Robot Hand

Abstract

This robot hand comprises: flexible fingers that are formed of an elastic body and that convey a conveyance object; and a strain sensor that is flexible, that is attached to a flexible finger, and that detects deformation of the flexible finger.

Description

[Technical field]

[0001] The present invention relates to a robot hand that transports an object. [Background technology]

[0002] Patent Document 1 describes a robot gripper control system. The robot gripper control system described in Patent Document 1 includes a gripper mechanism and two fingers. The two fingers operated by the gripper mechanism grip an object C. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 137265 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for a robot hand that can transport easily fragile objects without damaging them and can transport the objects at high speed.

[0005] An object of the present invention is to provide a robot hand that is capable of transporting a fragile object without damaging it and that is capable of transporting the object at high speed. [Means for solving the problem]

[0006] A robot hand according to one embodiment of the present invention includes: A soft finger that carries an object to be carried and is made of an elastic body; a strain sensor having flexibility, attached to the soft finger, and configured to detect deformation of the soft finger; It is equipped with: Effect of the Invention

[0007] A robot hand according to one embodiment of the present invention can transport objects that are easily damaged without damaging them, and can transport the objects at high speed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a robot hand 1 according to the first embodiment. [Diagram 2] FIG. 2 is a diagram showing the hand unit 11 of the robot hand 1. As shown in FIG. [Diagram 3] FIG. 3 is a diagram showing the hand unit 11 gripping the transport object Gr. [Figure 4] FIG. 4 is a diagram showing a hand unit 11a provided on a robot hand 1a according to a modified example of the first embodiment. [Diagram 5] FIG. 5 is a diagram showing a hand unit 21 included in a robot hand 2 according to the second embodiment. [Figure 6] FIG. 6 is an enlarged view of the first soft finger 212 of the hand portion 21. As shown in FIG. [Figure 7] FIG. 7 is a diagram showing a hand unit 31 included in a robot hand 3 according to the third embodiment. [Figure 8] FIG. 8 is a diagram showing a hand unit 41 included in a robot hand 4 according to the fourth embodiment. [Figure 9] FIG. 9 is a diagram showing the first soft finger 412 of the hand unit 41. As shown in FIG. [Figure 10] FIG. 10 is a diagram showing a hand unit 51 included in a robot hand 5 according to the fifth embodiment. [Figure 11] FIG. 11 is a diagram of the first soft finger 512 and the second soft finger 513 viewed in the negative direction of the Z axis. [Figure 12] FIG. 12 is a diagram showing a hand unit 51a according to a first modified example of the hand unit 51. As shown in FIG. [Figure 13] FIG. 13 is a diagram showing a hand unit 51b according to a second modified example of the hand unit 51. As shown in FIG. [Figure 14] FIG. 14 is a diagram showing a hand unit 51c according to a third modified example of the hand unit 51. As shown in FIG. [Figure 15] FIG. 15 is a diagram showing a hand unit 51d according to the fourth modified example of the hand unit 51. As shown in FIG. [Figure 16] FIG. 16 is a diagram of the first soft finger 512 and the second soft finger 513 of the hand portion 51d as viewed in the negative direction of the Z axis. [Figure 17] FIG. 17 is a diagram showing a hand unit 51e according to the fifth modification of the hand unit 51. As shown in FIG. [Figure 18] FIG. 18 is a diagram showing a hand portion 51f according to a sixth modified example of the hand portion 51. As shown in FIG. [Figure 19] FIG. 19 is a diagram showing a recess Hf2 provided in the second member SP5 of the hand portion 51e. [Figure 20] FIG. 20 is a diagram showing a recess Hf3 provided in the second member SP5 of the hand portion 51e. [Figure 21] FIG. 21 is a diagram showing a hand unit 61 included in a robot hand 6 according to the sixth embodiment. [Figure 22] FIG. 22 is a diagram of the first soft finger 612 as viewed in the positive direction of the Z axis. [Figure 23] FIG. 23 is a diagram showing a hand unit 61a according to a first modified example of the hand unit 61. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [First embodiment] The robot hand 1 according to the first embodiment will be described below with reference to the drawings. FIG. 1 is a diagram showing the robot hand 1 according to the first embodiment. FIG. 2 is a diagram showing a hand unit 11 of the robot hand 1. FIG. 3 is a diagram showing the hand unit 11 gripping a transport object Gr. In this embodiment, the transport object Gr is an object transported by the robot hand 1. The transport object Gr is, for example, food or an object that is easily damaged when subjected to a strong force, such as a precision part.

[0010] In the following, for ease of understanding, directions are defined as shown in FIG. 2. Specifically, the direction in which the first soft finger 112 and the second soft finger 113 are lined up is defined as the X-axis direction. At this time, the direction in which the first soft finger 112 and the second soft finger 113 are lined up in the order of the first soft finger 112, the second soft finger 113 is defined as the positive direction of the X-axis. Also, the direction in which the first soft finger 112 and the second soft finger 113 are lined up in the order of the second soft finger 113, the first soft finger 112 is defined as the negative direction of the X-axis. The direction in which the first soft finger 112 and the second soft finger 113 extend is defined as the Z-axis direction. The direction perpendicular to the X-axis direction and the Z-axis direction is defined as the Y-axis direction. The X-axis direction, the Y-axis direction, and the Z-axis direction are directions defined for convenience of explanation. Therefore, the X-axis direction, the Y-axis direction, and the Z-axis direction do not have to coincide with the X-axis direction, the Y-axis direction, and the Z-axis direction when the robot hand 1 is actually used.

[0011] 1 to 3, the robot hand 1 in this embodiment transports a transport object Gr. Specifically, the robot hand 1 includes an arm unit 10, a hand unit 11, a control unit 12, and a strain sensor 13. The control unit 12 controls the arm unit 10 and the hand unit 11, causing the robot hand 1 to transport the transport object Gr. This will be described in detail below.

[0012] The arm unit 10 has a plurality of arms and a plurality of joints. Each of the plurality of joints rotates about three axes. This allows the robot hand 1 to adjust the positional relationship between the robot hand 1 and the transport object Gr.

[0013] 1, the hand unit 11 includes a drive unit 111, a first soft finger 112, and a second soft finger 113. In other words, in this embodiment, the hand unit 11 includes a plurality of soft fingers. Therefore, in this embodiment, the robot hand 1 includes a plurality of soft fingers.

[0014] The driving unit 111 drives each of the multiple soft fingers. Specifically, as shown in Fig. 2, the driving unit 111 has a housing 111A and a driving mechanism 111B. The housing 111A surrounds the periphery of the driving mechanism 111B. In this way, the housing 111A protects the driving mechanism 111B from external impacts and the like. The material of the housing 111A is, for example, a metal (for example, steel or aluminum, etc.).

[0015] The driving mechanism 111B drives each of the multiple soft fingers. That is, in this embodiment, the driving mechanism 111B drives each of the first soft finger 112 and the second soft finger 113. Specifically, the driving mechanism 111B holds the first soft finger 112 and the second soft finger 113. The driving mechanism 111B moves the first soft finger 112 and the second soft finger 113, for example, in the X-axis direction. The driving mechanism 111B includes, for example, a motor, a gear, a rack, and the like. In this embodiment, the rack is, for example, a member on which teeth are formed that are arranged at equal intervals in the X-axis direction. In this case, the motor and the gear are connected. The motor rotates with the Z-axis direction as the center of rotation. As a result, the gear rotates with the Z-axis direction as the center of rotation. The gear and the rack are engaged with each other. As a result, when the gear rotates, the rack moves in the X-axis direction. The rack and the first soft finger 112 are connected. Therefore, as the rack moves in the X-axis direction, the first soft finger 112 moves in the X-axis direction. Similarly, the rack and the second soft finger 113 are connected. Therefore, as the rack moves in the X-axis direction, the second soft finger 113 moves in the X-axis direction. That is, the distance between the first soft finger 112 and the second soft finger 113 changes. For example, as shown in FIG. 2, when the transport object Gr is located between the first soft finger 112 and the second soft finger 113, the driving mechanism 111B moves the first soft finger 112 in the positive direction of the X-axis. As a result, the first soft finger 112 comes into contact with the transport object Gr (see FIG. 3). The driving mechanism 111B moves the second soft finger 113 in the negative direction of the X-axis. As a result, the second soft finger 113 comes into contact with the transport object Gr (see FIG. 3). That is, the first soft finger 112 and the second soft finger 113 come into contact with the transport object Gr, whereby the first soft finger 112 and the second soft finger 113 grip the transport object Gr. In other words, in this embodiment, the transport object Gr is a gripping object. The multiple soft fingers grip the gripping object. Hereinafter, the direction in which the driver 111 and the first soft finger 112 are arranged in the order of the first soft finger 112, the driver 111 is defined as the positive direction of the Z axis. The direction in which the driver 111 and the first soft finger 112 are arranged in the order of the driver 111, the first soft finger 112 is defined as the negative direction of the Z axis.

[0016] In this embodiment, the first soft finger 112 and the second soft finger 113 have, for example, a plate-like body extending in the Z-axis direction. Specifically, as shown in Figs. 2 and 3, the first soft finger 112 has a plate-like body having a first main surface S1 and a second main surface S2. The first main surface S1 and the second main surface S2 are the surfaces having the largest areas among the surfaces of the first soft finger 112. The first main surface S1 and the second main surface S2 are arranged in the positive direction of the X-axis in the order of the second main surface S2 and the first main surface S1.

