Piezoelectric sensor and hand

Abstract

The present application relates to a piezoelectric sensor and a hand, and provides a piezoelectric sensor capable of detecting the sliding of an object relative to an elastic body based on the friction force generated between the object and the elastic body, and a hand provided with the piezoelectric sensor. A piezoelectric sensor characterized by comprising: an elastic body; a piezoelectric element arranged at a position in contact with the elastic body and outputting a voltage signal when deformed along with the deformation of the elastic body; and a detection unit detecting the voltage signal output from the piezoelectric element, wherein when the elastic body relatively moves relative to an object after the elastic body is in contact with the object, the detection unit detects the kinetic friction force generated between the object and the elastic body based on the change of the voltage signal caused by the relative movement of the object.

Description

Technical Field

[0001] This invention relates to piezoelectric sensors and hand parts. Background Technology

[0002] Patent Document 1 discloses a robot with a gripping device equipped with a pressure-sensitive sensor, intended for use in industrial applications such as production lines. The pressure-sensitive sensor is a sensor that outputs pressure as an electrical signal.

[0003] The gripping device includes a pair of openable and closable gripping parts and pressure sensors disposed on the gripping parts. When the gripping parts grip the object, the pressure sensors come into contact with the object and deform, outputting a voltage signal. In the robot's control device, the gripping force of the gripping device is controlled based on this voltage signal.

[0004] This pressure sensor has a first electrode and a second electrode, and an intermediate layer disposed between them, which serves as a piezoelectric element that generates electricity through deformation. Electricity is generated by changes in electrostatic capacitance between each electrode and the intermediate layer. The pressure sensor functions by detecting the amount and presence of this electricity.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-72024

[0006] In the pressure sensor described in Patent Document 1, electricity is generated if the intermediate layer deforms; however, in order to generate electricity, pressure needs to be applied along the direction connecting the first electrode and the second electrode. Therefore, in this pressure sensor, for example, it is possible to detect the holding force experienced when the holding part holds the object being held.

[0007] However, even if the object being held slides relative to the gripping part, the gripping force hardly changes. Therefore, in the pressure sensor described in Patent Document 1, it is difficult to detect the sliding of the object being held relative to the gripping part. Summary of the Invention

[0008] The piezoelectric sensor described in the application examples of the present invention is characterized by comprising:

[0009] Elastomers;

[0010] A piezoelectric element is disposed at a position in contact with the aforementioned elastomer, and outputs a voltage signal when deformed in conjunction with the deformation of the aforementioned elastomer; and

[0011] The detection unit detects the voltage signal output from the piezoelectric element.

[0012] After the elastomer comes into contact with the object, when the elastomer moves relative to the object, the detection unit detects the dynamic friction force generated between the object and the elastomer based on the change in the voltage signal caused by the relative movement of the object.

[0013] The hand involved in the application examples of this invention is characterized in that,

[0014] The piezoelectric sensor described in the application examples of the present invention is provided. Attached Figure Description

[0015] Figure 1 This is a diagram showing the hand involved in the implementation method.

[0016] Figure 2 It is Figure 1 The perspective view shown is an enlarged view of the front end of the finger, and is a perspective view showing the piezoelectric sensor according to the first embodiment in disassembled form.

[0017] Figure 3 Observed from the position on the X-axis Figure 2 The top view of the piezoelectric sensor shown.

[0018] Figure 4 This is an example of an output circuit that amplifies the voltage generated by a piezoelectric element.

[0019] Figure 5 It is from all directions Figure 3 The diagram shown illustrates the deformation mode of the elastomer when a piezoelectric sensor applies force.

[0020] Figure 6 This indicates that in an elastomer... Figure 5 When the deformation mode shown is deformed, from Figure 3 The diagram shows an example of the waveform (output waveform) of the voltage signal output by the piezoelectric element.

[0021] Figure 7 This is a diagram illustrating an example of the output waveform from a piezoelectric element when sliding occurs between an object and an elastic body.

[0022] Figure 8 It was removed. Figure 7 The diagram shows one of the three output waveforms.

[0023] Figure 9 This is a diagram illustrating an example of the output waveform from a piezoelectric element when a piezoelectric sensor is moved along a surface with unevenness.

[0024] Figure 10 This is a side view showing the piezoelectric sensor according to the second embodiment.

[0025] Figure 11 It is from all directions Figure 10 The diagram shown illustrates the deformation mode of the elastomer when a piezoelectric sensor applies force.

[0026] Figure 12 This is a top view of the piezoelectric sensor according to the third embodiment, viewed from the position on the X-axis.

[0027] Figure 13 This indicates that in an elastomer... Figure 5 When the deformation mode shown is deformed, from Figure 12 The diagram shows an example of the waveform (output waveform) of the voltage signal output by the piezoelectric element.

[0028] Figure 14 This is a top view of the piezoelectric sensor according to the fourth embodiment, viewed from the position on the X-axis.

[0029] Figure 15 It is from all directions Figure 14 The diagram shown illustrates the deformation mode of the elastomer when a piezoelectric sensor applies force.

[0030] Figure 16 This is a top view of the piezoelectric sensor according to the fifth embodiment, viewed from the X-axis position.

[0031] Figure 17 This is a top view of the piezoelectric sensor according to the sixth embodiment, viewed from the X-axis position.

[0032] Figure 18 This is a top view of the piezoelectric sensor according to the seventh embodiment, viewed from the X-axis position.

[0033] Figure 19 It is from all directions Figure 18 The diagram shown illustrates the deformation mode of the elastomer when a piezoelectric sensor applies force.

[0034] Figure 20 This indicates that in an elastomer... Figure 19 When the deformation mode shown is deformed, from Figure 18 The diagram shows an example of the waveform (output waveform) of the voltage signal output by the piezoelectric element.

[0035] Figure 21 This is a top view of the piezoelectric sensor according to the eighth embodiment, viewed from the X-axis position.

[0036] Figure 22 This indicates that in an elastomer... Figure 19 When the deformation mode shown is deformed, from Figure 21The diagram shows an example of the waveform (output waveform) of the voltage signal output by the piezoelectric element.

[0037] Figure 23 This is a top view of the piezoelectric sensor according to the ninth embodiment, viewed from the X-axis position.

[0038] Figure 24 This is a top view of the piezoelectric sensor according to the tenth embodiment, viewed from the position on the X-axis.

[0039] Explanation of reference numerals in the attached figures

[0040] 1…Piezoelectric sensor, 1A…Piezoelectric sensor, 1B…Piezoelectric sensor, 1C…Piezoelectric sensor, 1D…Piezoelectric sensor, 1E…Piezoelectric sensor, 1F…Piezoelectric sensor, 1G…Piezoelectric sensor, 1H…Piezoelectric sensor, 1a…Piezoelectric sensor, 2…Elastomer, 3…Restriction part, 6…Holding part, 10…Hand, 11…Base, 12…Slider, 13…Slider, 14…Finger, 15…Finger, 16…Motor, 17…Motor, 21…Contact surface, 31…First wall, 32…First wall, 33…Second wall, 34…Second wall, 41…Piezoelectric element, 42…Piezoelectric element, 43…Piezoelectric element, 44…Piezoelectric element, 49…Output circuit , 141…Holding surface, 151…Holding surface, 201…First surface, 202…Second surface, 203…Third surface, 204…Fourth surface, 205…Fifth surface, 206…Sixth surface, 207…Convex surface, 351…Columnar part, 352…Columnar part, 353…Columnar part, 354…Columnar part, 491…Amplifier, 492…Power supply, 493…Power supply, 494…Detection unit, 495…Measuring unit, 496…Calculation unit, 497…Judgment unit, B…Region, C1…Change point, C2…Change point, C3…Change point, P…Peak value, TM…Time, TL…Allowable range, W…Object, d…Outer diameter, t1…Thickness, t2…Thickness, t3…Thickness. Detailed Implementation

[0041] Hereinafter, preferred embodiments of the piezoelectric sensor and hand of the present invention will be described in detail with reference to the accompanying drawings.

[0042] 1. Hands

[0043] First, the hands involved in the implementation method will be explained.

[0044] Figure 1 This is a diagram showing the hand involved in the implementation method. Furthermore, in Figure 1In this diagram, the X-axis, Y-axis, and Z-axis are defined as three mutually orthogonal axes. Arrows are used to indicate each axis, with the leading edge designated as "positive" and the base edge as "negative." In the following explanations, for example, "x-axis direction" includes both the positive and negative directions of the X-axis. Additionally, in the following explanations, the positive side of the Z-axis may sometimes be designated as "up" and the negative side as "down."

[0045] Figure 1 The hand 10 shown has a pair of fingers 14 and 15. By changing the distance between the fingers 14 and 15, it is possible to clamp and hold the object W from both sides, or to release the object W being held.

[0046] The hand 10 includes a base 11, a pair of sliders 12 and 13 that slide relative to the base 11, fingers 14 and 15 fixed to the sliders 12 and 13, motors 16 and 17 that slide the sliders 12 and 13, and a piezoelectric sensor 1. The structure of the hand is not limited to this.

[0047] Slider 12 and 13 are each capable of sliding relative to base 11 along the x-axis. Additionally, a motor 16 is connected to slider 12, causing slider 12 to slide. Similarly, a motor 17 is connected to slider 13, causing slider 13 to slide.

