Abstract:
Taught is a detection device for detecting impacts and the like, comprising an integrated microcontroller ( 1 ) which includes an RFID interface ( 101 ) and a non-volatile memory ( 201 ), the integrated microcontroller ( 1 ) being interfaced with at least one suitable sensing means ( 2 ) through a suitable digital interface ( 102 ), the integrated microcontroller ( 1 ) being provided with a power management logic ( 301 ) to manage operation modes of the detection device, power consumption of the sensing means ( 2 ) being managed by the power management logic ( 301 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Italian Patent Application No. GE2006A000091, filed Sep. 15, 2006, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to devices for detecting impacts, vibrations and the like, and particularly it relates to a device intended to be attached to articles to be transported or otherwise moved; more particularly, the invention relates to a device wherein one or more suitable sensors are interfaced with an RFID (Radio Frequency Identification) unit. 
     2. Description of the Prior Art 
     Devices for detecting impacts or the like, which comprise sensing means interfaced with a processor and reporting means by which the occurrence of a detected event is communicated, are known in the state of the art. A first problem with this type of devices is how data can be made available to the operator. Another problem is represented by the type of data sampling to be carried out, which has to provide an adaptive answer for different transport or movement requirements while preserving operation efficiency of the device for the whole time during which the same is attached to a given article. 
     Accordingly, the aim of the present invention is to provide a device for detecting impacts and the like, said device being able on one hand to communicate gathered data to an operator, and to achieve a collection of significant data even over a quite long time period on the other hand. To this end, it was investigated the possibility of integrating a processor-coupled RFID device with means for detecting impacts, mechanical stress and vibrations. 
     SUMMARY OF THE INVENTION 
     Thus, an object of the present invention is a detection device for detecting impacts and the like, comprising an integrated microcontroller which includes an RFID interface and a non-volatile memory, said integrated microcontroller being interfaced with at least one suitable sensing means through a suitable digital interface, said integrated micro-controller being provided with a power management logic able to manage operation modes of said detection device, power consumption of said sensing means being managed by said power management logic. 
     In a preferred embodiment, said sensing means is a three-axis accelerometer; preferably, such sensing means is provided with memory registers storing the detected data. Sensing means can work in a continuous sampling mode, at given time frames and over preset time periods. Furthermore, it can be possible to set threshold values which are programmable in suitable memory registers, and sensing means doesn&#39;t carry out any logging activity below these threshold values. 
     Another object of the present invention is a method for detecting impacts and/or mechanical stresses, which method can comprise the step of detecting data sensed by sensing means in a substantially continuous manner, said detection being carried out in programmable time frames. Alternatively, detection can comprise gathering data relative to the last event which exceeds a previously assigned threshold value, said detection being carried out in programmable time frames. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other advantages and features of the device and method according to the present invention will be apparent from the following description of an embodiment thereof, which is provided by way of illustration, and not by way of limitation, with reference to the accompanying drawings, wherein: 
         FIG. 1  is a block schematic diagram illustrating the configuration of an embodiment of the device according to the invention; 
         FIG. 2  is a block schematic diagram depicting the configuration of the acceleration sensor used in the embodiment of  FIG. 1 ; 
         FIG. 3  is a schematic graph showing logged signal versus detection time according to either of two modes described in the present invention; and 
         FIG. 4  is a flow chart describing the preferred embodiment of the software algorithm stored and executed by the device microcontroller (device firmware). 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates an embodiment of the device according to the present invention; reference numeral  1  denotes a microcontroller having an RF interface  101 , a non-volatile memory  201  integrated therein and a Real Time Clock Module  401  able to control and to manage the time by using embedded resources (internal oscillator) or external references (external oscillator or quartz modules). The selection between the time reference resources is programmable by the micro-controller. 
     The micro-controller can communicate with external devices through a special antenna interface  111  which enables communication with an operator provided with an RFID controller unit, and through a digital interface  102  which places the micro-controller in communication with sensing means  2 , such as a 3-axis accelerometer, whose features will be better described below. Power  301  of sensing means is managed by microprocessor  1 . 
       FIG. 2  illustrates the configuration of accelerometer  2  in detail; it comprises 3 sensors  212 ,  222  and  232 , which detect events on each of the axes respectively. Each sensor is connected to a controller  302  provided with a register  312  in which signal threshold values are stored. These threshold values are determined by and depend on the characteristics of the transport and of the product to be transported. Detected data are transferred from controller  302  to memory logs  412 ,  422  and  432 , and than to I/O interface  502 , which communicates with a digital interface  102  connected to microcontroller  1 . 