[0017] In the structure shown above, the first main surface S1 faces the transport object Gr. The first main surface S1 and the transport object Gr come into contact with each other. The first soft finger 112 is thin in the X-axis direction, and therefore bends in the negative direction of the X-axis. The first soft finger 112 is long in the Y-axis direction and the Z-axis direction, and therefore is less likely to deform in a direction perpendicular to the first main surface S1 and the second main surface S2 (the Y-axis direction shown in FIGS. 2 and 3).

[0018] In this embodiment, the first soft finger 112 does not necessarily have to be a plate-like body. In this embodiment, the first soft finger 112 may be, for example, in the shape of a polygonal prism.

[0019] In this embodiment, the first soft finger 112 and the second soft finger 113 are made of an elastic body made of a polymer material. In other words, in this embodiment, the multiple soft fingers are made of an elastic body made of a polymer material. The polymer material is, for example, an epoxy resin or an elastomer resin. Therefore, the first soft finger 112 and the second soft finger 113 are elastically deformed. Note that the first soft finger 112 and the second soft finger 113 may be made of a material other than a polymer material. The first soft finger 112 and the second soft finger 113 may be made of a metal such as aluminum.

[0020] The control unit 12 controls the arm unit 10 and the hand unit 11. The control unit 12 generates, for example, a signal for controlling the arm unit 10 (hereinafter referred to as a first control signal) and a signal for controlling the hand unit 11 (hereinafter referred to as a second control signal). Specifically, the control unit 12 includes a CPU (Central Processing Unit), a ROM, a RAM, and a communication interface (not shown). The CPU of the control unit 12 performs processing for generating the first control signal and the second control signal by reading a program stored in the ROM into the RAM.

[0021] The control unit 12 controls the arm unit 10 by transmitting a first control signal to the arm unit 10. For example, as shown in FIG. 1, the control unit 12 is connected to the arm unit 10 via a signal line Sig1. The control unit 12 transmits the first control signal to the arm unit 10 via the signal line Sig1. For example, the control unit 12 transmits a first control signal to the arm unit 10 to rotate each of the multiple joints. Each of the multiple joints rotates based on the first control signal. As a result, the robot hand 1 adjusts the positional relationship between the robot hand 1 and the transport object Gr.

[0022] The control unit 12 controls the hand unit 11 by transmitting the second control signal to the hand unit 11. For example, as shown in FIG. 2, the control unit 12 is connected to the hand unit 11 via a signal line Sig2. The control unit 12 transmits the second control signal to the hand unit 11 via the signal line Sig2. For example, the control unit 12 transmits the second control signal to the hand unit 11 to drive a motor of the drive mechanism 111B. The drive mechanism 111B moves each of the first soft finger 112 and the second soft finger 113 in the X-axis direction based on the second control signal.

[0023] The control unit 12 and the arm unit 10 do not necessarily have to be connected via the signal line Sig1. The control unit 12 and the arm unit 10 may be connected wirelessly, for example, via wireless LAN. Similarly, the control unit 12 and the hand unit 11 may be connected wirelessly, for example, via wireless LAN.

[0024] Incidentally, the robot hand 1 according to the present embodiment is provided with the strain sensor 13, and therefore, even if the transport object Gr is easily damaged, it can transport the transport object Gr without damaging it, and can transport the transport object Gr at high speed. This will be described in detail below.

[0025] The strain sensor 13 detects deformation of at least one of the multiple soft fingers. Specifically, the strain sensor 13 is attached to at least one of the multiple soft fingers. Then, the strain sensor 13 detects deformation of at least one of the multiple soft fingers. In the example shown in FIG. 2, the strain sensor 13 is attached to the first soft finger 112. Specifically, the strain sensor 13 is attached to the second main surface S2. The strain sensor 13 has a thin plate shape. The main surface of the strain sensor 13 is attached to the second main surface S2. That is, the main surface of the strain sensor 13 and the second main surface S2 are in contact with each other. In this embodiment, the strain sensor 13 is attached to the end of the first soft finger 112 in the negative direction of the Z axis. However, the strain sensor 13 does not need to be attached to the end of the first soft finger 112 in the negative direction of the Z axis. For example, the strain sensor 13 may be attached to the end of the first soft finger 112 in the positive direction of the Z axis.

[0026] The first soft finger 112 bends toward the negative direction of the X-axis. Therefore, the first main surface S1 of the first soft finger 112 expands along the Z-axis direction, and the second main surface S2 contracts along the Z-axis direction. As a result, the main surface of the strain sensor 13 contracts in accordance with the bending deformation of the first soft finger 112. Note that the attachment position of the strain sensor 13 is not limited to this example. The strain sensor 13 may be attached to the first main surface S1. In this case, the main surface of the strain sensor 13 contracts in accordance with the bending deformation of the first soft finger 112.

[0027] The strain sensor 13 has flexibility. Therefore, the strain sensor 13 deforms in accordance with the deformation of the first soft finger 112. That is, as the second main surface S2 contracts, the main surface of the strain sensor 13 also contracts. The strain sensor 13 has an output according to the contraction of the main surface of the strain sensor 13. The strain sensor 13 is, for example, either a strain gauge or a piezoelectric sensor.

[0028] When the strain sensor 13 is a piezoelectric sensor, the piezoelectric sensor generates a charge according to the displacement speed of the second principal surface S2. Specifically, the piezoelectric sensor generates a charge according to a differential value of the displacement amount of the second principal surface S2. The piezoelectric sensor includes a charge amplifier. The piezoelectric sensor converts the charge into a voltage signal (hereinafter referred to as a first signal) by the charge amplifier. The first signal is proportional to the displacement speed of the second principal surface S2. The piezoelectric sensor can estimate the amount of contraction of the second principal surface S2 (i.e., the amount of bending deformation of the first soft finger 112) by integrating the value of the first signal.

[0029] The piezoelectric sensor includes a piezoelectric film. The piezoelectric film is, for example, polylactic acid (PLA) or polyvinylidene fluoride (PVDF). In other words, when the strain sensor 13 is a piezoelectric sensor, the piezoelectric sensor includes polylactic acid or PVDF. Polylactic acid generates piezoelectricity by molecular orientation processing by stretching. When the piezoelectric film is polylactic acid, the piezoelectric film is attached to the first soft finger 112 so that the stretching direction forms an angle of 45 degrees with respect to the Z-axis direction. On the other hand, when the piezoelectric film is polyvinylidene fluoride, a piezoelectric film (a piezoelectric film having a piezoelectric tensor d33) that generates electric charge in response to deformation in the planar direction is attached to the second main surface S2.

[0030] When the strain sensor 13 is a strain gauge, the strain gauge detects the amount of deformation of the second principal surface S2 (the position of the second principal surface S2). The strain gauge is attached to the second principal surface S2 so that the resistance value decreases according to the amount of contraction of the second principal surface S2.

[0031] The piezoelectric sensor outputs a detection result based on the displacement speed. Therefore, the piezoelectric sensor can detect the displacement of the measurement object (the first soft finger 112 in this embodiment) that is frequently deformed with high sensitivity. Therefore, the piezoelectric sensor is suitable for the case where the first soft finger 112 is deformed relatively frequently and the amount of deformation is relatively small. On the other hand, the strain gauge is suitable for the case where the measurement object is deformed relatively infrequently and a relatively large deformation is to be detected.

[0032] The strain sensor 13 has a plate shape. In other words, one or more strain sensors include a plate-shaped strain sensor having a plate shape. Therefore, the strain sensor 13 has a thickness in the normal direction ND. In this case, the contact portion C1 is arranged along the normal direction ND of the strain sensor 13. This makes the strain sensor 13 less likely to bend in a direction perpendicular to the thickness direction (Y-axis direction and Z-axis direction in FIG. 2). Therefore, when the strain sensor 13 is attached to the first soft finger 112, the first soft finger 112 is more likely to bend in the normal direction ND but is less likely to bend in the Y-axis direction and Z-axis direction. Therefore, while the strain sensor 13 does not hinder detection of the deformation of the first soft finger 112, it is possible to make the first soft finger 112 less likely to bend in a direction in which it is not desired to bend (for example, the Y-axis direction and the Z-axis direction).

[0033] The control unit 12 controls the operations of the first soft finger 112 and the second soft finger 113 based on, for example, the output result of the strain sensor 13. Specifically, the control unit 12 is connected to the strain sensor 13 via, for example, a signal line Sig3. The control unit 12 receives the output result of the strain sensor 13 (hereinafter referred to as the output result R) via the signal line Sig3. Then, the control unit 12 acquires displacement information related to the displacement of the first soft finger 112 based on the output result R. In other words, the control unit 12 acquires displacement information related to the displacement of at least one of the multiple soft fingers based on the output results of one or more strain sensors.

[0034] The displacement information is a physical quantity or the like indicating the displacement of the first soft finger 112. The displacement information is, for example, the displacement amount of the first soft finger 112, the displacement speed of the first soft finger 112, or the acceleration in the displacement of the first soft finger 112. In other words, the displacement information includes the displacement speed of at least one of the multiple soft fingers.

