At the highest setting, the clutch is disabled to provide maximum torque. By sliding the clutch control  120  downwardly from the position shown in  FIG. 1 , a user may set a desired torque limit that is allowed to be generated by the drill  100 . Accordingly, at settings other than the highest setting, a torque above the setting of the clutch control  120  causes the clutch to activate. 
         [0023]    The head portion  104  includes a collet locking device  122  which is located around a bit holder  124 . The collet locking device  122  cooperates with the bit holder  124  to hold a bit  126  as shown in  FIG. 2 . A motor  128  located in the main housing portion  102  provides rotational energy for the bit  126 . Rotational energy from the motor  128  is passed to the bit  126  through a planetary gear system  130  and an articulating gear system  132 . 
         [0024]    The motor  128  is electrically connected to a printed circuit board  134  which in turn is electrically connected to a battery contact holder  136 . The contact holder  136  mates with battery pack receptacles on the battery pack  106  and transmits battery power to the printed circuit board  134 . The printed circuit board  134  includes a half-bridge rectifier circuit which converts the direct current from the battery pack  106  to an alternating current which is used to cause the motor  128  to rotate. 
         [0025]    Referring to  FIG. 3 , the power assisted tag  118  includes a label surface substrate  140 , an RFID substrate  142  and a backing substrate  144 . The label surface substrate  140  protects the RFID substrate  142 . Additionally, a design and/or information may be printed onto the label surface substrate. An adhesive (not shown) may be applied to the backing substrate  144  to provide for adherence of the power assisted tag  118  to the drill  100 . 
         [0026]    The RFID substrate  142  includes a printed circuit  146  which is schematically shown in  FIG. 4 . The printed circuit  146  includes a harvesting coil  150  which is connected to a microprocessor  152  through a rectifier and power conditioning unit  154 . A data transmitter/receiver coil  156  and a memory  158  are also connected to the microprocessor  152 . In this embodiment, a sensor  160  is further connected to the microprocessor  152 . 
         [0027]    The sensor  160  may be, for example, an accelerometer, displacement sensor, strain gauge, thermometer, or electromagnetic field (EMF) sensor. The sensor  160  provides a signal to the microprocessor  152  indicative of a sensed condition. The printed circuit  146  may include signal conditioners such as an A/D converter (not shown) to provide a signal conditioned to be used by the microprocessor as is known in the relevant art. 
         [0028]    The microprocessor  152  executes programs stored within the memory  158 , which is preferably a non-volatile memory, and sends signals indicative of a condition sensed by the sensor  160  to the memory  158  for storage. The microprocessor  152  further executes programs which manage communications through the data transmitter/receiver coil  156 . The data transmitter/receiver coil  156  also provides power to the printed circuit  146  when the power assisted tag  118  is being read as discussed below. The harvesting coil  150  provides power to the printed circuit  146  when the drill  100  is in operation. 
         [0029]    A reader  162  that may be used with the power assisted tag  118  is schematically shown in  FIG. 5 . The reader  162  includes a coil  164 , a microprocessor  166 , a power source  168 , a graphic user interface (GUI)  170 , a memory  172  and an input/output (I/O) device  174 . Power for the reader  162  is provided by the power source  168  which may be battery. The microprocessor  166  executes programs stored within the memory  172 , which is preferably a non-volatile memory. The memory  172  may further be used to store data received from the coil  164 , the GUI  170  and the I/O device  174 . The microprocessor  166  further executes programs which manage communications through the input/output device  174  and the GUI  170 . The GUI  170  includes a display screen for displaying information to a user as well as a keyboard or other input device whereby the user may control the operation of the reader  162 . The coil  164  is used to couple the reader  162  with the power assisted tag  118 . 
         [0030]    In operation, a user activates the drill  100  by compressing the variable speed trigger switch  110  which closes a circuit between the rechargeable battery pack  106  and the half-bridge rectifier circuit on the printed circuit board  134 . The half bridge rectifier circuit is controlled to provide an alternating current to the motor  128 . Specifically, the current is applied to the motor  128  in a known manner to generate a switching electromagnetic field. The switching electromagnetic field generates a force on the rotator (not shown) of the motor  128  causing the rotator to rotate which thus initiates an operating window. 
