End effector and robot

Abstract

To provide an end effector which performs a work through contact with an object, includes an elastic-deformable contact surface, can effectively protect a sensor for detecting a contact with the contact surface, and a robot with the end effector.SOLUTION: An end effector 5 performing a work through contact with an object comprises: an elastic member 29 which has an external surface constituting a contact surface 31 and is elastically deformable; a frame 27 which supports the elastic member; a tabular rigid member 23 which is supported by the elastic member and has higher rigidity than that of the elastic member; and a sensor 25 which is attached to the rigid member and detects a spatial distribution of physical amount related to the load applied to the rigid member.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to an end effector that performs operations by contacting an object and a robot including the end effector.

Background Art

[0002] Conventionally, as an end effector, a robot hand having a plurality of fingers like a human and gripping an object is known. The object to be gripped by such a robot hand does not necessarily have a flat outer surface, and may have a curved outer surface. Therefore, it is desirable that the contact surface of the finger portion (robot finger) of the robot hand be elastically deformable along the shape of the object.

[0003] Patent Document 1 discloses a robot finger including a retroreflective sensor. The robot finger includes a transparent shell, a transparent elastomer layer provided on the outer surface of the transparent shell, a half-mirror layer covering the transparent elastomer layer, a light source that emits light inside the transparent shell, and an imaging device that images the inside of the transparent shell. The light emitted from the light source passes through the inside of the transparent shell and is reflected by the half-mirror layer. The imaging device detects the reflected light as an imaging image.

[0004] When the robot finger contacts an object, the shape of the half-mirror layer is changed. As a result, the imaging image of the imaging device changes. By this change in the imaging image, it becomes possible to detect the contact of the robot finger with the object.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the robotic finger of Patent Document 1, in order to increase the shape change of the semi-mirror layer, the semi-mirror layer is provided on the outer surface of the transparent elastomer layer. However, repeated contact with an object may damage the semi-mirror layer, resulting in the inability to appropriately detect contact with the object.

[0007] Thus, in a robotic finger, it is desirable to dispose a sensor near the contact surface for detecting contact with an object. On the other hand, disposing a sensor or a detection structure (the semi-mirror layer in the case of Patent Document 1) near the contact surface that contacts the object may damage the sensor or the detection structure due to repeated contact with the object, etc., resulting in the inability to appropriately detect contact.

[0008] Therefore, in view of the above background, an object of the present invention is to provide an end effector that performs work by contacting an object, includes an elastically deformable contact surface, and can effectively protect a sensor for detecting contact with the contact surface, and a robot including the end effector.

Means for Solving the Problem

[0009] To solve the above problems, an aspect of the present invention is an end effector (5) that performs work by contacting an object, including an elastic member (29) having an outer surface constituting a contact surface (31) and being elastically deformable, a frame (27) that supports the elastic member, a plate-shaped rigid member (23) that is supported by the elastic member and has a higher rigidity than the elastic member, and a sensor (25) that is attached to the rigid member and detects a spatial distribution of a physical quantity related to a load applied to the rigid member.

[0010] According to this aspect, a contact surface is formed by an elastic member. When an object contacts the contact surface, the load applied to the contact surface is transmitted to the rigid member via the elastic member. Therefore, the contact with the contact surface can be detected by a sensor attached to the rigid member. As a result, since the sensor can be arranged at a position different from the contact surface, an end effector is provided that has an elastically deformable contact surface and can effectively protect the sensor for detecting the contact with the contact surface.

[0011] In the above aspect, preferably, the sensor is provided on the surface of the rigid member on the contact surface side.

[0012] According to this aspect, since the sensor is provided on the contact surface side of the rigid member, the sensor can be effectively protected.

[0013] In the above aspect, preferably, the frame has a tip portion (27B) covered by the elastic member.

[0014] According to this aspect, a contact surface can be provided at the tip portion of the frame.

[0015] In the above aspect, preferably, the rigid member is coupled to the frame via the elastic member.

[0016] According to this aspect, the contact with the contact surface can be favorably transmitted to the elastic member.

[0017] In the above aspect, preferably, the frame has a tip portion (27B) directly coupled to the rigid member and covered by the elastic member.