[0035] The control unit 12 controls the operation of the multiple soft fingers based on the displacement information. For example, the control unit 12 changes the positions of the first soft finger 112 and the second soft finger 113 based on the displacement information. Specifically, the control unit 12 drives the first soft finger 112 to move in the negative direction of the X-axis, or drives the second soft finger 113 to move in the positive direction of the X-axis, based on the displacement information. For example, the control unit 12 stores a target value of the displacement amount of the first soft finger 112 (hereinafter referred to as the target displacement amount) in advance. The control unit 12 estimates the displacement amount of the first soft finger 112 based on the output result of the strain sensor 13. The control unit 12 controls the first soft finger 112 and the second soft finger 113 (feedback control such as PID) so that the estimated displacement amount of the first soft finger 112 approaches the target displacement amount. This makes the displacement amount of the first soft finger 112 constant, and damage to the transport object Gr can be prevented.

[0036] The control unit 12 does not necessarily have to control the operation of the first soft finger 112 and the second soft finger 113 based on the output result of the strain sensor 13. The control unit 12 may generate an alert, for example, by turning on an LED or outputting an alarm based on the output result of the strain sensor 13. In this case, the control unit 12 stores in advance a limit value of the displacement amount of the first soft finger 112 (hereinafter referred to as the limit displacement amount). The control unit 12 estimates the displacement amount of the first soft finger 112 based on the output result of the strain sensor 13. The control unit 12 generates an alert when the estimated displacement amount of the first soft finger 112 exceeds the limit displacement amount. An operator who notices the alert can stop the operation of the robot hand 1 to prevent damage to the transport object Gr.

[0037] In the example shown in FIGS. 2 and 3, the robot hand 1 includes one strain sensor (strain sensor 13). However, the robot hand 1 may include two or more strain sensors. The two or more strain sensors may be attached to the first soft finger 112 and the second soft finger 113, respectively. In other words, in this embodiment, the robot hand 1 may include one or more strain sensors. The one or more strain sensors may detect deformation of at least one soft finger among the multiple soft fingers.

[0038] In addition, when the robot hand 1 includes two or more strain sensors, the two or more strain sensors are either strain gauges or piezoelectric sensors. Therefore, in this embodiment, the one or more strain sensors 13 are either strain gauges or piezoelectric sensors.

[0039] The strain sensor 13 does not necessarily have to be plate-shaped. The strain sensor 13 may have any shape as long as it does not hinder the movement of the first soft finger 112 to which the strain sensor 13 is attached. For example, the strain sensor 13 may be thread-shaped.

[0040] (Effects of the first embodiment) The robot hand 1 can transport the transport object Gr, which is easily damaged, without damaging it. Specifically, in this embodiment, the first soft finger 112 to which the strain sensor 13 is attached is made of an elastic body. In this case, the first soft finger 112 is easily deformed when the transport object Gr is transported. Therefore, the strain sensor 13 can easily detect the deformation of the first soft finger 112. This allows the control unit 12 to improve the accuracy of feedback control such as PID based on the deformation amount of the first soft finger 112. This allows the first soft finger 112 and the second soft finger 113 to transport the transport object Gr without damaging it. Alternatively, the control unit 12 may generate an alert based on the deformation amount of the first soft finger 112. In this case, the operator who notices the alert may stop the operation of the robot hand 1 and stop the operation of the first soft finger 112 and the second soft finger 113. In this case, damage to the transport object Gr can also be prevented.

[0041] Generally, when a robot hand transports an object to be transported at high speed, vibrations are likely to occur in the robot hand. This may cause the soft fingers to be displaced, and the object to be transported may come off the robot hand. However, in the robot hand 1, the strain sensor 13 is likely to detect deformation of the first soft fingers 112. In other words, it is likely to detect the displacement of the first soft fingers 112 caused by the vibration of the robot hand 1. Therefore, the control unit 12 can perform feedback control such as PID based on the displacement of the first soft fingers 112 caused by the vibration. Therefore, the robot hand 1 can transport the object to be transported Gr at high speed.

[0042] [Modification of the first embodiment] Hereinafter, a robot hand 1a according to a modification of the first embodiment will be described with reference to FIG. 4. FIG. 4 is a diagram showing a hand unit 11a included in the robot hand 1a according to the modification of the first embodiment. As shown in FIG. 4, the robot hand 1a differs from the robot hand 1 in that it does not include a second soft finger 113. In the robot hand 1a, the first soft finger 112 pushes the transport object Gr to transport the transport object Gr. When the first soft finger 112 transports the transport object Gr, the first soft finger 112 is deformed. Therefore, the robot hand 1a can prevent damage to the transport object Gr in the same manner as the robot hand 1.

[0043] [Second embodiment] A robot hand 2 (not shown) according to the second embodiment will be described below with reference to the drawings. FIG. 5 is a diagram showing a hand unit 21 provided in the robot hand 2 according to the second embodiment. FIG. 6 is an enlarged view of a first soft finger 212 of the hand unit 21. The robot hand 2 differs from the robot hand 1 in that it is provided with a first soft finger 212 having a structure different from that of the first soft finger 112. The robot hand 2 also differs from the robot hand 1 in that the attachment position of the strain sensor 13 is different. A detailed description will be given below. Note that the same structures as those of the robot hand 1 are denoted by the same reference numerals and description will be omitted.

[0044] As shown in Figs. 5 and 6, the first soft finger 212 has a first member FP which is a plate-like body extending in the Z-axis direction, and a second member SP which is a plate-like body extending in the Z-axis direction. In other words, at least one of the multiple soft fingers includes the first soft finger 212 which has the first member FP which is a plate-like body and the second member SP which is a plate-like body. The first member FP has a first main surface S12 and a second main surface S22. The first main surface S12 and the second main surface S22 are the surfaces having the largest areas among the surfaces of the first member FP. The first main surface S12 and the second main surface S22 are arranged in the positive direction of the X-axis in the order of the second main surface S22 and the first main surface S12.

[0045] The first principal surface S12 has a contact portion C21. The contact portion C21 comes into contact with the transport object Gr. More specifically, the first soft finger 212 moves in a normal direction ND of the first principal surface S12. The first soft finger 212 comes into contact with the transport object Gr at the contact portion C21 by moving in the normal direction ND. In this case, the normal direction ND coincides with the X-axis direction.

[0046] The second member SP has a first main surface S32 and a second main surface S42. The first main surface S32 and the second main surface S42 are the surfaces with the largest areas among the surfaces of the second member SP. The first main surface S32 and the second main surface S42 are arranged in the positive direction of the X-axis in the order of the second main surface S42 and the first main surface S32. The first main surface S32 is in contact with the second main surface S22.

[0047] The second member SP has a recess. Specifically, the first main surface S32 side of the second member SP is recessed. Therefore, a part of the first main surface S32 does not contact the second main surface S22. Due to the recess, a gap VD is formed in the first soft finger 212 as shown in Figs. 5 to 6. The gap VD is formed between the first member FP and the second member SP. At this time, the gap VD is formed at a position overlapping with the contact portion C21 when the first member FP is viewed in the normal direction ND of the first main surface S1. As a result, when the first member FP comes into contact with the transport object Gr at the contact portion C21, the first member FP is deformed so as to protrude toward the gap VD.

[0048] The second member SP supports the first member FP. Specifically, the first main surface S32 of the second member SP is in contact with the second main surface S22 to support the first member FP. However, since the second member SP has a recess, a part of the first main surface S32 is not in contact with the second main surface S22. Therefore, of the second main surface S22, the surface SU located on the positive side of the Z axis from the gap VD and the surface SD located on the negative side of the Z axis from the gap VD are in contact with the first main surface S32. At this time, the entire surface of the surface SU and the entire surface of the surface SD do not need to be in contact with the second main surface S22. If at least one point on the surface SU (for example, the second point P2 in FIG. 5) is in contact with the second main surface S22 and at least one point on the surface SD (for example, the first point P1 in FIG. 5) is in contact with the second main surface S22, the second member SP can support the first member FP. In other words, the second member SP supports the first member FP by contacting the second main surface S2 at at least two points.

[0049] In this embodiment, the strain sensor 13 detects the deformation of the first member FP. Specifically, the strain sensor 13 is attached to the second main surface S22. In other words, the first soft finger 212 has the second main surface S22 to which one or more strain sensors are attached. In addition, the strain sensor 13 is disposed in the gap VD. Therefore, when the first member FP comes into contact with the transport object Gr, the second main surface S22 of the first member FP expands, and the strain sensor 13 attached to the second main surface S22 expands in accordance with the expansion of the second main surface S22. As a result, the strain sensor 13 detects the deformation of the second main surface S22. In other words, one or more strain sensors are attached to the first member FP and detect the deformation of the first member FP.

[0050] The elastic modulus of the first member FP is lower than that of the second member SP. Therefore, when the robot hand 2 transports the transport object Gr, the first member FP is easily deformed. This makes it easier for the strain sensor 13 to detect the deformation of the first member FP. The material of the first member FP is, for example, urethane resin. The material of the second member SP is, for example, epoxy resin.

[0051] (Effects of the second embodiment) The robot hand 2 can transport the easily damaged transport object Gr without damaging it. Specifically, a gap VD is formed between the first member FP and the second member SP. As a result, when the first member FP comes into contact with the transport object Gr, the first member FP deforms toward the gap VD. At this time, since the strain sensor 13 is attached to the second main surface S22, the strain sensor 13 can easily detect the deformation of the first member FP. Therefore, the accuracy of the feedback control by the control unit 12 is improved. Alternatively, since the amount of deformation of the first member FP is easily detected, the control unit 12 can generate an alert more accurately. A worker who notices the alert can stop the operation of the robot hand 2, thereby preventing damage to the transport object Gr.

[0052] Furthermore, since the strain sensor 13 can easily detect the displacement of the first soft finger 212, the robot hand 2 can transport the transport object Gr at high speed in the same manner as the robot hand 1.

[0053] The robot hand 2 does not have to include the second soft fingers 113. In this case, similar to the robot hand 1a, the robot hand 2 transports the transport object Gr by pushing the transport object Gr with the first soft fingers 212. In this case, the robot hand 2 can transport the transport object Gr, which is easily damaged, without damaging it, and can transport the transport object Gr at high speed.

[0054] [Modification 1 of the second embodiment] The second soft finger 113 may have the same structure as the first soft finger 212. The control unit 12 may use the output result of the strain sensor 13 of the second soft finger 113 in addition to the output result of the strain sensor 13 of the first soft finger 212. This can improve the accuracy of the feedback control of the control unit 12. Alternatively, the control unit 12 can generate an alert more accurately. Therefore, the robot hand 2 can transport the transport object Gr, which is easily damaged, without damaging it.

[0055] [Modification 2 of the second embodiment] The recess may be provided in the first member FPb. That is, the gap VD may be formed in the first soft finger 212 by providing a recess in the first member FPb.

[0056] [Modification 3 of the second embodiment] The gap VD may not be formed in the first soft finger 212. For example, the first soft finger 212 may be formed by stacking a plurality of layers. The softness of each of the plurality of layers is different. The strain sensor 13 is located between the layers in the plurality of layers. The strain sensor 13 deforms in accordance with the deformation of the plurality of layers.

[0057] [Third embodiment] The robot hand 3 according to the third embodiment will be described below with reference to the drawings. FIG. 7 is a diagram showing a hand unit 31 provided in the robot hand 3 according to the third embodiment. The robot hand 3 differs from the robot hand 1 in that it is provided with a first soft finger 312 having a structure different from the first soft finger 112. This will be described in detail below. Note that the same structures as those of the robot hand 1 are denoted by the same reference numerals and description thereof will be omitted.

[0058] The first soft finger 312 has a first member FP3 and a second member SP3, each of which has a polygonal prism shape. In other words, at least one of the multiple soft fingers includes the first soft finger 312 having the first member FP3, each of which has a polygonal prism shape. The first member FP3 and the second member SP3 are arranged in the negative direction of the Z axis in this order: the second member SP3, the first member FP3.

[0059] The first member FP3 has a triangular prism shape having a first side T1, a second side T2, a third side T3, and two bottom surfaces (not shown). The first side T1 faces in the positive direction of the X-axis. The second side T2 faces obliquely with respect to the positive direction of the X-axis and the positive direction of the Z-axis. The third side T3 faces in the negative direction of the Z-axis. The first side T1 and the third side T3 are perpendicular to each other. The two bottom surfaces are shaped like a right triangle. The two bottom surfaces are perpendicular to the first side T1, the second side T2, and the third side T3.

[0060] The first side surface T1 has a contact portion C31. The contact portion C31 comes into contact with the transport object Gr. In this case, the first soft finger 312 moves in the normal direction NDT of the first side surface T1 to come into contact with the transport object Gr at the contact portion C31.

[0061] The second member SP3 has a polygonal prism shape. The second member SP3 has a shape in which the end of a rectangular parallelepiped in the negative direction of the Z axis is cut obliquely. A first side surface T4 of the obliquely cut portion faces obliquely with respect to the positive direction of the X axis and the negative direction of the Z axis. In other words, the first side surface T4 of the obliquely cut portion faces the second side surface T2. The first side surface T4 is in contact with the second side surface T2.

[0062] The second member SP3 has a recess. Specifically, a part of the second member SP3 on the first side face T4 side is recessed. Therefore, a part of the first side face T4 does not contact the second side face T2. Due to the recess, a gap VD3 is formed in the first soft finger 312. The gap VD3 is formed between the first member FP3 and the second member SP3. The gap VD3 is formed at a position overlapping with the contact portion C31 when the first member FP3 is viewed in the normal direction NDT. Therefore, when the first soft finger 312 and the second soft finger 313 transport the transport object Gr, the gap VD3, the contact portion C31, and the transport object Gr overlap with each other when viewed in the normal direction NDT. The gap VD3 is located between the first position P13 and the second position P23 in the X-axis direction. Also, the gap VD3 is located between the first position P13 and the second position P23 in the Z-axis direction.

[0063] The second member SP3 supports the first member FP3. Specifically, the first side surface T4 of the second member SP3 is in contact with the second side surface T2 to support the first member FP3. However, since the second member SP3 has a recess, a part of the first side surface T4 is not in contact with the second side surface T2. Therefore, of the first side surface T4, a surface SU3 located on the positive side of the Z axis from the gap VD3 and a surface SD3 located on the negative side of the Z axis from the gap VD3 are in contact with the second side surface T2. In this case, the entire surface of the surface SU3 and the entire surface of the surface SD3 do not need to be in contact with the second side surface T2. As long as at least one point on the surface SU3 (for example, the second point P23 in FIG. 7) is in contact with the second side surface T2 and at least one point on the surface SD3 (for example, the first point P13 in FIG. 7) is in contact with the second side surface T2, the second member SP3 can support the first member FP3. In other words, the second member SP3 supports the first member FP3 by coming into contact with at least two points on the second side surface T2.

[0064] A strain sensor 13 is attached to the second side surface T2. In other words, one or more strain sensors are attached to the second side surface T2. The strain sensor 13 is disposed in the gap VD3. Therefore, when the first member FP3 comes into contact with the transport object Gr, the second side surface T2 of the first member FP3 expands, and the strain sensor 13 attached to the second side surface T2 expands in accordance with the expansion of the second side surface T2. As a result, the strain sensor 13 detects the deformation of the second side surface T2, thereby detecting the deformation of the first member FP3. In other words, one or more strain sensors are attached to the first member FP3 and detect the deformation of the first member FP3.

[0065] The elastic modulus of the first member FP3 is lower than the elastic modulus of the second member SP3. Therefore, the first member FP3 is easily deformed when the robot hand 3 transports the transport object Gr. This makes it even easier for the strain sensor 13 to detect the deformation of the first member FP3.

[0066] The second soft finger 313 has a structure symmetrical to the first soft finger 312. Specifically, an axis AS extending in the Z-axis direction is defined. In this case, when the hand unit 31 is viewed in the Y-axis direction, the second soft finger 313 is symmetrical to the first soft finger 312 with respect to the axis AS. However, the second soft finger 313 differs from the first soft finger 312 in that no strain sensor is attached and no gap is provided. The structure of the second soft finger 313 is the same as the structure of the first soft finger 312 except for the differences described above, and therefore description thereof will be omitted.

[0067] (Effects of the third embodiment) The robot hand 3 can transport the easily damaged transport object Gr without damaging it. Specifically, a gap VD3 is formed between the first member FP3 and the second member SP3. As a result, when the first member FP3 comes into contact with the transport object Gr, the first member FP3 deforms toward the gap VD3. At this time, since the strain sensor 13 is attached to the second side surface T2, the strain sensor 13 can easily detect the deformation of the first member FP3. Therefore, the accuracy of the feedback control by the control unit 12 is improved. Alternatively, since the amount of deformation of the first member FP3 can be easily detected, the control unit 12 can generate an alert more accurately. An operator who notices the alert can stop the operation of the robot hand 3 to prevent damage to the transport object Gr.

[0068] In addition, since the strain sensor 13 can easily detect the displacement of the first soft finger 312, the robot hand 3 can transport the transport object Gr at high speed, similar to the robot hand 1.

[0069] The robot hand 3 does not have to include the second soft fingers 313. In this case, similar to the robot hand 1a, the robot hand 3 transports the transport object Gr by pushing the transport object Gr with the first soft fingers 312. In this case, the robot hand 3 can also prevent damage to the transport object Gr and transport the transport object Gr at high speed.

[0070] [Modification 1 of the third embodiment] The recess may be provided in the first member FP3. That is, the first soft finger 312 may have a gap VD3 formed therein by providing a recess in the first member FP3.

[0071] [Modification 2 of the third embodiment] A plurality of strain sensors 13 may be attached to the second side surface T2. For example, the robot hand 1 includes a first piezoelectric sensor and a second piezoelectric sensor. The first piezoelectric sensor generates a charge according to, for example, deformation in the planar direction (e.g., has a piezoelectric tensor d33). The second piezoelectric sensor generates a charge according to, for example, the direction of torsion of the second piezoelectric sensor (e.g., has a piezoelectric tensor d14). When the robot hand 3 includes the first piezoelectric sensor and the second piezoelectric sensor, the magnitude of the force in the X-axis direction and the force in the Z-axis direction applied to the first soft finger 312 can be estimated. In other words, the magnitude of the force in the X-axis direction and the force in the Z-axis direction applied to the transported object Gr (e.g., gravity applied to the transported object Gr) can be estimated.

[0072] [Fourth embodiment] A robot hand 4 (not shown) according to the fourth embodiment will be described below with reference to the drawings. FIG. 8 is a diagram showing a hand unit 41 included in the robot hand 4 according to the fourth embodiment. FIG. 9 is a diagram showing details of a first soft finger 412 of the hand unit 41. The robot hand 4 differs from the robot hand 1 in that it includes a first soft finger 412 having a different structure from the first soft finger 112 and a second soft finger 413 having a different structure from the second soft finger 113. A detailed description will be given below. Note that structures similar to those of the robot hand 1 will be denoted by the same reference numerals and will not be described.

