Sensing Device

Abstract

A sensing device is provided that is capable of highly accurate measurements and reduces power consumption while using energy harvesting technology. [Solution] This sensing device comprises a sensor unit that converts a signal output from an object into an electrical signal, a storage element that accumulates power generated by an energy harvesting element, a signal generation circuit that becomes conductive and outputs a control signal when the amount of power stored in the storage element reaches a predetermined value or more, and a transmitter that transmits the electrical signal from the sensor unit to the outside based on the control signal. The signal generation circuit comprises a first controlled rectifier that receives an input signal from its anode, and a second controlled rectifier that receives the input signal from its anode and has a gate connected to the cathode of the first controlled rectifier.

Description

[Technical Field]

[0001] The present invention relates to a sensing device. [Background technology]

[0002] Sensing devices are known for detecting various conditions of objects, and with the advancement of the IoT society, the demand for sensing devices is increasing. Sensing devices are required to be able to measure with high precision and determine conditions accurately, while also requiring low power consumption.

[0003] Development is also underway for sensing devices that use so-called energy harvesting technology to supplement or eliminate the need for external power sources or batteries. If sensing devices using such energy harvesting technology become widespread, the effort required for battery replacement and maintenance will also be reduced. However, sensing devices using energy harvesting technology have a limited amount of power they can generate, so there are still many issues to be addressed in terms of measurement accuracy and reliability, as well as limitations on the amount of data they can transmit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7107492 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above-mentioned problems, an object of the present invention is to provide a sensing device that is capable of highly accurate measurements and reduces power consumption while using energy harvesting technology. [Means for solving the problem]

[0006] A sensing device according to the present invention includes a sensor unit that converts a signal output from an object into an electrical signal, a power storage element that stores power generated by an energy harvesting element, a signal generation circuit that becomes conductive and outputs a control signal when the amount of power stored in the power storage element reaches a predetermined value or more, and a transmitter that transmits the electrical signal from the sensor unit to the outside based on the control signal. The signal generation circuit includes a first controlled rectifier that receives an input signal from its anode, and a second controlled rectifier that receives the input signal from its anode and has a gate connected to the cathode of the first controlled rectifier. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a sensing device that is capable of highly accurate measurement and reduces power consumption while using energy harvesting technology. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating a sensing device 1 according to a first embodiment. [Figure 2] FIG. 1 is a schematic diagram illustrating a sensing device 1 according to a first embodiment. [Figure 3] FIG. 1 is a schematic diagram illustrating a sensing device 1 according to a first embodiment. [Figure 4] 2 is a circuit diagram showing an example of the configuration of a trigger signal generating circuit 30 of the sensing device 1 according to the first embodiment. FIG. [Figure 5] 2 is a circuit diagram showing an example of the configuration of a trigger signal generating circuit 30 of the sensing device 1 according to the first embodiment. FIG. [Figure 6] 2 is a circuit diagram showing an example of the configuration of a trigger signal generating circuit 30 of the sensing device 1 according to the first embodiment. FIG. [Figure 7] 4 is a graph illustrating the operation of the trigger signal generation circuit 30 according to the first embodiment. [Figure 8] 4 is a graph illustrating the operation of the trigger signal generation circuit 30 according to the first embodiment. [Figure 9]4 is a graph illustrating the operation of the trigger signal generation circuit 30 according to the first embodiment. [Figure 10] An outline of the operation (determination of the state) of the sensing device 1 according to the first embodiment will be described. [Figure 11] An outline of the operation (determination of the state) of the sensing device 1 according to the first embodiment will be described. [Figure 12] An outline of the operation (determination of the state) of the sensing device 1 according to the first embodiment will be described. [Figure 13] An outline of the operation (determination of the state) of the sensing device 1 according to the first embodiment will be described. [Figure 14] FIG. 4 is a circuit diagram illustrating a sensing device 1 according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may be designated by the same numerals. Note that the accompanying drawings show embodiments and implementation examples according to the principles of the present disclosure, but these are for understanding the present disclosure and are not to be used to interpret the present disclosure in a limiting manner. The descriptions in this specification are merely typical examples and are not intended to limit the scope or application of the present disclosure in any way.