[0048] By selecting the rotation direction of motors 16 and 17, sliders 12 and 13 can be moved in opposite directions, allowing fingers 14 and 15 to move closer together or further apart. This allows the object W to be grasped or released via fingers 14 and 15. Furthermore, the hand 10 can be configured to move one of fingers 14 and 15 while fixing the other.

[0049] Piezoelectric sensors 1 are respectively provided on the finger portions 14 and 15. The piezoelectric sensors 1 are located on the opposing surfaces of the finger portions 14 and 15, namely the gripping surfaces 141 and 151. When an object W is held between the gripping surfaces 141 and 151, the piezoelectric sensors 1 are positioned between the gripping surfaces 141 and 151 and the object W. Therefore, each piezoelectric sensor 1 receives a reaction force from the object W and outputs a voltage corresponding to that reaction force. Thus, the hand portion 10 has the function of detecting the gripping state of the object W based on the output voltage from the piezoelectric sensors 1. Alternatively, the piezoelectric sensor 1 may be provided only on one of the finger portions 14 and 15.

[0050] The above description pertains to the hand 10, but the piezoelectric sensor 1 can also be used in various devices other than the hand 10, such as tactile sensors, game controllers, remote control controllers, MR (Mixed Reality) controllers, flexible user interfaces, and various ON / OFF sensors.

[0051] 2. The piezoelectric sensor according to the first embodiment

[0052] Next, the piezoelectric sensor according to the first embodiment will be described.

[0053] Figure 2 It is Figure 1 The perspective view shown is an enlarged view of the front end of the finger portion 14, and is a perspective view showing the piezoelectric sensor 1 according to the first embodiment in disassembled form. Figure 3 Observed from the position on the X-axis Figure 2 The top view of the piezoelectric sensor 1 shown.

[0054] Figure 2 and Figure 3 The piezoelectric sensor 1 shown is mounted on the gripping surface 141 of the finger portion 14. The piezoelectric sensor 1 includes an elastic body 2, a limiting part 3, a piezoelectric element 41, and an output circuit 49 having a detection part 494.

[0055] The elastic body 2 is elastic and is configured to contact the gripping surface 141. Alternatively, any object may be sandwiched between the elastic body 2 and the gripping surface 141. Elasticity refers to the property of deforming according to the applied force and returning to its original shape when the force is removed. Therefore, if a force is applied to the elastic body 2, the elastic body 2 deforms, and the force is transmitted to all parts of the elastic body 2.

[0056] Figure 2 and Figure 3 The elastomer 2 shown is formed in a plate shape extending in the YZ plane and has 6 faces. The two faces that intersect the Y-axis are designated as the first face 201 and the second face 202, the two faces that intersect the X-axis are designated as the third face 203 and the fourth face 204, and the two faces that intersect the Z-axis are designated as the fifth face 205 and the sixth face 206.

[0057] The third surface 203 and the fourth surface 204 are two main surfaces in the elastic body 2 that have a face-back relationship. The third surface 203 faces the object W, and the fourth surface 204 is fixed to the holding surface 141. Figure 3 The third surface 203 and the fourth surface 204 shown are both rectangular in shape. Additionally, in Figure 2 In the elastic body 2 shown, the central portion of the third surface 203 becomes a convex surface 207. Therefore, when the third surface 203 comes into contact with the object W, the convex surface 207 can make preferential contact. As a result, when force is applied to the elastic body 2, the force can be transmitted from the central portion of the third surface 203 towards the periphery.

[0058] Examples of constituent materials of elastomer 2 include rubber, elastomers, and foaming resins. Among these, examples of rubber include polyisobutylene, polyisoprene, chloroprene rubber, butyl rubber, silicone rubber, fluororubber, acrylic rubber, polyurethane rubber, ethylene propylene rubber, cis-butadiene rubber, acrylonitrile butadiene rubber, and styrene butadiene rubber.

[0059] Figure 2 and Figure 3 The limiting part 3 shown is provided on the gripping surface 141, forming a frame shape that surrounds the elastic body 2. The inner surface of the limiting part 3 contacts the outer surface of the elastic body 2. That is, when the third surface 203 of the elastic body 2 is viewed from above, the elastic body 2 is housed inside the limiting part 3. In addition, there may be some gaps between the limiting part 3 and the elastic body 2. Furthermore, any object may be clamped between the limiting part 3 and the gripping surface 141.

[0060] The limiting part 3 has two first wall portions 31 and 32 extending along the Z-axis and two second wall portions 33 and 34 extending along the Y-axis.

[0061] The thickness t1 of each of the first wall portions 31 and 32 is greater than the thickness t2 of the second wall portions 33 and 34. Therefore, the bending stiffness of the first wall portions 31 and 32 is higher than that of the second wall portions 33 and 34. As a result, the first wall portions 31 and 32 are not easily deformed even when pressed by the elastic body 2. That is, the first wall portions 31 and 32 face the first surface 201 and the second surface 202 of the elastic body 2 in its natural state. Specifically, the first wall portions 31 and 32 are in contact with the first surface 201 and the second surface 202 of the elastic body 2, or are adjacent to it through a small gap. Therefore, when the elastic body 2 is subjected to force and attempts to deform in the Y-axis direction, this deformation is restricted. Furthermore, the thickness of the first wall portions 31 and 32 is referred to as the length in the Y-axis direction.

[0062] The thicknesses of the second wall portions 33 and 34 are each thinner than those of the first wall portions 31 and 32. Therefore, the second wall portions 33 and 34 have lower bending stiffness compared to the first wall portions 31 and 32. As a result, the second wall portions 33 and 34 are easily deformed when pressed by the elastic body 2. That is, the second wall portions 33 and 34 are in contact with the elastic body 2 in its natural state or are adjacent to it through a small gap. Therefore, when the elastic body 2 is subjected to force and attempts to deform in the Z-axis direction, the second wall portions 33 and 34 also deform along the Z-axis, resulting in bending deformation in the Z-axis direction. At this time, the two ends of the second wall portions 33 and 34 in the Y-axis direction, due to their connection with the first wall portions 31 and 32, hardly shift. Furthermore, the thickness of the second wall portions 33 and 34 refers to their length in the Z-axis direction.

[0063] The material of the limiting part 3 is not specifically limited; for example, resin material, ceramic material, metal material, etc. can be cited.

[0064] The thickness of the first wall portions 31 and 32 is appropriately set according to the constituent material, but as an example, it is preferably 0.5 mm or more and 20 mm or less, and more preferably 1 mm or more and 10 mm or less. Thus, the first wall portions 31 and 32 have sufficient bending rigidity and are particularly resistant to deformation even when force is applied to the elastic body 2.

[0065] The thickness of the second walls 33 and 34 is appropriately set according to the constituent materials, but as an example, it is preferably 60% or less of the thickness of the first walls 31 and 32, and more preferably 5% or more and 40% or less. Thus, the second walls 33 and 34 have sufficient flexibility, and if force is applied to the elastic body 2, they will easily deform. Therefore, deformation is easily transmitted to the piezoelectric element 41, which can improve the sensitivity of the piezoelectric sensor 1.

[0066] Although not shown, the piezoelectric element 41 includes a piezoelectric body and a pair of electrodes disposed via the piezoelectric body. For example, when the piezoelectric body is bent or deformed, a voltage is generated between the electrodes through the piezoelectric effect. By detecting the voltage output from the piezoelectric element 41, the direction and magnitude of the applied force can be determined.

[0067] Figure 2 The piezoelectric element 41 shown is disposed between the fifth surface 205 of the elastic body 2 and the second wall portion 33. Furthermore, when the second wall portion 33 undergoes bending deformation along with the deformation of the elastic body 2, the piezoelectric element 41 also undergoes bending deformation. In this way, by fixing a portion of the piezoelectric element 41 to the second wall portion 33, damage to the piezoelectric element 41 caused by bending deformation can be suppressed. That is, by reinforcing the piezoelectric element 41 with the second wall portion 33, the piezoelectricity of the piezoelectric element 41 is less likely to decrease even when it undergoes repeated bending deformation in a short period. In addition, the piezoelectric element 41 easily returns to its original shape when the load is removed. That is, the following ability of the piezoelectric element 41 relative to the deformation of the elastic body 2 is improved. Therefore, it is possible to suppress the decrease in force detection accuracy.

[0068] Examples of piezoelectric materials that constitute piezoelectric bodies include piezoelectric ceramics such as lead zirconate titanate (PZT), barium titanate, and lead titanate, as well as piezoelectric plastics such as polyvinylidene fluoride and polylactic acid.

[0069] Furthermore, the piezoelectric effect is anisotropic, depending on the piezoelectric constant of the piezoelectric material. In this embodiment, the piezoelectric material is selected such that a voltage is generated between the electrodes in accordance with the bending deformation produced in the Z-axis direction. Therefore, the direction and magnitude of the force acting on the elastic body 2 can be determined based on the output from the piezoelectric element 41. For example, dpiezoelectric constant can be used to represent this piezoelectricity.31 wait.

[0070] Materials used to form electrodes include, for example, monomers or alloys of Al, Cu, Ni, Ag, Au, etc.

[0071] Figure 4 This is an example of an output circuit that amplifies the voltage generated by the piezoelectric element 41.

[0072] Figure 4 The output circuit 49 shown includes an amplifier 491, a power supply 492, a power supply 493, and a detection unit 494. A piezoelectric element 41 is connected between the inverting and non-inverting input terminals of the amplifier 491. The power supply 492 is connected to the non-inverting input terminal. The power supply 493 is connected to the power supply terminal of the amplifier 491. The detection unit 494 is connected to the output terminal of the amplifier 491.

[0073] In such an output circuit 49, the voltage generated by the piezoelectric element 41 is amplified and output as a voltage signal with a large amplitude. Furthermore, as... Figure 4 As shown, when power supply 492 is connected to the input terminal of amplifier 491, the input signal is offset by power supply 492. Therefore, the detection unit 494 outputs an offset voltage, that is, a voltage signal that increases or decreases according to the reference voltage. Furthermore, power supply 492 can be set only as needed and can also be omitted.

[0074] The detection unit 494 has the functions of detecting the time change of the voltage signal based on the increase or decrease of the reference voltage, and determining whether there is sliding between the object W and the piezoelectric sensor 1 based on the voltage value. Figure 2 and Figure 4 The detection unit 494 shown, as an example, includes a measurement unit 495, an arithmetic unit 496, and a judgment unit 497. The measurement unit 495 measures the amplitude of the voltage signal output from the amplifier 491. The arithmetic unit 496 calculates the increase or decrease of the voltage signal amplitude relative to a reference voltage. The judgment unit 497 compares the calculation result of the arithmetic unit 496, for example, with a preset allowable range, and outputs the result.

[0075] At least a portion of the detection unit 494 is composed of hardware including a processor, memory, and external interfaces. For example, a CPU (Central Processing Unit) can be used as the processor. The detection unit 494 performs its functions by reading and executing a program stored in memory. However, the hardware structure is not limited to this; it can also be a structure incorporating LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or the like.

[0076] Furthermore, the output circuit structure of the piezoelectric sensor 1 is not limited to... Figure 4 The circuit structure shown could also be, for example, a circuit that includes a charge amplifier.

[0077] Figure 5 It is from all directions Figure 3 The diagram shown illustrates the deformation mode of the elastic body 2 when the piezoelectric sensor 1 applies force. Figure 6 This indicates that in the elastomer 2 with Figure 5 When the deformation mode shown is deformed, from Figure 3 A diagram showing an example of the waveform (output waveform) of the voltage signal output by the piezoelectric element 41. Furthermore, in Figure 6 The example shown illustrates the waveform of the relative potential with respect to a reference voltage.

[0078] When no force is applied to the piezoelectric sensor, since the elastic body 2 maintains its natural state, therefore... Figure 5 As shown in the upper left figure, the piezoelectric element 41 does not deform. Therefore, theoretically, the piezoelectric element 41 does not generate voltage.

[0079] If a downward force is applied to piezoelectric sensor 1, then as Figure 5 As shown by the arrow in the upper right figure, a downward pulling force is applied to the third surface 203 of the elastic body 2. Consequently, the elastic body 2 deforms by being pulled downwards, and the piezoelectric element 41 undergoes downward bending deformation. At this time, as... Figure 6 As shown, the piezoelectric element 41 outputs a voltage signal that is negative relative to a reference voltage. That is, it outputs a voltage signal that decreases from the reference voltage. This allows determination that a downward force has been applied to the piezoelectric sensor 1. Furthermore, the output direction of the voltage signal relative to the reference voltage is determined by the polarization direction of the piezoelectric element and the circuit structure; therefore, the output direction of the voltage signal can also be opposite to that described above. In this case, the following outputs also become the opposite.

[0080] Furthermore, when the object W is held in the hand 10 and is moved to keep the object W in the air, the weight of the object W exerts a downward force on the piezoelectric sensor 1. Therefore, the state in which the hand 10 lifts the object W can be determined based on the output waveform from the piezoelectric element 41.

[0081] If an upward force is applied to piezoelectric sensor 1, then as Figure 5 As shown by the arrow in the lower left figure, an upward pulling force is applied to the third surface 203 of the elastic body 2. Consequently, the elastic body 2 deforms by being pulled upwards, and the piezoelectric element 41 undergoes upward bending deformation. At this time, as... Figure 6 As shown, the piezoelectric element 41 outputs a voltage signal that is positive relative to a reference voltage. That is, it outputs a voltage signal that increases from the reference voltage. Therefore, it is possible to determine that an upward force has been applied to the piezoelectric sensor 1.

[0082] Furthermore, while keeping the object W held by the hand 10 in place, moving the hand 10 to press the lower surface of the object W against the object applies an upward force to the piezoelectric sensor 1. Therefore, the state in which the hand 10 presses the object W against the object can be determined based on the output waveform from the piezoelectric element 41.

[0083] If a pressing force is applied to the piezoelectric sensor 1, that is, ... Figure 5 The force exerted by the elastic body 2 shown, pressing from the positive X-axis side to the negative X-axis side, is as follows: Figure 5 As shown by the arrow in the lower right figure, the third surface 203 of the elastic body 2 undergoes deformation extending in the vertical direction. Consequently, because the elastic body 2 extends in the vertical direction, the piezoelectric element 41 undergoes upward bending deformation. However, the amount of bending deformation is smaller compared to the case where the aforementioned upward force is applied. Therefore, as... Figure 6 As shown, the piezoelectric element 41 outputs a positive voltage signal with a voltage value relatively small compared to the reference voltage. Therefore, it is possible to determine the direction of the pressure applied to the piezoelectric sensor 1.

[0084] Furthermore, if the object W is held by the hand 10, the reaction force from the object W will press the piezoelectric sensor 1 against the holding surface 141. Therefore, the state of the hand 10 holding the object W can be determined based on the output waveform from the piezoelectric element 41.

[0085] The above examples illustrate the deformation modes, but the deformation directions of the up and down directions can also be other than those.

[0086] Here, we assume that the object W held by hand 10 is pressed forcefully against the ground, for example. In this case, Figure 5 The upward arrow shown corresponds to the direction of the reaction force exerted on the object W from the ground when the hand 10 presses the object W onto the ground. This reaction force is a deformation force that deforms the elastic body 2. Accompanying the deformation of the elastic body 2, the piezoelectric element 41 undergoes bending deformation, thus enabling the detection of the direction and magnitude (bending radius) of the bending deformation.

[0087] On the other hand, friction is generated between the object W and the elastic body 2. With the deformation force and friction force in balance, the positional relationship between the object W and the hand 10 is maintained. In this case, no slippage occurs between the object W and the piezoelectric sensor 1.

[0088] Subsequently, if the hand 10 is moved downwards as a whole, the force pressing the object W onto the ground gradually increases. Furthermore, if the deformation force exceeds the frictional force, sliding occurs between the object W and the elastic body 2. The frictional force just before sliding occurs is defined as "static friction." Since the frictional force just before sliding occurs is equal to the deformation force, static friction can be detected by the piezoelectric element 41. When sliding occurs, the frictional force decreases compared to the static frictional force. The frictional force at the time of sliding is defined as "dynamic friction." Since dynamic friction is smaller than static friction, the voltage signal output from the piezoelectric element 41 can distinguish between the occurrence of static friction and the occurrence of dynamic friction. Furthermore, since the frictional force at the time of sliding is also balanced with the deformation force, dynamic friction can be detected by the piezoelectric element 41. In addition, dynamic friction is continuously detected during sliding, so the output waveform from the piezoelectric element 41 is a waveform containing the peak value corresponding to the static frictional force and the voltage value corresponding to the dynamic frictional force observed subsequently.

[0089] Figure 7 This is a diagram showing an example of the output waveform from the piezoelectric element 41 when sliding occurs between the object W and the elastic body 2. Figure 7 The horizontal axis represents time, and the vertical axis represents the output voltage from the piezoelectric element 41. Additionally, in Figure 7 In the figure, the output waveforms of the holding force of the object W, i.e. the distance between the piezoelectric sensor 1 and the object W, are superimposed as they change in three stages.

[0090] Figure 7 The output waveform shown includes a peak P that appears shortly after the effective voltage value is observed, and a region B in which a voltage value lower than the peak P is observed thereafter.

[0091] The peak value P corresponds to the bending deformation of the piezoelectric element 41 when static friction is generated. Similarly, region B corresponds to the bending deformation of the piezoelectric element 41 when kinetic friction is generated. As described above, since kinetic friction is smaller than static friction, region B is lower than the peak value P. Therefore, if region B is detected after the peak value P is detected, it can be determined that sliding has occurred between the object W and the elastic body 2. In other words, the piezoelectric sensor 1 can detect the kinetic friction corresponding to region B based on the presence of both the peak value P and region B, and thus detect the presence or absence of sliding.

[0092] Figure 8 It was removed. Figure 7 The diagram shows one of the three output waveforms. When determining whether slippage exists, the judgment unit 497, included in the detection unit 494, first detects the peak value P. Since the peak value P is a maximum value, it can be determined, for example, based on the presence or absence of the maximum value. Next, the judgment unit 497 sets an allowable range TL based on the height of the peak value P. The allowable range TL is preferably, for example, a range of 20% or more and less than 100% of the height of the peak value P, and more preferably a range of 40% or more and less than 100%. Next, the judgment unit 497 can determine whether slippage exists based on the time TM during which region B continuously falls within this allowable range TL. The time TM is appropriately set according to the type of object W, the size of the elastic body 2, the level of noise, etc., but as an example, it is preferably 0.1 seconds or more, and more preferably 0.5 seconds or more. Furthermore, the judgment process is not limited to this.

[0093] The presence or absence of slippage can be detected as described above. Therefore, when performing an action such as pressing an object W held by the hand 10 onto the ground, the piezoelectric sensor 1 can detect any signs that the object W is about to fall off the hand 10. As a result, the action of the hand 10 can be changed before the object W falls off. That is, the hand 10 can take an avoidance action to prevent the object W from falling off.

[0094] Furthermore, the detection of the presence or absence of sliding, as described above, does not depend on the holding force of the object W. Figure 7 As mentioned above, the output waveforms are shown when the magnitude of the holding force is changed in three stages. Even when the holding force is changed, the peak P and region B can be identified in each output waveform.

[0095] Furthermore, the detection of the presence or absence of sliding, as described above, does not depend on the relative velocity between the object W and the elastic body 2 during sliding. Although not illustrated, even if the relative velocity changes, the peak P and region B can be identified in the output waveform from the piezoelectric element 41.

[0096] Furthermore, the object W is not limited to Figure 1The image shows an object that can be held. For example, when the piezoelectric sensor 1 is brought into direct contact with the ground (the object) and moved along the ground, it can also obtain... Figure 7 The output waveform is shown. In this case, the static and dynamic friction forces generated between the ground and the elastic body 2 can be detected, and the presence or absence of sliding can be detected based on this. Furthermore, when the ground has unevenness, the output waveform produces a change accompanying the unevenness.

[0097] Figure 9 This is a diagram showing an example of the output waveform from the piezoelectric element 41 when the piezoelectric sensor 1 is moved along a surface with unevenness. Figure 9 The horizontal axis represents time, and the vertical axis represents the output voltage from the piezoelectric element 41. Additionally, in Figure 9 In the diagram, the output waveforms of the distance between the ground and the piezoelectric sensor 1, i.e. the force exerted on the piezoelectric sensor 1 from the ground, are superimposed in two stages.

[0098] Figure 9 The output waveform shown also includes a peak value P and a region B where the voltage value is lower than the peak value P. Therefore, by using a voltage waveform based on... Figure 9 The output waveform shown can also detect whether there is sliding between the piezoelectric sensor 1 and objects such as the ground that are not being held.

[0099] in addition, Figure 9 The output waveform shown reflects the unevenness of the ground. The common features identified in both output waveforms are... Figure 9 The points of change shown are C1, C2, and C3. The times when these points of change are observed correspond to the times when the piezoelectric sensor 1 passes over the unevenness of the ground. Thus, the piezoelectric sensor 1 can capture not only the presence or absence of sliding, but also shape changes such as unevenness on the surface of the object W. That is, the piezoelectric sensor 1 can indirectly capture unevenness based on the change in kinetic friction when passing over unevenness.

[0100] As described above, the piezoelectric sensor 1 according to this embodiment includes an elastic body 2, a piezoelectric element 41, and a detection unit 494. The piezoelectric element 41 is disposed at a position in contact with the elastic body 2 and outputs a voltage signal when it deforms along with the deformation of the elastic body 2. The deformation of the piezoelectric element 41 refers to the change in shape of the piezoelectric element 41 from when the elastic body 2 is not deformed. Furthermore, after the elastic body 2 comes into contact with the object W, when the elastic body 2 moves relative to the object W, the detection unit 494 detects the dynamic friction force generated between the object W and the elastic body 2 based on the change in the voltage signal caused by the relative movement of the object W.

[0101] Based on this piezoelectric sensor 1, the dynamic friction force generated between the object W and the elastic body 2 can be detected. Specifically, when the elastic body 2 deforms in accordance with the object W, the change in the amount of deformation can be captured by the piezoelectric element 41, thus distinguishing between static and dynamic friction forces for detection. Therefore, dynamic friction force can be detected, and the presence or absence of sliding between the object W and the elastic body 2 can be detected based on a comparison with static friction force. As a result, for example, a hand 10 that can easily determine whether it stably holds the object W can be realized.

[0102] Furthermore, since the force is transmitted to the piezoelectric element 41 via the elastomer 2, it is possible to suppress the direct application of impact to the piezoelectric element 41. As a result, the piezoelectric element 41 is less prone to damage.

[0103] Furthermore, the hand 10 described in the above embodiment is equipped with the piezoelectric sensor 1 as described above.

[0104] When using piezoelectric sensor 1 Figure 1 In the case of the hand 10 shown, for example, it is possible to not only hold the object W, but also detect whether or not sliding occurs between the held object W and the elastic body 2. Furthermore, in the hand 10 equipped with the piezoelectric sensor 1 described above, in addition to holding the object W, it is possible to determine, for example, the state of lifting the object W and the state of pressing the object W against an object. Furthermore, the piezoelectric sensor 1 is configured to contact the elastic body 2 with the object W. Therefore, even when the piezoelectric sensor 1 contacts the object W, it is not easy to generate a large impact, so even if the object W has low rigidity, it is not easy to damage the object W, and the object W can be held by the hand 10. In addition, damage to the piezoelectric element 41 accompanying the impact can be suppressed. Furthermore, the hand 10 may also be equipped with the piezoelectric sensor according to the embodiments described later.

[0105] Furthermore, in the piezoelectric sensor 1 of this embodiment, when the elastomer 2 comes into contact with the object W, the detection unit 494 detects the static friction force generated between the object W and the elastomer 2 based on the voltage signal output from the piezoelectric element 41.

[0106] Based on such a piezoelectric sensor 1, the elasticity of the elastomer 2 can be utilized to effectively generate a persistent static friction force between the object W and the elastomer 2. Therefore, the static friction force can be stably detected based on the voltage signal output from the piezoelectric element 41, regardless of the surface condition of the object W.

[0107] Furthermore, in the piezoelectric sensor 1 according to this embodiment, as described above, the elastic body 2 has a first surface 201. Additionally, the piezoelectric sensor 1 includes a limiting portion 3, which is disposed facing the first surface 201 of the elastic body 2 and limits the deformation of the elastic body 2. Moreover, a portion of the piezoelectric element 41 is fixed to the limiting portion 3.

[0108] Based on this structure, when force is applied to the elastic body 2 from multiple different directions, such as upward, downward, and pressing, the direction of force application can be detected. Therefore, in the hand 10 equipped with this piezoelectric sensor 1, in addition to holding the object W, it is possible to determine, for example, whether the object W is lifted or pressed against an object. Thus, the hand 10 can be moved appropriately according to these different states, improving convenience.

[0109] Furthermore, in the piezoelectric sensor 1 according to this embodiment, the elastomer 2 has a second surface 202 opposite to the first surface 201. Furthermore, the limiting portion 3 includes two first wall portions 31 and 32, and two second wall portions 33 and 34. The two first wall portions 31 and 32 are positioned facing the first surface 201 and facing the second surface 202, respectively. The two second wall portions 33 and 34 connect the first wall portions 31 and 32, and are thinner than the first wall portions 31 and 32. Furthermore, the piezoelectric element 41 is fixed to the second wall portion 33.

[0110] With this structure, since the piezoelectric element 41 is fixed to the second wall portion 33, the durability of the piezoelectric element 41 is improved, and the following of the deformation of the piezoelectric element 41 relative to the elastomer 2 is improved.

[0111] Furthermore, the elastomer 2 has a third surface 203 forming a rectangular shape. Furthermore, the elastomer 2 is formed into a plate shape with this third surface 203 as the main surface.

[0112] With this structure, since the relatively wide third surface 203 faces the object W, a wider contact area between the object W and the elastic body 2 can be ensured. This allows for the application of a larger force to the elastic body 2, increasing the displacement of the fifth surface 205 facing the piezoelectric element 41. Consequently, the sensitivity of the piezoelectric sensor 1 can be further improved.

[0113] Furthermore, the shape of the third face 203 is not limited to a rectangle; it can also be other shapes, such as a square or a polygon. Additionally, it can be a shape with rounded or chamfered corners.

[0114] In addition, such as Figure 2 As shown, the elastomer 2 has a convex curved surface 207 as the contact surface that contacts the object W. The convex curved surface 207 is located away from the piezoelectric element 41.

[0115] With this structure, even if the convex surface 207 comes into contact with the object W, contact between the piezoelectric element 41 and the object W can be avoided. This prevents damage to the piezoelectric element 41. Furthermore, because the elastic body 2 is elastic, even if the piezoelectric element 41 is positioned away from the convex surface 207, the frictional force generated between the elastic body 2 and the object W will be effectively converted into deformation of the piezoelectric element 41. Therefore, frictional force can be efficiently detected in the piezoelectric element 41. As a result, a piezoelectric sensor 1 with excellent sensitivity is achieved.

[0116] In addition, the elastomer 2 can replace the convex surface 207 and have a convex surface of any shape. However, if it is a convex surface 207, it is easy to realize a piezoelectric sensor 1 that can detect forces applied from all directions well.

[0117] 3. The piezoelectric sensor involved in the second embodiment

[0118] Next, the piezoelectric sensor according to the second embodiment will be described.