[0073] In this embodiment, the first soft finger 412 and the second soft finger 413 are cylindrical bodies with a cavity CAV provided therein (see FIG. 9). In other words, the multiple soft fingers include the first soft finger 412, which is a cylindrical body with a cavity CAV provided therein. Therefore, the first soft finger 412 has an inner surface IS of a cylindrical body and an outer surface OS of a cylindrical body. The outer surface OS has a contact portion C41 that comes into contact with the transport object Gr (see FIG. 9).

[0074] The first flexible finger 412 bends in response to a change in air pressure in the cavity CAV. Specifically, the first flexible finger 412 bends toward the contact portion C41. More specifically, the first flexible finger 412 has a bellows-structured portion Be that is a polymeric elastic body. The portion Be is located on the opposite side of the outer surface OS from the contact portion C41. Specifically, the portion Be has a plurality of inner walls IB aligned along the Z-axis direction. The plurality of inner walls IB have a plurality of convex shapes that protrude in the positive direction of the X-axis. When the air pressure in the cavity CAV increases, the plurality of inner walls IB are pressed toward the negative direction of the X-axis by the increased air pressure. This causes the intervals between the plurality of inner walls IB aligned in the Z-axis direction to increase. Therefore, the portion Be side of the outer surface OS expands along the Z-axis direction. On the other hand, the inner surface IS on the contact portion C41 side is a flat surface. Therefore, even if the air pressure in the cavity CAV increases, it does not expand along the Z-axis direction. As a result, the first flexible finger 412 bends toward the contact portion C41 side. On the other hand, when the air pressure of the cavity CAV is low, the portion Be side of the outer surface OS does not shrink. Therefore, when the air pressure of the cavity CAV decreases, the first flexible finger 412 returns to its shape before bending. Similarly, the second flexible finger 413 bends in response to a change in the air pressure of the cavity CAV. The first flexible finger 412 and the second flexible finger 413 convey the conveying object Gr by bending. In the case of the structure shown above, the driving mechanism 111B has, for example, an electromagnetic valve, a vent valve, and a compressor. The control unit 12 changes the air pressure of the cavity CAV by opening and closing the electromagnetic valve to send air from the compressor to the cavity CAV or by venting air from the cavity CAV through the vent valve.

[0075] The first soft finger 412 has an elastic plate material ST. The plate material ST has a plate shape extending in the Z-axis direction, for example. The plate material ST has a first main surface SS1 and a second main surface SS2. The first main surface SS1 and the second main surface SS2 are arranged in the positive direction of the X-axis in this order: the second main surface SS2, the first main surface SS1.

[0076] The plate material ST is attached to the contact portion C41 side of the inner surface IS of the first soft finger 412. Specifically, the plate material ST is attached to the inner surface IS so that the first main surface SS1 and the inner surface IS are in contact with each other. Therefore, the plate material ST bends toward the contact portion C41 side in response to a change in air pressure in the cavity CAV.

[0077] In this embodiment, the strain sensor 13 is attached to the plate material ST. Specifically, the strain sensor 13 is attached to the plate material ST so that the main surface of the strain sensor 13 is in contact with the second main surface SS2. Therefore, the strain sensor 13 detects the deformation of the plate material ST. Specifically, the strain sensor 13 attached to the second main surface SS2 expands in accordance with the expansion of the second main surface SS2. As a result, the strain sensor 13 detects the deformation of the second main surface SS2. In other words, the strain sensor 13 detects the deformation of the first soft finger 412 to which the plate material ST is attached by detecting the deformation of the plate material ST.

[0078] The plate material ST may have a cavity inside. A jamming layer is provided in the cavity of the plate material ST. The jamming layer has a plurality of layers made of one or more films or one or more sheets. The jamming layer changes its rigidity according to a change in frictional force between the plurality of layers. For example, when the air pressure in the cavity of the plate material ST is reduced, the frictional force between the plurality of layers increases. In this case, the rigidity of the jamming layer increases. Therefore, the rigidity of the first soft finger 412 to which the plate material ST is attached increases. On the other hand, when the air pressure in the cavity of the plate material ST is increased, the frictional force between the plurality of layers of the jamming layer decreases. In this case, the rigidity of the jamming layer decreases. Therefore, the rigidity of the first soft finger 412 to which the plate material ST is attached decreases.

[0079] In this embodiment, the control unit 12 may adjust the air pressure of the plate material ST. Specifically, the driving mechanism 111B sends the air of the compressor into the cavity of the plate material ST in the same manner as the cavity CAV. The control unit 12 adjusts the air pressure of the plate material ST by controlling the driving mechanism 111B.

[0080] In order to prevent damage to the transport object Gr, the robot hand 4 transports the transport object Gr with a low gripping force by the first soft fingers 412 and the second soft fingers 413. However, when the robot hand 4 moves the transport object Gr at high speed, centrifugal force may be applied to the transport object Gr. Therefore, when the gripping force by the first soft fingers 412 and the second soft fingers 413 is low, the transport object Gr may come off the first soft fingers 412 and the second soft fingers 413 due to the centrifugal force. Therefore, in this embodiment, when the first soft fingers 412 and the second soft fingers 413 move at high speed while gripping the transport object Gr, the control unit 12 performs control to reduce the air pressure of the plate material ST. This increases the rigidity of the jamming layer and increases the rigidity of the first soft fingers 412. Therefore, the gripping force of the transport object Gr by the first soft fingers 412 and the second soft fingers 413 increases. When the robot hand 4 finishes moving the transport object Gr, the control unit 12 returns the air pressure in the plate material ST to the original value. This makes it possible to prevent a high gripping force from being applied to the transport object Gr for a long period of time.

[0081] The control unit 12 may change the air pressure of the plate material ST based on the output result of the strain sensor 13. For example, the control unit 12 stores a threshold value for the deformation amount of the first soft finger 412 in advance. When the deformation amount of the first soft finger 412 detected by the strain sensor 13 becomes less than the threshold value (for example, when a force is applied to the first soft finger 412 by centrifugal force and the deformation amount of the first soft finger 412 becomes small), the control unit 12 reduces the air pressure of the plate material ST. This increases the rigidity of the first soft finger 412 and the second soft finger 413, and it is possible to prevent the gap between the first soft finger 412 and the second soft finger 413 from widening. Therefore, it is possible to prevent the transport object Gr from falling off. When the deformation amount of the first soft finger 412 detected by the strain sensor 13 becomes equal to or greater than the threshold value, the control unit 12 returns the air pressure of the plate material ST to the original value. In this case, the threshold value is set based on the deformation amount of the first soft finger 412 when the transport object Gr falls off the first soft finger 412 and the second soft finger 413, for example.

[0082] (Effects of the fourth embodiment) The robot hand 4 can transport the transport object Gr, which is easily damaged, without damaging it. Specifically, the plate material ST is attached to the contact portion C41 side of the inner surface IS, and the strain sensor 13 is attached to the plate material ST. As a result, when the first soft finger 412 comes into contact with the transport object Gr, the plate material ST is deformed. The strain sensor 13 can detect the deformation of the plate material ST, thereby detecting the deformation of the first soft finger 412. Therefore, the accuracy of the feedback control by the control unit 12 is improved. Alternatively, since the amount of deformation of the first soft finger 412 can be easily detected by attaching the strain sensor 13 to the plate material ST, the control unit 12 can generate an alert more accurately. The operator who notices the alert can stop the operation of the robot hand 4, thereby preventing damage to the transport object Gr.

[0083] Furthermore, since the strain sensor 13 can easily detect the displacement of the first soft finger 412, the robot hand 4 can transport the transport object Gr at high speed in the same manner as the robot hand 1.

[0084] The robot hand 4 does not have to include the second soft fingers 413. In this case, similar to the robot hand 1a, the robot hand 4 transports the transport object Gr by pushing the transport object Gr with the first soft fingers 412. In this case, the robot hand 4 can also prevent damage to the transport object Gr and transport the transport object Gr at high speed.

[0085] [Fifth embodiment] Hereinafter, the robot hand 5 (not shown) according to the fifth embodiment will be described with reference to the drawings. Fig. 10 is a diagram showing a hand unit 51 included in the robot hand 5 according to the fifth embodiment. Fig. 11 is a diagram showing the first soft finger 512 and the second soft finger 513 as viewed in the negative direction of the Z axis. In Figs. 10 and 11, the strain sensor 13 is seen through.

[0086] The hand unit 51 differs from the hand unit 21 in that it includes a first soft finger 512 having a different configuration from the first soft finger 212, and a second soft finger 513 having a different configuration from the second soft finger 113. Specifically, the first soft finger 512 includes a first member FP5 having a different configuration from the first member FP, and a second member SP5 having a different configuration from the second member SP.

[0087] 10, the second member SP5 differs from the second member SP in that the gap VD is not formed in the second member SP5. The material of the second member SP5 is an epoxy resin, an elastomer resin, or the like.

[0088] As shown in Fig. 10, the first member FP5 differs from the first member FP in that it is not held by the driving mechanism 111B. The first member FP5 is in contact with an end of the second member SP5 in the negative direction of the Z axis. The first member FP5 is not in contact with an end of the second member SP5 in the positive direction of the Z axis. The elastic modulus of the first member FP5 is smaller than that of the second member SP5. The material of such a first member FP5 is, for example, silicone rubber.