     Management logic of sensor  302  is such to be able to write a value in memory registers  412 ,  422  and  432 . This value can be either a direct value continuously read by acceleration sensors  212 ,  222  and  232  or the maximum value achieved within a programmable time frame and with a threshold which can be set through the configuration register  312 . Microcontroller has the task to decide which mode will be selected, and the selected mode will be set through digital interface  102 . 
     Operation of the device according to the present invention will become evident from the following, with particular reference to  FIG. 3 .  FIG. 3  illustrates a diagram showing time on x-axis, and signal detected by accelerometer  2  on y-axis, as it can be logged in the non-volatile memory  201  of microcontroller  1 . This diagram emphasizes two different operation modes; in the case denoted by A, at a given time-point t 0 , sensing means and micro-controller are activated, and signal values detected by sensing means and sampled within a time frame Δt, which is small at will and anyway substantially smaller than the activation time frame of sensing means, are stored in the non-volatile memory  201  of microcontroller  1 . This type of detection provides a quite accurate accelerometer curve according to sampling rate Δt, and it is preferable when it is necessary to learn the entire history of mechanical stresses encountered by the article provided with the device of the present invention. In this case, threshold values set in the register  312  of controller  302  will be ignored, and system will log substantially all data detected by sensors  212 ,  222  and  232  during sampling periods. However, despite the accuracy of this type of logging, the above-described mode is not very suitable to monitor impacts for a given article in a large time frame because of the limited non-volatile memory resources of the microcontroller, and because of the power consumption of the microcontroller itself, which could be powered by battery packs for example. 
     In the other type of sampling, at time-point t 1 , microcontroller  1  enters a power saving mode during a programmable time frame t 2 −t 1 . However, during the time frame ranging from t 1  to t 2 , sensing means  2  is activated and it is programmed to store the last acceleration breach in its memory registers  412 ,  422  and  432 , the acceleration breach having been previously set in the threshold log  312 . At time point t 2 , microcontroller  1  will automatically exit the power saving mode, it will read memory logs  412 ,  422  and  432  of accelerometer sensing means  2 , it will verify if an acceleration breach has occurred during time frame t 2 −t 1  and, if this is the case, it will log the event in its non-volatile memory  201 . The acceleration breach event will be recorded saving the time information t 2  together with the acceleration samples coming from the  412 - 422 - 432  registers. It is clear that the recording data will be as much as accurate as the less the t 2 −t 1  time is. At the final destination of a given good on which the device described on this invention has been applied it will be possible to know not only if a specific mechanical “shock” happened and when but also its direction and intensity. 
     Of course, this type of sampling appears more suitable than the first type described when it is desirable to monitor an article over very long time periods and when it is possible to limit analysis to major events, thus saving device power over a substantially longer time period than the first type of sampling. These two operation modes for the device can be used either as an alternative to each other or jointly, according to the type of information that the operator wants to obtain. 
     In any case, management of power consumption for sensing means is totally programmable through signal  301 . Microcontroller can decide if sensing means should not be powered while it is in power-saving mode, or if sensing means should be continuously powered. Of course, if microcontroller doesn&#39;t provide power to sensing means, sensing means cannot acquire acceleration data. 
       FIG. 4  illustrates the preferred embodiment of the firmware stored and running inside the device microcontroller. This algorithm will be executed at every programmed activation period (that can be set-up by a specific RF command). Another RF command can be used also to avoid the accelerometer sensor programming at every wake-up time. After the set-up of the parameters of the device in step  20 , the next step is represented by the check of the presence of an error flag at  21 ; the error flag is related to the program which set up into the accelerometer sensor, and the threshold values for the sensor are programmed at the first switching on of the device, according to the steps  23  and  24  of the flow chart of  FIG. 4 . At every subsequent wake up of the device, if the values for the accelerometer correspond to the values required, the procedure goes to the step  30 , in which is selected the operating mode. 
     The device firmware could have both the “Shock” or “Acceleration Recording” logging functionalities or implementing only a single branch. In the case of “shock” recording, the procedure comprise a step  31  in which is verified if the acceleration exceeded the given threshold values; a record is then saved in the memory of the device, containing the time and the value of the violation; the memory is checked at this step  40  for its state. If the memory is over, an error flag is then set as in step  42 ; if the memory is not over, the in step  41  is carried out the management of the pointers of the memory. In the case of the simple “acceleration recording”, as according to step  34 , the data retrieved from the sensor are recorded in the memory until the same is over. In both the above discussed cases, the procedure ended up with the stand by step  44 , the device being waiting for the next wake-up as set-up in step  20 .