[0119] Figure 10 This is a side view showing the piezoelectric sensor according to the second embodiment. Furthermore, in Figure 10 In this diagram, we define the x-axis, y-axis, and z-axis as three mutually orthogonal axes. Arrows are used to represent each axis, with the leading edge designated as "positive" and the base edge as "negative." In the following explanations, for example, "x-axis direction" includes both the positive and negative directions of the x-axis. Additionally, in the following explanations, sometimes the positive z-axis is designated as "up," the negative z-axis as "down," the positive y-axis as "right," and the negative y-axis as "left."

[0120] The second embodiment will be described below, but the description will focus on the differences from the first embodiment, and descriptions of the same items will be omitted. Furthermore, in each figure, the same reference numerals will be used to label structures identical to those in the first embodiment.

[0121] The piezoelectric sensor 1a according to the second embodiment is the same as the piezoelectric sensor 1 according to the first embodiment, except that the shape of the elastomer 2 and the arrangement of the piezoelectric element 41 are different, and that a holding part 6 is provided instead of the limiting part 3.

[0122] Figure 10 The piezoelectric sensor 1a shown includes an elastomer 2, a piezoelectric element 41, and a holding part 6. Furthermore, although... Figure 10 Although not shown in the figure, the piezoelectric sensor 1a also has an output circuit 49 with the detection unit 494 described above.

[0123] Figure 10The elastomer 2 shown is formed in a cylindrical shape centered on an axis parallel to the X-axis. The elastomer 2 possesses elasticity inherent to the material itself, and also elasticity derived from its cylindrical shape. Therefore, the elastomer 2 exhibits good elasticity in the yz plane.

[0124] in addition, Figure 10 The portion of the outer surface of the cylinder of the elastomer 2 shown, on the negative Z-axis side, is the contact surface 21 that contacts the object W. In the piezoelectric sensor 1a, the function is well achieved by bringing this contact surface 21 into contact with the object W.

[0125] Figure 10 The retaining part 6 shown holds the upper part of the elastic body 2 at its lower part. The upper part of the retaining part 6 is fixed to the fingers 14 and 15 of the hand part 10, for example. As a result, the distance between the elastic body 2 and the object W can be adjusted according to the destination.

[0126] Figure 10 The piezoelectric element 41 shown is disposed on the outer surface of the elastic body 2 away from the contact surface 21. Specifically, the piezoelectric element 41 is disposed on the outer surface of the elastic body 2 between the holding portion 6 and the position closest to the positive y-axis.

[0127] With this structure, even if the contact surface 21 of the elastomer 2 comes into contact with the object W, contact between the piezoelectric element 41 and the object W can be avoided. This prevents damage to the piezoelectric element 41. Furthermore, since the elastomer 2 is cylindrical, even if the piezoelectric element 41 is positioned away from the contact surface 21, the frictional force generated between the elastomer 2 and the object W is effectively converted into deformation of the piezoelectric element 41. Therefore, frictional force can be efficiently detected within the piezoelectric element 41. As a result, a highly sensitive piezoelectric sensor 1a is achieved.

[0128] Figure 11 It is from all directions Figure 10 The diagram shown illustrates the deformation mode of the elastic body 2 when the piezoelectric sensor 1a applies force.

[0129] When no force is applied to the piezoelectric sensor 1a, the elastic body 2 remains in its natural state. Therefore, the piezoelectric element 41, as Figure 11 As shown in the figure above, maintain the initial shape. Set the output voltage from the piezoelectric element 41 in this state as the initial state.

[0130] If an upward force is applied to the piezoelectric sensor 1a, then as Figure 11As shown in the middle figure, the elastic body 2 is deformed in a flattened manner in the vertical direction. As a result, the bending radius of the piezoelectric element 41 decreases, and the output voltage from the piezoelectric element 41 changes from its initial state. Therefore, based on this, it is possible to determine the state in which an upward force is applied. Such a state in which only an upward force is applied corresponds, for example, to the state in which static friction is generated between the object W and the elastic body 2.

[0131] If we start from the state where the elastic body 2 is deformed under pressure in the vertical direction, such as Figure 11 As shown in the figure below, when a force is applied to the left of the piezoelectric sensor 1a, the elastic body 2 deforms such that the holding part 6 and the contact surface 21 are offset in the left-right direction (y-axis direction). As a result, the bending radius of the piezoelectric element 41 increases compared to when an upward force is applied to the piezoelectric sensor 1a. Consequently, it is possible to determine the state in which a leftward force is applied to the piezoelectric sensor 1a. This state of a leftward force application corresponds, for example, to a state in which kinetic friction is generated between the object W and the elastic body 2.

[0132] As described above, the piezoelectric sensor 1a according to this embodiment, like the first embodiment, can detect both static and kinetic friction. Therefore, in the piezoelectric sensor 1a, it is also possible to obtain static and kinetic friction forces corresponding to each other. Figures 7-9 The same output waveform. Therefore, in this embodiment, the same effect as in the first embodiment can be obtained.

[0133] Furthermore, the outer diameter d of the elastomer 2 in its natural state is not particularly limited, but is preferably 10 mm or more and 100 mm or less, and more preferably 20 mm or more and 80 mm or less.

[0134] In addition, the thickness t3 of the elastomer 2 is not particularly limited, but is preferably 1 mm or more and 10 mm or less, and more preferably 2 mm or more and 8 mm or less.

[0135] 4. The piezoelectric sensor involved in the third embodiment

[0136] Next, the piezoelectric sensor according to the third embodiment will be described.

[0137] Figure 12 This is a top view of the piezoelectric sensor according to the third embodiment, viewed from the position on the X-axis.

[0138] The third embodiment will be described below, but the description will focus on the differences from the first embodiment, and descriptions of the same items will be omitted. Furthermore, in each figure, the same reference numerals will be used to label structures identical to those in the first embodiment.

[0139] The piezoelectric sensor 1A according to the third embodiment is the same as the piezoelectric sensor 1 according to the first embodiment, except that it has a piezoelectric element 42 in addition to a piezoelectric element 41.

[0140] like Figure 12 As shown, the piezoelectric element 42 is disposed between the elastic body 2 and the second wall portion 34. Furthermore, when the second wall portion 34 undergoes bending deformation along with the deformation of the elastic body 2, the piezoelectric element 42 also undergoes bending deformation in the same way. The structure of the piezoelectric element 42 is the same as that of the piezoelectric element 41.

[0141] Furthermore, the relationship between the bending deformation direction of piezoelectric element 42 and the output waveform from piezoelectric element 42 can be the same as the relationship between the bending deformation direction of piezoelectric element 41 and the output waveform from piezoelectric element 41, but preferably the opposite. That is, when piezoelectric element 42 is bent in the same direction as piezoelectric element 41, it is preferable that the signs of the output voltage signals are different. Therefore, the direction of the force applied to the elastic body 2 can be determined more accurately based on the output waveforms from the two piezoelectric elements 41 and 42. As a result, when sliding occurs between the object W and the elastic body 2, it is possible to more accurately determine whether the object W slides upwards or downwards relative to the elastic body 2.

[0142] Figure 13 This indicates that in the elastomer 2 with Figure 5 When the deformation mode shown is deformed, from Figure 12 A diagram showing an example of the waveform (output waveform) of the voltage signal output by the piezoelectric elements 41 and 42. Furthermore, Figure 13 The output waveform shown is the waveform when the piezoelectric elements 41 and 42 are bent in the same direction, and the system is set to output voltage signals with different signs. Additionally, in Figure 13 The example shown illustrates the waveform of the relative potential with respect to a reference voltage.

[0143] If a downward force is applied to the piezoelectric sensor 1A, the piezoelectric elements 41 and 42 will bend downwards. Therefore, voltage signals with different signs will be output from the piezoelectric elements 41 and 42. For example, in... Figure 13 In the example shown, a downward force applied to the piezoelectric sensor 1A can be determined based on the fact that the sign of the voltage signal output from piezoelectric element 41 is negative relative to the reference voltage, and the sign of the voltage signal output from piezoelectric element 42 is positive relative to the reference voltage. Furthermore, based on this state of applied downward force, the static and dynamic frictional forces generated between the object W and the elastic body 2 can be detected. Moreover, the direction of the voltage signal relative to the reference voltage is determined by the polarization direction of the piezoelectric element and the circuit structure; therefore, the output direction can also be the opposite of that described above. In this case, the subsequent output will also be the opposite result.

[0144] If an upward force is applied to the piezoelectric sensor 1A, the piezoelectric elements 41 and 42 will bend upwards. Therefore, voltage signals with different signs will be output from the piezoelectric elements 41 and 42. For example, in... Figure 13 In the example shown, an upward force applied to the piezoelectric sensor 1A can be determined based on the fact that the sign of the voltage signal output from the piezoelectric element 41 is positive relative to the reference voltage, and the sign of the voltage signal output from the piezoelectric element 42 is negative relative to the reference voltage. Furthermore, based on this state of an applied upward force, the static and dynamic frictional forces generated between the object W and the elastic body 2 can be detected.

[0145] If a pressing force is applied to the piezoelectric sensor 1A, that is, ... Figure 12 When the elastic body 2 is pressed from the positive X-axis to the negative X-axis, the piezoelectric element 41 undergoes an upward bending deformation, and the piezoelectric element 42 undergoes a downward bending deformation. Therefore, voltage signals of the same sign are output from the piezoelectric elements 41 and 42. Thus, the direction of the pressing force applied to the piezoelectric sensor 1A can be determined.

[0146] In this third embodiment, the same effect as in the first embodiment can be obtained.

[0147] As described above, when viewed from above on the third surface 203, the elastic body 2 of the piezoelectric sensor 1A has a fifth surface 205 and a sixth surface 206, which are two opposing surfaces corresponding to the two opposing sides. Furthermore, piezoelectric elements 41 and 42 are positioned facing the fifth surface 205 and the sixth surface 206.

[0148] Based on this structure, for example, by making the signs of the voltage signals output when bending in the same direction different in the piezoelectric elements 41 and 42, it is possible to set the voltage signals output from the piezoelectric elements 41 and 42 as signals where one increases from the reference voltage and the other decreases from the reference voltage. Thus, the difference in waveforms of the voltage signals output from the piezoelectric elements 41 and 42 becomes clearer. As a result, even if noise enters the voltage signal, for example, the direction of the force applied to the elastic body 2 can be easily determined.

[0149] 5. The piezoelectric sensor according to the fourth embodiment

[0150] Next, the piezoelectric sensor according to the fourth embodiment will be described.

[0151] Figure 14 This is a top view of the piezoelectric sensor according to the fourth embodiment, viewed from the position on the X-axis.

[0152] The fourth embodiment will now be described, but the description will focus on the differences from the first embodiment, and descriptions of identical items will be omitted. Furthermore, in each figure, structures identical to those in the first embodiment will be labeled with the same reference numerals.

[0153] In the piezoelectric sensor 1B according to this embodiment, the elastic body 2 has a second surface 202 opposite to the first surface 201. In addition, the limiting part 3 has two first wall portions 31 and 32. The first wall portion 31 is disposed at a position facing the first surface 201 of the elastic body 2, and the first wall portion 32 is disposed at a position facing the second surface 202 of the elastic body 2.

[0154] That is, in the first embodiment described above, the limiting part 3 has two first wall portions 31 and 32, and two second wall portions 33 and 34. In contrast, in this embodiment, the second wall portions 33 and 34 are omitted. As a result, in this embodiment, as... Figure 14 As shown, the limiting part 3 consists of only two first wall parts 31 and 32.

[0155] Furthermore, in the first embodiment described above, the piezoelectric element 41 is fixed to the second wall portion 33, while in this embodiment, the piezoelectric element 41 is fixed in a manner that connects the first walls 31 and 32. Specifically, the piezoelectric element 41 is disposed at a position facing the fifth surface 205 of the elastic body 2, and the positive Y-axis end of the piezoelectric element 41 is fixed to the first wall portion 31, while the negative Y-axis end of the piezoelectric element 41 is fixed to the first wall portion 32.

[0156] Based on this structure, similar to the first embodiment, the deformation of the elastomer 2 is restricted by two first wall portions 31 and 32 extending along the Z-axis. Furthermore, in this embodiment, the second wall portions 33 and 34 present in the first embodiment are omitted. Therefore, the fifth surface 205 of the elastomer 2 is not restricted by deformation based on the second wall portions 33 and 34. As a result, the deformation of the piezoelectric element 41 is more likely to increase compared to the first embodiment.

[0157] Therefore, by arranging the piezoelectric element 41 at the position facing the fifth surface 205, the sensitivity of the piezoelectric sensor 1B can be further improved.

[0158] Figure 15 It is from all directions Figure 14 The diagram shown illustrates the deformation mode of the elastic body 2 when the piezoelectric sensor 1B applies force.

[0159] If a downward force is applied to the piezoelectric sensor 1B, then as Figure 15 As shown in the upper right figure, the piezoelectric element 41 undergoes a downward bending deformation. At this time, as... Figure 10As shown, a voltage signal that is negative relative to a reference voltage is output from the piezoelectric element 41. Therefore, it can be determined that a downward force is applied to the piezoelectric sensor 1B.

[0160] If an upward force is applied to the piezoelectric sensor 1B, then as Figure 15 As shown in the lower left figure, the piezoelectric element 41 undergoes upward bending deformation. Therefore, as... Figure 10 As shown, a voltage signal that is positive relative to a reference voltage is output from the piezoelectric element 41. Therefore, it can be determined that an upward force has been applied to the piezoelectric sensor 1B.

[0161] If a pressing force is applied to the piezoelectric sensor 1B, that is, ... Figure 15 The force exerted by the elastic body 2 shown, pressing from the positive X-axis side to the negative X-axis side, is as follows: Figure 15 As shown in the lower right figure, the piezoelectric element 41 undergoes upward bending deformation, but the amount of deformation is smaller compared to the case where the aforementioned upward force is applied. Therefore, as... Figure 10 As shown, the piezoelectric element 41 outputs a positive voltage signal with a voltage value relatively small compared to the reference voltage. Therefore, it is possible to determine the direction of the force applied to the piezoelectric sensor 1B.

[0162] In the fourth embodiment described above, the same effects as in the first embodiment can also be obtained.

[0163] 6. The piezoelectric sensor according to the fifth embodiment

[0164] Next, the piezoelectric sensor according to the fifth embodiment will be described.

[0165] Figure 16 This is a top view of the piezoelectric sensor according to the fifth embodiment, viewed from the X-axis position.

[0166] The fifth embodiment will now be described, but the description will focus on the differences from the third and fourth embodiments, and descriptions of identical items will be omitted. Furthermore, in each figure, structures identical to those in the third and fourth embodiments will be labeled with the same reference numerals.

[0167] The piezoelectric sensor 1C according to the fifth embodiment is the same as the piezoelectric sensor 1B according to the fourth embodiment, except that it has a piezoelectric element 42 in addition to a piezoelectric element 41.

[0168] like Figure 16As shown, the piezoelectric element 42 is fixed in such a way that the first walls 31 and 32 are connected. Specifically, the piezoelectric element 42 is disposed at a position facing the sixth surface 206 of the elastic body 2, and the positive Y-axis end of the piezoelectric element 42 is fixed to the first wall 31, and the negative Y-axis end of the piezoelectric element 42 is fixed to the first wall 32.

[0169] Based on this structure, similarly to the third embodiment, for example, by making the signs of the voltage signals output when bending in the same direction different among the piezoelectric elements 41 and 42, it is possible to set the voltage signals output from the piezoelectric elements 41 and 42 as signals where one increases from the reference voltage and the other decreases from the reference voltage. Therefore, the difference between the two becomes clear, and even in the case of noise entering the output signal, the direction of the force applied to the elastic body 2 can be easily determined.

[0170] In the fifth embodiment described above, the same effects as in the first to fourth embodiments can be obtained.

[0171] 7. The piezoelectric sensor according to the sixth embodiment

[0172] Next, the piezoelectric sensor according to the sixth embodiment will be described.

[0173] Figure 17 This is a top view of the piezoelectric sensor according to the sixth embodiment, viewed from the X-axis position.

[0174] The sixth embodiment will be described below, but the description will focus on the differences from the fourth embodiment, and descriptions of the same items will be omitted. Furthermore, in each figure, the same reference numerals will be used to label structures identical to those in the fourth embodiment.

[0175] The piezoelectric sensor 1D according to the sixth embodiment is the same as the piezoelectric sensor 1B according to the fourth embodiment, except that the shape of the limiting part 3 is different.

[0176] Figure 17 The limiting part 3 shown has four columnar parts 351 to 354. The four columnar parts 351 to 354 are arranged at positions corresponding to the four corners of the elastic body 2.

[0177] With this structure, the limiting part 3 can be reduced to the minimum required volume. Therefore, it is possible to achieve a lightweight piezoelectric sensor 1D.

[0178] The columnar portion 351 is disposed at one of the four corners of the elastic body 2, on the positive side of the Y-axis and the positive side of the Z-axis; the columnar portion 352 is disposed at one of the four corners of the elastic body 2, on the positive side of the Y-axis and the negative side of the Z-axis; the columnar portion 353 is disposed at one of the four corners of the elastic body 2, on the negative side of the Y-axis and the positive side of the Z-axis; and the columnar portion 354 is disposed at one of the four corners of the elastic body 2, on the negative side of the Y-axis and the negative side of the Z-axis.

[0179] like Figure 17 As shown, the piezoelectric element 41 is fixed in such a way that the columnar portions 351 and 353 are connected.

[0180] In the sixth embodiment described above, the same effects as in the fourth embodiment can be obtained.

[0181] 8. The piezoelectric sensor according to the seventh embodiment

[0182] Next, the piezoelectric sensor according to the seventh embodiment will be described.

[0183] Figure 18 This is a top view of the piezoelectric sensor according to the seventh embodiment, viewed from the X-axis position.

[0184] The seventh embodiment will now be described, but the description will focus on the differences from the fifth and sixth embodiments, and descriptions of identical items will be omitted. Furthermore, in each figure, structures identical to those in the fifth and sixth embodiments will be labeled with the same reference numerals.

[0185] The piezoelectric sensor 1E according to the seventh embodiment is the same as the piezoelectric sensor 1D according to the sixth embodiment, except that it has a piezoelectric element 43 in addition to a piezoelectric element 41.