         [0031]    Additionally, as the electromagnetic field is rotated, the electromagnetic field sweeps across and couples with the harvesting coil  150 . The coupling of the moving electromagnetic field with the harvesting coil  150  induces a current in the harvesting coil  150  which is conducted to the rectifier and power conditioning unit  154 . The rectifier and power conditioning unit  154  receives the current from the harvesting coil  150  and converts the current into a stable DC voltage which powers the microprocessor  152  and associated components. In one embodiment, the microprocessor  152  causes a counter (not shown) to be incremented each time a stable DC voltage is initially provided. The counter may thus be used to identify the number of on/off cycles of the drill  100 . 
         [0032]    The sensor  160 , which in this embodiment is an EMF sensor, also detects the electromagnetic field generated by the motor  128 . The sensor  160  then passes a signal to the microprocessor  152  indicative of the rate at which the electromagnetic field is rotating through the sensor  160 . The microprocessor  152  receives the signal from the sensor  160 . In one embodiment, the data correlating to the signal is stored in the memory  158  along with a time tag. Alternatively, the microprocessor  152  may perform some level of signal processing, and store the processed data in the memory  158 . Processing of the signal received from the sensor  160  may be desired to compress the data prior to storage in the memory  158 . 
         [0033]    The microprocessor  152  may further store data identifying the direction of rotation of the motor  128  in the memory  158 . This may be accomplished, for example, by identifying the position of the reversing button  112 . Likewise, the position of the clutch control  120  may be stored in the memory  158 . If desired, the commands executed by the microprocessor  152  may vary the periodicity at which the various data is stored. For example, data corresponding to the position of the reversing button  112  and the clutch control  120  may be recorded only when the sensor  120  detects the start of an operating window. Rather than using a time tag, the duration of the operating window could then be determined by determining the number of data points stored during the particular window. Alternatively, data corresponding to the position of the reversing button  112  or the clutch control  120  may further be recorded each time that the position of the reversing button  112  or the clutch control  120  is repositioned during an operating window. 
         [0034]    When the operator no longer desires rotation of the motor  128 , the variable speed trigger switch  110  is released. Accordingly, the circuit between the rechargeable battery pack  106  and the half-bridge rectifier circuit on the printed circuit board  134  is broken. Therefore, the half bridge rectifier circuit ceases to provide an alternating current to the motor  128  and the electromagnetic field is no longer switched. Accordingly, the motor  128  ceases to rotate. 
         [0035]    Additionally, because the electromagnetic field is either no longer coupled with the harvesting coil  150  or not moving, current is no longer induced within the power assisted tag  118 . Therefore, the rectifier and power conditioning unit  154  is de-energized, removing power from the microprocessor  152 . Accordingly, no further data associated with the signal from the sensor  160  is stored in the memory  158  and the operating window is closed. 
         [0036]    In the foregoing example, the commands executed by the microprocessor  152  set the number of samples of sensed data collected per second, the duration of data collection, the periodicity with which data was stored, and whether the data stored was an instantaneous reading from the sensor  160  or an integrated value. Additionally, while the embodiment of  FIG. 4  shows a single sensor  160 , other embodiments include multiple sensors. In such embodiments, the periodicity and sequence of sampling of the sensors may be controlled by the commands executed by the microprocessor. 
         [0037]    Moreover, the rectifier and power conditioning unit  154  may be constructed to allow for some amount of residual power after the motor  128  is de-energized. Accordingly data may continue to be stored for a period of time after the operating window closes. 
         [0038]    The data stored in the memory  158  may thereafter be used, for example, by a maintenance facility when the drill  100  is presented for maintenance, refurbishment, etc. To obtain the data from the memory  158 , the reader  162  is energized. The operator then uses the GUI  170  to control the microprocessor  166  to obtain the data stored in the memory  158 . In response to the user input, the microprocessor executes commands stored in the memory  172  which causes energy to be applied to the coil  164 . The energization of the coil  164  causes an electromagnetic field to be generated which couples with the data transceiver/receiver coil  156 . 
         [0039]    The coupling of the transceiver/receiver coil  156  provides energy to the microprocessor  152 , thereby energizing the microprocessor  152 . The microprocessor  166  then causes the electromagnetic field to be modulated, thereby transmitting a command to the microprocessor  152  to transmit data stored in the memory  158 . The microprocessor  152  detects the command and executes commands whereby data in the memory  158  is read. The microprocessor then transmits the data through the transceiver/receiver coil  156 . The transmitted data is received by the coil  164  and passed to the microprocessor  166 . The received data is then stored within the memory  172 . Additionally or alternatively, the received data may be displayed on the GUI  170  or re-transmitted through the I/O device  174 . 
