JP2009291874A - Joint device, robot arm, and finger unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint device, a robot arm and a finger unit can prevent a speed reducer from being damaged by releasing an external force acting on the speed reducer even when an excessive force exceeding an allowable external torque acts on the speed reducer assembled in the joint device of a robot. <P>SOLUTION: A joint member J includes a harmonic drive H having a wave generator 31 rotated around a predetermined axis P by the output of a motor M assembled in link members L transmitted thereto through a transmission mechanism T, a flexible spline 32 having an inner peripheral section joined to the outer peripheral section of the wave generator 31, and a circular spline 34 having, on the inner peripheral section, a tooth section 38 meshed with a tooth section 37 formed on the outer peripheral section of the flexible spline 32. The flexible spline 32 is connected to one link member L1 through a torque limiting mechanism R, and the circular spline 34 is connected to the other link member L2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a joint device in which a pair of link members are connected via a joint member that rotates around a predetermined axis, a robot arm using the joint device, and a finger unit.

  Industrial grippers (hereinafter also referred to as “hands”) used in production sites often use mechanical grippers that hold objects with an opening and closing mechanism such as a pliers. It consists of a mechanism having three links, such as two links or a three-jaw chuck that move relatively to grip the object.

  Such a mechanical gripper does not require advanced control, and since it opens and closes mechanically, a reliable repetitive motion is guaranteed, but since the gripping operation is realized mechanically, it is determined at the production site. It guarantees secure gripping on objects of known shape aligned in position and orientation, but it is difficult to properly grip complex shaped parts with various curved surfaces such as cast parts and press-formed parts. If the position / posture where the object is placed, or the shape and dimensions of the object are slightly different, such as bulk parts, it is no longer possible to use one mechanical gripper.

  Therefore, at the production site, a visual sensor is introduced to measure the position and orientation of parts by complex shape recognition processing to determine the gripping points that can be gripped by the mechanical gripper, and depending on the shape and size of the target object Therefore, it is necessary to introduce a complicated robot system that requires a great cost such as preparing a plurality of mechanical grippers and replacing the grippers each time according to an object.

  On the other hand, a person can perform complex work skillfully with a hand composed of five fingers having a plurality of joints. If a universal robot hand having a structure and shape similar to that of a human hand and having a motion control function similar to that of a human hand can be realized, the robot can be controlled by a single hand mechanism. This makes it possible to perform complicated and complicated tasks. Moreover, the special work tool developed every time according to the robot is no longer necessary, and the robot can also perform work using general-purpose work tools conventionally used by humans.

  Under such a background, in order to realize a robot hand having a mechanism like a human hand and a skillful work function like a human hand, a plurality of fingers having a plurality of joints imitating a human hand. A universal robot hand composed of

  As such a robot hand, as shown in FIG. 11, Patent Document 1 discloses a robot hand structure capable of moving similar to a human hand, that is, a plurality of fingers having four joints J100, J200, J300, and J400. In a robot hand that is arranged and has a motor that drives each joint, the axes of the first joint J100 and the second joint J200 on the base side of each finger are orthogonal at one point so that the two joints can be driven independently. In addition, there has been proposed a robot hand characterized in that two motors are provided on the palm for one finger.

  In the above-mentioned document, the third joint J300 and the fourth joint are driven by one motor by driving the shaft of the fourth joint J400 through the four-joint link mechanism L that is drivingly connected to the motor M300 for the third joint J300. A configuration in which the joint J400 can be simultaneously rotated in the same direction and a configuration in which a force sensor S100 is provided at the fingertip have been proposed.

  However, the links L300 and L400 connected by the joint drive the link L300 from the motor M300 via the gear type reduction mechanism, and further drive the drive transmission mechanism such as a link and a wire from the reduction mechanism, in this case, a four-link. When adopting a configuration such as driving the link L400 via the mechanism L, accurate finger movement control is difficult due to backlash of the gear caused by the speed reduction mechanism and play due to mechanical play caused by the drive transmission mechanism. In addition, in order to transmit power from the motor to the drive transmission mechanism via the speed reduction mechanism, it is necessary for the drive transmission mechanism to transmit a large amount of torque, which increases the size of the drive transmission mechanism and thus the size of the robot hand. There was a problem of inviting.

  Therefore, the inventors of the present application, as shown in Patent Document 2, effectively remove the mechanical rattle of the drive system, and devise on the mounting of the sensing system such as force sense, so that We have proposed joint devices that can realize subtle motions, robot fingers that can be compactly designed using joint devices, and joint devices that aim to provide universal robot hands.

Specifically, as shown in FIG. 12, a flex spline fixed to one link member L101, and a circular spline in which a thin portion formed to extend in a direction intersecting the rotation axis is fixed to the other link member L202. A first drive mechanism T101 that incorporates a harmonic drive speed reducer H101 comprising a joint member and transmits the output of a motor (actuator) M101 housed in the base end side link member L101 to the base end side wave generator; Harmonic drive deceleration in which the output of the motor M101 is incorporated into the joint member adjacent to the proximal end wave generator via the transmission shaft S101 accommodated in the first transmission mechanism T101 and the link member L202 adjacent to the proximal end side link member L101. Second transmission to the wave generator of machine H202 A joint device having a mechanism T202.
Japanese Patent Laid-Open No. 11-156778 JP 2007-152528 A

  As described above, if a system for driving the link by transmitting the power from the actuator to the joint shaft via the speed reducer as the drive mechanism of the joint device, the power can be increased by the speed reducer. An actuator also has an advantage that a large power necessary for driving the joint link can be obtained.

  As an actuator, an electric motor such as a DC motor is often used for ease of handling. However, since an electric motor generally has high speed rotation and low torque, it is used via a reduction gear with a high reduction ratio in a robot joint mechanism. It will be necessary.

  Since the joint drive mechanism composed of such an actuator and speed reducer is inferior in back drivability (moving the actuator output shaft from the joint axis), most of the external torque acts on the drive link from the environment to the structure of the speed reducer. Will act.

  Therefore, a reduction gear used for a joint device used for a robot arm, a robot finger, or the like needs to have sufficient structural strength against external torque.

  In addition, the robot joint device is required to be designed so that a smaller and lighter reduction gear having a high reduction ratio is compactly arranged in a limited space because of the necessity of speeding up the movement and reducing the weight of the mechanism. .

  However, when trying to obtain a reduction gear having a small and light weight and a high reduction ratio, the tooth shape must be reduced, and it is difficult to obtain sufficient structural strength against the external torque acting on the output shaft. .

  Therefore, when operating the robot arm or the like, there is a problem that it is required to use the robot arm in a limited manner so that the force acting on the joint link mechanism from the environment is within the allowable external torque range of the reduction gear output shaft. It was.

  In view of the above-described problems, an object of the present invention is to release an external force acting on a speed reducer even when an excessive force exceeding an allowable external torque is applied to a speed reducer incorporated in a robot joint device. It is the point which provides the joint apparatus, the robot arm, and the finger unit which can prevent damage of the above.

  In order to achieve the above-mentioned object, a first characteristic configuration of the joint device according to the present invention is a joint member that rotates a pair of link members around a predetermined axis as described in claim 1 of the claims. A wave generator that rotates around the predetermined axis by transmitting an output of a motor assembled to one of the link members to the joint member via a transmission mechanism, and the wave generator. Harmonic drive reduction mechanism comprising: a flexspline having an inner peripheral portion that joins with the outer peripheral portion; and a circular spline in which a tooth portion that meshes with a tooth portion formed on the outer peripheral portion of the flexspline is formed on the inner peripheral portion The flex spline is fixed to one link member via a torque limiting mechanism, and the circular spline is fixed to the other link member. In that it is directly or indirectly fixed to the click member.

  According to the above characteristic configuration, when the output of the motor is transmitted to the wave generator constituting the harmonic drive speed reduction mechanism via the transmission mechanism, it is transmitted to the circular spline via the flex spline, so that it is fixed to the circular spline. The other link member rotates relatively around the rotation axis of the wave generator with respect to the one link member fixed to the flexspline. When an external force greater than the holding torque by the torque limiting mechanism is applied in the opposite direction to the rotational torque applied to the other link member by the motor via the joint member, the torque limiting mechanism causes the joint member to be Since the external torque applied to the harmonic drive speed reduction mechanism is released by rotating in the direction opposite to the rotational torque, the joint device can be prevented from being damaged.

  In the second characteristic configuration, as described in claim 2, in addition to the first characteristic configuration described above, the torque limiting mechanism includes an annular pressure receiving body fixed to one link member, a rolling shaft, A plurality of rollers arranged in the circumferential direction of the pressure receiving body in a posture in which the core is inclined at a predetermined angle with respect to the radial direction of the pressure receiving body, and an annular holding for holding each roller so as to roll freely at a predetermined interval And an annular pressurizing member that is disposed opposite to the pressure receiving body with the roller interposed therebetween, and an annular rotational friction mechanism that is externally fitted to the extension shaft of the flexspline, the extension shaft, and the pressure receiving portion. A fixing mechanism for fixing the body to the body directly or indirectly with a predetermined tightening force via the pressure body is provided.

  According to the above configuration, when the pair of link members are relatively rotated in the axial direction of the extension shaft of the flexspline with a predetermined tightening force by the fixing mechanism, each roller is moved to the pressure receiving body and Roll while in contact with the pressurized body. Since each roller moves along the rotation path of the extension shaft while being restricted by the holding body to roll in a direction inclined by a predetermined angle with respect to the rotation path of the extension shaft, each roller and pressure receiving body A frictional force proportional to the axial tightening force of the extension shaft is generated between the pressure member and the pressure member. At that time, since each roller generates sliding friction while rolling, a stable resistance force is always obtained by dynamic friction without generating static friction. Therefore, the allowable external torque for the pair of link members can be appropriately adjusted by appropriately setting the axial tightening force of the extension shaft by the fixing mechanism.

  In the third characteristic configuration, as described in the third aspect, in addition to the second characteristic configuration described above, the fastening force between the extension shaft and the pressure receiving body by the fixing mechanism is dynamically increased. It is in the point provided with the actuator to adjust.

  According to the configuration described above, the allowable external torque of the torque limiting mechanism can be dynamically adjusted as appropriate according to the environment in which the joint device is used.

  The fourth feature configuration is applied to the other link member via the joint member by the motor, in addition to any one of the first to third feature configurations described above. When an external force greater than the holding torque by the torque limiting mechanism is applied in the direction opposite to the rotational torque, the joint member is configured to rotate in the direction opposite to the rotational torque by the torque limiting mechanism, One of the link members is provided with a stopper mechanism so that the link member is held in a specific posture that is linearly positioned.

  According to the above configuration, when an external force greater than the holding torque by the torque limiting mechanism is applied in the direction opposite to the rotational torque applied to the other link member by the motor via the joint member, the torque limitation is performed. The mechanism rotates the joint member in the direction opposite to the rotational torque to protect the harmonic drive speed reduction mechanism from breakage, and the link member comes into contact with the stopper mechanism and takes a unique posture. Large external force can be supported.

  The characteristic configuration of the robot arm according to the present invention is that, as described in the fifth aspect of the present invention, the joint device having any one of the first to fourth characteristic configurations described above is incorporated.

  According to the above-described configuration, the above-described joint device is incorporated into the joint of the robot arm to protect the harmonic drive speed reducer with a high reduction ratio and rotate to the position of the mechanical stopper when an excessive external force acts on the drive link. Thus, a unique posture capable of supporting a large external force mechanically can be adopted by itself. As a result, it is possible to realize a robot arm that can cope with a mechanical interaction with the outside world over a wide range.

  The characteristic configuration of the finger unit according to the present invention is a finger unit that is used in a universal robot hand and includes a plurality of joint devices, as described in claim 6, and includes any one of the first to fourth aspects described above. The joint device having the characteristic configuration is incorporated.

  According to the above-described configuration, when an excessive force exceeding the holding torque of the torque limiting mechanism is applied to the harmonic drive incorporated in each joint device, the external force that mechanically acts on the harmonic drive is released mechanically. Can be prevented from being damaged. In other words, a joint device, robot arm, and finger unit that are closer to humans can be realized.

  As described above, according to the present invention, even if an excessive force exceeding the allowable external torque is applied to the reduction gear incorporated in the joint device of the robot, the external force acting on the reduction gear is released to break down the reduction gear. It is now possible to provide a joint device, a robot arm, and a finger unit that can prevent the above.

  Embodiments of a joint device, a robot arm, and a finger unit according to the present invention will be described below.

  As shown in FIG. 1, the joint device 1 is fixed to a pair of link members L1, L2, a joint member J that rotates the pair of link members L1, L2 around an axis P, and one link member L1. A motor M with a built-in encoder having a rotation shaft in a direction orthogonal to the axis P and a transmission mechanism T, and the output of the motor M fixed to one end of the link member L1 is transmitted to the link member L1 via the transmission mechanism T. The link member L2 connected to the joint member J is rotated relative to the link member L1 by being transmitted to the joint member J pivotally supported at the end and rotating around the axis P. It is configured. A stopper mechanism 13 is fixed to the other end side of the link member L1 with a screw 14 so that the link member L2 is held in a specific posture that is linearly positioned with respect to the link member L1.

  The transmission mechanism T includes a small-diameter bevel gear G1, a large-diameter bevel gear G2 that meshes with the bevel gear G1, a spur gear G3, and a spur gear G4 that meshes with the spur gear G3. The bevel gear G1 is fitted and connected to the output shaft of the motor M, the bevel gear G2 is fitted and fixed to the rotating shaft of the spur gear G3 with a set screw 15, and the joint member J is connected to the rotating shaft of the spur gear G4.

  The joint member J includes a harmonic drive speed reduction mechanism (hereinafter referred to as “harmonic drive”) H and a torque limiting mechanism R.

  The harmonic drive H includes a wave generator 31 as an input portion configured by an elliptical cam and a bearing fitted on the outer periphery thereof, and a rotating portion in which a tooth portion is formed on the outer periphery of the opening portion by a thin cup-shaped metal elastic body. And a circular spline 34 serving as an output portion in which two teeth are formed at the same pitch as the flexspline 32 on the circumference of the ring-shaped rigid body. Has been. The wave generator 31 is fitted and fixed to the rotating shaft of the spur gear G4 of the transmission mechanism T with a set screw 16, and an extension shaft 33 as a fixing portion is fixed to the cup bottom surface portion of the flexspline 32. The extension shaft 33 is The circular spline 34 is supported via a bearing 35. A casing 36 is fixed to the outer periphery of the circular spline 34, and a link member L2 is connected to the casing 36. Note that when the link member L2 is directly connected to the outer periphery of the circular spline 34, the casing 36 is not necessarily provided.

  As shown in FIG. 2, when the output of the motor M is transmitted to the wave generator 31 via the transmission mechanism T and rotates in the direction indicated by the broken line arrow in the figure, the flexspline 32 is elastically deformed accordingly, and the flexspline As the meshing position of the tooth part 37 formed on the outer peripheral part of 32 and the tooth part 38 formed on the inner peripheral part of the circular spline 34 meshing with the tooth part 37 sequentially moves, the circular with respect to the flexspline 32 is moved. The spline 34 rotates relatively in the direction indicated by the solid arrow in the figure. Since the number of teeth of the tooth portion 37 is two less than the number of teeth of the tooth portion 38, the output from the motor M is thereby decelerated.

  The torque limiting mechanism R includes a rotational friction mechanism 40 that can obtain rotational friction according to a tightening force in the direction of the axis P, and a fixing mechanism 50 that fastens and fixes the rotational friction mechanism 40 with a predetermined tightening force. .

  As shown in FIGS. 3A, 3 </ b> B, and 3 </ b> C, the rotational friction mechanism 40 allows the rolling axis b to roll at a predetermined inclination angle θ with respect to the axis P and the vertical direction a. A plurality of rollers 42 held by the holding body 43 along the rotation path of the pressure receiving body 41 are sandwiched between the opposed surfaces of the pressure receiving body 41 and the pressure body 45 with a predetermined tightening force. The plurality of rollers 42 has a cylindrical shape that extends uniformly in the direction of the rolling axis b, and is arranged to be freely rollable at equal intervals in the circumferential direction of the pressure receiving body 41 by a holding hole 44 formed in a holding body 43 described later. ing. Further, both end surfaces of each roller 42 are formed in a convex spherical shape in order to reduce friction with the holding body 43. The pressure receiving body 41 and the pressure body 45 only need to have a flat contact surface with the roller 42, and the shape is not limited to an annular shape.

  The holding body 43 is formed such that the thickness in the direction of the axis P is smaller than the outer diameter of the roller 42. A plurality of holding holes 44 for holding the rollers 42 are formed in the holding body 43, and the rollers 42 are accommodated in the holding holes 44 so as to be able to roll. Each holding hole 44 is formed such that the rolling axis b of the roller 42 is inclined by a predetermined angle θ with respect to the radial direction a of the pressure receiving body 41 as shown in FIG.

  Therefore, as shown in FIG. 3D, when the pressure receiving body 41 and the pressurizing body 45 are rotated in a state where the pressure receiving body 41 and the pressurizing body 45 are pressed in the direction of the axis P, the roller 42 rotates while contacting the pressure receiving body 41 and the pressurizing body 45. The holder 43 also rotates following this movement. At this time, each roller 42 is restricted by the holding body 43 from rolling in the direction inclined by the angle θ with respect to the rotation trajectory of the pressure receiving body 41 and the pressure body 45, and the pressure receiving body 41 and the pressure body. Therefore, a frictional force proportional to the load in the direction of the axis P is generated between each roller 42, the pressure receiving body 41, and the pressing body 45.

  That is, the pressure receiving body 41 and the pressurizing body 45 rotate relative to each other for the first time by the rotational torque exceeding the above-described frictional force.

  The above-described rotational friction device 40 is externally fitted to the extension shaft 33 of the flexspline 32, and the cylindrical body 55 is externally fitted and fixed to the extension shaft 33 as the fixing mechanism 50, a surrounding male screw is formed, and a spring washer 53 is formed. When the nut 51 is screwed through the pressure receiving body 41, the pressure receiving body 41 and the pressure body 45 are fastened and fixed in the direction of the axis P with a predetermined tightening force. The nut 51 can be fixed to the extension shaft 33 by the set screw 52 so as to have an arbitrary tightening force. Thus, the holding force proportional to the load in the direction of the axis P can be applied to the relative rotational movement of the pressure receiving body 41 and the pressure body 45 by the tightening force of the nut 51, and the set screw By adjusting and fixing the tightening force by 51, the holding torque of the torque limiting mechanism R can be controlled very easily. In addition, when a screw is formed on the outer periphery of the extension shaft 33 and engaged with the nut 51, the cylindrical body 55 is not necessarily provided.

  The fixing mechanism 50 is not limited to a configuration in which the tightening force between the output shaft 33 and the pressure receiving body 41 is fixed by the nut 51, the set screw 52, and the spring washer 53, and the tightening force is dynamically adjusted. An actuator may be provided. As such an actuator, an ultrasonic motor, a piezoelectric element, an air cylinder, or the like can be used.

  When an ultrasonic motor is used, the rotary friction device 40 is externally fitted to the extension shaft 33, the piezoelectric ceramic and the stator constituting the ultrasonic motor are externally fitted, and then meshed with the external screw formed on the extension shaft 33. What is necessary is just to make it the structure which fits the rotor in which the screw | thread was formed. When a flexural wave is generated in the stator using the ultrasonic vibration generated by the piezoelectric ceramic and the rotor is rotated using the traveling wave, the rotor rotates along the extension shaft 33 along with the rotation. Since it moves in the direction of the center P, the tightening force of the rotational friction mechanism 40 in the direction of the axis P can be arbitrarily adjusted.

  When a piezoelectric element is used, the piezoelectric element may be sandwiched between the nut 51 and the rotational friction mechanism 40 instead of the spring washer 53 or via the spring washer 53. By applying a voltage to the piezoelectric element, the thickness of the piezoelectric element itself is displaced, so that the tightening force in the direction of the axis P of the rotary friction mechanism 40 can be arbitrarily adjusted.

  In the case of using an air cylinder, the air cylinder may be sandwiched between the nut 51 and the rotary friction mechanism 40 instead of the spring washer 53 or via the spring washer 53. By adjusting the air pressure injected from the outside into the air cylinder, the tightening force in the direction of the axis P of the rotary friction mechanism 40 can be arbitrarily adjusted.

  With the above-described configuration, the joint device 1 rotates the motor M in one direction so that the output drives the wave generator 31 of the harmonic drive H through the transmission mechanism T, and the flex spline 32 has the torque limiting mechanism R. Since the circular spline 34 rotates around the axis P, the link member L2 rotates relative to the link member L1 (hereinafter referred to as “forward rotation”). Will be. By rotating the motor M in the reverse direction, the link member L2 rotates in the direction opposite to the normal rotation (hereinafter referred to as “negative rotation”).

  Here, when an external force larger than the holding torque by the torque limiting mechanism R is applied in the direction opposite to the rotational torque applied to the link member L2 by the motor M via the joint member J, the pressure receiving body 41 of the rotational friction mechanism 40. The pressure body 45 starts to rotate relatively, and the output shaft 33 rotates in the direction opposite to the rotational torque (hereinafter referred to as “reverse rotation”) with the external force, so that the external force causes the harmonic drive H to rotate. The risk of breakage is avoided.

  At the time of forward rotation, when the link member L2 continues to rotate reversely and comes into contact with the stopper mechanism 13, the link members L1 and L12 are in a unique posture positioned linearly and support external force. At the time of negative rotation, the link member L2 continues to rotate in reverse and contacts the link member L1 to support the external force.

  The joint member J can be provided with an encoder that detects a rotation angle of the link member L2 around the axis P with respect to the link member L1. The rotation angle of the link member L2 can be detected by an encoder provided in the motor M at the time of positive rotation and negative rotation, that is, when rotating with the rotation by the motor M. At the time of reverse rotation with the motor M, the rotation angle of the link member L2 can be detected by the encoder provided in the motor M and the encoder provided in the joint member J. That is, it is possible to detect that an external force larger than the holding torque by the torque limiting mechanism R is applied in the direction opposite to the rotational torque applied to the link member L2, and the link member L2 is rotated in the direction opposite to the rotational torque by the external force. .

  The stopper mechanism 13 is provided with a contact sensor that detects contact with the link member L2, detects that the link member L2 is in a unique posture linearly positioned with the link member L1, and is provided in the motor M. The rotation angle detected by the encoder provided to the encoder and the encoder provided in the joint member J may be reset.

  Next, the structure which used the above-mentioned joint apparatus for the joint of the finger unit of a universal robot hand is demonstrated.

  As shown in FIG. 4A, the universal robot hand U includes a base 60 corresponding to a human palm, a thumb (first finger), an indicating finger (second finger), a middle finger (third finger) of the human hand. ), Five finger units corresponding to the ring finger (fourth finger) and the little finger (fifth finger) (hereinafter also referred to as “finger”) F1, F2, F3, F4, and F5.

  Each finger F is composed of a plurality of link devices L and a plurality of joint devices that are connected via a plurality of joint members J that rotate the link member L around a predetermined axis.

  As shown in FIG. 4B, the finger F2 has a first joint member J21 rotatable around the first axis P21 connected to the other end of the link member L21 having one end connected to the base body 60. One end of the link member L22 is connected to the one joint member J21, and the second joint member J22 that is rotatable around the second axis P22 orthogonal to the first axis P21 is connected to the other end of the link member L22. One end of the link member L23 is connected to the joint member J22, and the other end of the link member L23 is connected to the third joint member J23 that can rotate around the third axis P23 parallel to the second axis P22. One end of the link member L24 is connected to the member J23, and the other end of the link member L24 is connected to the fourth joint member J24 that can rotate around the fourth axis P24 parallel to the third axis P23, and the fourth joint member J24's phosphorus Members L25 is constituted connected. The fingers F3, F4, and F5 have the same configuration.

  By the rotation of the first joint member J21, the fingers F2, F3, F4, and F5 are displaced so that the interval between the fingers F2, F3, F4, and F5 is widened or narrowed, and the object is grasped or released by the rotation of the second joint member J22 to the fourth joint member J24. It is configured to be displaceable.

  As shown in FIG. 4C, the finger F1 is connected to the other end of the link member L11, one end of which is connected to the base 60, and a first joint member J11 that is rotatable around the first axis P11. One end of the link member L12 is connected to the one joint member J11, and the other end of the link member L12 is connected to the second joint member J12 rotatable around the second axis P12 orthogonal to the first axis P11. One end of the link member L13 is connected to the joint member J12, and the other end of the link member L13 is connected to the third joint member J13 that can rotate around the third axis P13 parallel to the first axis P12. One end of the link member L14 is connected to the member J13, and the other end of the link member L14 is connected to the fourth joint member J14 that is rotatable around the fourth axis P14 parallel to the first axis P12. The phosphorus that composes the fingertip at J14 Are components L15 is connected

  By rotating the first joint member J11 and placing the finger body F1 so as to face the finger body F2, the object can be held between the finger body F1 and the finger body F2. Since the fingers F3, F4, F5 are arranged in parallel with the finger F2, the finger F1 is also arranged opposite to the fingers F3, F4, F5, and the finger F1, the fingers F3, F4, F5 are arranged. It is possible to sandwich the object even between. Further, since the axial centers P of the first joint members J of the finger bodies F2, F3, F4, and F5 are parallel to each other, the fingers F2, F3, F4, and F5 can be sandwiched between them.

  Since the fingers F1, F2, F3, F4, and F5 have basically the same structure, the finger F2 will be described below as a representative. As shown in FIGS. 5A and 5B, the output of the motor M21 fixed to the link member L21 is transmitted to the harmonic drive H21 of the joint member J21 via the transmission mechanism T21, and the link member L22 (L22a, 22b). And the output of the motor M22 fixed to the link member L22 is transmitted to the harmonic drive H22 of the joint member J22 via the transmission mechanism T22 to rotate the link member L23 (L23a, 23b). The output of the motor M23 thus transmitted is transmitted to the harmonic drive H23 of the joint member J23 via the transmission mechanism T23 to rotate the link members L24 (L24a, L24b). Since the link members L22a and L22b are fixed to the motor M22, respectively, the link members L22a and L22b are expressed as the link member L22 without being particularly distinguished from each other. The same applies to the link members L23 and L24.

  The output of the motor M23 is transmitted to the harmonic drive H24 of the joint member J24 connected to the link member 24 via the transmission mechanism T23 and the transmission mechanism T24, and is configured to rotate the link member L25 constituting the fingertip.

  Therefore, by rotating the motors M22 and M23 in one direction, the harmonic drives H22, H23, and H24 are rotated through the transmission mechanisms T22, T23, and T24, and the joint members J22, J23, and J24 are axial. The joint members J22, J23, and J24 are pivoted in the gripping direction around the P22, P23, and P24, and the motors M22, M2, and M23 are rotationally driven in the opposite directions, so that each of the joint members J22, J23, and J24 has an axis P22, The finger unit F2 is driven to swing in the opening direction around P23 and P24.

  Next, an example of the gripping operation of the finger unit F2 will be described in detail. As shown in FIG. 6A, when the finger unit F2 is opposed to the object to be grasped 90 and the motors M22 and M23 are rotated in one direction, the joint members J22, J23, and J24 are rotationally driven in the grasping direction. When the gripping object 90 comes into contact with the link member L23 connected to the proximal-side joint member J22, a reaction force from the gripping object 90 is received, and when the strength exceeds the holding torque, the torque limiting mechanism R22 is operated by the motor. The rotational torque generated by M22 is not transmitted to the harmonic drive H22. That is, the link member L23 does not rotate with respect to the link member L21. At this time, the link member L23 continues to contact the object with a constant contact force by the rotational driving force of the motor M22. The same operation is repeated with respect to the joint members J23 and J24 and the link members L24 and L25, so that the object can be supported by a plurality of points. The state at this time is shown in FIG.

  When the motors M22, M23 are rotated in the reverse direction from the state shown in FIG. 6B, the joint members J22, J23, J24 are rotationally driven in the direction to open the grasped object 90, and the link member L is connected to each joint device. The finger unit F2 is in a unique posture by rotating until it comes into contact with the stopper mechanism. The state at this time is shown in FIG.

  In other words, after the gripping operation described above that is performed by rotating the motors M22 and M23 in the forward direction, the joint members J22, J23, and J24 that rotate in the reverse direction are rotated by rotating the motors M22 and M23 in the reverse direction. In conjunction with this, the link members L23, L24, and L25 are rotationally driven in the reverse direction, and the link members L23, L24, and L25 contacting the object are separated from the grasped object 90. Thereafter, since the rotation of the link members L23, L24, L25 is blocked at a predetermined position by the stopper mechanism, the torque limiting mechanism R is operated, and the outputs of the motors M22, M23 are not transmitted to the link member L, and a constant initial value is obtained. It will be possible to reliably return to the posture.

  Note that the holding torque of the torque limiting mechanism R of each joint member J may be set to the same value, or set to individual strengths according to the environment in which the finger unit F and the universal robot hand U are used. May be.

  Next, an example of the case where there is an external force 91 due to an obstacle or the like during the gripping operation by the finger unit F2 will be described.