[0010] Although the present embodiment has been described in sufficient detail to enable those skilled in the art to implement the present disclosure, it should be understood that other implementations and forms are possible, and that changes in configuration and structure and substitutions of various elements are possible without departing from the scope and spirit of the technical ideas of the present disclosure. Therefore, the following description should not be interpreted as being limited thereto.

[0011] [First embodiment] A sensing device 1 according to a first embodiment will be described with reference to Fig. 1. Here, as an example, a sensing device that detects the operating state (normal or various abnormalities) of a pump PM as a sensing target will be described, but the present invention is not limited to this. Furthermore, the sensing device 1 illustrated in Fig. 1 is only an example, and the sensing target is not limited to a specific object or device.

[0012] 1, the sensing device 1 includes sensors S1 and S2, an energy harvesting element (VEH) 20, a capacitor (power storage element) C1, a trigger signal generating device 30, a wireless transmitter 50, a wireless receiver 60, and a computer (PC) 70. The devices preceding the wireless transmitter 50 constitute a sensor signal transmitting unit 200, and the devices following the wireless receiver 60 constitute a sensor signal receiving unit 300.

[0013] The sensors S1 and S2 are sensors installed in the pump PM, which is the sensing target, and are vibration sensors, for example. By bringing the vibration sensors S1 and S2 into contact with or close to the housing of the pump PM, it is possible to detect vibrations occurring in the pump PM. The output signals of the sensors S1 and S2 are converted into digital signals by A / D converters 11 and 12 and transmitted to a wireless transmitter 50 as appropriate. The sensors S1 and S2 are also not limited to a specific type and may include, for example, an acceleration sensor, an optical sensor, an ultrasonic sensor, a magnetic sensor, etc.

[0014] The energy harvesting element 20 is an element for converting various types of energy into electric power and collecting it. The energy harvesting element 20 may be an element that generates either AC power or DC power, and FIG. 1 shows an element that generates AC power. In the case of an element that generates AC power, the energy harvesting element 20 has an internal rectifier circuit (not shown in FIG. 1) that converts the AC power into DC power and outputs it. In the case of an element that generates DC power, the energy harvesting element 20 can output the DC power as is. The DC power output by the energy harvesting element 20 is temporarily stored in a capacitor C1.

[0015] The trigger signal generating circuit 30 detects the voltage V across the terminals of the capacitor C1. c becomes equal to or greater than a predetermined value, the computer 70 generates a trigger signal (control signal) and transmits it to the wireless transmitter 50. In response to this trigger signal, the wireless transmitter 50 superimposes sensor signals (electrical signals) received from the sensors S1 and S2 via the A / D converters 11 and 12 onto a transmission wave and transmits the superimposed signal to the wireless receiver 60. The wireless receiver 60 transmits the sensor signals received via the reception wave to the computer 70. The computer 70 analyzes the sensor signals and other acquired information to make judgments and perform various calculations regarding the state of the pump PM being sensed.

[0016] Specifically, the computer 70 may include a wireless transmission interval transmitting unit 71, a measurement signal acquiring unit 72, a learning unit 73, and a state determining unit 74 to determine the state of the pump PM. The wireless transmission interval 71 acquires data related to the transmission interval of the measurement signals of the sensors S1 and S2 transmitted from the wireless transmitting unit 50. The measurement signal acquiring unit 72 acquires data related to the measurement signals (voltages) of the sensors S1 and S2 in accordance with the received wireless signals. The learning unit 73 learns from a combination of the obtained wireless transmission interval data, measurement data, etc., to generate a machine learning model. The state determining unit 74 determines the state of the pump PM in accordance with the obtained measurement results and the learning results of the learning unit 73.

[0017] 2, a DC / DC converter 40 can be provided between the trigger signal generation device 30 and the wireless transmitter 50. The DC / DC converter 40 can appropriately step up or step down the output signal of the trigger signal generation device 30 and output it to the wireless transmitter 50.

[0018] 3 shows a configuration in which the energy harvesting element 20 is an element that outputs DC power. Because it outputs DC power, the energy harvesting element 20 does not have a rectifier circuit, and the output DC power is converted by a DC / DC converter 40' before being charged into a capacitor C1. The other configurations are substantially the same as those in FIGS. 1 and 2.

[0019] An example of the configuration of the trigger signal generation circuit 30 will be described with reference to Fig. 4. Fig. 4 illustrates a case where the energy harvesting element 20 includes a power generation element 21 that generates AC power, and a rectifier circuit 22.

[0020] The trigger signal generating circuit 30 includes, for example, a first control rectifier M1, a second control rectifier M2, and a gate resistor 31 (with a resistance value R G ), and output resistor 32 (resistance value R L ) is provided.

[0021] The first controlled rectifier M1 and the second controlled rectifier M2 have gate-cathode voltages equal to or greater than the threshold voltage V th1 , V th2 The first control rectifier M1 is a programmable unijunction transistor (PUT) with an operating current of less than 1 μA, and the second control rectifier M2 is a thyristor (SCR) with an operating current several hundred to several thousand times that of the first control rectifier M1.

[0022] The gate resistor 31 is connected between the gate of the first controlled rectifier M1 and the ground terminal, and the voltage V c Gate voltage V according to gateThis gate voltage V gate is the threshold voltage V of the first controlled rectifier M1. th1 When the first control rectifier M1 is turned on, the cathode voltage V of the first control rectifier M1 trigger The cathode voltage V trigger is the threshold voltage V of the second controlled rectifier M2 th2 When this occurs, the second control commutator M2 also switches to a conductive state (turns on).

[0023] FIG. 5 shows another example of the configuration of the trigger signal generating circuit 30. This differs from the example in FIG. 4 in that thyristors are used as both the first controlled rectifier M1 and the second controlled rectifier M1. The output resistor 32 is the same as the output resistor 32 in FIG. 4, but the gate resistor 33 differs from the gate resistor 31 in FIG. 4 in that one end is connected to the anode side of the capacitor C1. This configuration also differs from the example in FIG. 4 in terms of the rising timing of the trigger signal because the threshold voltage is different, but the basic operation is the same.

[0024] 6 shows yet another example of the configuration of the trigger signal generating circuit 30. This example differs from the example in FIG. 4 in that a thyristor (SCR) and a PUT are used as the first controlled rectifier M1 and the second controlled rectifier M2, respectively. The output resistor 32 is the same as the output resistor 32 in FIG. 4, but one end of the gate resistor 33 is connected to the anode side of the capacitor C1, as in the case of FIG. 5. This configuration also differs from the example in FIG. 4 in terms of the rising timing of the trigger signal, etc., because the threshold voltage is different, but the basic operation is the same.

[0025] 7 to 9, the operation of the trigger signal generation circuit 30 of the first embodiment will be described. c , and the output voltage V out 8 is an example of a graph showing the change over time of the terminal voltage V before and after the first controlled rectifiers M1 and M2 are switched to the conductive state (Turn on) and the non-conductive state (Turn off).c , and the output voltage V out 9 is an example of a graph showing an enlarged view of the change in the terminal voltage Vc and the output current I before and after the first control rectifiers M1 and M2 are switched to the conductive state (Turn on) and the non-conductive state (Turn off). A 10 is an example of a graph showing changes in

[0026] As shown in FIG. 7, the voltage V across the terminals of the capacitor C1 increases due to power generation by the energy harvesting element 20. c rises, and the threshold voltage V th1 When the voltage V reaches the threshold, the trigger signal generating circuit 30 is activated to discharge the charge in the capacitor C1, and the trigger voltage V is output from the output resistor 32. out Specifically, the terminal voltage V c rises and the threshold voltage V th1 As a result, the first controlled rectifier M1 becomes conductive, and the cathode voltage V trigger The cathode voltage V trigger is the threshold voltage V th2 When this happens, the second control rectifier M2 also switches to a conducting state (Turn on). As a result, the trigger current I A flows, and the output voltage V out (=I A ×R L ) is output. In this way, the trigger signal generating circuit 30 including the first controlled rectifier M1 and the second controlled rectifier M2 outputs the threshold voltage V th2 Instead, the threshold voltage V of the first controlled rectifier M1 th1 The trigger signal can be raised with