[0186] The piezoelectric element 43 is fixed in such a way that the columnar portions 353 and 354 are connected.

[0187] That is, the piezoelectric sensor 1E has multiple piezoelectric elements 41 and 43. Furthermore, since the piezoelectric elements 41 and 43 are installed in different directions, they deform in different directions along with the deformation of the elastic body 2.

[0188] Specifically, the fifth embodiment described above also includes multiple piezoelectric elements 41 and 42, but these piezoelectric elements 41 and 42 deform in the same deformation direction along with the deformation of the elastic body 2. For example, since the piezoelectric elements 41 and 42 have a detection axis parallel to the Z-axis, when a downward force is applied to the elastic body 2, both piezoelectric elements 41 and 42 undergo downward bending deformation.

[0189] In contrast, in the piezoelectric sensor 1E according to this embodiment, a piezoelectric element 41 is disposed at a position on the fifth surface 205 facing the elastic body 2, while a piezoelectric element 43 is disposed at a position on the second surface 202 facing the elastic body 2. That is, the piezoelectric element 41 has a detection axis parallel to the Z-axis, while the piezoelectric element 43 has a detection axis parallel to the Y-axis. Therefore, the piezoelectric sensor 1E can detect not only the deformation of the elastic body 2 in the Z-axis direction, but also the deformation in the Y-axis direction.

[0190] In the seventh embodiment described above, the same effects as in the fifth and sixth embodiments can be obtained.

[0191] Figure 19 It is in response to Figure 18 The diagram shown illustrates the deformation modes of the elastic body 2 when the piezoelectric sensor 1E is subjected to force from various directions. Figure 20 This indicates that in the elastomer 2 with Figure 19 When the deformation mode shown is deformed, from Figure 18 A diagram showing an example of the waveform (output waveform) of the voltage signal output by the piezoelectric elements 41 and 43. Furthermore, in Figure 20 The example shown illustrates the waveform of the relative potential with respect to a reference voltage.

[0192] If a downward force is applied to the piezoelectric sensor 1E, then as Figure 19 As shown by the arrow in the upper right figure, a downward pulling force is applied to the third surface 203 of the elastic body 2. Consequently, the piezoelectric element 41 undergoes downward bending deformation. At this time, as... Figure 20 As shown, the piezoelectric element 41 outputs a voltage signal that is negative relative to a reference voltage. This allows determination that a downward force has been applied to the piezoelectric sensor 1E. Furthermore, based on this applied downward force, the static and dynamic friction forces generated between the object W and the elastic body 2 can be detected. On the other hand, the piezoelectric element 43 hardly deforms. Therefore, the piezoelectric element 43 outputs a voltage signal that increases or decreases relative to the reference voltage with almost no change.

[0193] If an upward force is applied to the piezoelectric sensor 1E, then as Figure 19 As shown by the arrow in the left-middle diagram, an upward pulling force is applied to the third surface 203 of the elastic body 2. Consequently, the piezoelectric element 41 undergoes upward bending deformation. At this time, as... Figure 20As shown, the piezoelectric element 41 outputs a voltage signal that is positive relative to a reference voltage. This allows determination that an upward force has been applied to the piezoelectric sensor 1E. Furthermore, based on this applied upward force, the static and dynamic friction forces generated between the object W and the elastic body 2 can be detected. On the other hand, the piezoelectric element 43 hardly deforms. Therefore, the piezoelectric element 43 outputs a voltage signal that increases or decreases relative to the reference voltage with almost no change.

[0194] If a pressing force is applied to the piezoelectric sensor 1E, that is, ... Figure 19 The force exerted by the elastic body 2 shown, pressing from the positive X-axis side to the negative X-axis side, is as follows: Figure 19 As shown by the arrows in the right-hand diagram, the third surface 203 of the elastic body 2 undergoes a four-way expanding deformation. Consequently, the piezoelectric element 41 undergoes an upward bending deformation. At this time, as... Figure 20 As shown, the piezoelectric element 41 outputs a positive voltage signal with a voltage value relatively small compared to the reference voltage. Additionally, the piezoelectric element 43 undergoes a bending deformation in the leftward direction (the direction on the negative side of the Y-axis). At this time, as... Figure 20 As shown, the piezoelectric element 43 outputs a positive voltage signal with a voltage value relatively small compared to the reference voltage. These voltage waveforms allow determination of the force applied in the pressing direction to the piezoelectric sensor 1E.

[0195] If a force is applied to the piezoelectric sensor 1E in the left direction (towards the negative Y-axis), then as follows: Figure 19 As shown by the arrow in the lower left diagram, a force pulling to the left is applied to the third surface 203 of the elastic body 2. Consequently, the piezoelectric element 43 undergoes a bending deformation to the left. At this time, as... Figure 20 As shown, the piezoelectric element 43 outputs a voltage signal that is positive relative to a reference voltage. This allows determination that a leftward force has been applied to the piezoelectric sensor 1E. Furthermore, based on this state of a leftward applied force, the static and dynamic friction forces generated between the object W and the elastic body 2 can be detected. On the other hand, the piezoelectric element 41 hardly deforms. Therefore, the piezoelectric element 41 outputs a voltage signal that increases or decreases relative to the reference voltage with almost no change.

[0196] If a force is applied to the piezoelectric sensor 1E in the right direction (positive Y-axis direction), then as follows: Figure 19 As shown by the arrow in the lower right diagram, a force pulling to the right is applied to the third surface 203 of the elastic body 2. Consequently, the piezoelectric element 43 undergoes a bending deformation to the right. At this time, as... Figure 20As shown, the piezoelectric element 43 outputs a voltage signal that is negative relative to a reference voltage. This allows determination that a force to the right has been applied to the piezoelectric sensor 1E. Furthermore, based on this applied rightward force, the static and dynamic friction forces generated between the object W and the elastic body 2 can be detected. On the other hand, the piezoelectric element 41 hardly deforms. Therefore, the piezoelectric element 41 outputs a voltage signal that increases or decreases relative to the reference voltage with almost no change.

[0197] The above examples illustrate the deformation modes, but deformation directions such as up, down, left, and right can also be other directions.

[0198] As described above, when viewed from above on the third surface 203, the elastic body 2 of the piezoelectric sensor 1E has a fifth surface 205 and a second surface 202, which are two adjacent surfaces corresponding to the two adjacent sides. Furthermore, piezoelectric elements 41 and 43 are positioned facing the fifth surface 205 and the second surface 202.

[0199] Based on this structure, even when forces are applied from more directions compared to the fourth embodiment, a piezoelectric sensor 1E capable of detecting the direction of force application can be achieved. Specifically, for example, it is possible to detect forces applied not only in the upward and downward directions, but also in the left and right directions. Therefore, based on the output of the piezoelectric sensor 1E, various movements of the hand 10 can be captured more comprehensively. As a result, the hand 10 can move more appropriately, thereby improving convenience.

[0200] 9. The piezoelectric sensor according to the eighth embodiment

[0201] Next, the piezoelectric sensor according to the eighth embodiment will be described.

[0202] Figure 21 This is a top view of the piezoelectric sensor according to the eighth embodiment, viewed from the X-axis position.

[0203] The eighth embodiment will be described below, but the description will focus on the differences from the sixth and seventh embodiments, and descriptions of the same items will be omitted. Furthermore, in each figure, structures identical to those in the sixth and seventh embodiments will be labeled with the same reference numerals.

[0204] The piezoelectric sensor 1F according to the eighth embodiment is the same as the piezoelectric sensor 1E according to the seventh embodiment, except that it also includes piezoelectric elements 42 and 44 in addition to piezoelectric elements 41 and 43.

[0205] The piezoelectric element 42 is fixed by connecting the columnar portions 352 and 354. The piezoelectric element 44 is fixed by connecting the columnar portions 351 and 352.

[0206] That is, the piezoelectric sensor 1F has multiple piezoelectric elements 41 to 44. Specifically, when viewed from above on the third surface 203, the elastic body 2 of the piezoelectric sensor 1F has four outer surfaces corresponding to the four sides forming the outer edge, namely a first surface 201, a second surface 202, a fifth surface 205, and a sixth surface 206. Furthermore, as... Figure 21 As shown, piezoelectric element 41 is positioned facing the fifth surface 205, piezoelectric element 42 is positioned facing the sixth surface 206, piezoelectric element 43 is positioned facing the second surface 202, and piezoelectric element 44 is positioned facing the first surface 201.

[0207] With this structure, since four piezoelectric elements 41-44 are arranged to surround the elastic body 2, a voltage signal is output from at least two piezoelectric elements regardless of the direction in which force is applied to the elastic body 2. Therefore, the piezoelectric sensor 1F according to this embodiment has the effects of both the fifth embodiment and the seventh embodiment. Specifically, for example, it is possible to detect forces applied in the upward, downward, leftward, and rightward directions separately, and the voltage signals output from the two piezoelectric elements are set such that one increases from the reference voltage and the other decreases from the reference voltage. Therefore, forces applied in each direction can be detected with higher accuracy.

[0208] Figure 22 This indicates that elastomer 2 is in Figure 19 During deformation in the deformation mode shown, from Figure 21 A diagram showing an example of the waveform (output waveform) of the voltage signal output by the piezoelectric elements 41-44. Furthermore, in Figure 22 The example shown illustrates the waveform of the relative potential with respect to a reference voltage.