[0089] In this embodiment, the strain sensor 13 is provided in the first member FP5. The strain sensor 13 extends in the Z-axis direction. The strain sensor 13 has a principal surface Sh1 and a principal surface Sh2 (the surface having the largest area among the surfaces of the strain sensor 13) aligned in the X-axis direction. The normal direction Hd of the principal surfaces Sh1 and Sh2 coincides with the X-axis direction. The strain sensor 13 is not inclined with respect to the Z-axis direction. The strain sensor 13 detects the deformation of the first member FP5. Specifically, in the example shown in FIG. 10, when the robot hand 5 grasps the transport object Gr, a force toward the negative direction of the X-axis is applied to the first member FP5. As a result, the first member FP5 is deformed so as to protrude in the negative direction of the X-axis. The strain sensor 13 detects the deformation of the first member FP5.

[0090] The second soft finger 513 has a shape symmetrical to the first soft finger 512. Other configurations of the second soft finger 513 are the same as those of the first soft finger 512. Therefore, a description of other configurations of the second soft finger 513 will be omitted.

[0091] In the robot hand 5, the strain sensor 13 does not necessarily have to be provided on the second soft finger 513.

[0092] (Effects of the fifth embodiment) For the same reasons as those of the robot hand 1, the robot hand 5 as described above can transport the easily damaged object Gr without damaging it.

[0093] [Modification 1 of the hand unit 51] Hereinafter, a description will be given of a hand unit 51a according to a first modified example of the hand unit 51 with reference to the drawings. Fig. 12 is a diagram showing a hand unit 51a according to a first modified example of the hand unit 51. In Fig. 12, the strain sensor 13 is seen through.

[0094] The hand unit 51a differs from the hand unit 51 in that the strain sensor 13 is inclined with respect to the X-axis direction. Specifically, the normal direction Hd of the principal surfaces Sh1 and Sh2 of the strain sensor 13 is inclined with respect to the X-axis direction at an angle greater than 0° and smaller than 90°. As shown in FIG. 12, the principal surface Sh1 of the strain sensor 13 faces the positive direction of the X-axis. This allows the strain sensor 13 to detect a force in the X-axis direction applied to the strain sensor 13. In addition, the principal surface Sh1 of the strain sensor 13 faces the negative direction of the Z-axis. This allows the strain sensor 13 to detect a force in the Z-axis direction applied to the strain sensor 13. In other words, the hand unit 51a can detect both the force in the X-axis direction and the force in the Z-axis direction applied to the strain sensor 13. In the case of the above-described configuration, the signal output from the strain sensor 13 is a composite wave obtained by combining a signal output by the strain sensor 13 deforming in the X-axis direction and a signal output by the strain sensor 13 deforming in the Z-axis direction.

[0095] In addition, when the main surfaces Sh1, Sh2 of the strain sensor 13 are inclined at an angle of 45 degrees with respect to the Z-axis direction, the strain sensor 13 can detect both the forces in the X-axis direction and the forces in the Z-axis direction applied to the strain sensor 13 more evenly.

[0096] The configuration of the second soft finger 513 is the same as that of the first soft finger 512, except that the second soft finger 513 has a symmetrical shape to the first soft finger 512. Therefore, a description of the second soft finger 513 will be omitted.

[0097] [Modification 2 of the hand unit 51] Hereinafter, the hand unit 51b according to the second modified example of the hand unit 51 will be described with reference to the drawings. Fig. 13 is a diagram showing the hand unit 51b according to the second modified example of the hand unit 51. Fig. 13 is a diagram showing the first soft finger 512 and the second soft finger 513 of the hand unit 51b as viewed in the negative direction of the Z axis. Fig. 13 shows the strain sensors 13a and 13b in a see-through state.

[0098] The hand unit 51b differs from the hand unit 51 in that a plurality of strain sensors are provided on the first soft finger 512. In the example shown in Fig. 13, the strain sensor 13a and the strain sensor 13b are provided on the first soft finger 512. The normal direction of the principal surfaces Sh1a and Sh2a of the strain sensor 13a coincides with the X-axis direction. The normal direction of the principal surfaces Sh1b and Sh2b of the strain sensor 13b coincides with the X-axis direction.

[0099] The strain sensor 13a is provided at an end of the first member FP5 in the negative direction of the Y axis. Therefore, the strain sensor 13a can easily detect deformation of the end of the first member FP5 in the negative direction of the Y axis. The strain sensor 13b is provided at an end of the first member FP5 in the positive direction of the Y axis. Therefore, the strain sensor 13b can easily detect deformation of the end of the first member FP5 in the positive direction of the Y axis.

[0100] The configuration of the second soft finger 513 is the same as that of the first soft finger 512, except that the second soft finger 513 has a symmetrical shape to the first soft finger 512. Therefore, a description of the second soft finger 513 will be omitted.

[0101] It should be noted that three or more strain sensors may be provided on the first soft finger 512. It should be noted that three or more strain sensors may be provided on the second soft finger 513.

[0102] [Modification 3 of the hand unit 51] Hereinafter, a description will be given of a hand unit 51c according to a third modified example of the hand unit 51 with reference to the drawings. Fig. 14 is a view showing a hand unit 51c according to a third modified example of the hand unit 51. In Fig. 14, the strain sensors 13a and 13b are seen through.

[0103] As shown in FIG. 14, the hand unit 51c differs from the hand unit 51b in that the strain sensor 13a is inclined with respect to the Y-axis direction and the strain sensor 13b is inclined with respect to the Y-axis direction.

[0104] The principal surface Sh1a of the strain sensor 13a faces the positive direction of the X-axis and also faces the positive direction of the Y-axis. Therefore, the strain sensor 13a can detect both the forces in the X-axis direction and the forces in the Y-axis direction applied to the strain sensor 13a, similar to the strain sensor 13 in the hand unit 51a.

[0105] The principal surface Sh1b of the strain sensor 13b faces the positive direction of the X-axis and the negative direction of the Y-axis. Therefore, the strain sensor 13b can detect both the forces in the X-axis direction and the forces in the Y-axis direction applied to the strain sensor 13b, similar to the strain sensor 13 in the hand part 51a. The same is true for the strain sensors 13c and 13d.

[0106] The configuration of the second soft finger 513 is the same as that of the first soft finger 512, except that the second soft finger 513 has a symmetrical shape to the first soft finger 512. Therefore, a description of the second soft finger 513 will be omitted.

[0107] [Variation 4 of the hand unit 51] Hereinafter, the hand unit 51d according to the fourth modified example of the hand unit 51 will be described with reference to the drawings. Fig. 15 is a diagram showing the hand unit 51d according to the fourth modified example of the hand unit 51. Fig. 16 is a diagram showing the first soft finger 512 and the second soft finger 513 of the hand unit 51d as viewed in the negative direction of the Z axis. In Figs. 15 and 16, the strain sensors 13a, 13b, 13c, and 13d are seen through.

[0108] As shown in Figures 15 and 16, the hand portion 51d differs from the hand portion 51c in that the main surfaces Sh1a, Sh2a of the strain sensor 13a are inclined with respect to the Z-axis direction, and the main surfaces Sh1b, Sh2b of the strain sensor 13b are inclined with respect to the Z-axis direction.

[0109] For example, the principal surface Sh1a of the strain sensor 13a faces in the positive direction of the X-axis, the positive direction of the Y-axis, and the negative direction of the Z-axis. In this case, the strain sensor 13a detects a force in the Z-axis direction applied to the strain sensor 13a in addition to the forces in the X-axis direction and the Y-axis direction applied to the strain sensor 13a.

[0110] For example, the main surface Sh1b of the strain sensor 13b faces the positive direction of the X-axis, faces the negative direction of the Y-axis, and faces the negative direction of the Z-axis. In this case, the strain sensor 13b detects a force in the Z-axis direction applied to the strain sensor 13b in addition to a force in the X-axis direction and a force in the Y-axis direction applied to the strain sensor 13b. In other words, the hand unit 51d can detect forces in three directions applied to the first member FP5.

[0111] The configuration of the second soft finger 513 is the same as that of the first soft finger 512, except that it has a symmetrical shape to the first soft finger 512. Therefore, a description of the second soft finger 513 will be omitted.

[0112] In the above configuration, the principal surface of the strain sensor 13a faces the positive direction of the X-axis, the positive direction of the Y-axis, and the negative direction of the Z-axis. The principal surface of the strain sensor 13b faces the positive direction of the X-axis, the negative direction of the Y-axis, and the negative direction of the Z-axis. The principal surface of the strain sensor 13c attached to the second soft finger 513 faces the negative direction of the X-axis, the positive direction of the Y-axis, and the negative direction of the Z-axis. The principal surface of the strain sensor 13d attached to the second soft finger 513 faces the negative direction of the X-axis, the negative direction of the Y-axis, and the negative direction of the Z-axis. At this time, for example, when a force in the Z-axis rotation direction is applied to the first member FP5, the strain sensors 13a and 13b are stretched. The strain sensors 13c and 13d in the second soft finger 513 are also stretched by the force in the Z-axis rotation direction. Therefore, in this modified example, it is possible to determine whether or not a force is being applied to the first member FP5 of the first soft finger 512 and the first member of the second soft finger 513 in the Z-axis rotation direction.