[0027] On the other hand, the discharge of capacitor C1 progresses and the voltage between its terminals V c decreases, and the current I A When the voltage V V drops below the holding current, the second control commutator M2 is switched to a non-conducting state (turned off). c The first controlled rectifier M1 is supplied with a voltage V between its anode and terminals.c is supplied, and by including a second control rectifier M2 whose gate is connected to the cathode of the first control rectifier M1, the voltage V between the terminals c is the threshold voltage of the first control rectifier M1 where there is th1 When it rises to, a trigger signal is raised, and the voltage V between the terminals c When it drops below the holding current of the second control rectifier M2, the trigger can be dropped. When the trigger signal falls, the capacitor C1 returns to the charged state again, and the above operation is repeated. In the present embodiment, the trigger signal can be dropped before the capacitor C1 becomes empty, and even when the energy harvesting element 20 can generate only a minute amount of power, it becomes possible to periodically transmit the detection outputs of the sensors S1 and S2 periodically.

[0028] Incidentally, it is preferable that the threshold voltages Vth1 and Vth2 of the first control rectifier M1 and the second control rectifier M2 are such that Vth1 < Vth2. When Vth1 < Vth2, the stored power of the charged capacitor C1 can be discharged from an early timing and the discharge can be stopped at an early timing, thereby maintaining the stored power of the capacitor C1 and shortening the transmission interval of the sensor signal.

[0029] However, in the case where the load is a high voltage or when there is no need to shorten the transmission interval of the sensor signal, it is also possible to set Vth1 > Vth2. In this case, the trigger signal generation circuit 30 raises the trigger signal after the stored power of the capacitor C1 becomes considerably high to start discharging the capacitor C1, and then does not drop the trigger signal until the stored power of the capacitor C1 almost runs out. Thus, the threshold voltages of the first control rectifier M1 and the second control rectifier M2 can be appropriately set according to the required operation, measurement accuracy, etc.

[0030] As a first comparative example, consider the case where the trigger signal generation circuit 30 consists of a single PUT. In this case, the PUT becomes conductive and raises the trigger signal when the voltage V between the terminals of the capacitor c is in a minute stage, while the trigger current IA The PUT cannot switch to a non-conductive state unless the value of is extremely small. Therefore, in a trigger signal generation circuit 30 configured solely with a PUT, most of the power generated by the energy harvesting element 20 and stored in the capacitor C1 is discharged, resulting in a long waiting time until the capacitor C1 is recharged. In this case, regular measurement becomes difficult, and problems remain with the reliability of the measurement.

[0031] As a second comparative example, consider a case where the trigger signal generating circuit 30 is composed of a single thyristor. In this case, the thyristor is connected to the capacitor via a voltage V c is not conducted at the minute stage, and the terminal voltage V c is the threshold voltage V th1 , the trigger signal generating circuit 30 will only become conductive when it exceeds . Therefore, in the trigger signal generating circuit 30 configured with a single thyristor, the power generated by the energy harvesting element 20 and stored in the capacitor cannot be used unless it is sufficiently large. For this reason, as in the first comparative example, periodic measurement becomes difficult, and problems remain with respect to the reliability of the measurement.

[0032] An overview of the operation of the sensing device 1 will be described with reference to Fig. 10. As will be described in detail later, the sensing device 1 identifies the relationship between the sensor signals detected by the sensors S1 and S2 and the wireless transmission intervals by the wireless transmitter 50, and applies the identified result to a machine learning model, which is the result of machine learning, to determine the state of the pump PM, which is the sensing target. As an example, as shown in Fig. 10, it can determine which of a plurality of states the pump PM is in (e.g., six states: State 1 (stable), State 2 (unstable), State 3 (overturned), State 4 (forward tilt), State 5 (sideways tilt), and State 6 (backward tilt)).

[0033] The computer 70 of the sensing device 1 and an external computer linked thereto learn the sensor signals output by the sensors S1 and S2, the wireless transmission intervals, and the state of the pump PM at that time as learning data, and generate a machine learning model (trained model). The computer 70 can use the machine learning model to determine the state of the pump PM based on newly measured data (evaluation data).