[0018] According to this aspect, the rigid member can be favorably supported by the frame.

[0019] In the above aspect, preferably, the sensor detects the pressure distribution applied to the rigid member.

[0020] According to this aspect, it is possible to detect the spatial distribution of a physical quantity related to the load applied to the rigid member when a load is transmitted to the rigid member upon contact with the contact surface.

[0021] In the above aspect, preferably, the sensor detects the stress distribution of the rigid member.

[0022] According to this aspect, it is possible to detect the spatial distribution of a physical quantity related to the load applied to the rigid member when a load is transmitted to the rigid member upon contact with the contact surface.

[0023] In the above aspect, preferably, a control device (13) for acquiring load information related to the load acting on the contact surface is provided based on the output of the sensor.

[0024] According to this aspect, information (load information) related to the load acting on the contact surface can be acquired based on the output of the sensor.

[0025] In the above aspect, preferably, the load information includes any one of the action point of the load, the magnitude of the load, and the direction of the load.

[0026] According to this aspect, it is possible to acquire information required for controlling the end effector.

[0027] In the above aspect, preferably, a robot (1) provided with the above end effector, having a drive device (11) for displacing the end effector, and the control device gives a drive instruction to the drive device based on the load information.

[0028] According to this aspect, it is possible to provide a robot that acquires load information based on the detection result of the sensor and controls the end effector.

Advantages of the Invention

[0029] According to the above aspects, an end effector that performs operations in contact with an object, includes an elastically deformable contact surface, and can effectively protect a sensor for detecting a load applied to the contact surface, and a robot including the end effector can be provided.

Brief Description of Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0031] Hereinafter, the end effector and the robot according to the present embodiment of the present invention will be described with reference to the drawings.

[0032] <<First Embodiment>> The end effector is provided at the tip of a robot arm 3 that constitutes the arm of a so-called humanoid robot 1. The end effector corresponds to a so-called robot hand 5 that performs various operations by contacting an object. Operations performed by the robot hand 5 may include, for example, gripping an object, manipulating an object, tracing the surface of an object, and the like.

[0033] As shown in FIG. 1, the robot hand 5 includes a palm portion 7 that constitutes a portion corresponding to a human palm, and a plurality of finger portions 9 that constitute portions corresponding to human fingers.

[0034] The palm portion 7 has a substantially flat plate shape. Each finger portion 9 includes a proximal phalanx 9A rotatably connected to the palm portion 7 at its proximal end, a middle phalanx 9B rotatably (also referred to as rotatably) connected to the free end of the proximal phalanx 9A at its proximal end, and a distal phalanx 9C rotatably connected to the free end of the middle phalanx 9B at its proximal end.

[0035] In this embodiment, as shown in FIG. 1, the robot hand 5 includes five finger portions 9 corresponding to a human thumb, index finger, middle finger, ring finger, and little finger. The four finger portions 9 corresponding to the index finger, middle finger, ring finger, and little finger are each connected to the palm portion 7 so as to be uniaxially rotatable about an axis X extending substantially parallel to the main surface of the palm portion 7 at the proximal end of the proximal phalanx 9A. The finger portion 9 corresponding to the thumb is connected to the palm portion 7 so as to be rotatable about an axis X extending substantially parallel to the main surface of the palm portion 7 and an axis Y orthogonal to the axis X at the proximal end of the proximal phalanx 9A.

[0036] The five finger portions 9 are each connected to the palm portion 7 so as to be rotatable only in a direction approaching one side surface (corresponding to the palm side) of the palm portion 7 from an extended position extending along the palm portion 7. Hereinafter, for convenience of explanation, when the finger portion 9 is rotated about the axis X, the surface on the side of the finger portion 9 approaching the palm portion 7 is described as the front surface, and the surface facing away from the front surface is described as the back surface. The front surface corresponds to the palm side surface of a human hand, and the back surface corresponds to the back side surface of a human hand.