[0113] [Variation 5 of the hand unit 51] Hereinafter, a hand unit 51e according to Modification 5 of the hand unit 51 will be described with reference to the drawings. Fig. 17 is a diagram showing a hand unit 51e according to Modification 5 of the hand unit 51. Fig. 17 shows a see-through view of the strain sensor 13 and the through hole He.

[0114] As shown in FIG. 17, the hand unit 51e differs from the hand unit 51 in that a through hole He is provided in the second member SP5. The through hole He penetrates the second member SP5 in the X-axis direction. When viewed in the X-axis direction, the through hole He overlaps with the strain sensor 13. When the first member FP5 comes into contact with the transport object Gr, the first member FP5 deforms so as to protrude toward the through hole He. In other words, the first member FP5 deforms so as to protrude in the negative direction of the X-axis. Therefore, the first member FP5 is more likely to deform than a hand unit in which a through hole is not provided in the second member. As a result, the strain sensor 13 can more easily detect the deformation of the first member FP5.

[0115] In the case of the above configuration, the worker can adjust the magnitude of the signal output from the strain sensor 13. For example, the worker prepares a member (hereinafter referred to as a first adjustment member) that is smaller than the size of the cross section of the through hole He when viewed in the X-axis direction. The worker adjusts the magnitude of the signal by filling a part of the through hole He with the first adjustment member. For example, the first adjustment member has a semicircular shape. The worker fills the negative side of the X-axis and the negative side of the Z-axis in the through hole He with the semicircular first adjustment member. This reduces the depth of the through hole He. In this case, the deformation amount of the first member FP5 is smaller than the deformation amount of the first member FP5 in which the through hole He is not filled with the first adjustment member. Therefore, the deformation amount of the strain sensor 13 is reduced. Note that when the negative side of the X-axis and the negative side of the Z-axis in the through hole He are filled with the semicircular first adjustment member, the shape of the through hole He is semicircular when viewed in the X-axis direction.

[0116] The worker can adjust the magnitude of the signal output from the strain sensor 13 by adjusting the thickness of the first adjustment member. For example, if the worker wants to reduce the magnitude of the signal from the strain sensor 13, he fills a part of the through hole He with a thick first adjustment member. On the other hand, if the worker wants to increase the magnitude of the signal from the strain sensor 13, he fills a part of the through hole He with a thin first adjustment member.

[0117] The configuration of the second soft finger 513 is the same as that of the first soft finger 512, except that the second soft finger 513 has a symmetrical shape to the first soft finger 512. Therefore, a description of the second soft finger 513 will be omitted.

[0118] [Modification 6 of the hand unit 51] Hereinafter, a hand portion 51f according to the sixth modified example of the hand portion 51 will be described with reference to the drawings. Fig. 18 is a view showing the hand portion 51f according to the sixth modified example of the hand portion 51. Fig. 18 shows the strain sensor 13 and the recess Hf1 in a see-through manner.

[0119] As shown in Fig. 18, the hand part 51f differs from the hand part 51e in that the second member SP5 has a recess Hf1 instead of a through hole He. The recess Hf1 does not penetrate the second member SP5. In the second member SP5, the first main surface S32 of the second member SP5 is recessed toward the negative direction of the X-axis by the recess Hf1. The recess Hf1 overlaps with the strain sensor 13 when viewed in the X-axis direction. The strain sensor 13 in the hand part 51f can easily detect deformation of the first member FP5 in the same manner as the strain sensor 13 in the hand part 51e.

[0120] The configuration of the second soft finger 513 is the same as that of the first soft finger 512, except that the second soft finger 513 has a symmetrical shape to the first soft finger 512. Therefore, a description of the second soft finger 513 will be omitted.

[0121] The recess Hf1 may be provided in the second member SP5 by the method described below. A through hole (hereinafter referred to as a first through hole) that penetrates the second member SP5 in the X-axis direction is provided in the second member SP5. The worker prepares a member (hereinafter referred to as a second adjustment member) that has the same shape as the first through hole when viewed in the X-axis direction. The worker fills the negative side of the X-axis in the first through hole with the second adjustment member. By the method described above, the worker can provide the recess Hf1 in the second member SP5 instead of the first through hole.

[0122] The worker can adjust the magnitude of the signal output from strain sensor 13 by adjusting the thickness of the second adjustment member. For example, if the worker wants to reduce the magnitude of the signal from strain sensor 13, he fills the first through hole with a thicker second adjustment member. On the other hand, if the worker wants to increase the magnitude of the signal from strain sensor 13, he fills the first through hole with a thinner second adjustment member.

[0123] [Variations in the shape of the recess] Modified examples of the shape of the recess will be described below with reference to the drawings. Fig. 19 is a view showing a recess Hf2 provided in the second member SP5 of the hand part 51e. Fig. 20 is a view showing a recess Hf3 provided in the second member SP5 of the hand part 51e. Fig. 19 shows a see-through view of the strain sensor 13 and the recess Hf2. Fig. 20 shows a see-through view of the strain sensor 13 and the recess Hf3.

[0124] For example, as shown in FIGS. 19 and 20, a recess Hf2 or a recess Hf3 having a shape different from that of the recess Hf1 may be provided in the second member SP5 instead of the recess Hf1.

[0125] As shown in FIG. 19, the inner side surface of the second member SP5 formed by the recess Hf2 is tapered. The cross-sectional area of ​​the recess Hf2 becomes smaller as it approaches the second main surface S42 of the second member SP5. When the first member FP5 is deformed, the first member FP5 comes into contact with the inner side surface of the second member SP5 formed by the recess Hf2. The first member FP5 is less likely to deform after coming into contact with the inner side surface of the second member SP5 formed by the recess Hf2. Therefore, the output value from the strain sensor 13 in the robot hand 5 in which the recess Hf2 is provided in the second member SP5 tends to be smaller than the output value of the strain sensor 13 in the robot hand 5 in which the recess Hf1 is provided in the second member SP5. By providing the robot hand 5 with this structure, even in a case in which the output value of the strain sensor 13 in the robot hand 5 in which the recess Hf1 is provided in the second member SP5 exceeds the limit, it is possible to adjust the output value of the strain sensor 13 so that it does not exceed the limit.

[0126] As shown in FIG. 20, the inner side of the second member SP5 formed by the recess Hf3 is tapered. Furthermore, the inner side of the second member SP5 formed by the recess Hf3 draws an arc when viewed in the Y-axis direction. The cross-sectional area of ​​the recess Hf3 becomes smaller as it approaches the second main surface S42 of the second member SP5. As a result, when the first member FP5 is deformed, the first member FP5 comes into contact with the inner side of the second member SP5 formed by the recess Hf3. After the first member FP5 comes into contact with the inner side of the second member SP5 formed by the recess Hf3, it is difficult for the first member FP5 to deform further. Therefore, the output value from the strain sensor 13 in the robot hand 5 in which the recess Hf3 is provided in the second member SP5 tends to be smaller than the output value of the strain sensor 13 in the robot hand 5 in which the recess Hf1 is provided in the second member SP5. By providing this structure to the robot hand 5, it becomes possible to adjust the output value of the strain sensor 13 so that it does not go off the scale, even in cases where the output value of the strain sensor 13 in the robot hand 5 in which a recess Hf1 is provided in the second member SP5 goes off the scale.

[0127] As described above, the shape of the recess provided in the second member SP5 changes the magnitude of the signal output from the strain sensor 13. Therefore, the operator can adjust the magnitude of the signal output from the strain sensor 13 by changing the shape of the recess provided in the second member SP5.

[0128] [Sixth embodiment] Hereinafter, the robot hand 6 (not shown) according to the sixth embodiment will be described with reference to the drawings. Fig. 21 is a diagram showing a hand unit 61 included in the robot hand 6 according to the sixth embodiment. Fig. 22 is a diagram showing a first soft finger 612 as viewed in the positive direction of the Z axis.

[0129] The hand unit 61 differs from the hand unit 11a in that it includes a first soft finger 612 having a different configuration from the first soft finger 112. The first soft finger 612 includes a first portion F1, a second portion F2, a third portion F3, and a measurement sensor Pr1. The first portion F1, the second portion F2, and the third portion F3 are arranged in the positive direction of the X-axis in the order of the second portion F2, the first portion F1, and the third portion F3.

[0130] 21 and 22, the second portion F2 extends from the driving portion 111 in the negative direction of the Z axis. The second portion F2 is in contact with the driving portion 111. The second portion F2 is held by the driving portion 111.

[0131] 21 and 22, the third portion F3 extends from the driving portion 111 in the negative direction of the Z axis. The third portion F3 is in contact with the driving portion 111. The third portion F3 is held by the driving portion 111.

[0132] The first portion F1 is in contact with a part of the main surface of the second portion F2 and a part of the main surface of the third portion F3. The first portion F1 is fixed to an end of the second portion F2 in the negative direction of the Z axis and an end of the third portion F3 in the negative direction of the Z axis. As shown in FIG. 22, the first portion F1 includes an outer circumferential portion F1a and an inner circumferential portion F1b.

[0133] As shown in FIG. 22, the outer peripheral portion F1a has a tubular shape having an inner peripheral surface and an outer peripheral surface. In this embodiment, the outer peripheral portion F1a has a cylindrical shape. The outer peripheral surface of the outer peripheral portion F1a is in contact with a part of the main surface of the second portion F2 and a part of the main surface of the third portion F3. The material of such an outer peripheral portion F1a is epoxy resin, elastomer resin, or the like. Note that the outer peripheral portion F1a does not necessarily have to have a cylindrical shape as long as it has a cylindrical shape.