[0034] In this embodiment, the generation of a machine learning model (supervised learning) based on the sensor signal, the wireless transmission interval, and the state of the pump PM at that time can be performed using well-known techniques such as a k-nearest neighbor method, a linear classifier, a statistical classifier, a decision tree classifier, a support vector machine, or a tree-structured ensemble classifier (Light GBM).

[0035] FIG. 12 shows a method for plotting the measurement results (wireless transmission interval, sensor signal) obtained by the sensing device 1 of this first embodiment on a two-dimensional graph and determining the state of the pump PM (e.g., six states: State 1 (stable), State 2 (unstable), State 3 (overturned), State 4 (forward tilt), State 5 (sideways tilt), and State 6 (backward tilt)) using, for example, a k-nearest neighbor method. When the measurement results are plotted with the wireless transmission interval on the horizontal axis and the sensor signal (voltage) on the vertical axis, plots relating to the same state are clustered close to each other. The machine learning model learns this tendency and can determine the state of the pump PM from which later measurement results were obtained using, for example, a k-nearest neighbor method.

[0036] As can be seen from Figure 12, by using two factors, the wireless transmission interval and the sensor signal, the plot points are clearly separated between different states, making it easy to determine multiple states. The graphs in Figures 13(a) to 13(c) each show either the wireless transmission interval, the signal (voltage) of sensor S1, or the signal (voltage) of sensor S2 on the horizontal axis, and the frequency (density) of occurrence of those signals on the vertical axis. Unlike Figure 12, each graph shows the distribution of only one factor, so the measured values ​​are distributed closely among multiple states. Therefore, it is not easy to determine the state of the pump PM based on the measured values ​​from Figures 13(a) to 13(c).

[0037] To generate a machine learning model, only data from normal conditions (sensor signals and wireless transmission intervals) are collected, and a machine learning model is generated based on the collected data (unsupervised learning).Then, based on the machine learning model, the state of the pump PM can be determined according to subsequent measurement data.In this case, machine learning methods such as the Local Outliner Factor method, the One-Class Support Vector Machine method, and the Isolation Forest method can be used.

[0038] As described above, in the sensing device 1 of the first embodiment, energy is generated by the energy harvesting element 20 and stored in the capacitor C1. When the amount of stored energy reaches or exceeds a predetermined value, the trigger signal generation circuit 30 is activated and measurement signals of the sensors S1 and S2 are transmitted from the wireless transmitter 50 to the wireless receiver 60. By including the controlled commutators M1 and M2 connected as described above, the trigger signal generation circuit 30 can transmit the power stored in the capacitor C1 to the wireless transmitter 50 at a desired timing. Note that, although the above example describes a case where the trigger signal generation circuit 30 is configured with two stages of controlled commutators, it is not necessary to have two stages, and three or more stages of similar controlled commutators can be connected.

[0039] [Second embodiment] Next, a sensing device 1 according to a second embodiment will be described with reference to Fig. 14. The sensing device 1 according to the second embodiment is similar to the first embodiment in that it is a sensing device driven by an energy harvesting element 20, but differs from the first embodiment in that it also has an external power supply or a battery (hereinafter referred to as a battery EB) as a supplementary power source in addition to the energy harvesting element 20. The circuit illustrated in Fig. 14 has a trigger signal generating circuit 30 configured to include a PUT and a thyristor (SCR), similar to the example in Fig. 4, but is not limited to this, and the structures of Figs. 5 and 6 can also be adopted.

[0040] The sensing device 1 of this second embodiment is equipped with a drive signal generation circuit 80 that receives a trigger signal (control signal) from the trigger signal generation circuit 30 and outputs a relay signal (drive signal for driving the wireless transmitter 50) to the wireless transmitter 50, and this drive signal generation circuit 80 is powered by a battery EB.