[0209] If a downward force is applied to the piezoelectric sensor 1F, the piezoelectric element 41 will undergo a downward bending deformation, such as... Figure 22 As shown, for example, it outputs a negative voltage signal. Additionally, the piezoelectric element 42 also undergoes downward bending deformation, such as... Figure 22 As shown, for example, the output is a voltage signal that is positive relative to the reference voltage.

[0210] If an upward force is applied to the piezoelectric sensor 1F, the piezoelectric element 41 will undergo upward bending deformation, such as... Figure 22 As shown, for example, it outputs a positive voltage signal. Additionally, the piezoelectric element 42 also undergoes upward bending deformation, such as... Figure 22 As shown, for example, a negative voltage signal is output relative to a reference voltage.

[0211] If a pressing force is applied to the piezoelectric sensor 1F, that is, ... Figure 21 When the elastic body 2 is pressed from the positive X-axis to the negative X-axis, the piezoelectric element 41 undergoes an upward bending deformation, the piezoelectric element 42 undergoes a downward bending deformation, the piezoelectric element 43 undergoes a leftward bending deformation, and the piezoelectric element 44 undergoes a rightward bending deformation. Figure 22 As shown, for example, the output voltage value is a positive voltage signal that is relatively small compared to the reference voltage.

[0212] If a force is applied to the left of the piezoelectric sensor 1F, the piezoelectric element 43 will bend and deform to the left, as shown below. Figure 22 As shown, for example, it outputs a positive voltage signal. Additionally, the piezoelectric element 44 also undergoes a bending deformation in the leftward direction, such as... Figure 22 As shown, for example, the output voltage signal is negative relative to the reference voltage.

[0213] If a force is applied to the right on the piezoelectric sensor 1F, the piezoelectric element 43 will bend and deform to the right, as shown below. Figure 22 As shown, for example, it outputs a negative voltage signal. Additionally, the piezoelectric element 44 also undergoes a rightward bending deformation, such as... Figure 22 As shown, for example, the output is a voltage signal that is positive relative to the reference voltage.

[0214] In the eighth embodiment described above, the same effects as in the sixth and seventh embodiments can be obtained.

[0215] 10. The piezoelectric sensor according to the ninth embodiment

[0216] Next, the piezoelectric sensor according to the ninth embodiment will be described.

[0217] Figure 23 This is a top view of the piezoelectric sensor according to the ninth embodiment, viewed from the X-axis position.

[0218] The ninth embodiment will now be described, but the description will focus on the differences from the third embodiment, and descriptions of the same items will be omitted. Furthermore, the same reference numerals will be used to label the same structures as in the third embodiment in each drawing.

[0219] The piezoelectric sensor 1G according to the ninth embodiment is the same as the piezoelectric sensor 1A according to the third embodiment, except that the limiting part 3 is formed into a ring shape.

[0220] With the restrictor 3 forming a ring shape, when viewing the third surface 203 of the elastic body 2 from above, as... Figure 23As shown, the elastic body 2 is formed into a circle. That is, the third surface 203 of the elastic body 2 is formed into a circle. A circle includes a true circle, an oblong, an ellipse, etc.

[0221] In this way, by having a circular top view shape for the elastic body 2, the shape anisotropy of the elastic body 2 is reduced compared to the case where the top view shape of the elastic body 2 is rectangular. As a result, it is possible to detect the direction and magnitude of the force while suppressing the sensitivity deviation caused by the direction of the force applied to the piezoelectric sensor 1G.

[0222] The portion of the circular limiting portion 3 on the positive Y-axis side is the first wall portion 31, and the portion on the negative Y-axis side is the first wall portion 32. The portion on the positive Z-axis side is the second wall portion 33, and the portion on the negative Z-axis side is the second wall portion 34.

[0223] Furthermore, on the side surfaces of the elastomer 2, that is, the surface other than the third surface 203 and the fourth surface 204, the portion on the positive Y-axis side is the first surface 201, the portion on the negative Y-axis side is the second surface 202, the portion on the positive Z-axis side is the fifth surface 205, and the portion on the negative Z-axis side is the sixth surface 206. The first wall portion 31 is positioned facing the first surface 201, the first wall portion 32 is positioned facing the second surface 202, the second wall portion 33 is positioned facing the fifth surface 205, and the second wall portion 34 is positioned facing the sixth surface 206.

[0224] Furthermore, in the second embodiment described above, a piezoelectric element 41 is provided between the elastic body 2 and the second wall portion 33, and a piezoelectric element 42 is provided between the elastic body 2 and the second wall portion 34. In this embodiment, the piezoelectric element 41 is fixed on the side of the second wall portion 33 opposite to the elastic body 2, and the piezoelectric element 42 is provided on the side of the second wall portion 34 opposite to the elastic body 2.

[0225] In the ninth embodiment described above, the same effect as in the second embodiment can be obtained.

[0226] 11. The piezoelectric sensor according to the tenth embodiment

[0227] Next, the piezoelectric sensor according to the tenth embodiment will be described.

[0228] Figure 24 This is a top view of the piezoelectric sensor according to the tenth embodiment, viewed from the position on the X-axis.

[0229] The tenth embodiment will be described below, but the description will focus on the differences from the seventh and ninth embodiments, and descriptions of the same items will be omitted. Furthermore, in each figure, the same reference numerals will be used to label structures identical to those in the seventh and ninth embodiments.

[0230] The piezoelectric sensor 1H according to the tenth embodiment is the same as the piezoelectric sensor 1E according to the seventh embodiment, except that the limiting part 3 is formed into a ring shape.

[0231] With the restrictor 3 forming a ring shape, when viewing the third surface 203 of the elastic body 2 from above, as... Figure 24 As shown, the elastomer 2 is circular.

[0232] In this way, by having a circular top view shape for the elastic body 2, the shape anisotropy of the elastic body 2 is reduced compared to the case where the top view shape of the elastic body 2 is rectangular. As a result, it is possible to detect both the direction and magnitude of the force while suppressing the sensitivity deviation caused by the direction of the force applied to the piezoelectric sensor 1H.

[0233] Figure 24 The limiting part 3 shown has four columnar parts 351 to 354. Columnar part 351 is located on the positive side of the Y-axis and the positive side of the Z-axis, with the center of the elastic body 2 as a reference. Columnar part 352 is located on the positive side of the Y-axis and the negative side of the Z-axis. Columnar part 353 is located on the negative side of the Y-axis and the positive side of the Z-axis. Columnar part 354 is located on the negative side of the Y-axis and the negative side of the Z-axis. Furthermore, columnar parts 351 and 352 are positioned facing the first surface 201, and columnar parts 353 and 354 are positioned facing the second surface 202. Furthermore, piezoelectric element 41 is fixed by connecting columnar parts 351 and 353, and piezoelectric element 43 is fixed by connecting columnar parts 353 and 354.

[0234] In the tenth embodiment described above, the same effects as in the seventh and ninth embodiments can be obtained.

[0235] The piezoelectric sensor and hand of the present invention have been described above based on the illustrated embodiments. However, the piezoelectric sensor and hand of the present invention are not limited to the above embodiments. For example, they can be replaced with any structure in which each part of the above embodiments has the same function, any additional components can be added to the above embodiments, and multiple above embodiments can be combined.

Claims

1. A piezoelectric sensor, characterized in that, have: Elastomers; A piezoelectric element is disposed at a position in contact with the elastomer and outputs a voltage signal when it deforms along with the deformation of the elastomer. as well as The detection unit detects the voltage signal output from the piezoelectric element. After the elastomer comes into contact with the object, and the elastomer moves relative to the object, the detection unit detects the dynamic friction force generated between the object and the elastomer based on the change in the voltage signal caused by the relative movement of the object. The elastomer has a first surface. The piezoelectric sensor includes a limiting portion disposed on the first surface facing the elastic body, which limits the deformation of the elastic body. A portion of the piezoelectric element is fixed to the limiting portion.

2. The piezoelectric sensor according to claim 1, characterized in that, When the elastomer comes into contact with the object, the detection unit detects the static friction force generated between the object and the elastomer based on the voltage signal output from the piezoelectric element.

3. The piezoelectric sensor according to claim 1, characterized in that, The elastomer has a second surface facing the first surface. The limiting part includes two first wall portions disposed at a position facing the first surface and a position facing the second surface. The ends of the piezoelectric element are fixed to the two first wall portions.

4. The piezoelectric sensor according to claim 1, characterized in that, The elastomer has a second surface facing the first surface. The limiting part includes two first wall portions disposed at positions facing the first surface and facing the second surface, and a second wall portion that connects the first wall portions to each other and is thinner than the first wall portions. The piezoelectric element is fixed to the second wall portion.

5. The piezoelectric sensor according to claim 1, characterized in that, The elastomer is formed into a plate shape with the third surface as the main surface. The third surface is rectangular in shape.

6. The piezoelectric sensor according to claim 1, characterized in that, The elastomer has a contact surface that contacts the object. The contact surface forms a convex curved surface and is located away from the piezoelectric element.

7. A hand, characterized in that, The piezoelectric sensor is provided according to any one of claims 1 to 6.

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