[0134] As shown in FIG. 22, the inner peripheral portion F1b has a cylindrical shape having an inner peripheral surface and an outer peripheral surface. In this embodiment, the inner peripheral portion F1b has a cylindrical shape. The inner peripheral portion F1b is surrounded by the outer peripheral portion F1a. The outer peripheral surface of the inner peripheral portion F1b is in contact with the inner peripheral surface of the outer peripheral portion F1a. The inner peripheral portion F1b is fixed to the outer peripheral portion F1a. The material of such inner peripheral portion F1b is, for example, silicone rubber. Note that the inner peripheral portion F1b does not necessarily have to be cylindrical as long as it is cylindrical.

[0135] The measurement sensor Pr1 is a probe for measuring a physical quantity such as the surface roughness of an object. As shown in Fig. 21 and Fig. 22, the end of the measurement sensor Pr1 in the positive direction of the Z axis is surrounded by an inner circumference F1b and an outer circumference F1a. The end of the measurement sensor Pr1 in the positive direction of the Z axis is fixed by the inner circumference F1b. The end of the measurement sensor Pr1 in the negative direction of the Z axis is exposed from the inner circumference F1b and the outer circumference F1a.

[0136] When the robot hand 6 grips the transport object Gr, the measurement sensor Pr1 comes into contact with the transport object Gr. At this time, the measurement sensor Pr1 can measure the surface roughness, etc., of the transport object Gr.

[0137] In this embodiment, the robot hand 6 is equipped with three strain sensors 13a, 13b, and 13c. As shown in Fig. 22, the strain sensors 13a, 13b, and 13c are provided in the inner peripheral portion F1b. The strain sensors 13a, 13b, and 13c surround the measurement sensor Pr1. The main surfaces of the strain sensors 13a, 13b, and 13c face the direction in which the measurement sensor Pr1 is located.

[0138] The strain sensors 13a, 13b, and 13c detect the deformation of the inner circumference F1b. Specifically, the measurement sensor Pr1 comes into contact with the surface of an object such as the transport object Gr, and moves in the X-axis direction along the surface of the object. This applies, for example, a force in the X-axis direction to the measurement sensor Pr1. In this case, the inner circumference F1b deforms toward the positive direction of the X-axis or the negative direction of the X-axis. As shown in FIG. 21, the main surface of the strain sensor 13a faces the negative direction of the X-axis and the positive direction of the Y-axis. The main surface of the strain sensor 13b faces the positive direction of the X-axis and the positive direction of the Y-axis. Therefore, the strain sensors 13a and 13b can detect the deformation of the inner circumference F1b in the positive direction of the X-axis or the negative direction of the X-axis, and the deformation of the inner circumference F1b in the positive direction of the Y-axis or the negative direction of the X-axis.

[0139] Also, for example, a force in the Y-axis direction is applied to the measurement sensor Pr1. In this case, the inner peripheral portion F1b is deformed in the positive direction of the Y-axis or the negative direction of the Y-axis. The main surface of the strain sensor 13c faces the Y-axis direction. Therefore, the strain sensor 13c can detect the deformation of the inner peripheral portion F1b in the positive direction of the Y-axis or the negative direction of the Y-axis.

[0140] Even if the magnitude of the force applied by the hand unit 61 to an object such as the transport target Gr is always constant, the outputs of the strain sensors 13a, 13b, and 13c change depending on the surface roughness of the object. Therefore, the robot hand 6 can also measure the surface roughness of an object such as the transport target Gr based on the outputs of the strain sensors 13a, 13b, and 13c.

[0141] The robot hand 6 may be used to transport a transport object Gr. For example, as shown in Fig. 20, the robot hand 6 may transport the transport object Gr by pushing the transport object Gr with the first soft fingers 612.

[0142] [Modification 1 of the hand unit 61] Hereinafter, a description will be given of the hand unit 61a according to the first modified example of the hand unit 61 with reference to the drawings. Fig. 23 is a diagram showing the hand unit 61a according to the first modified example of the hand unit 61.

[0143] 23, the hand unit 61a differs from the hand unit 61 in that it includes a second soft finger 613. The configuration of the second soft finger 613 is the same as the configuration of the first soft finger 612, except that the second soft finger 613 has a symmetrical shape to the first soft finger 612.

[0144] In the hand unit 61a, the measurement sensor Pr1 and the measurement sensor Pr2 provided on the second soft finger 613 pinch the transport object Gr. In this way, the hand unit 61a transports the transport object Gr. At this time, the measurement sensor Pr2 comes into contact with the transport object Gr. The measurement sensor Pr2 measures, for example, the surface roughness of the transport object Gr in the same manner as the measurement sensor Pr1.

[0145] In this modification, the main surfaces of the strain sensors 13a, 13b, and 13c may be inclined with respect to the Z-axis direction. In this case, the control unit 12 in this modification can determine whether or not a force in the Z-axis rotation direction is applied to the first portion F1, similarly to the control unit 12 in the robot hand 5 including the hand unit 51d.

[0146] [Other embodiments] The first to sixth embodiments and their respective modified examples may be combined as appropriate.

[0147] The number of strain sensors provided in the robot hands 1, 1a, 2, 3, 4, 5, and 6 described above is an example. Therefore, the robot hands 1, 1a, 2, 3, 4, 5, and 6 may be provided with more than the number of strain sensors described above. For example, the robot hands 1, 1a, 2, 3, and 4 may be provided with two or more strain sensors. For example, the robot hand 5 provided with the hand unit 51, the hand unit 51a, the hand unit 51e, or the hand unit 51f may be provided with three or more strain sensors. For example, the robot hand 5 provided with the hand unit 51b, the hand unit 51c, or the hand unit 51d may be provided with five or more strain sensors. For example, the robot hand 6 provided with the hand unit 61 may be provided with four or more strain sensors. For example, the robot hand 6 provided with the hand unit 61a may be provided with seven or more strain sensors.

[0148] The number of soft fingers provided on the robot hands 1, 1a, 2, 3, 4, 5, and 6 described above is an example. Therefore, the robot hands 1, 1a, 2, 3, 4, 5, and 6 may have soft fingers more than the number described above. For example, the robot hands 1, 2, 3, 4, and 5 may have three or more soft fingers. Similarly, the robot hand 6 provided with the hand part 61a may have three or more soft fingers. In the case of the above configuration, the drive mechanism 11B holds each of the three or more soft fingers. At this time, the drive mechanism 11B has a mechanism capable of driving each of the three or more soft fingers. The three or more soft fingers grip the transport object Gr so as to surround the periphery of the transport object Gr when viewed in the Z-axis direction. [Explanation of symbols]

[0149] 1, 1a, 2, 3, 4, 5, 6: Robot hand 13: Strain sensor 112,212,312,412,512,612: 1st flexible finger 113,313,413,513,613:Second flexible finger Gr: Transported object

Claims

1. A soft finger that carries an object to be carried and is made of an elastic body; a strain sensor having flexibility, attached to the soft finger, and configured to detect deformation of the soft finger; Equipped with The soft finger includes a first member that is a plate-like body and a second member that is a plate-like body, The strain sensor is attached to the first member and detects a deformation of the first member; The first member has a first main surface having a contact portion that contacts the transported object, and a second main surface to which the strain sensor is attached, the second member supports the first member by contacting the second main surface at at least two points; a recess is provided in the first member or the second member, thereby forming a gap in the soft finger; the gap is formed between the first member and the second member, and is formed at a position overlapping the contact portion when the first member is viewed in a normal direction of the first main surface, The soft finger moves in the normal direction to contact the transport object at the contact portion. Robot hand.

2. A soft finger that carries an object to be carried and is made of an elastic body; a strain sensor having flexibility, attached to the soft finger, and configured to detect deformation of the soft finger; Equipped with The soft finger includes a first member and a second member each having a polygonal prism shape, The strain sensor is attached to the first member and detects a deformation of the first member; The first member has a first side surface having a contact portion that contacts the transported object, and a second side surface to which the strain sensor is attached, the second member supports the first member by contacting the second side surface at at least two points; A recess is provided in the first member or the second member, so that a gap is formed in the soft finger, the gap is formed between the first member and the second member, and is formed at a position overlapping the contact portion when the first member is viewed in a normal direction of the first side surface, The soft finger moves in the normal direction to contact the transport object at the contact portion. Robot hand.

3. The elastic modulus of the first member is lower than the elastic modulus of the second member. The robot hand according to claim 1 or 2.

4. The strain sensor is either a strain gauge or a piezoelectric sensor. The robot hand according to claim 1 or 2.

5. The piezoelectric sensor includes polylactic acid or PVDF. The robot hand according to claim 4.

6. The strain sensor includes a plate-shaped strain sensor, The contact portion is disposed along a normal direction of the plate-shaped strain sensor. The robot hand according to claim 1 or 2.

7. acquiring displacement information related to the displacement of the soft finger based on an output result of the strain sensor; controlling the movement of the soft finger based on the displacement information; Further comprising a control unit, The robot hand according to claim 1 or 2.

8. The displacement information includes a displacement speed of the soft finger. The robot hand according to claim 7.

9. The soft finger is made of a polymeric material. The robot hand according to claim 1 or 2.

10. The soft finger includes a plurality of soft fingers. The robot hand according to claim 1 or 2.

11. The transport object is a grasp object, The plurality of soft fingers grasp the object to be grasped. The robot hand according to claim 10.

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