[0037] The middle phalanx 9B is also connected to the proximal phalanx 9A so as to be rotatable only toward the front side from an extended position extending along the proximal phalanx 9A. The distal phalanx 9C is also connected to the middle phalanx 9B so as to be rotatable only toward the front side from an extended position extending along the middle phalanx 9B. By rotating the proximal phalanx 9A, the middle phalanx 9B, and the distal phalanx 9C respectively, the finger part 9 can be bent and extended.

[0038] The robot 1 includes a plurality of drive devices 11 that drive to bend and extend the finger parts 9 respectively, and a control device 13 that controls the driving of the drive devices 11 respectively.

[0039] The drive device 11 can rotate the finger parts 9 such that the proximal phalanx 9A, the middle phalanx 9B, and the distal phalanx 9C rotate independently. The drive device 11 may be based on a so-called wire drive method having an electric motor and a wire that connects the electric motor to each of the proximal phalanx 9A, the middle phalanx 9B, and the distal phalanx 9C. The drive device 11 and the control device 13 may be provided in a body part (not shown) of the robot 1, or may be provided inside the robot arm 3.

[0040] When the robot hand 5 grips an object, the control device 13 bends the finger parts 9 respectively, moves them so that the front surfaces of the finger parts 9 approach the object, and brings the front surfaces (palmar surfaces) of the finger parts 9 (mainly the distal phalanx 9C) into contact with the surface of the object.

[0041] Next, the configuration of the distal phalanx 9C will be described in detail. Each distal phalanx 9C constitutes the tip of the finger part 9. The distal phalanx 9C has a main body 21, a claw member 23 provided on the back surface side of the main body 21, and a sensor 25 provided on the surface side of the claw member 23.

[0042] FIG. 2(A) shows a cross section (also referred to as a longitudinal section) in the direction (extending direction) connecting the proximal end and the free end of the distal phalanx 9C, and FIG. 2(A) shows a cross section (also referred to as a transverse section) in the direction orthogonal to the extending direction of the distal phalanx 9C.

[0043] As shown in FIGS. 2(A) and 2(B), the main body 21 includes a frame 27 that forms a skeleton and an elastic member 29 supported by the frame 27.

[0044] As shown in FIG. 2(A), the frame 27 is a rod-shaped member, and at its proximal end, it has a connecting portion 27A rotatably connected to the middle phalanx 9B (specifically, the frame constituting the middle phalanx 9B). The frame 27 may be constituted by, for example, a metal member or a relatively rigid resin member. A tip portion 27B having a quadrangular prism shape is provided on the free end side of the frame 27. The free end portion of the frame 27 is constituted by this tip portion 27B.

[0045] The elastic member 29 is provided at the tip portion 27B of the frame 27. The elastic member 29 is more easily elastically deformed than the frame 27, and in this embodiment, it is constituted by an elastically deformable resin material such as rubber or elastomer. In this embodiment, on the side of the middle phalanx 9B of the elastic member 29, a receiving recess 29A that is recessed to receive the frame 27 is provided. The tip portion 27B is coupled to the elastic member 29 in a state of being inserted into the receiving recess 29A. Thereby, the tip portion 27B of the frame 27 is in a state of being completely covered by the elastic member 29.

[0046] The surface side (palm side) of the distal phalanx 9C, including its outer surface, is constituted by the elastic member 29. The surface side (palm side) of the elastic member 29 constitutes a portion corresponding to the belly of a human finger. The outer surface of the surface side of the elastic member 29 mainly comes into contact with an object when the robot hand 5 grips the object or traces the surface of the object. Hereinafter, the outer surface of the surface side of the elastic member 29 is referred to as the contact surface 31. The contact surface 31 is constituted by the elastic member 29.

[0047] The claw member 23 is in the shape of a plate along the back surface of the main body 21. The claw member 23 is, for example, a rigid member that is more difficult to elastically deform than the elastic member 29, and is formed of a harder material (for example, hard plastic, etc.) compared to the material constituting the elastic member 29. Note that the claw member 23 is preferably more easily elastically deformed than the frame 27.

[0048] As shown in FIGS. 2(A) and 2(B), the claw member 23 is arranged along the outer surface on the back surface side of the elastic member 29 and is directly connected to the elastic member 29. Thereby, the claw member 23 is connected to the frame 27 via the elastic member 29 and is supported by the frame 27 via the elastic member 29.

[0049] In the present embodiment, as shown in FIG. 2(B), the claw member 23 is gently curved along the direction orthogonal to the extending direction of the distal phalanx portion 9C (the direction from the proximal end side to the distal end side) (hereinafter, the left - right direction).

[0050] The sensor 25 includes a sheet - shaped detection portion 25A. The detection portion 25A of the sensor 25 is arranged between the claw member 23 (rigid member) and the main body 21. It is desirable that the detection portion 25A of the sensor 25 is attached to the surface on the contact surface 31 side of the claw member 23 (that is, the surface on the elastic member 29 side). Thereby, since the detection portion 25A of the sensor 25 is not exposed, the detection portion 25A can be effectively protected. However, the detection portion 25A of the sensor 25 may be provided on the surface opposite to the contact surface 31 side of the claw member 23. In this case, in order to protect the detection portion 25A of the sensor 25, the detection portion 25A of the sensor 25 may be coated with parylene or the like.

[0051] The sensor 25 detects the spatial distribution of a physical quantity related to the load applied to the claw member 23 (rigid member) in the detection unit 25A (hereinafter referred to as the load physical quantity). The spatial distribution of the load physical quantity detected by the sensor 25 may be the distribution of pressure (pressure distribution) applied to at least a part of the claw member 23. Alternatively, the spatial distribution of the physical quantity detected by the sensor 25 may be the spatial distribution of stress (stress distribution) generated in at least a part of the claw member 23. The sensor 25 may be composed of strain gauges arranged in a matrix, or may be composed of ferroelectric piezoelectric elements arranged in a matrix. Alternatively, the sensor 25 may be composed of capacitance sensors arranged in a matrix.

[0052] When an object contacts the contact surface 31, a load is transmitted to the claw member 23 (rigid member) via the elastic member 29, and the load physical quantity detected by the sensor 25 changes. For example, as shown in Fig. 3(A), assume a case where the distal phalanx 9C contacts the target object O at the contact surface 31 and receives a load F. At this time, the elastic member 29 elastically deforms due to the load from the object contacting the contact surface 31, and pressure is applied to the back surface of the claw member 23. That is, the load applied to the contact surface 31 is transmitted to the claw member 23 by the elastic member 29. Fig. 4(A) shows, as a shaded graph, the simulation result of the pressure distribution (pressure distribution) applied to the claw member 23 when a load is applied as shown in Fig. 3(A).

[0053] Similarly, when the distal phalanx 9C contacts the target object O at the contact surface 31 and receives a load F as shown in Fig. 3(B), pressure is applied to the back surface of the claw member 23. Fig. 4(B) shows, as a shaded graph, the simulation result of the pressure distribution (pressure distribution) applied to the claw member 23 at this time. In Fig. 4(A) and Fig. 4(B), it is shown that the darker the color, the higher the pressure. From Fig. 4(A) and Fig. 4(B), it can be understood that the pattern shown by the pressure distribution depends on the acting point of the load, the magnitude of the load, and the direction of the load.

[0054] When a load is applied to the contact surface 31, pressure is applied to the claw member 23, and stress is generated inside the claw member 23. Therefore, it can be predicted that the pattern shown by the stress distribution generated inside the claw member 23 also depends on the point of action of the load, the magnitude of the load, and the direction of the load.

[0055] As shown in FIG. 5(A), when the distal phalanx 9C contacts the object O to be targeted at the contact surface 31 and receives a load F, the simulation result of the stress distribution generated inside the claw member 23 is shown as a shaded graph in FIG. 6(A). Similarly, as shown in FIG. 5(B), when the distal phalanx 9C contacts the object O to be targeted at the contact surface 31 and receives a load F, the simulation result of the stress distribution generated inside the claw member 23 is shown as a shaded graph in FIG. 6(B). Note that in FIGS. 6(A) and 6(B), it is shown that the higher the stress, the darker the shade. It can be understood from FIGS. 6(A) and 6(B) that the pattern shown by the stress distribution depends on the point of action of the load, the magnitude of the load, and the direction of the load.

[0056] Thus, the spatial distribution of the load physical quantity detected by the sensor 25, such as the pressure applied to the claw member 23 (rigid member) and the stress generated in the claw member 23, reflects the position of the point of action of the load applied to the contact surface 31, the magnitude of the load, and the direction of the load.

[0057] The sensor 25 is connected to the control device 13. The control device 13 acquires information related to the load applied to the distal phalanx 9C (hereinafter referred to as load information) based on the detection result of the sensor 25. The control device 13 can control the drive device 11 based on the acquired load information. The load information acquired by the control device 13 includes at least one of the point of action, magnitude, and direction of the load applied to the contact surface 31.

[0058] Hereinafter, the configuration of the control device 13 for acquiring load information and controlling the drive device 11 will be described in detail.

[0059] As shown in FIG. 7, the control device 13 can be configured by a computer including a processor 41 such as a CPU or an MPU, a memory 43 such as a RAM or a ROM, and a storage device 45 (also referred to as a storage) such as an HDD or an SSD.

[0060] As shown in FIG. 8, the control device 13 includes a storage unit 51, a load information acquisition unit 53, and a command unit 55 as functional units for acquiring load information and controlling the drive device 11.

[0061] The storage unit 51 is configured by the storage device 45. The storage unit 51 stores a learned model for acquiring load information related to the load applied to the contact surface 31 from the spatial distribution of the physical quantity detected by the sensor 25. The learned model may be based on a known neural network (NN). Specifically, the learned model may be based on a CNN (convolutional neural network) including ResNet (residual network) or the like. When aiming to reduce the processing load, the learned model may be configured by a known library such as scikit-learn.

[0062] The load information acquisition unit 53 can be configured by the processor 41 performing processing based on a program stored in the memory 43 and the storage device 45. The load information acquisition unit 53 (processor 41) acquires load information using the learned model stored in the storage unit 51 based on the spatial distribution of the physical quantity detected by the sensor 25. That is, the load information acquisition unit 53 converts the spatial distribution of the physical quantity detected by the sensor 25 into load information. The load information includes at least one of the position of the action point of the load applied to the contact surface 31, the magnitude of the load, and the direction of the load.

[0063] Based on the load information acquired by the load information acquisition unit 53, the instruction unit 55 sets the driving amount of each of the driving devices 11 and issues a driving instruction (also referred to as a driving command) to drive by the driving amount corresponding to the driving device 11. By this driving instruction, the driving device 11 is driven and the end effector 9C (end effector) is displaced. A series of operations from the acquisition of load information to the driving instruction realizes operations such as gripping an object by the robot hand 5, manipulating the object, and tracing the surface of the object.

[0064] Next, the effects of the end effector (robot hand 5) and the robot 1 configured as described above will be described.

[0065] When the contact surface 31 of the end effector 9C contacts an object, the elastic member 29 constituting the contact surface 31 elastically deforms. Due to this elastic deformation, a load is applied to the claw member 23, and the sensor 25 detects the load distribution. The control device 13 acquires load information on the load applied to the contact surface 31 based on the load distribution detected by the sensor 25.

[0066] When the contact surface 31 of the end effector 9C contacts an object, a load distribution is generated in the claw member 23 due to the load transmission caused by the elastic deformation of the elastic member 29, and by detecting the load distribution, load information on the load applied to the contact surface 31 is acquired. Therefore, the sensor 25 can be arranged at a position different from the contact surface 31, and load information taking into account the displacement of the contact position accompanying the deformation of the contact surface 31 due to the contact force can be acquired, contributing to the improvement of the control ability of the end effector (robot hand 5).

[0067] In addition, since the sensor 25 (specifically, the detection unit 25A) is arranged between the main body 21 and the claw member 23, the sensor 25 is not exposed to the outside. Further, since the sensor 25 is fixed to the inner part (the part on the contact surface 31 side) of the claw member 23 having a higher rigidity than the elastic member 29, the sensor 25 can be effectively protected.

[0068] For example, in order to perform compliance control of a robot hand, a small 6-axis force sensor may be provided on a frame forming the skeleton of a finger portion. In this case, the control device calculates the contact position at the fingertip portion, the contact force applied to the fingertip portion, etc. based on the detection result of the 6-axis force sensor.

[0069] In such a robot hand, in order to secure a space for installing the 6-axis force sensor, it may be difficult to install an elastic member with a sufficient thickness on the front side (palm side) of the finger portion. In that case, when the finger portion comes into contact with an object, the contact force applied to the front side of the finger portion is difficult to be dispersed, which is disadvantageous in realizing stable grasping of the object.

[0070] On the other hand, an elastic member 29 with a sufficient thickness can be provided on the front side (palm side) of the distal phalanx portion 9C of the robot hand 5 according to the present invention. Therefore, it is advantageous in realizing stable grasping of an object. Further, since the robot hand 5 (robot 1) can be configured without using a 6-axis force sensor, the cost related to the robot hand 5 can be suppressed.

[0071] In addition, in "GelSight Svelte: A Human Finger-shaped Single-camera Tactile Robot Finger with Large Sensing Coverage and Proprioceptive Sensing" (arXiv:2309.10885, URL: https: / / arxiv.org / abs / 2309.10885; hereinafter referred to as the prior paper) by Jialiang Zhao and Edward H. Adelson, a method of tracking markers on the epidermis of the finger using camera images to obtain local normal and shear forces is discussed. In this method, it is pointed out that since the movement of the markers depends on the texture and unevenness (texture) of the contact surface, it is not easy to accurately obtain the global acting forces and torques acting on the entire finger. Also, in the estimation of contact force information based on camera images, it is speculated that there are problems in terms of computational complexity, accuracy, and repeatability. For example, in the case of multi-point contact such as the contact of multiple screws, a deterioration in accuracy is expected in the process of summarizing the multiple states of the complex contact surface. Also, the sensing range is considered to be limited by the thickness and rigidity of the silicone elastomer that makes up the finger part.

[0072] In addition, in the prior paper, to overcome this, a method of estimating the global acting forces and torques acting on the entire finger by tracking the movement of the markers provided on the backbone constituting the backbone frame is proposed.

[0073] However, in the method of the prior paper, since the movement of the markers is tracked using camera images, a distance for focusing is required. Also, since the markers are required to be aligned in the camera field of view, interference of the markers within the field of view is not allowed, the frame shape is restricted, and the size of the end effector increases. The increase in the size of the end effector leads to limitations in the reachable space and is considered to impair the workability of the end effector. In addition, for internal transparency, there are restrictions on material selection, and it is considered that reinforcing materials such as fillers cannot be applied to increase the strength and durability of the fingertip.

[0074] On the other hand, in the above-described finger portion 9, the contact force information acting on the entire finger is converted into a planar pattern depending on the deformation of the claw member 23 after passing through the flexible structure, and since the feature amounts can be classified, it is considered that the discrimination ability of the contact force is enhanced compared to the estimation based on the information within the limited range (on the backbone) described in the prior literature. Also, since the contact force information can be acquired without sacrificing the flexible structure (thickness and flexibility) at the tip of the finger portion 9, it is considered that the constraints of the prior literature can be overcome from the viewpoints of the load range and the reachable work area.

[0075] Further, in the present embodiment, the claw member 23 is gently curved along a direction orthogonal to the direction from the proximal end side to the distal end side of the distal phalanx portion 9C. Therefore, in the spatial distribution of the load physical quantity, the characteristics of the load applied to the contact surface 31 are likely to appear at the edge in the direction orthogonal to the direction from the proximal end side to the distal end side of the claw member 23 (rigid member). Therefore, by configuring the claw member 23 to be curved in the left-right direction, the load information applied to the contact surface 31 can be more clearly and easily acquired.

[0076] The spatial distribution of the physical quantity related to the load applied to the claw member 23 also depends on the shape and hardness of the frame 27, etc. For example, by making the shape of the frame 27 non-uniform and having local changes, it can be expected that characteristics will appear in the pattern of the spatial distribution of the physical quantity detected by the sensor 25. Therefore, by designing the shape of the frame 27 so that characteristics are likely to appear in the spatial distribution of the load physical quantity detected by the sensor 25 when gripping an object to be gripped, the detection sensitivity by the sensor 25 can be enhanced.

[0077] Similarly, it is considered that the spatial distribution of the physical quantity related to the load applied to the claw member 23 also depends on the shape of the claw member 23, etc. Therefore, by designing the shape of the claw member 23 so that characteristics are likely to appear in the spatial distribution of the load physical quantity detected by the sensor 25 when gripping an object to be gripped, the detection sensitivity by the sensor 25 can be enhanced.

[0078] In this embodiment, the claw member 23 is coupled to the frame 27 via the elastic member 29. Therefore, compared with the case where the claw member 23 is directly coupled to the frame 27, due to the elastic deformation of the elastic member 29 caused by contact with the contact surface 31, a load is more likely to be applied to the claw member 23. Therefore, the physical quantity of the load applied to the claw member 23 by the sensor 25 is more easily detected, and the load information is more easily obtained appropriately by the control device 13.

[0079] <<Second Embodiment>> The end effector (robot hand 5) and the robot 1 according to the second embodiment differ in the structure of the distal phalanx portion 9C, and since the other configurations are the same as those in the first embodiment, the description of the other configurations is omitted.

[0080] FIG. 9(A) shows a longitudinal sectional view of the distal phalanx portion 9C of the robot hand 5 according to the second embodiment, and FIG. 9(A) shows a cross-sectional view of the distal phalanx portion 9C of the robot hand 5 according to the second embodiment. As shown in FIGS. 9(A) and 9(B), the distal phalanx portion 9C has, similarly to the first embodiment, a main body 21, a claw member 23 provided on the back side surface of the main body 21, and a sensor 25 provided on the claw member 23.

[0081] The main body 21 has, similarly to the first embodiment, a frame 27 and an elastic member 29. However, different from the first embodiment, the frame 27 is coupled to the elastic member 29 in a state of being accommodated in a recess 61 provided on the outer surface of the elastic member 29. Thereby, the tip portion 27B of the frame 27 is covered by the elastic member 29 on the front side (palm side).

[0082] The claw member 23 is arranged to integrally cover the frame 27 and the elastic member 29 from the back side, and is directly coupled to the tip portion 27B and the elastic member 29. The elastic member 29 constitutes a contact surface 31 on its front surface side (palm side), and the claw member 23 and the frame 27 are provided on the back surface side of the elastic member 29.

[0083] Similar to the first embodiment, the sensor 25 detects the distribution of the load physical quantity of the claw member 23 and outputs it to the control device 13. Based on the detection result of the sensor 25, the control device 13 uses the learned model to acquire load information. As shown in FIG. 9(B), the sensor 25 (specifically, its detection unit 25A) may be arranged so as to avoid the frame 27 on the surface of the claw member 23 on the side of the elastic member 29.

[0084] Next, the effects of the end effector (robot hand 5) and the robot 1 configured as described above will be described. Also in this embodiment, the contact surface 31 is constituted by the elastic member 29. When the contact surface 31 touches an object, the elastic member 29 is elastically deformed, and a load distribution is generated on the claw member 23. Therefore, based on the detection result by the sensor 25, it is possible to accurately acquire load information including at least one of the action point of the load applied to the contact surface 31, the magnitude of the load, and the direction of the load. Further, since the sensor 25 is provided at a position away from the contact surface 31 as in the first embodiment, the sensor 25 can be effectively protected.

[0085] Also, in the second embodiment, the claw member 23 is directly coupled to the frame 27. Therefore, the claw member 23 can be well supported by the frame 27.

[0086] With the above, the description of the specific embodiments is completed, but the present invention is not limited to the above embodiments and modification examples, and can be widely modified and implemented.

[0087] In the above embodiment, an example in which the end effector constitutes the robot hand 5 imitating a human hand has been described, but the present invention is not limited to this aspect. The end effector may be provided at any part of the robot 1 that performs work by contacting an object, such as the foot of the humanoid robot 1 or the tip portion of the robot hand 5 of an industrial machine.

[0088] There is a case (for example, a gripper or the like) where the end effector includes two finger portions 9 that approach and separate from each other, and the finger portions 9 are configured to grip an object by contacting the side surfaces of the object. In that case, it is preferable that the portions of the finger portions 9 on the side that approach each other are constituted by an elastic member 29, and the contact surface 31 is constituted by the elastic member 29. Further, a claw member 23 is preferably provided on the side surface of the finger portion 9 on the side opposite to the contact surface 31.

[0089] In the above embodiment, the control device 13 uses a learned model based on a known neural network (NN) method to convert the spatial distribution of the physical quantity detected by the sensor 25 into load information. However, the conversion method is not limited to those based on a neural network. The control device 13 may be configured to perform known feature amount analysis such as t-SNE on the spatial distribution of the physical quantity detected by the sensor 25 and acquire load information based on the acquired feature amount.

[0090] In the above embodiment, the case where load information is acquired based on the spatial distribution of the load physical quantity detected by the sensor 25 and the robot 1 grips an object with the robot hand 5 has been described. However, in addition, the load information is also useful when the robot 1 performs various operations such as tracing or stroking an object with the robot hand 5.

[0091] In addition, although the claw member 23 was arranged along the outer surface of the elastic member 29, a concave portion 63 is formed in the elastic member 29 along the edge of the claw member 23. As shown in FIG. 10, the claw member 23 may be fixed to the elastic member 29 in a state where the edge of the claw member 23 is accommodated in the concave portion 63. Thereby, it becomes difficult for the claw member 23 to fall off from the elastic member 29, and the influence of the elastic deformation of the elastic member 29 is likely to appear at the edge portion. Note that the claw member 23 may be accommodated in the concave portion 63 at the edge on the proximal end side in the extending direction, or may be accommodated in the concave portion 63 at the left and right edges (hereinafter, side edges 91, see FIG. 10).

[0092] The claw member 23 may be curved in the left - right direction and configured such that the elastic modulus (Young's modulus) of the two side edge portions 91 and the elastic modulus of the portion located between the two side edge portions 91 (hereinafter referred to as the central portion 92; see FIG. 10) are different. Specifically, the side edge portion 91 may be made of a material that is more easily elastically deformed (has a lower elastic modulus) than the central portion 92. As a result, the strain generated in the side edge portion 91 becomes larger, so that the detection sensitivity by the sensor 25 can be improved. Also, since a portion (hard portion) that is more difficult to elastically deform than the side edge portion 91 is provided in the central portion 92 of the claw member 23, compared with the case where no hard portion is provided in the central portion 92 and the entire claw member 23 is made of a soft material having the same elastic modulus as the side edge portion 91, it is possible to increase the rigidity of the claw member 23.

Explanation of Reference Numerals

[0093] 1: Robot 5: Robot hand (an example of an end effector) 11: Driving device 13: Control device 23: Claw member (an example of a rigid member) 25: Sensor 27: Frame 27B: Tip portion 29: Elastic member 31: Contact surface

Claims

1. An end effector that performs work by contacting an object, having an outer surface that constitutes a contact surface, an elastic member that can be elastically deformed, a frame that supports the elastic member, a plate-like rigid member that is supported by the elastic member and has higher rigidity than the elastic member, and a sensor that is attached to the rigid member and detects the spatial distribution of a physical quantity related to the load applied to the rigid member. An end effector comprising the same.

2. The end effector according to claim 1, wherein the sensor is provided on the surface of the rigid member on the contact surface side.

3. The end effector according to claim 1, wherein the frame has a tip portion covered by the elastic member.

4. The end effector according to claim 3, wherein the rigid member is coupled to the frame via the elastic member.

5. The end effector according to claim 1, wherein the frame has a tip portion to which the rigid member is directly coupled and is covered by the elastic member.

6. The end effector according to claim 1, wherein the sensor detects the pressure distribution applied to the rigid member.

7. The end effector according to claim 1, wherein the sensor detects the stress distribution of the rigid member.

8. The end effector according to any one of claims 1 to 7, further comprising a control device that acquires load information related to the load acting on the contact surface based on the output of the sensor.

9. The end effector according to claim 8, wherein the load information includes any one of the action point of the load, the magnitude of the load, and the direction of the load.

10. A robot comprising the end effector according to claim 9, having a drive device that displaces the end effector, wherein the control device gives a drive instruction to the drive device based on the load information.

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