[0041] The drive signal generation circuit 80 includes a timer IC 81, a relay circuit 82, a transistor 83, a resistor 84, a resistor 85, a capacitor 86, and an output resistor 87. When a trigger signal from the trigger signal generation circuit 30 rises, the transistor 83 becomes conductive. The timer IC 81 counts a predetermined period when the input voltage V2 drops to a specified value, and outputs a voltage V3 that rises thereafter. The transistor 83 and the resistor 84 function as a trigger circuit that generates a trigger signal using the battery EB as a power source when the trigger signal from the trigger signal generation circuit 30 rises. The rise period of the voltage V3 corresponds to the RC time constant determined by the resistor 85 and the capacitor 86. The voltage V3 is output to the relay circuit 82, which causes the voltage across the output resistor 87 (voltage V4) to rise and be input to the wireless transmitter 50.

[0042] The sensing device 1 of this second embodiment also has a battery EB, but the battery EB simply functions as a power supply for driving the timer IC 81 and the relay circuit 82 when the drive signal generation circuit 80 is operating, and functions as a standby power supply when the trigger signal of the trigger signal generation circuit 30 has not yet risen, and its power consumption is extremely small. Therefore, the sensing device 1 of this second embodiment can also achieve the same effects as the first embodiment.

[0043] [others] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0044] 1...Sensing device PM: Pump (sensing target) S1, S2...Sensors 11, 12...A / D converter 20...Energy harvesting element 21...Power generating element 22... Rectifier circuit 30...Trigger signal generating device 31, 33...Gate resistors 32...Output resistance 40...DC / DC converter 50...Radio transmitter 60...Radio receiver 70...Computer 71...Radio transmission interval transmitter 72...Measurement signal acquisition unit 73...Study Department 74...Status determination unit 80...Signal transmission circuit 81...Timer IC 82...Relay circuit 83...Transistor 84...Resistance element 85...Resistance element 86...Capacitor 87...Output resistor element 200...sensor signal transmitting unit 300...sensor signal receiving unit C1...Capacitor EB…Battery M1, M2…Control commutator

Claims

1. a sensor unit that converts a signal output from the object into an electrical signal; a storage element that stores the power generated by the energy harvesting element; a signal generating circuit that is turned on to output a control signal when the amount of charge stored in the storage element reaches a predetermined value or more; a transmitter that transmits the electrical signal from the sensor unit to the outside based on the control signal; Equipped with The signal generating circuit a first controlled commutator receiving an input signal from its anode; a second controlled rectifier having an anode supplied with the input signal and a gate connected to the cathode of the first controlled rectifier; A sensing device comprising:

2. The sensing device of claim 1 , wherein a first threshold voltage of the first control rectifier is smaller than a second threshold voltage of the second control rectifier.

3. 2. The sensing device of claim 1, wherein the first controlled rectifier is a programmable unijunction transistor and the second controlled rectifier is a thyristor.

4. a calculation unit that analyzes a state of the object based on the electrical signal of the sensor unit received from the transmission unit, The sensing device according to claim 1 , wherein the calculation unit analyzes the state of the object based on a relationship between the electrical signal and a transmission interval, which is an interval at which the transmission unit transmits the electrical signal.

5. The calculation unit a learning unit that learns the relationship between the electrical signal and the transmission interval to generate a machine learning model; a state determination unit that determines a state of the object based on the machine learning model and information on the newly obtained electrical signal and the transmission interval; The sensing device of claim 4 further comprising:

6. a drive signal generating circuit that generates a drive signal for driving the transmitter based on the control signal of the signal generating circuit; The drive signal generating circuit a battery or external power source; a trigger circuit that generates a trigger signal based on the control signal and uses the battery or the external power supply as a power source; a timer circuit that operates based on the trigger signal; a relay circuit that is turned on based on an output of the timer circuit and outputs the drive signal to the transmitter; The sensing device of claim 1 , comprising:

7. a calculation unit that analyzes a state of the object based on the electrical signal of the sensor unit received from the transmission unit, The sensing device according to claim 6 , wherein the calculation unit analyzes the state of the object based on a relationship between the electrical signal and a transmission interval, which is an interval at which the transmission unit transmits the electrical signal.

8. The calculation unit a learning unit that learns the relationship between the electrical signal and the transmission interval to generate a machine learning model; a state determination unit that determines a state of the object based on the machine learning model and information on the newly obtained electrical signal and the transmission interval; The sensing device of claim 7 further comprising:

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