         [0040]    Once the data has been transmitted from the power assisted tag  118 , the data may be used to determine a variety of information. By way of example, the number of operating windows as well as the runtime of the drill  100  may be determined. Additionally, the strength of the electromagnetic field sensed by the sensor  160  can be associated with the torque which was exerted by the drill  100  during the operating windows. 
         [0041]    The information that is desired may vary over the course of the useful life of a tool. Accordingly, the particular sensor or suite of sensors used may be determined so as to provide all of the information desired over the life of a particular tool. Alternatively, the sensor or suite of sensors used for the particular tool may be varied by the addition of sensors and/or the replacement of the power assisted tag. Such modifications may include, the addition of a temperature sensor which allows for the temperature of a critical component to be determined. Thus, in the event that a particular component is determined to exhibit degraded characteristics, increased monitoring of the component is possible. 
         [0042]    Moreover, the power assisted tag may be incorporated into a network of sensors which may be power assisted, passive or active. Thus, a plurality of temperature sensors may be positioned at locations on or near various components of a power hand tool that allow for the determination of the operating temperature of the various components while an EMF sensor could be placed at a location that optimizes coupling with the electromagnetic field generated by the motor of the tool. The information from the temperature sensors and/or the EMF sensor may then be transmitted to the power assisted tag for later transmission. 
         [0043]    The information obtained from a power assisted tag may be used for a variety of analysis. For example, the information may be stored to provide trending data over the life of the power tool. The trending data provides may be used to predict when future maintenance will be required. The data may also be compared to stored data for diagnoses of problems with the power hand tool. 
         [0044]    In an alternative embodiment, a power assisted tag which may be an RFID tag may be used in conjunction with an alternating current motor in a power tool. By way of example,  FIG. 6  depicts a circular saw  180 . The saw  180  includes a housing  182  and a power cord  184 . The power cord  184  is used to provide power to the saw  180 . A power assisted tag  186  is located on the housing  182 . An AC motor (not shown) is located within the housing. 
         [0045]    The power assisted tag  186  is schematically shown in  FIG. 7 . The power assisted tag  186  includes a harvesting coil  188  which is connected to a microprocessor  190  through a rectifier and power conditioning unit  192 . A data transmitter/receiver coil  194  and a memory  196  are also connected to the microprocessor  190 . 
         [0046]    In the embodiment of  FIG. 7 , the power assisted tag  186  does not include a dedicated sensor. Rather, the harvesting coil  188  is used as a sensor. Specifically, when an alternating current is applied to the motor (not shown) in a known manner, a rotating electromagnetic field is generated by the stator windings (not shown). The rotating electromagnetic field sweeps across and couples with the harvesting coil  188 . The coupling of the moving electromagnetic field with the harvesting coil  188  induces a current in the harvesting coil  188  which is conducted to the rectifier and power conditioning unit  192 . The rectifier and power conditioning unit  192  receives the current from the harvesting coil  188  and converts the current into a stable DC voltage which powers the microprocessor  190  and associated components. The microprocessor  190  may include a counter (not shown) to be incremented when an operating window is initiated in the foregoing manner. The counter may thus be used to identify the number of on/off cycles of the tool  180 . 
         [0047]    In the same manner as the drill  100 , the speed of rotation of the tool  180  may be determined from the rate at which the electromagnetic field generated by the tool  180  rotates as sensed by the harvesting coil  188 . Additional operational insight into the tool  180  may be obtained through the voltage and current produced by the harvesting coil  188  which may be stored in the memory  196 . For example, as the torque on the circular saw  180  increases, the strength of the electromagnetic field generated in the stator increases resulting in a higher inductive current from the harvesting coil  188 . 
         [0048]    Because the electromagnetic field generated by an AC motor generally has a magnetic flux larger than that of the electromagnetic field generated by a switching magnetic field of the type set discussed above with respect to the drill  100 , a smaller harvesting coil may be used. Alternatively, the power assisted tag may be placed at a location on the housing which is located in a weaker portion of the rotating electromagnetic field. If additional power is required, then a power assisted tag may be directly wired to the power supply for the motor. In a further embodiment, the harvesting coil of a power assisted tag may be configured as a transformer with a core so as to harvest energy from the stator windings. 
         [0049]    While the present invention has been illustrated by the description of exemplary processes and system components, and while the various processes and components have been described in considerable detail, applicant does not intend to restrict or in any limit the scope of the appended claims to such detail. Additional advantages and modifications will also readily appear to those skilled in the art. The invention in its broadest aspects is therefore not limited to the specific details, implementations, or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept.