Robot joint device and robot having profiling function including the same

Abstract

To provide a robot joint device capable of reliably solving a problem due to an impact or vibration by sufficiently absorbing the impact or vibration applied to various directions, and a robot having a profiling function including the robot joint device.SOLUTION: A robot joint device 3, 71 of the present invention connects a plurality of links constituting a robot so as to be able to move relatively to each other. The robot joint device 3, 71 includes: an X-axis elastic deformation allowing mechanism 17, 73 that allows elastic deformation with respect to an X-axis among three axes orthogonal to each other; and a Y-axis elastic deformation allowing mechanism 18, 74 that allows elastic deformation independently from the X-axis elastic deformation allowing mechanism 17, 73, with respect to a Y-axis.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a robot joint device that connects multiple links constituting a robot so that they can move relative to each other, and to a robot with a tracing function that includes the same. [Background technology]

[0002] A joint device is provided between the multiple links that make up a robot, as a connecting device. The joint device incorporates a motor, a reducer, and the like, connecting the links so that they can move relative to each other. Recently, robots with a tracking function have been widely used, which allow a robot hand to perform a predetermined task while tracing the shape of an unknown object. A problem with such robots with a tracking function is known: impacts generated when the robot hand comes into contact with the object are transmitted to adjacent links via the joint device, leading to malfunctions. Another problem with robots with a tracking function is that high-frequency vibrations from the motor are transmitted to adjacent links via the joint device, reducing the accuracy of the tracking control of the robot hand.

[0003] Therefore, in order to prevent such problems from occurring, it has been proposed to configure the joint device as a so-called series elastic actuator (SEA) (see, for example, paragraph

[0024] and Figure 2 of the specification of Patent Document 1). That is, by further including an elastic member such as a spring in this joint device, the motor, the elastic member, and the adjacent link are connected in series. With this type of joint device, the above-mentioned impacts and vibrations are absorbed by the elastic deformation of the elastic member, thereby suppressing the occurrence of malfunctions in each part and improving the accuracy of the tracking control of the robot hand. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-180666 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional joint devices configured as series elastic actuators have the problem of being unable to adequately absorb shocks and vibrations acting in various directions. Specifically, the only direction in which elastic deformation of the joint device is permitted by an elastic member such as a spring is the translational direction along one of three mutually orthogonal axes. Therefore, shocks and vibrations acting in the rotational direction about that axis or in the translational or rotational directions about the other two of the three axes are not absorbed by the elastic member, resulting in the problem of being unable to reliably resolve problems caused by these shocks and vibrations.

[0006] The present invention has been made in light of the above circumstances, and its object is to provide a robot joint device that can fully absorb shocks and vibrations acting in various directions, thereby more reliably resolving problems caused by such shocks and vibrations, and a robot with a tracing function that is equipped with the same. [Means for solving the problem]

[0007] A robot joint device according to one embodiment of the present invention is a robot joint device that connects multiple links that make up the robot to allow relative movement, and has a first axis elastic deformation allowing mechanism that allows elastic deformation for a first axis among three mutually perpendicular axes, and a second axis elastic deformation allowing mechanism that allows elastic deformation for a second axis different from the first axis, independently of the first axis elastic deformation allowing mechanism.

[0008] In addition, in a robot joint device according to one aspect of the present invention, the first axis elastic deformation allowing mechanism may allow elastic deformation in at least one of a translation direction along the first axis and a rotation direction around the first axis, and the second axis elastic deformation allowing mechanism may allow elastic deformation in at least one of a translation direction along the second axis and a rotation direction around the second axis.

[0009] In addition, in a robot joint device according to one aspect of the present invention, the first axis elastic deformation allowing mechanism may include a base frame fixed to the robot, a first frame supported by the base frame so as to be rotatable about the first axis and / or so as to be translatable along the first axis, and a restoring force acting portion that applies a force to the first frame in a direction opposite to the rotational direction and / or translational direction.

[0010] In addition, in the robot joint device according to one aspect of the present invention, the restoring force application portion may be a spring member interposed between the base frame and the first frame.

[0011] In addition, in a robot joint device according to one aspect of the present invention, the first axis elastic deformation allowing mechanism may further have a stopper portion that restricts rotation and / or translation of the first frame beyond a predetermined range.

[0012] In addition, in a robot joint device according to one aspect of the present invention, the stopper portion may have a regulating protrusion protruding from either the base frame or the first frame, and a regulating surface formed on the other frame against which the regulating protrusion abuts.

[0013] Furthermore, in a robot joint device according to one aspect of the present invention, the second axis elastic deformation allowing mechanism may include a second frame supported by the first frame so as to be rotatable about the second axis and / or so as to be translatable along the second axis, and a restoring force acting unit that applies a force to the second frame in a direction opposite to the rotational direction and / or translational direction of the second frame.

[0014] In addition, in a robot joint device according to one aspect of the present invention, the second axis elastic deformation allowing mechanism may further have a stopper portion that restricts rotation and / or translation of the second frame beyond a predetermined range.

[0015] Furthermore, a robot joint device according to one aspect of the present invention may further include a third axis elastic deformation allowing mechanism that allows elastic deformation of a third axis that is perpendicular to each of the first axis and the second axis, independently of the first axis elastic deformation allowing mechanism and the second axis elastic deformation allowing mechanism, and the third axis elastic deformation allowing mechanism may include a third frame that is supported by the second frame so as to be rotatable about the third axis and / or so as to be translatable along the third axis, and a restoring force application unit that applies a force to the third frame in a direction opposite to the rotational direction and / or translational direction.

[0016] In addition, in a robot joint device according to one aspect of the present invention, one of the plurality of links may constitute a base end of a robot hand that manipulates an object, and the other may constitute a tip end of a robot arm that brings the robot hand closer to the object.

[0017] A robot with a tracing function according to one aspect of the present invention is a robot with a tracing function that causes a robot hand to perform a predetermined task while tracing the shape of an object, and is equipped with a joint device of the robot, a proximity sensor that detects the posture of the robot hand, a memory unit that pre-stores a target posture of the robot hand, a difference calculation unit that calculates the difference between the detected posture of the robot hand and the target posture, and a control unit that controls the posture of the robot hand so that the difference is small.

[0018] In addition, in a robot with a copying function according to one aspect of the present invention, the specified task may be one or more tasks selected from the group consisting of a task of grasping an object, a task of leaving the grasped object stationary, a task of measuring physical quantities of the grasped object, a task of optimally controlling the position and attitude of the robot based on tilt and position information of the grasped object, a task of approaching the contents of a container along the wall surface of the container, which is the object, a task of assembling another grasped part to one part, which is the object, and a task of pressing a button, which is the object.

[0019] Furthermore, in a robot joint device according to one aspect of the present invention, the first frame may be supported by the base frame so as to be rotatable about the first axis, and the return force application portions may each be supported so as to be rotatable about the first axis, and a pair of scissors frames may be provided so that their tip ends move away from each other as the first frame rotates; scissors biasing members may be provided so as to connect the tip ends of the pair of scissors frames to each other, and may bias the pair of scissors frames so that their tip ends move closer to each other in a neutral state in which the first frame is not rotating; and scissors restricting members may restrict the rotation of the pair of scissors frames so that the tip ends of the pair of scissors frames do not move closer to each other beyond a predetermined distance.

[0020] In the robot joint device according to one aspect of the present invention, the scissors biasing member may be a tension coil spring.

[0021] In addition, in a robot joint device according to one aspect of the present invention, the first axis elastic deformation allowing mechanism may further have a stopper portion that restricts rotation of the first frame beyond a predetermined range.

[0022] In addition, in a robot joint device according to one aspect of the present invention, the stopper portion may have a regulating protrusion protruding from either the base frame or the first frame, and a regulating surface formed on the other frame against which the regulating protrusion abuts.

[0023] Furthermore, in a robot joint device according to one aspect of the present invention, the second frame may be supported by the first frame so as to be rotatable about the second axis, and the return force application portions may each be supported so as to be rotatable about the second axis, and a pair of scissors frames may be provided so that their tip ends move away from each other as the second frame rotates; scissors biasing members may be provided so as to connect the tip ends of the pair of scissors frames to each other, and may bias the pair of scissors frames so that their tip ends move closer to each other in a neutral state in which the second frame is not rotating; and scissors restricting members may restrict the rotation of the pair of scissors frames so that the tip ends of the pair of scissors frames do not move closer to each other beyond a predetermined distance.

[0024] Furthermore, a robot with a copying function according to one aspect of the present invention is a robot with a copying function that causes a robot hand to perform a predetermined task while copying the shape of an object, and may include: a finger that constitutes the robot hand and grasps the object; a robot arm that brings the robot hand close to the object; a robot joint device according to any one of claims 13 to 17 that connects the robot hand and the robot arm to each other; and a parallel link component that constitutes the robot hand and, together with the finger and the robot joint device, constitutes a parallel link mechanism. [Effects of the Invention]

[0025] According to one aspect of the present invention, a robot joint device and a robot with a tracking function equipped with the same can sufficiently absorb impacts and vibrations acting in various directions, thereby more reliably resolving problems caused by these impacts and vibrations. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a diagram schematically showing the configuration of a robot 1, 70 with a copying function according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic perspective view of a proximity sensor unit 7 as seen from above. [Figure 3] FIG. 3 is a schematic perspective view of the proximity sensor unit 7 as seen from below. [Figure 4] FIG. 2 is a schematic perspective view showing the configuration of a joint device 3 and a robot hand 4. [Figure 5] 5 is a schematic side view of the joint device 3 and the robot hand 4 as viewed from the direction A in FIG. 4. [Figure 6] FIG. 2 is a schematic plan view of the joint device 3 and the robot hand 4. [Figure 7] 5 is a schematic side view of the joint device 3 and the robot hand 4 as viewed from the direction B in FIG. 4. [Figure 8] FIG. 7 is a schematic cross-sectional view showing a cross section taken along line CC in FIG. [Figure 9] FIG. 3 is a schematic perspective view showing the assembly of the joint device 3 and the robot hand 4 to the proximity sensor unit 7. [Figure 10] FIG. 2 is a block diagram showing the functional configuration of the robot 1 with a tracing function. [Figure 11] 10 is an explanatory diagram for explaining the operation of the X-axis elastic deformation allowing mechanism 17 of the joint device 3. FIG. [Figure 12] 10 is an explanatory diagram for explaining the operation of the Y-axis elastic deformation allowing mechanism 18 of the joint device 3. FIG. [Figure 13] 10 is an explanatory diagram for explaining the operation of the Z-axis elastic deformation allowing mechanism 19 of the joint device 3. FIG. [Figure 14]FIG. 2 is a schematic perspective view showing the configuration of one joint device 71 and a robot hand 72 as viewed from the front side. [Figure 15] FIG. 15 is a schematic side view of FIG. 14 as viewed from the Y-axis direction. [Figure 16] FIG. 16 is a schematic side view showing a state in which the pair of scissors frames are not shown in FIG. 15. [Figure 17] FIG. 2 is a schematic rear view showing the overall configuration of the robot hand 72. [Figure 18] FIG. 10 is a diagram for explaining the operation of the Y-axis elastic deformation allowing mechanism 74, and is a partially enlarged view of the periphery of the restoring force acting portion 90. [Figure 19] FIG. 10 is a diagram for explaining the operation of the Y-axis elastic deformation allowing mechanism 74, and is a partially enlarged view of the periphery of a stopper portion 89. [Figure 20] 4A and 4B are explanatory diagrams for explaining the effects of the parallel link mechanism 101. DETAILED DESCRIPTION OF THE INVENTION

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A robot joint device and a robot with a copying function including the same according to an embodiment of the present invention will be described below with reference to the drawings.

[0028] (Configuration of robot with tracing function) First, the configuration of a copying robot equipped with a robot joint device according to a first embodiment of the present invention will be described. FIG. 1 is a diagram schematically showing the configuration of a copying robot 1 according to a first embodiment of the present invention. The copying robot 1 includes a robot arm 2, a pair of joint devices 3, and a robot hand 4. Note that the numbers of the robot arms 2, joint devices 3, and robot hands 4 are not limited to those in this embodiment and can be appropriately modified in design depending on the type of work to be performed by the copying robot 1.

[0029] The robot arm 2 moves the robot hand 4 toward or away from an object Ob by deforming and moving in multiple axial directions. As shown in Fig. 1, the robot arm 2 has a plurality of arm link sections 5, a plurality of arm joint sections 6 that connect adjacent arm link sections 5 to allow relative movement, and a pair of proximity sensor units 7 attached to the arm link sections 5 located at the tip.

[0030] The pair of proximity sensor units 7 serves to detect the movement of the robot hand 4. Figures 2 and 3 show the configuration of the proximity sensor unit 7, with Figure 2 being a schematic perspective view seen from above and Figure 3 being a schematic perspective view seen from below. Each proximity sensor unit 7 has an arm fixing frame 8, a proximity sensor 10, and a joint fixing frame 11.

[0031] The arm fixing frame 8 serves to fix the proximity sensor unit 7 to the tip of the robot arm 2. As shown in Fig. 2, the arm fixing frame 8 is a plate-like member made of resin or the like, and has a rectangular shape in a plan view, with its tip having a wide square shape in a plan view. As shown in Fig. 3, a sensor accommodating groove 12 for accommodating the proximity sensor 10 is formed on the back surface of the arm fixing frame 8. The sensor accommodating groove 12 has an elongated rectangular shape extending from the base end to the tip of the arm fixing frame 8 in a plan view.

[0032] The proximity sensor 10 serves to detect the posture of the robot hand 4. As shown in FIG. 3 , the proximity sensor 10 includes a substrate 60 and multiple infrared sensors 61. The substrate 60 has a rectangular shape in plan view that is approximately the same as the sensor accommodating groove 12 of the arm fixing frame 8, and its thickness is set to be approximately equal to or slightly smaller than the groove depth of the sensor accommodating groove 12. Meanwhile, the multiple infrared sensors 61 have the function of irradiating light onto a reflector 20 of the joint device 3 (described later) to detect the distance and angle to the reflector 20 in a non-contact manner. The multiple infrared sensors 61 are each mounted on one longitudinal end of the surface of the substrate 60. The proximity sensor 10 configured in this manner is fixed to the arm fixing frame 8 with screws or the like after the substrate 60 is accommodated inside the sensor accommodating groove 12. Any conventionally known proximity sensor (including so-called proximity sensors) can be used as the proximity sensor 10.

[0033] The joint fixing frame 11 serves to fix the proximity sensor unit 7 to the joint device 3 while ensuring a space of a predetermined width below the infrared sensor 61. As shown in Figures 2 and 3, this joint fixing frame 11 has four pillars 13 extending parallel to one another in the vertical direction, four beams 14 extending horizontally and connecting adjacent pillars 13, an upper mounting portion 15 formed by the tops of the pillars 13 and the upper surfaces of two opposing beams 14, and a lower mounting portion 16 formed by the bottoms of the pillars 13 and the lower surfaces of the two opposing beams 14. The joint fixing frame 11 configured in this manner has the tip of the arm fixing frame 8 disposed on the upper mounting portion 15 and fixed with screws or the like.

[0034] As shown in Figure 1, a pair of proximity sensor units 7 configured in this manner are fixed to the tip of the robot arm 2 by screws or the like, with the proximity sensors 10 (see Figure 3) facing downward.

[0035] The pair of joint devices 3 serve to connect the robot hand 4 to the robot arm 2 so that the robot hand 4 can move relative to the robot arm 2. Figures 4 and 5 show the configurations of the joint device 3 and the robot hand 4, with Figure 4 being a schematic perspective view and Figure 5 being a schematic side view seen from direction A in Figure 4. The joint device 3 has an X-axis elastic deformation allowing mechanism 17 (the "first-axis elastic deformation allowing mechanism" according to the present invention), a Y-axis elastic deformation allowing mechanism 18 (the "second-axis elastic deformation allowing mechanism" according to the present invention), a Z-axis elastic deformation allowing mechanism 19 (the "third-axis elastic deformation allowing mechanism" according to the present invention), and a reflector 20.

[0036] The X-axis elastic deformation allowing mechanism 17 serves to allow the robot hand 4 to elastically deform in a rotational direction about the X-axis (the "first axis" according to the present invention) among three mutually orthogonal axes. Here, FIG. 6 is a schematic plan view of the joint device 3 and the robot hand 4. As shown in FIGS. 4 to 6, the X-axis elastic deformation allowing mechanism 17 has a base frame 21, a first frame 22, a pair of stopper portions 23, and a pair of restoring force acting springs 24 (the "restoring force acting portion" according to the present invention). Note that for ease of explanation, the reflector 20 is not shown in FIG. 6.

[0037] The base frame 21 serves to fix the joint device 3 to the proximity sensor unit 7 constituting the robot arm 2. The base frame 21 is made of metal or the like and is a rectangular cylindrical member having a substantially square outer shape in a plan view and a hollow interior. As shown in FIGS. 4 and 5, the base frame 21 has a pair of bearing holes 25 and a pair of cutout grooves 26. The material, shape in a plan view, and size of the base frame 21 are not limited to those in this embodiment and can be modified as needed within the range in which it can be placed on the lower mounting portion 16 of the joint fixing frame 11.

[0038] The pair of bearing holes 25 serves to rotatably support the rotation shaft 27 of the first frame 22. As shown in Figures 4 and 5, the pair of bearing holes 25 are formed so as to penetrate opposing positions of the base frame 21 with an internal cavity in between. The pair of bearing holes 25 each have a circular cross section perpendicular to the axial direction, and the inner diameters thereof are set to be equal to each other.

[0039] The pair of cutout grooves 26 function to form the stopper portion 23 in cooperation with a restricting protrusion 30 of the first frame 22, which will be described later. As shown in Figures 4 and 5, the pair of cutout grooves 26 are formed by cutting out the peripheral portions of the pair of bearing holes 25 in the base frame 21 from the top surface thereof to a predetermined depth so as to communicate with the bearing holes 25. The pair of cutout grooves 26 are also formed so as to be positioned diagonally across an axis connecting the centers of the pair of bearing holes 25. In the region adjacent to the bearing holes 25, the depth of the cutout grooves 26 is set so that the bottoms thereof are at the same height as the centers of the bearing holes 25.

[0040] The first frame 22 serves to enable relative movement in a rotational direction about the X-axis with respect to the base frame 21. The first frame 22 is made of metal or the like, has a substantially rectangular outer shape in a plan view, and is a hollow, square-tube-shaped member. Here, FIG. 7 is a schematic side view of the joint device 3 and the robot hand 4 as viewed from direction B in FIG. 4. However, for ease of explanation, the base frame 21 is not shown in FIG. 7. As shown in FIGS. 4 to 7, the first frame 22 has a pair of rotation shafts 27, a pair of bearing holes 28, and a pair of cutout grooves 29.

[0041] The pair of rotating shafts 27 are cylindrical members made of metal or the like. As shown in Fig. 7, the rotating shafts 27 are provided so as to protrude outward from both end surfaces in the long side direction of the first frame 22. The outer diameter and axial length of the pair of rotating shafts 27 are set to a size that allows them to be inserted into the pair of bearing holes 25 of the base frame 21, respectively.

[0042] The pair of bearing holes 28 serves to rotatably support a rotating shaft 35 of the second frame 32, which will be described later. As shown in Figures 4 and 7, the pair of bearing holes 28 are formed so as to penetrate through positions opposing each other in the short side direction of the first frame 22 with an internal cavity therebetween, i.e., so that the axial direction of each hole is perpendicular to the axial direction of the rotating shaft 27. The pair of bearing holes 28 each have a circular cross section perpendicular to the axial direction, and the inner diameters of the holes are set to be equal to each other.

[0043] The pair of cutout grooves 29 function to form stopper portions 33 in cooperation with restricting protrusions 38 of the second frame 32, which will be described later. As shown in Figures 4 and 7, the pair of cutout grooves 29 are formed by cutting out the peripheral portions of the pair of bearing holes 28 in the first frame 22 from the top surface thereof to a predetermined depth so as to communicate with the bearing holes 28. The pair of cutout grooves 29 are formed so as to be positioned diagonally across an axis connecting the centers of the pair of bearing holes 28. In the region adjacent to the bearing holes 28, the depth of the cutout grooves 29 is set so that the bottoms thereof are at the same height as the centers of the bearing holes 28.

[0044] The first frame 22 configured in this manner is housed in the internal cavity of the base frame 21, and the pair of rotation shafts 27 thereof are inserted into the pair of bearing holes 25 of the base frame 21, respectively. As a result, the first frame 22 is supported at both ends by the base frame 21 in a state in which it can rotate around the pair of rotation shafts 27. Note that the material, shape in a plan view, and size of the first frame 22 are not limited to those in this embodiment and can be modified in design as appropriate, as long as they can be housed in the internal cavity of the base frame 21.

[0045] The pair of stopper portions 23 (see

[0031] ) serves to restrict the rotation of the first frame 22 within a predetermined range. As shown in FIGS. 4 and 5, the stopper portions 23 have a pair of restricting protrusions 30 and a pair of restricting surfaces 31. The pair of restricting protrusions 30 are provided so as to protrude outward from both end surfaces of the first frame 22 in the long-side direction. The thickness of the restricting protrusions 30 is set smaller than the depth of the notched grooves 26 of the base frame 21. The upper surface of the restricting protrusion 30 is formed so as to form the same plane as the upper surface of the first frame 22. The lower surface of the restricting protrusion 30 is inclined at an acute angle with respect to the upper surface. In other words, the thickness of the restricting protrusion 30 is gradually reduced from the side closer to the rotation shaft 27 to the side farther away from the rotation shaft 27. Meanwhile, the pair of restricting surfaces 31 are formed as bottom surfaces of the pair of notched grooves 26 of the base frame 21, and are slightly inclined with respect to the upper surface of the base frame 21. When the rotation shaft 27 of the first frame 22 is inserted into the bearing hole 25 of the base frame 21, the stopper portion 23 configured as described above has the pair of regulating protrusions 30 housed in the pair of cutout grooves 26 of the base frame 21. At this time, the upper surface of the regulating protrusion 30 is flush with the upper surface of the base frame 21, while the lower surface of the regulating protrusion 30 is spaced upward from the regulating surface 31.

[0046] The pair of restoring force acting springs 24 (see

[0031] ) bias the first frame 22 in the direction opposite to its rotation, thereby acting as a restoring force on the first frame 22, i.e., a force to return it to the position before rotation. These restoring force acting springs 24 are so-called leaf springs, and as shown in FIGS. 4 and 6, have a band-like shape in plan view. The width dimension of these restoring force acting springs 24 is set to be approximately equal to the width of the upper surface of the base frame 21, and the longitudinal dimension is set to be larger than the opening width of the notched grooves 26 of the base frame 21. The pair of restoring force acting springs 24 configured in this manner are each arranged so as to cover the upper parts of the pair of notched grooves 26 of the base frame 21. One longitudinal end of each restoring force acting spring 24 is fixed to the upper surface of the base frame 21 by a screw or the like, while the other longitudinal end is arranged without being fixed to the base frame 21. As a result, when no external force acts on these restoring force acting springs 24, the restoring force acting springs 24 maintain a flat shape, with the other longitudinal end abutting the upper surface of the base frame 21. On the other hand, when an upward external force acts on the restoring force acting springs 24, the restoring force acting springs 24 are able to elastically deform with the fixed one longitudinal end as a fulcrum, moving the other longitudinal end away from the upper surface of the base frame 21.

[0047] The Y-axis elastic deformation allowing mechanism 18 (see

[0030] ) serves to allow the robot hand 4 to elastically deform in a rotational direction about the Y-axis (the "second axis" according to the present invention) among the three mutually orthogonal axes. As shown in Figs. 4 and 6, this Y-axis elastic deformation allowing mechanism 18 has a second frame 32, a pair of stopper parts 33, and a pair of restoring force acting springs 34.

[0048] The second frame 32 serves to enable relative movement in the rotational direction about the Y-axis with respect to the first frame 22. The second frame 32 is a rectangular cylindrical member made of metal or the like and having a substantially square outer shape in a plan view. Here, FIG. 8 is a schematic cross-sectional view showing a cross section taken along line CC in FIG. 6. As shown in FIGS. 4 and 8, the second frame 32 has a rotation shaft 35, a cylindrical extension 36, and a spring accommodating groove 37.

[0049] The rotating shaft 35 is a cylindrical member made of metal or the like. As shown in Figures 4 and 8, the rotating shaft 35 penetrates the second frame 32 in the direction of one side, with both axial ends thereof protruding outward, and is fixed to the second frame 32 so as not to move relative to the second frame 32. The outer diameter and axial length of the rotating shaft 35 are set to be large enough that both axial ends protruding outward from the second frame 32 can be inserted into the pair of bearing holes 28 of the first frame 22, respectively.

[0050] The cylindrical extension 36 serves to radially support the third frame 40 of the Z-axis elastic deformation allowing mechanism 19, which will be described later. As shown in FIGS. 4 and 6 , the cylindrical extension 36 is made of a metal or the like, has a circular outer shape that is inscribed in the second frame 32 in a plan view, and is a hollow cylindrical member. One axial end face of the cylindrical extension 36 is fixed to the upper surface of the second frame 32. The internal cavity of the cylindrical extension 36 has a circular cross section and is formed to penetrate the entire second frame 32 in the height direction. Note that the material, cross-sectional shape, and axial length of the cylindrical extension 36 are not limited to those in this embodiment and can be appropriately modified in design as long as they are capable of supporting the third frame.

[0051] The spring accommodating groove 37 serves to accommodate a restoring force acting spring 42 of the Z-axis elastic deformation allowing mechanism 19, which will be described later. As shown in Fig. 8, this spring accommodating groove 37 has a circular cross section and is formed to extend from the bottom surface of the second frame 32 in the height direction. The groove depth of this spring accommodating groove 37 is set to be approximately equal to the height dimension of the second frame 32. Note that the cross-sectional shape and groove depth of the spring accommodating groove 37 are not limited to those of this embodiment and can be modified as appropriate within a range that can accommodate the restoring force acting spring 42.

[0052] The second frame 32 configured in this manner is housed in the internal cavity of the first frame 22 with the cylindrical extension portion 36 facing up, and both axial ends of the rotation shaft 35 are inserted into the pair of bearing holes 28 of the first frame 22, respectively. As a result, the second frame 32 is supported by the first frame 22 in a state where it can rotate around the rotation shaft 35. The axial direction of the rotation shaft 35 of the second frame 32 is perpendicular to the axial direction of the rotation shaft 27 of the first frame 22. Note that the material, shape in a plan view, and size of the second frame 32 are not limited to those in this embodiment and can be modified as appropriate within the range that can be accommodated in the internal cavity of the first frame 22.

[0053] The pair of stopper portions 33 (see

[0042] ) serves to restrict the rotation of the second frame 32 within a predetermined range. As shown in FIGS. 4 and 7, these stopper portions 33 have a pair of restricting protrusions 38 and a pair of restricting surfaces 39. The pair of restricting protrusions 38 are provided to protrude outward from both end surfaces of the second frame 32 from which the rotation shaft 35 protrudes. The thickness of the restricting protrusions 38 is set smaller than the depth of the notched groove 29 of the first frame 22. The upper surface of the restricting protrusion 38 is formed to form the same plane as the upper surface of the rectangular cylindrical portion of the second frame 32. The lower surface of the restricting protrusion 38 is inclined at an acute angle with the upper surface. In other words, the thickness of the restricting protrusion 38 is gradually reduced from the side closer to the rotation shaft 35 to the side farther away from the rotation shaft 35. On the other hand, the pair of restriction surfaces 39 are formed as bottom surfaces of the pair of cutout grooves 29 of the first frame 22, and are slightly inclined with respect to the upper surface of the first frame 22. In the stopper portion 33 configured in this manner, when the rotation shaft 35 of the second frame 32 is inserted into the bearing hole 28 of the first frame 22, the pair of restriction protrusions 38 are housed inside the pair of cutout grooves 29 of the first frame 22. At this time, the upper surface of the restriction protrusion 38 forms the same plane as the upper surface of the first frame 22, while the lower surface of the restriction protrusion 38 is spaced upward from the restriction surfaces 39.

[0054] The pair of restoring force acting springs 34 (see

[0042] ) bias the second frame 32 in the direction opposite to its rotation, thereby acting as a restoring force on the second frame 32, i.e., a force that returns the second frame 32 to its pre-rotation position. These restoring force acting springs 34 are so-called leaf springs, and as shown in FIGS. 4 and 6, have a strip-like shape in plan view. The width dimension of these restoring force acting springs 34 is set to be approximately equal to the width of the upper surface of the first frame 22, and the longitudinal dimension is set to be greater than the opening width of the notched grooves 29 of the first frame 22. The pair of restoring force acting springs 34 configured in this manner are each disposed so as to cover the upper portions of the pair of notched grooves 29 of the first frame 22. One longitudinal end of each restoring force acting spring 34 is fixed to the upper surface of the first frame 22 by a screw or the like, while the other longitudinal end is disposed without being fixed to the first frame 22. As a result, when no external force acts on these restoring force acting springs 34, the restoring force acting springs 34 maintain a flat shape, with the other longitudinal end abutting the upper surface of the first frame 22. On the other hand, when an upward external force acts on the restoring force acting springs 34, the restoring force acting springs 34 are able to elastically deform, with the fixed one longitudinal end as a fulcrum, such that the other longitudinal end moves away from the upper surface of the first frame 22.

[0055] The Z-axis elastic deformation allowing mechanism 19 (see

[0030] ) serves to allow the robot hand 4 to elastically deform in the translation direction along the Z-axis (the "third axis" according to the present invention) among the three mutually orthogonal axes. As shown in FIG. 8, this Z-axis elastic deformation allowing mechanism 19 has a third frame 40, a stopper portion 41, and a restoring force acting spring 42.

[0056] The third frame 40 serves to enable relative movement in the translation direction along the Z axis with respect to the second frame 32. The third frame 40 is a cylindrical member made of metal or the like. The outer diameter and axial length of the third frame 40 are set to a size that allows it to be inserted into the internal cavity of the second frame 32. As shown in FIGS. 5 and 8, the third frame 40 configured in this manner has a shaft insertion slot 43, a reflector mounting hole 44, a spring fixing portion 45, and a hand mounting portion 46 (see FIG. 5).

[0057] The rotation shaft 35 of the second frame 32 is inserted through the shaft insertion slot 43. As shown in FIG. 8 , this shaft insertion slot 43 extends in the axial direction of the third frame 40 in side view, and its lower end is formed to have a semicircular cross section, giving it an elongated hole shape. The shaft insertion slot 43 is formed to penetrate the third frame 40 in its radial direction. The groove width of the shaft insertion slot 43 is set to be equal to or slightly larger than the diameter of the rotation shaft 35 of the second frame 32. The groove length of the shaft insertion slot 43 is set appropriately taking into account the distance the third frame 40 can be moved in the translational direction along the Z axis.

[0058] The reflector 20 constituting the joint device 3 is attached to the reflector mounting hole 44. As shown in Fig. 8, this reflector mounting hole 44 is a hole having a circular cross section, and is formed to extend in the axial direction from the upper end surface of the third frame 40. The lower end of this reflector mounting hole 44 communicates with the upper end of the elongated shaft insertion hole 43. Note that the cross-sectional shape, formation position, and axial length of the reflector mounting hole 44 are not limited to this embodiment, and can be modified in design as appropriate depending on the shape of the reflector 20, etc.

[0059] The spring fixing portion 45 is used to fix one end of the restoring force acting spring 42. As shown in Figures 7 and 8, this spring fixing portion 45 is provided in a ring shape by protruding radially from the outer circumferential surface of the axially intermediate portion of the third frame 40. The outer diameter of this spring fixing portion 45 is set to be larger than the outer diameter of the spring accommodating groove 37 of the second frame 32.

[0060] The hand attachment portion 46 is used to attach the robot hand 4 to the joint device 3. As shown in FIG. 5, the hand attachment portion 46 is formed as a flat surface extending in the axial direction at the lower end of the third frame 40.

[0061] The third frame 40 configured as described above is inserted into the internal cavity of the second frame 32 with the end face where the reflector mounting hole 44 is formed facing up, allowing it to slide up and down. The sliding direction of the third frame 40 is perpendicular to the axial direction of the rotation shaft 27 of the first frame 22 and perpendicular to the axial direction of the rotation shaft 35 of the second frame 32. Furthermore, the upper portion of the third frame 40 is radially supported by the cylindrical extension portion 36 of the second frame 32, preventing radial wobble during sliding. The rotation shaft 35 of the second frame 32 is radially inserted into the elongated shaft insertion hole 43 of the third frame 40. As a result, the relative positional relationship between the rotation shaft 35 and the elongated shaft insertion hole 43 changes as the third frame 40 slides. Specifically, the rotation shaft 35 moves within the elongated shaft insertion hole 43 in the groove length direction.

[0062] The stopper portion 41 (see

[0050] ) serves to restrict the sliding of the third frame 40 within a predetermined range. As shown in FIG. 8, this stopper portion 41 is composed of a restriction surface 47. This restriction surface 47 is formed as the bottom surface of the shaft insertion slot 43 of the third frame 40, and has a semicircular cross section that approximately matches the lower half of the rotation shaft 35 of the second frame 32.

[0063] The restoring force acting spring 42 (see

[0050] ) biases the third frame 40 in the direction opposite to the sliding direction, thereby acting as a restoring force on the third frame 40, i.e., a force that returns the third frame 40 to the position before sliding. The restoring force acting spring 42 is a so-called compression coil spring, and has an outer diameter and wire diameter that can be accommodated in the spring accommodating groove 37 of the second frame 32. The free length of the restoring force acting spring 42 is set to be greater than the groove depth of the spring accommodating groove 37. As shown in FIG. 8, the restoring force acting spring 42 configured in this manner has its upper portion accommodated in the spring accommodating groove 37 of the second frame 32, and its upper end portion fixed to the bottom of the spring accommodating groove 37. Meanwhile, the lower portion of the restoring force acting spring 42 protruding outside the second frame 32 is wound around the third frame 40, and its lower end portion is fixed to the spring fixing portion 45 of the third frame 40.

[0064] The reflector 20 (see

[0030] ) serves as a measurement object when the proximity sensor 10 detects the posture of the robot hand 4. As shown in FIG. 8 , the reflector 20 has a disk portion 48 and an attachment protrusion 49. The disk portion 48 serves to reflect light emitted from the infrared sensor 61. The disk portion 48 is a flat plate member having a substantially circular shape in a plan view, and its diameter is set to a size taking into consideration the range of light emitted by the infrared sensor 61. On the other hand, the attachment protrusion 49 is used to attach the reflector 20 to the third frame 40. The attachment protrusion 49 protrudes from the center of one surface of the disk portion 48 and has a circular cross section. The outer diameter of the attachment protrusion 49 is set to be substantially equal to the inner diameter of the reflector attachment hole 44 of the third frame 40. The reflector 20 configured in this manner is fixed and attached to the upper end of the third frame 40 by inserting and fixing the attachment protrusion 49 into the reflector attachment hole 44.

[0065] 9 is a schematic perspective view showing the assembly of the joint device 3 and the robot hand 4 to the proximity sensor unit 7. The joint device 3 configured as described above is placed on the lower mounting portion 16 of the joint fixing frame 11 that configures the proximity sensor unit 7 with the reflector 20 facing up, with the base frame 21 that configures the X-axis elastic deformation allowing mechanism 17 facing the axial direction of its bearing hole 28 in the X-axis direction, and is fixed with screws or the like. Here, a space S of a predetermined width is secured between the lower mounting portion 16 and the upper mounting portion 15 of the joint fixing frame 11, so that the reflector 20 located above the base frame 21 can move freely within this space S.

[0066] The robot hand 4 (see

[0022] ) plays a role in manipulating an unknown object Ob while following the shape of the object Ob, and in this embodiment, in gripping the object Ob. As shown in FIG. 1, the robot hand 4 has a pair of opposing fingers 50 (corresponding to the "links" of the present invention). The pair of fingers 50 are formed by bending a metal plate or the like, and as shown in FIGS. 4 and 5, each has a joint attachment portion 51 and an object acting portion 52.

[0067] The joint mounting portion 51 is used to mount the finger 50 to the joint device 3. This joint mounting portion 51 has a flat shape that generally matches the hand mounting portion 46 of the third frame 40 in a plan view. On the other hand, the object acting portion 52 serves to contact the object Ob and apply a force to it. This object acting portion 52 has a tapered shape that gradually narrows from the base end side to the tip end side in a plan view, and is provided so as to extend generally parallel to the joint mounting portion 51 at a predetermined interval in a side view.

[0068] As shown in FIG. 1, the pair of fingers 50 configured in this manner are arranged so that their object action portions 52 face each other at a predetermined distance, and as shown in FIG. 5, their respective joint mounting portions 51 are abutted against the hand mounting portions 46 of the pair of third frames 40 of the joint device 3 and fixed with screws or the like. The object Ob is then sandwiched between the object action portions 52 of the pair of fingers 50, thereby enabling the robot hand 4 to grasp the object Ob. The shape and number of the fingers 50 can be changed as desired depending on the manner in which the object Ob is to be manipulated. For example, the number of fingers 50 is not limited to two as in the present embodiment, but may be one, three, or more.

[0069] (Functional configuration of a robot with a tracing function) Next, a functional configuration of the copying robot 1 according to the first embodiment of the present invention will be described. Fig. 10 is a block diagram showing the functional configuration of the copying robot 1. The copying robot 1 has a robot arm 2, a joint device 3, a robot hand 4, a proximity sensor 10, a memory unit 54, a difference calculation unit 53, a communication bus 55, and a control unit 56.

[0070] The robot arm 2, the joint device 3, the robot hand 4, and the proximity sensor 10 have been described above, and therefore further description will be omitted here. The memory unit 53 serves to store various programs and temporary information. As shown in FIG. 10 , the memory unit 53 pre-stores a target posture 57 of the robot hand 4 corresponding to each task to be performed by the robot hand 4. The difference calculation unit 53 serves to calculate the difference between the posture of the robot hand 4 detected by the proximity sensor 10 and the target posture 57 stored in the memory unit 53. The communication bus 55 serves to electrically connect the various components constituting the copying robot 1 to each other. The control unit 56 serves to control the operation of each component via the communication bus 55. The control unit 56 controls the posture of the robot hand 4 so as to reduce the difference calculated by the difference calculation unit 53, and causes the robot hand 4 to perform a predetermined task.

[0071] The predetermined tasks performed by the robot hand 4 include, for example, one or more tasks selected from the group consisting of tasks of grasping an object Ob, tasks of leaving the grasped object Ob stationary, tasks of measuring physical quantities of the grasped object Ob, tasks of optimally controlling the position and posture of the robot 1 with a tracing function based on the tilt and position information of the grasped object Ob, tasks of approaching the contents of a container which is the object Ob along the wall surface, tasks of assembling one grasped part to another part which is the object Ob, and tasks of pressing a button which is the object Ob.

[0072] (Operation of the robot joint device and its effects) Next, the operation and effects of the joint device 3 of the robot according to the first embodiment of the present invention will be described. FIG. 11 is an explanatory diagram for explaining the operation of the X-axis elastic deformation allowing mechanism 17 of the joint device 3, showing the joint device 3 as viewed from the X-axis direction. First, when the fingers 50 of the robot hand 4 are not in contact with the object Ob and no external force is acting on the fingers 50, as shown in FIG. 4, the upper surface of the first frame 22 is substantially flush with the upper surface of the base frame 21. At this time, as shown in FIG. 11(a), the upper surfaces of the pair of restricting protrusions 30 constituting the pair of stopper portions 23 are in contact with the lower surfaces of the restoring force acting springs 24, respectively, and the lower surfaces thereof are spaced apart from the restricting surfaces 31.

[0073] Next, when the tracking control of the robot hand 4 is started and the object action portion 52 of the finger 50 comes into contact with the object Ob and starts to move along its surface, an external force acts on the finger 50. Then, a rotational moment acts from the third frame 40, to which the finger 50 is attached, via the second frame 32, causing the first frame 22 to rotate clockwise or counterclockwise about the rotation axis 27. For example, in FIG. 11( a), which shows one of the pair of stopper portions 23, when the first frame 22 rotates clockwise about the rotation axis 27, the restricting projection 30 protruding from the first frame 22 also rotates clockwise about the rotation axis 27 against the restoring force of the restoring force acting spring 24. As a result, the restoring force acting spring 24 elastically deforms with its base end fixed to the base frame 21 as a fulcrum, moving its tip end away from the top surface of the base frame 21, as shown in FIG. 11( b).

[0074] Meanwhile, at this time, in the other of the pair of stopper portions 23, as shown in FIG. 11( c), the restricting protrusion 30 rotates counterclockwise around the rotation shaft 27, causing the upper surface thereof to move away from the lower surface of the restoring force acting spring 24. Then, when the first frame 22 rotates counterclockwise about the rotation shaft 27 by approximately 7°, the lower surface of the restricting protrusion 30 in the other stopper portion 23 comes into contact with the restricting surface 31, thereby restricting the counterclockwise rotation of the first frame 22. Furthermore, when the external force acting on the finger 50 decreases, in one of the stopper portions 23 shown in FIG. 11( b), the restricting protrusion 30 rotates counterclockwise around the rotation shaft 27 due to the restoring force of the restoring force acting spring 24 that attempts to return to the state before elastic deformation. Accordingly, the first frame 22 also rotates counterclockwise around the rotation shaft 27 and returns to the state shown in FIG. 11( a). The angle by which the first frame 22 can rotate counterclockwise at the other stopper portion 23 is not limited to 7° in this embodiment, and can be arbitrarily modified in design.

[0075] 11(a) showing one stopper portion 23, when the first frame 22 rotates counterclockwise around the rotation shaft 27, the restricting projection 30 rotates counterclockwise around the rotation shaft 27, causing the upper surface of the restricting projection 30 to move away from the lower surface of the restoring force acting spring 24. At this time, in the other stopper portion 23, as shown in FIG. 11(b), the restricting projection 30 rotates clockwise around the rotation shaft 27 against the restoring force of the restoring force acting spring 24. As a result, in this other stopper portion 23, the restoring force acting spring 24 elastically deforms with its base end fixed to the first frame 22 as a fulcrum so as to move its tip end away from the upper surface of the first frame 22.

[0076] Thereafter, when the first frame 22 rotates counterclockwise about the rotation axis 27 at one of the stopper portions 23 by approximately 7°, the lower surface of the restricting protrusion 30 comes into contact with the restricting surface 31, thereby restricting the counterclockwise rotation of the first frame 22. Furthermore, when the external force acting on the finger 50 decreases, the restricting protrusion 30 at the other of the stopper portions 23 shown in FIG. 11(b) rotates counterclockwise about the rotation axis 27 due to the restoring force of the restoring force acting spring 24, which attempts to return to the state before elastic deformation. Accordingly, the first frame 22 also rotates counterclockwise about the rotation axis 27 and returns to the state shown in FIG. 11(a). Note that the angle by which the first frame 22 can rotate counterclockwise at one of the stopper portions 23 is not limited to 7° in this embodiment and can be arbitrarily modified in design.

[0077] In this way, the X-axis elastic deformation allowing mechanism 17 allows the joint device 3 to elastically deform in the rotational direction about the X-axis, so that the elastic deformation of the joint device 3 can absorb a portion of external forces such as impacts acting on the finger 50. This can prevent problems such as jammed fingers in the finger 50 and malfunctions in various parts of the robot arm 2 due to external forces such as impacts. Furthermore, the elastic deformation of the joint device 3 can also absorb a portion of the high-frequency vibrations of the motor built into the joint device 3. This can prevent problems such as a decrease in the accuracy of tracking control due to such vibrations being transmitted to the robot hand 4.

[0078] Furthermore, the pair of stopper portions 23 restricts the rotation of the first frame 22 both clockwise and counterclockwise within a certain range. Therefore, the elastic deformation of the joint device 3 in the rotational direction about the X-axis is restricted within a certain range, and at the limit of this range, the joint device 3 is locked and unable to elastically deform around the X-axis. Therefore, when the joint device 3 is locked, by gripping the object Ob with the pair of fingers 50 of the robot hand 4, the object Ob can be clamped with a stronger force than when the joint device 3 is elastically deformable around the X-axis without restriction. This allows the robot hand 4 to grip the object Ob more stably and reliably.

[0079] 12 is an explanatory diagram for explaining the operation of the Y-axis elastic deformation allowing mechanism 18 of the joint device 3, and shows the joint device 3 as viewed from the Y-axis direction. However, for ease of explanation, the base frame 21 is not shown in FIG. 12. First, when the fingers 50 of the robot hand 4 are not in contact with the object Ob and no external force is acting on the fingers 50, the upper surface of the second frame 32 is substantially flush with the upper surface of the first frame 22, as shown in FIG. 4. At this time, the upper surfaces of the pair of restricting protrusions 38 constituting the pair of stopper portions 33 are in contact with the lower surfaces of the restoring force acting springs 34, respectively, and the lower surfaces thereof are spaced apart from the restricting surfaces 39.

[0080] Next, the tracking control of the robot hand 4 is started, and when the object action portion 52 of the finger 50 comes into contact with the object Ob and starts to move along its surface, an external force acts on the finger 50. Then, due to a rotational moment acting via the third frame 40 to which the finger 50 is attached, the second frame 32 rotates clockwise or counterclockwise about the rotation axis 35. For example, in FIG. 12( a) showing one of the pair of stopper portions 33, when the second frame 32 rotates clockwise about the rotation axis 35, the restricting projection 38 protruding from the second frame 32 also rotates clockwise about the rotation axis 35 against the restoring force of the restoring force acting spring 34. As a result, the restoring force acting spring 34 elastically deforms with its base end fixed to the first frame 22 as a fulcrum, moving its tip end away from the top surface of the first frame 22, as shown in FIG. 12( b).

[0081] Meanwhile, at this time, in the other of the pair of stopper portions 33, as shown in FIG. 12( c), the restricting protrusion 38 rotates counterclockwise around the rotation shaft 35, causing the upper surface thereof to move away from the lower surface of the restoring force acting spring 34. Then, when the second frame 32 rotates counterclockwise about the rotation shaft 35 by approximately 7°, the lower surface of the restricting protrusion 38 in the other stopper portion 33 comes into contact with the restricting surface 39, thereby restricting the counterclockwise rotation of the second frame 32. Furthermore, when the external force acting on the finger 50 decreases, in one of the stopper portions 33 shown in FIG. 12( b), the restricting protrusion 38 rotates counterclockwise around the rotation shaft 35 due to the restoring force of the restoring force acting spring 34, which attempts to return to its state before elastic deformation. Accordingly, the second frame 32 also rotates counterclockwise around the rotation shaft 35 and returns to the state shown in FIG. 12( a). The angle by which the second frame 32 can rotate counterclockwise at the other stopper portion 33 is not limited to 7° in this embodiment, and can be arbitrarily modified in design.

[0082] 12(a) showing one stopper portion 33, when the second frame 32 rotates counterclockwise around the rotation shaft 35, the restricting projection 38 rotates counterclockwise around the rotation shaft 35, causing the upper surface of the restricting projection 38 to move away from the lower surface of the restoring force acting spring 34. At this time, in the other stopper portion 33, as shown in FIG. 12(b), the restricting projection 38 rotates counterclockwise around the rotation shaft 35 against the restoring force of the restoring force acting spring 34. As a result, the restoring force acting spring 34 elastically deforms with its base end fixed to the first frame 22 as a fulcrum so as to move its tip end away from the upper surface of the first frame 22.

[0083] Thereafter, when the second frame 32 rotates counterclockwise about the rotation axis 35 at one of the stopper portions 33 by approximately 7°, the lower surface of the restricting protrusion 38 abuts against the restricting surface 39, thereby restricting the counterclockwise rotation of the second frame 32. Furthermore, when the external force acting on the finger 50 decreases, the restricting protrusion 38 at the other of the stopper portions 33 shown in FIG. 12(b) rotates counterclockwise about the rotation axis 35 due to the restoring force of the restoring force acting spring 34, which attempts to return to the state before elastic deformation. Accordingly, the second frame 32 also rotates counterclockwise about the rotation axis 35 and returns to the state shown in FIG. 12(a). Note that the angle by which the second frame 32 can rotate counterclockwise at one of the stopper portions 33 is not limited to 7° as in the present embodiment and can be arbitrarily modified in design.

[0084] In this way, the Y-axis elastic deformation allowing mechanism 18 allows the joint device 3 to elastically deform in the rotational direction about the Y-axis, so that part of the external force, such as an impact, acting on the finger 50 can be absorbed by the elastic deformation of the joint device 3. Furthermore, the pair of stopper portions 33 restricts the rotation of the second frame 32 about the Y-axis within a certain range. Therefore, the range of elastic deformation allowed by the joint device 3 about the Y-axis is restricted to a certain range, and at the limit point, the joint device 3 is locked so that it cannot elastically deform about the Y-axis. As a result, the Y-axis elastic deformation allowing mechanism 18 also provides the same effects as those provided by the X-axis elastic deformation allowing mechanism 17.

[0085] 13 is an explanatory diagram for explaining the operation of the Z-axis elastic deformation allowing mechanism 19 of the joint device 3. First, when the finger 50 of the robot hand 4 is not in contact with the object Ob and no external force is acting on the finger 50, as shown in FIG. 8, the third frame 40 is in a state in which the rotation shaft 35 of the second frame 32 is inserted through the longitudinal middle portion of the shaft insertion slot 43. At this time, the restoring force acting spring 42 is in a free length state because no compressive force is acting on it.

[0086] Next, the tracking control of the robot hand 4 is initiated. When the object action portion 52 of the finger 50 contacts the object Ob and begins to move along its surface, an external force acts on the finger 50. An upward external force acts as a component of the external force on the third frame 40 to which the finger 50 is attached. As a result, the third frame 40 begins to slide upward along the internal cavity of the second frame 32, as shown in FIG. 13( a). Accordingly, the restoring force acting spring 42, whose lower end is fixed to the third frame 40 and whose upper end is fixed to the second frame 32, elastically deforms so that the distance between its ends decreases, and is gradually compressed. Thereafter, the third frame 40 continues to slide upward against the restoring force of the restoring force acting spring 42. Then, as shown in FIG. 13( b), the rotation shaft 35 of the second frame 32 abuts against the restricting surface 39, which is the bottom surface of the elongated shaft insertion hole 43, thereby restricting the upward sliding movement of the third frame 40. Furthermore, when the external force acting on the finger 50 becomes smaller, the third frame 40 starts to slide downward due to the restoring force of the restoring force acting spring 42 which tries to return to the state before elastic deformation. Then, the third frame 40 passes through the state of Fig. 13(a) and returns to the state of Fig. 8 in which the length of the restoring force acting spring 42 becomes the free length.

[0087] In this way, the Z-axis elastic deformation allowing mechanism 19 allows the joint device 3 to elastically deform in the translational direction along the Z-axis, so that part of the external force, such as an impact, acting on the finger 50 can be absorbed by the elastic deformation of the joint device 3. Furthermore, the stopper portion 41 restricts the sliding of the third frame 40 to a certain range. Therefore, the elastic deformation in the translational direction along the Z-axis allowed by the joint device 3 is restricted to a certain range, and at the limit point, the joint device 3 is locked so that it cannot elastically deform in the Z-axis direction. As a result, the Z-axis elastic deformation allowing mechanism 19 also provides the same effects as those provided by the X-axis elastic deformation allowing mechanism 17.

[0088] (Variation) The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention as defined by the claims. For example, the following modifications can be considered for the first embodiment of the present invention.

[0089] In this embodiment, the X-axis elastic deformation allowing mechanism 17 allows elastic deformation in the rotational direction about the X-axis, the Y-axis elastic deformation allowing mechanism 18 allows elastic deformation in the rotational direction about the Y-axis, and the Z-axis elastic deformation allowing mechanism 19 allows elastic deformation in the translational direction along the Z-axis. However, the X-axis elastic deformation allowing mechanism 17 may be any mechanism that allows elastic deformation of the joint device 3 about the X-axis, i.e., allows elastic deformation in at least one of the rotational direction about the X-axis and the translational direction along the X-axis. Therefore, for example, the X-axis elastic deformation allowing mechanism 17 is not limited to that of this embodiment, and may be a mechanism that allows elastic deformation of the joint device 3 only in the translational direction along the X-axis, or a mechanism that allows elastic deformation of the joint device 3 in both the rotational direction about the X-axis and the translational direction along the X-axis. The same applies to the Y-axis elastic deformation allowing mechanism 18 and the Z-axis elastic deformation allowing mechanism 19.

[0090] In this embodiment, the X-axis is set as the first axis, the Y-axis as the second axis, and the Z-axis as the third axis according to the present invention. However, the first, second, and third axes according to the present invention can be arbitrarily selected from a combination of the X-axis, Y-axis, and Z-axis.

[0091] In this embodiment, the restoring force application portion according to the present invention is configured by a spring member such as a leaf spring or a coil spring. However, the restoring force application portion is not limited to this embodiment as long as it can apply a restoring force to the first frame 22, the second frame 32, and the third frame 40 in the direction opposite to the direction of movement thereof, and can also be configured by, for example, a conventionally known damper or motor.

[0092] In this embodiment, the stopper portion 23 of the X-axis elastic deformation mechanism 17 has its restricting protrusion 30 provided on the first frame 22 and its restricting surface 31 provided on the base frame 21. However, the stopper portion 23 may be configured in the opposite manner, with its restricting protrusion 30 provided on the base frame 21 and its restricting surface 31 provided on the first frame 22. The same applies to the stopper portion 33 of the Y-axis elastic deformation mechanism 18 and the stopper portion 41 of the Z-axis elastic deformation mechanism 19.

[0093] In this embodiment, the restoring force acting spring 42 constituting the Z-axis elastic deformation allowing mechanism 19 is provided so as to apply a downward restoring force to the third frame 40 when an upward external force acts thereon, as shown in Fig. 13. However, instead of or in addition to this, it is also possible to separately provide a restoring force acting spring 42 so as to apply an upward restoring force to the third frame 40 when a downward external force acts thereon.

[0094] Next, a robot joint device according to a second embodiment of the present invention will be described. The robot joint device according to the second embodiment solves the problems of the robot joint device 3 according to the first embodiment. More specifically, in the joint device 3 of the first embodiment, in a neutral state in which no external force is acting on the fingers 50, the restricting protrusions 30, 38 constituting the stopper portions 23, 33 merely abut against the restoring force acting springs 24, 34, and no restoring force is applied from the restoring force acting springs 24, 34. Therefore, when gripping a small object Ob from this neutral state, only a small restoring force is applied to the restricting protrusions 30, 38 from the slightly elastically deformed restoring force acting springs 24, 34. This results in an insufficient gripping force on the object Ob by the fingers 50, which causes the object Ob to easily fall.

[0095] Furthermore, in the joint device 3 according to the first embodiment, a large force is applied from the regulating protrusions to the restoring force acting springs 24, 34, which are relatively short leaf springs, and therefore the restoring force acting springs 24, 34 are prone to plastic deformation. When such plastic deformation occurs, a gap is created between the regulating protrusions 30, 38 and the restoring force acting springs 24, 34 in the neutral state, causing rattles in the regulating protrusions 30, 38, which makes the above-mentioned problem of the object Ob falling even more pronounced.

[0096] Furthermore, in the joint device 3 according to the first embodiment, when grasping an object Ob, the pair of fingers 50, which are opposed to each other in the neutral state and extend vertically, assume a posture such that the distance between the fingers 50 gradually increases from the base end toward the tip end when the restoring force acting springs 24, 34 pressed by the restricting projections 30, 38 elastically deform. As a result, the direction of the force applied to the object Ob by the pair of fingers 50 is slightly inclined downward from the horizontal. In this case, a vertically downward component of the force occurs, reducing the gripping force of the fingers 50 on the object Ob, which can lead to the problem of the object Ob easily falling. The joint device for a robot according to the second embodiment aims to solve these problems.

[0097] (Configuration of robot with tracing function) First, the configuration of a copying robot equipped with a robot joint device according to a second embodiment of the present invention will be described. As shown in Fig. 1, a copying robot 70 according to the second embodiment includes a robot arm 2, a pair of joint devices 71, and a robot hand 72. Here, the robot arm 2 has the same configuration as the copying robot 1 according to the first embodiment, so its description will be omitted here and the same reference numerals as those in the first embodiment will be used.

[0098] The pair of joint devices 71 serves to connect the robot hand 72 to the robot arm 2 so that the robot hand 72 can move relative to the robot arm 2. FIG. 14 is a schematic perspective view, seen from the front, showing the configuration of one of the pair of joint devices 71 and the robot hand 72. The joint device 71 has an X-axis elastic deformation allowing mechanism 73 (the "first-axis elastic deformation allowing mechanism" according to the present invention), a Y-axis elastic deformation allowing mechanism 74 (the "second-axis elastic deformation allowing mechanism" according to the present invention), a Z-axis elastic deformation allowing mechanism 19 (the "third-axis elastic deformation allowing mechanism" according to the present invention), and a reflecting plate 20. Here, the Z-axis elastic deformation allowing mechanism 19 and the reflecting plate 20 have the same configuration as in the first embodiment, and therefore their explanations are omitted here and the same reference numerals as in the first embodiment are used.

[0099] The X-axis elastic deformation allowing mechanism 73 serves to allow the robot hand 72 to elastically deform in a rotational direction about the X-axis (the "first axis" according to the present invention) among three mutually orthogonal axes. Here, FIG. 15 is a schematic side view of FIG. 14 as viewed from the Y-axis direction. As shown in FIGS. 14 and 15, the X-axis elastic deformation allowing mechanism 73 has a base frame 75, a first frame 76, a stopper portion 77, and a restoring force acting portion 78.

[0100] The base frame 75 serves to fix the joint device 71 to the proximity sensor unit 7 that constitutes the robot arm 2. As shown in FIG. 14, this base frame 75 is a member made of metal or the like and has a substantially T-shaped external shape when viewed from the front. The base frame 75 configured in this manner has its upper end fixed to the bottom of the arm fixing frame 8 that constitutes the proximity sensor unit 7 by screws or the like (not shown). The material, shape, and size of the base frame 75 are not limited to those in this embodiment and can be modified in design as appropriate.

[0101] First frame 76 serves to enable relative movement in a rotational direction about the X-axis with respect to base frame 75. First frame 76 is a member made of metal or the like and having a substantially U-shaped outer shape in a plan view. As shown in FIGS. 14 and 15 , first frame 76 has X-rotation shaft 79. X-rotation shaft 79 is a cylindrical member made of metal or the like, and is provided so as to protrude outward from a position facing an opening in the U-shaped first frame 76. First frame 76 configured in this manner is supported by base frame 75 so as to be rotatable forward and backward by X-rotation shaft 79 inserted through base frame 75. Note that the material, shape, and size of first frame 76 are not limited to those described in this embodiment and can be modified in design as appropriate.

[0102] The stopper portion 77 serves to restrict the rotation of the first frame 76 within a predetermined range. As shown in FIGS. 14 and 15 , the stopper portion 77 has a notched groove 80 and a restricting protrusion 81. The notched groove 80 is formed by cutting out the lower end of the base frame 75 into an inverted U-shaped cross section. An inner surface 82 of the notched groove 80 serves as the "restricting surface" according to the present invention. The restricting protrusion 81 is a cylindrical member made of metal or the like, and its outer diameter is set smaller than the width of the notched groove 80. The base end of the restricting protrusion 81 is fixed to a position below the X rotation shaft 79 on the first frame 76 and extends outward substantially parallel to the X rotation shaft 79. The tip end of the restricting protrusion 81 is disposed within the notched groove 80 and spaced apart from the inner surface 82. Here, the distance between the regulating protrusion 81 and the inner surface 82 of the cutout groove 80 is set so that the regulating protrusion 81 comes into contact with the inner surface 82 of the cutout groove 80 when the first frame 76 is rotated by approximately 7° in the forward direction or approximately 7° in the reverse direction relative to the base frame 75. The shape, size, and formation position of the cutout groove 80 and the regulating protrusion 81 can be appropriately changed in design depending on the rotation angle that should be allowed for the first frame 76, etc.

[0103] The restoring force acting portion 78 acts to apply a force to the first frame 76 in the direction opposite to the rotation direction of the first frame 76. As shown in Figures 14 and 15, the restoring force acting portion 78 has a pair of scissors frames 83, a scissors biasing member 84, and a scissors regulating member 85.

[0104] One of the pair of scissors frames 83 applies a force in the reverse direction when the first frame 76 rotates forward, and the other applies a force in the reverse direction when the first frame 76 rotates backward. As shown in Figures 14 and 15 , these scissors frames 83 are hook-shaped members made of resin or the like in a plan view, and each has a regulated surface 86 and a pressed surface 87. The pair of scissors frames 83 configured in this manner are arranged so that their regulated surfaces 86 and pressed surfaces 87 face each other at a predetermined distance, and are each supported by the X rotation shaft 79 of the first frame 76 so as to be rotatable in both forward and reverse directions.

[0105] Scissor restricting member 85 serves to restrict the rotation of the tip ends of the pair of scissors frames 83 so that they do not approach each other beyond a predetermined distance. This scissors restricting member 85 is a cylindrical member made of metal or the like, and is inserted into base frame 75 at a position above X rotation axis 79, with its base end fixed to base frame 75 and provided so as to extend toward first frame 76 substantially parallel to X rotation axis 79. The tip end of this scissors restricting member 85 is located between the opposing regulated surfaces 86 of the pair of scissors frames 83.

[0106] The scissors biasing member 84 serves to bias the pair of scissors frames 83 so that their tips approach each other. This scissors biasing member 84 is a so-called tension coil spring, one end of which is fixed to the tip of one scissors frame 83 and the other end of which is fixed to the tip of the other scissors frame 83. In a neutral state in which the first frame 76 is not subjected to external force and is not rotating, the scissors biasing member 84 is extended from its natural length. That is, in the neutral state, the pair of scissors frames 83 are biased so that their tips approach each other by receiving a tensile force from the scissors biasing member 84. In this neutral state, the pair of scissors frames 83 are stopped in a balanced state where their regulated surfaces 86 abut against the scissors regulating members 85 and their pressed surfaces 87 abut against the regulating projections 81.

[0107] The Y-axis elastic deformation allowing mechanism 74 serves to allow the robot hand 72 to elastically deform in a rotational direction about the Y-axis (the "second axis" according to the present invention) among the three mutually orthogonal axes. As shown in FIG. 15 , the Y-axis elastic deformation allowing mechanism 74 has a second frame 88, a stopper portion 89, and a restoring force acting portion 90.

[0108] The second frame 88 serves to enable relative movement in a rotational direction about the Y axis with respect to the first frame 76. As shown in FIG. 15 , the second frame 88 is a cylindrical member made of metal or the like, and has a pair of Y rotation shafts 91. The pair of Y rotation shafts 91 are columnar members made of metal or the like, and are provided so as to protrude from the outer circumferential surface at positions facing each other across the center of the second frame 88. The second frame 88 configured in this manner is disposed in an opening of the first frame 76, which is substantially U-shaped in plan view, and the pair of Y rotation shafts 91 are inserted through the first frame 76, thereby being supported by the first frame 76 to be rotatable forward and reverse about the Y axis. The material, shape, and size of the second frame 88 are not limited to those described in this embodiment and can be modified as appropriate.

[0109] The stopper portion 89 serves to restrict the rotation of the second frame 88 within a predetermined range. FIG. 16 is a schematic side view of FIG. 15 , omitting the illustration of a pair of scissors frames 95 (described later). The stopper portion 89 has a notched groove 92 and a restricting protrusion 93. The notched groove 92 is formed by cutting out an inverted U-shaped cross section from the lower end of the first frame 76. An inner surface 94 of the notched groove 92 constitutes the "restricting surface" according to the present invention. The restricting protrusion 93 is a cylindrical member made of metal or the like, and its outer diameter is set smaller than the width of the notched groove 92. The base end of the restricting protrusion 93 is fixed to a position below the Y rotation shaft 91 on the outer circumferential surface of the second frame 88 and extends substantially parallel to the Y rotation shaft 91. The tip end of the restricting protrusion 93 is disposed within the notched groove 92, spaced apart from the inner surface 94. The distance between the regulating protrusion 93 and the inner surface 94 of the cutout groove 92 is set so that the regulating protrusion 93 comes into contact with the inner surface 94 of the cutout groove 92 when the second frame 88 rotates by approximately 7° in the forward direction or approximately 7° in the reverse direction relative to the first frame 76. The shape, size, and formation position of the cutout groove 92 and the regulating protrusion 93 can be appropriately changed in design depending on the rotation angle that should be allowed for the second frame 88, etc.

[0110] The restoring force acting portion 90 acts to apply a force to the second frame 88 in the direction opposite to the rotation direction of the second frame 88. As shown in FIG. 15 , the restoring force acting portion 90 has a pair of scissors frames 95, a scissors biasing member 96, and a scissors regulating member 97.

[0111] One of the pair of scissors frames 95 applies a force in the reverse direction when the second frame 88 rotates forward, and the other applies a force in the reverse direction when the second frame 88 rotates backward. These scissors frames 95 are made of resin or the like and are hook-shaped in plan view, and each has a regulated surface 98 formed on the outside of the hook shape and a pressed surface 99 formed on the inside of the hook shape and approximately perpendicular to the regulated surface 98. The pair of scissors frames 95 configured in this manner are arranged so that their regulated surfaces 98 and pressed surfaces 99 face each other at a predetermined distance, and each is supported by one of a pair of Y rotation shafts 91 of the second frame 88 so as to be rotatable in the forward and reverse directions. The material and shape of the pair of scissors frames 95 are not limited to those in this embodiment and can be modified as appropriate.

[0112] The scissors restricting member 97 serves to restrict the rotation of the pair of scissors frames 95 so that the tips of the scissors frames 95 do not approach each other by more than a predetermined distance. This scissors restricting member 97 is a cylindrical member made of metal or the like, and is inserted into the first frame 76 at a position to the side of the Y rotation shaft 91, with its base end fixed to the first frame 76 and extending outward from the first frame 76 substantially parallel to the Y rotation shaft 91. The tips of the scissors restricting member 97 are located between the opposing restricted surfaces 98 of the pair of scissors frames 95. The material, shape, and forming position of the scissors restricting member 97 can be appropriately modified in design depending on the shape, position, etc. of the pair of scissors frames 95.

[0113] The scissors biasing member 96 serves to bias the pair of scissors frames 95 so that their tips approach each other. This scissors biasing member 96 is a so-called tension coil spring, one end of which is fixed to the tip of one scissors frame 95 and the other end of which is fixed to the tip of the other scissors frame 95. The scissors biasing member 96 is extended from its natural length in a neutral state in which the second frame 88 is not subjected to external force and is not rotating. That is, in the neutral state, the pair of scissors frames 95 are biased so that their tips approach each other by receiving a tensile force from the scissors biasing member 96. In this neutral state, the pair of scissors frames 95 are stopped in a balanced state where their regulated surfaces 98 abut against the scissors regulating members 97 and their pressed surfaces 99 abut against the regulating projections 93.

[0114] The robot hand 72 plays a role of grasping an unknown object Ob while following the shape of the object Ob. Here, Fig. 17 is a schematic rear view showing the overall configuration of the robot hand 72. The robot hand 72 includes a pair of fingers 100 (corresponding to the "link" according to the present invention) and a pair of parallel link components 101.

[0115] The pair of fingers 100 are L-shaped members made of metal or the like in a side view, and each includes a joint attachment portion 102 for attachment to the joint device 71 and an object action portion 103 for contacting and applying force to the object Ob. As shown in FIG. 17 , the pair of fingers 100 configured in this manner are arranged so that the object action portions 103 face each other at a predetermined distance, and one end of each joint attachment portion 102 is rotatably supported by the third frame 40 of the joint device 71. The other end of each joint attachment portion 102 is rotatably supported by a pair of parallel link components 101. The object action portions 103 of the pair of fingers 100 sandwich the object Ob from both sides, allowing the robot hand 72 to grasp the object Ob. The shape and number of the fingers 100 can be changed as desired depending on the manner in which the object Ob is to be manipulated. For example, the number of fingers 100 is not limited to two as in this embodiment, but may be one or three or more.

[0116] The pair of parallel link components 101, together with the finger 100 and the joint device 71, each serve to configure a so-called parallel link mechanism. As shown in FIG. 17 , each parallel link component 101 includes an arm mounting portion 104 for mounting to the robot arm 2, a finger support portion 105 for supporting the finger 100, and a biaxial connecting portion 106 that connects the arm mounting portion 104 and the finger support portion 105 rotatably around the X-axis and the Y-axis. In each of the pair of parallel link components 101 configured in this manner, the arm mounting portion 104 is fixed to the robot arm 2 with a screw or the like, and the finger support portion 105 rotatably supports the finger 100, more specifically, the other end of the joint mounting portion 102. Note that the design of the components and shapes of the pair of parallel link components 101 can be modified as appropriate within the scope in which a parallel link mechanism can be configured together with the finger 100 and the joint device 71.

[0117] (Functional configuration of a robot with a tracing function) Next, a functional configuration of a tracking robot 70 according to a second embodiment of the present invention will be described. As shown in Fig. 10, the tracking robot 70 includes a robot arm 2, a joint device 71, a robot hand 72, a proximity sensor 10, a difference calculation unit 53, a memory unit 54, a communication bus 55, and a control unit 56.

[0118] The configurations of the joint device 71 and the robot hand 72 of the second embodiment are as described above, and therefore a description thereof will be omitted here. The robot arm 2, proximity sensor 10, difference calculation unit 53, memory unit 54, communication bus 55, and control unit 56 have the same configurations as those of the first embodiment, and therefore a description thereof will be omitted here and the same reference numerals as those of the first embodiment will be used. Furthermore, like the robot hand 4 of the first embodiment, the robot hand 72 of the second embodiment also performs various tasks, including the task of grasping an object Ob.

[0119] (Operation of the robot joint device and its effects) Next, we will explain the operation and effects of the joint device 71 of the robot according to the second embodiment of the present invention. Since the operations of the X-axis elastic deformation allowing mechanism 73 and the Y-axis elastic deformation allowing mechanism 74 that constitute the joint device 71 are basically the same, for the sake of convenience, we will explain the operation of the Y-axis elastic deformation allowing mechanism 74 here.

[0120] 18 and 19 are diagrams for explaining the operation of the Y-axis elastic deformation allowing mechanism 74, with Fig. 18 being a partially enlarged view of the periphery of the restoring force application portion 90, and Fig. 19 being a partially enlarged view of the periphery of the stopper portion 89. First, in a neutral state in which the finger 100 of the robot hand 72 is not in contact with the object Ob and no external force is acting on the finger 100, the cylindrical second frame 88 is in a state in which its central axis is oriented vertically, as shown in Fig. 16. At this time, the restricting protrusion 93 that constitutes the stopper portion 89 is disposed inside the notched groove 92 that also constitutes the stopper portion 89, spaced apart from the inner surface 94 thereof.

[0121] 15, the pair of scissors frames 95 constituting the restoring force acting portion 90 are stopped at a position where their regulated surfaces 98 abut against the scissors regulating members 97 and their pressed surfaces 99 abut against the regulating projections 93. At this time, the pair of scissors frames 95 are each subjected to a tensile force from the scissors urging member 96, and are thus urged in directions in which their tip ends approach each other. As a result, the second frame 88 is always in a state in which a restoring force is applied, including in the neutral state.

[0122] Next, the tracking control of the robot hand 72 is initiated, and when the object action portion 103 of the finger 100 comes into contact with the object Ob and begins to move along its surface, an external force acts on the finger 100. Then, due to a rotational moment acting from the third frame 40 to which the finger 100 is attached, the second frame 88 rotates clockwise or counterclockwise about the Y rotation axis 91. For example, in FIG. 15 , when the second frame 88 rotates clockwise about the Y rotation axis 91, the restricting protrusion 93 protruding from the second frame 88 also rotates clockwise about the Y rotation axis 91 against the return force of the scissors biasing member 96. At this time, as shown in FIG. 18( a), one of the scissors frames 95A starts to rotate clockwise following the second frame 88 as its pressure-receiving surface 99 is pressed by the restricting protrusion 93. As a result, the distance between the tips of the pair of scissors frames 95 becomes wider than in the neutral state, and the scissors biasing member 96, which is a tension coil spring, becomes more extended than in the neutral state. Therefore, the pair of scissors frames 95 each receive a tensile force from the scissors biasing member 96 that is greater than in the neutral state, and their tips are biased more strongly in the direction of approaching each other. At this time, the clockwise rotation of the other scissors frame 95B is restricted by its regulated surface 98 abutting against the scissors regulating member 97, so that the other scissors frame 95B remains stopped and does not rotate clockwise, regardless of the tensile force received from the scissors biasing member 96.

[0123] Thereafter, when the second frame 88 rotates clockwise by approximately 7°, the restricting protrusion 93 constituting the stopper portion 89 comes into contact with the inner surface 94 of the notched groove 92, as shown in Figure 19(a). This restricts further clockwise rotation of the second frame 88 and the one scissors frame 95A that follows it. Then, when the external force acting on the finger 100 is released, the one scissors frame 95A rotates counterclockwise due to the return force received from the scissors biasing member 96, and returns to the neutral state.

[0124] 15, when the second frame 88 rotates counterclockwise around the Y-rotation shaft 91, the restricting protrusion 93 protruding from the second frame 88 also rotates counterclockwise around the Y-rotation shaft 91 against the return force of the scissors biasing member 96. At this time, as shown in FIG. 18(b), the other scissors frame 95B starts to rotate counterclockwise following the second frame 88 as its pressed surface 99 is pressed by the restricting protrusion 93. As a result, the distance between the tips of the pair of scissors frames 95 becomes wider than in the neutral state, and the scissors biasing member 96, which is a tension coil spring, becomes further stretched than in the neutral state. Therefore, the pair of scissors frames 95 each receive a tensile force from the scissors biasing member 96 that is greater than in the neutral state, and thus the tips of the pair of scissors frames 95 are more strongly biased in directions toward each other. At this time, one of the scissors frames 95A is prevented from rotating counterclockwise by its regulated surface 98 abutting against the scissors regulating member 97, and therefore remains stopped and does not rotate counterclockwise regardless of the tensile force received from the scissors biasing member 96.

[0125] Thereafter, when the second frame 88 rotates counterclockwise by approximately 7°, the restricting protrusion 93 constituting the stopper portion 89 comes into contact with the inner surface 94 of the notched groove 92, as shown in Figure 19(b). This restricts further counterclockwise rotation of the second frame 88 and the other scissors frame 95B that follows it. Then, when the external force acting on the finger 100 is released, the other scissors frame 95B rotates clockwise due to the restoring force received from the scissors biasing member 96, and returns to the neutral state.

[0126] As described above, in the joint device 71 according to the second embodiment, a certain return force is already acting on the second frame 88 from the scissors biasing member 96 in the neutral state. Therefore, when gripping a small object Ob in the neutral state, even if the scissors biasing member 96 is only slightly extended, a fairly large return force acts on the second frame 88, and as a reaction to this, the fingers 100 have a fairly large gripping force. Therefore, even in a state close to the neutral state, the object Ob can be securely gripped by the fingers 100, and the problem of the object Ob dropping due to insufficient gripping force can be prevented.

[0127] In the second embodiment, a tension coil spring is used as the scissors biasing member 96 that applies a restoring force to the second frame 88. This tension coil spring has characteristics that make it less susceptible to plastic deformation than the leaf spring used as the restoring force applying spring 24 in the first embodiment. Therefore, even if a large force is applied to the fingers 100, rattle of the second frame 88 caused by plastic deformation of the scissors biasing member 96 is unlikely to occur, and the problem of the object Ob dropping due to insufficient gripping force can be more reliably prevented.

[0128] Furthermore, in the second embodiment, the Y-axis elastic deformation allowing mechanism 74 is provided with one restoring force application portion 90 and one stopper portion 89, thereby applying a restoring force to the second frame 88 regardless of the rotational direction and restricting the rotation within a predetermined range. Therefore, compared to the Y-axis elastic deformation allowing mechanism 18 of the first embodiment which is provided with a pair of restoring force application springs 34 and a pair of stopper portions 33, the joint device 71 of the second embodiment has the advantage of being able to reduce the size and cost of the entire device by reducing the number of components.

[0129] In the joint device 71 according to the second embodiment, the robot hand 72 includes a pair of parallel link components 101 as shown in FIG. 17 . The pair of parallel link components 101, together with the fingers 100 and the joint device 71, constitute a parallel link mechanism. FIG. 20 is an explanatory diagram illustrating the effect of the parallel link mechanism 101. With such a parallel link component 101, as shown in FIG. 20( a), even if a force is applied to the fingers 100 and the first frame 76 rotates about the X-axis or the second frame 88 rotates about the Y-axis, the finger support portion 105 rotates about the X-axis or the Y-axis in response to the force, thereby holding the pair of fingers 100 in a position in which their object acting portions 103 extend vertically. Therefore, the distance between the pair of fingers 100 is constant from the base end to the tip end, so that the force that the object Ob receives from the pair of fingers 100 is only a horizontal force, and no vertically downward force component is generated. This prevents the problem of a decrease in the gripping force of the object Ob due to the generation of a component force. When the fingers 100 receive a force from the object Ob in the Z-axis direction, the pair of fingers 100 assumes a posture in which the distance between them gradually narrows from the base end toward the tip end, as shown in FIG. 20(b). Therefore, the force that the object Ob receives from the pair of fingers 100 is in a direction that is slightly obliquely upward from the horizontal. In this case, although the gripping force of the object Ob decreases by the amount of the component force generated by the force, the direction of the component force is vertically upward, so the problem of the object Ob dropping is unlikely to occur.

[0130] (Variation) In the second embodiment, tension coil springs are used as the scissors biasing members 84, 96. However, the scissors biasing members 84, 96 are not limited to this, and other elastic members that are less susceptible to plastic deformation, or conventionally known dampers or motors that do not undergo plastic deformation, can also be used. In addition, the various modifications described in the first embodiment can also be applied to the second embodiment. [Industrial Applicability]

[0131] The robot joint device according to the present invention can be applied not only between a robot arm and a robot hand, but also to other positions in a robot with a tracking function, for example, as an arm joint portion connecting adjacent arm links in a robot arm. [Explanation of symbols]

[0132] 1. Robot with tracing function 2. Robotic Arm 3 Joint device 4. Robot Hand 10 Proximity sensor 17 X-axis elastic deformation tolerance mechanism (first axis elastic deformation tolerance mechanism) 18 Y-axis elastic deformation tolerance mechanism (second axis elastic deformation tolerance mechanism) 19 Z-axis elastic deformation tolerance mechanism (third axis elastic deformation tolerance mechanism) 21 Base Frame 22 First Frame 24, 34, 42 Return force acting spring (return force acting part) 23, 33, 41 Stopper part 30,38 Regulatory protrusion 31, 39, 47 Regulatory aspects 32 Second Frame 40 Third Frame Ob Object 70 Robot with tracing function 71 Joint device 72 Robot Hand 73 X-axis elastic deformation tolerance mechanism (first axis elastic deformation tolerance mechanism) 74 Y-axis elastic deformation tolerance mechanism (second axis elastic deformation tolerance mechanism) 75 base frame 76 First Frame 77,89 Stopper part 78,90 Return force acting part 81,93 Regulatory protrusion 82,94 Inner surface (regulation surface) 83, 95 Scissor frame 84, 96 Scissor biasing member 88 Second Frame 100 Fingers 101 Parallel link component

Claims

1. A robot joint device that connects multiple links constituting a robot so that they can move relative to each other, a first axis elastic deformation allowing mechanism that allows elastic deformation about a first axis among three axes that are orthogonal to each other; a second axis elastic deformation allowing mechanism that allows elastic deformation of a second axis different from the first axis independently of the first axis elastic deformation allowing mechanism; A robot joint device comprising:

2. 2. The robot joint device according to claim 1, wherein the first axis elastic deformation allowing mechanism allows elastic deformation in at least one of a translation direction along the first axis and a rotation direction about the first axis, and the second axis elastic deformation allowing mechanism allows elastic deformation in at least one of a translation direction along the second axis and a rotation direction about the second axis.

3. The first axial elastic deformation allowing mechanism is a base frame fixed to the robot; a first frame supported by the base frame to be rotatable about the first axis and / or to be translatable along the first axis; a return force application unit that applies a force to the first frame in a direction opposite to the rotational direction and / or translational direction of the first frame; 2. The robot joint device according to claim 1, further comprising:

4. 4. The robot joint device according to claim 3, wherein the restoring force acting portion is a spring member interposed between the base frame and the first frame.

5. 4. A robot joint device according to claim 3, wherein the first axis elastic deformation allowing mechanism further comprises a stopper portion that restricts rotation and / or translation of the first frame beyond a predetermined range.

6. 6. The robot joint device according to claim 5, wherein the stopper portion has a regulating protrusion protruding from one of the base frame and the first frame, and a regulating surface formed on the other of the base frame and against which the regulating protrusion abuts.

7. The second axial elastic deformation allowing mechanism is a second frame supported by the first frame to be rotatable about the second axis and / or to be translatable along the second axis; a return force application unit that applies a force to the second frame in a direction opposite to the rotational direction and / or translational direction of the second frame; 4. The robot joint device according to claim 3, further comprising:

8. 8. A robot joint device according to claim 7, wherein the second axis elastic deformation allowing mechanism further has a stopper portion that restricts rotation and / or translation of the second frame beyond a predetermined range.

9. a third axis elastic deformation allowing mechanism that allows elastic deformation of a third axis perpendicular to each of the first axis and the second axis, independently of the first axis elastic deformation allowing mechanism and the second axis elastic deformation allowing mechanism; The third axial elastic deformation allowing mechanism is a third frame supported by the second frame to be rotatable about the third axis and / or to be translatable along the third axis; a restoring force application unit that applies a force to the third frame in a direction opposite to the rotational direction and / or translational direction of the third frame; 8. The robot joint device according to claim 7, further comprising:

10. 10. A robot joint device according to claim 1, wherein one of the plurality of links constitutes a base end of a robot hand that manipulates an object, and the other of the plurality of links constitutes a tip end of a robot arm that brings the robot hand closer to the object.

11. A robot with a tracing function that causes a robot hand to perform a predetermined task while tracing the shape of an object, The robot joint device according to claim 10; a proximity sensor for detecting the posture of the robot hand; a storage unit that stores a target posture of the robot hand in advance; a difference calculation unit that calculates a difference between the detected posture of the robot hand and the target posture; a control unit that controls the posture of the robot hand so that the difference becomes small; A robot with a copying function, characterized by comprising:

12. 12. The robot with a copying function according to claim 11, wherein the predetermined task is one or more tasks selected from the group consisting of a task of gripping an object, a task of leaving the gripped object stationary, a task of measuring physical quantities of the gripped object, a task of optimally controlling the position and attitude of the robot based on tilt and position information of the gripped object, a task of approaching an object contained in a container along a wall surface of the object, a task of assembling one gripped part to another part that is the object, and a task of pressing a button that is the object.

13. the first frame is supported by the base frame so as to be rotatable about the first axis; The restoring force acting portion is a pair of scissors frames each supported rotatably about the first axis and provided such that their tip portions move away from each other as the first frame rotates; a scissors biasing member that is provided by connecting the tip ends of the pair of scissors frames to each other and biases the pair of scissors frames so that the tip ends approach each other in a neutral state in which the first frame does not rotate; a scissors regulating member that regulates the rotation of each of the pair of scissors frames so that the tip ends of the pair of scissors frames do not approach each other beyond a predetermined distance; 4. The robot joint device according to claim 3, further comprising:

14. 14. The robot joint device according to claim 13, wherein the scissors biasing member is a tension coil spring.

15. 14. The robot joint device according to claim 13, wherein the first axis elastic deformation allowing mechanism further comprises a stopper portion that restricts rotation of the first frame beyond a predetermined range.

16. 16. The robot joint device according to claim 15, wherein the stopper portion has a regulating protrusion protruding from one of the base frame and the first frame, and a regulating surface formed on the other of the base frame and against which the regulating protrusion abuts.

17. the second frame is supported by the first frame so as to be rotatable about the second axis; The restoring force acting portion is a pair of scissors frames each supported rotatably about the second axis and provided such that their tip portions move away from each other as the second frame rotates; a scissors biasing member that is provided by connecting the tip ends of the pair of scissors frames to each other and biases the pair of scissors frames so that the tip ends approach each other in a neutral state in which the second frame does not rotate; a scissors regulating member that regulates the rotation of each of the pair of scissors frames so that the tip ends of the pair of scissors frames do not approach each other beyond a predetermined distance; 8. The robot joint device according to claim 7, further comprising:

18. A robot with a tracing function that causes a robot hand to perform a predetermined task while tracing the shape of an object, a finger that configures the robot hand and grips an object; a robot arm that brings the robot hand close to an object; a robot joint device according to any one of claims 13 to 17, which connects the robot hand and the robot arm to each other; a parallel link component that constitutes the robot hand and that constitutes a parallel link mechanism together with the fingers and a joint device of the robot; A robot with a copying function, characterized by comprising:

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