  As shown in FIG. 6A, when the finger unit F2 is opposed to the object to be grasped 90 and the motors M22 and M23 are rotated in one direction, the joint members J22, J23, and J24 are rotationally driven in the grasping direction. At this time, as shown in FIG. 7A, when there is an obstacle or the like in the vicinity of the grasped object 90 and an external force 91 greater than the holding torque of the torque limiting mechanism R24 acts on the link member L24, the torque limiting mechanism R24 is The rotational torque of the motor M23 is not transmitted to the link member L25. The joint member J23 is rotated by the external force in the direction opposite to the rotational torque by the motor M23, and the link member L24 is rotated in the reverse direction until it comes into contact with the stopper mechanism of the link member L23 as shown in FIG. In this way, the harmonic drive H23 of the joint member J23 can avoid the possibility of damage.

  Furthermore, by providing a force sensor at the joint side end of the link member of the finger unit, it is possible to detect distortion applied to the finger. As the force sensor, any strain detecting element such as a strain gauge type pressure sensor or a piezoelectric element can be used.

  Moreover, it can detect that the finger unit contacted the holding | grip target object by providing a tactile sensor in the center part of the link member of a finger unit.

  As described above, the force sensor and the tactile sensor are provided on the link member of the finger unit, so that the posture control and pressure control of the finger can be performed regardless of the shape of the sandwiched object. The configuration can be appropriately configured as described in JP-A-2006-198748.

  The structure of the above-described finger unit and universal robot hand is only an explanation of the basic elements, and when actually designed, various changes are allowed within the range where the effects of the present invention are exhibited. Is. For example, it is possible to cover the finger unit with an elastic resin cover so that the object to be grasped can be protected from impact.

  Therefore, according to the universal robot hand U provided with the above-described finger unit F, even if the shape or size of the object slightly changes, the position / Even if the postures are different from each other, the gripping operation can be appropriately performed. Furthermore, based on the information from the force sensor and the tactile sensor provided in the finger unit F, the actuator can dynamically adjust the tightening force of the joint member J so as to flexibly respond to the object to be grasped. be able to. In addition, when an external force greater than the holding torque by the torque limiting mechanism is applied by an obstacle or the like while the finger unit is operating such as gripping, the pressure receiving body and the pressure body of the rotational friction mechanism start to rotate relatively, Since the output shaft rotates in the direction opposite to the rotational torque in accordance with the external force, the possibility that the external force damages the harmonic drive H is avoided, the link member comes into contact with the stopper mechanism, and the pair of link members have a unique posture. In such a state, a larger external force can be supported.

  The joint device described above can be used not only for the finger unit of a universal robot hand but also for the joint of a robot arm. In this case as well, when the joint device rotates the link member, if an external force greater than the holding torque by the torque limiting mechanism provided in the joint device is applied, the pressure receiving body and the pressure body of the rotational friction mechanism are relative to each other. Since the output shaft rotates in the direction opposite to the rotational torque with the external force, the possibility that the external force damages the harmonic drive speed reduction mechanism is avoided, and the link member comes into contact with the stopper mechanism, and the pair of link members In a state where is in a peculiar posture, an external force larger than the holding torque by the harmonic drive can be supported.

  As described above, the finger unit and the universal robot hand U do not require a high degree of control, and since a reliable repetitive operation is guaranteed to mechanically open and close, and a gripping operation is realized mechanically, cast parts and presses It is possible to properly grip complex shaped parts with various curved surfaces such as molded parts, and the position and orientation of the gripping object such as bulk parts, or the shape and dimensions of the gripping object Even if it is slightly different, gripping operation can be performed, and if an excessive force exceeding the holding torque of the torque limiting mechanism is applied to the harmonic drive incorporated in each joint device, the external force that mechanically acts on the harmonic drive Can be opened to prevent damage to the harmonic drive. That is, it is possible to realize a joint device, a robot arm, and a finger unit that are closer to humans.

  Hereinafter, another embodiment of the joint device, the robot arm, and the finger unit according to the present invention will be described.

  In the above-described embodiment, the stopper mechanism 13 is fixed to the other end side of the link member L1 by the screw 14 so that the link member L2 is held in a specific posture that is linearly positioned with respect to the link member L1. Although the configuration has been described, the stopper mechanism is not limited to this, and a plate-like body as a stopper mechanism is arranged to extend from the upper end portion of the link member L1 toward the link member L2, and the link member L2 and the stopper mechanism come into contact with each other. Thus, the link member L2 may be configured to prevent rotation in the reverse direction at a predetermined position, and the specific configuration thereof can be changed as appropriate.

  In the above-described embodiment, the rotational friction mechanism 40 has been described in which the rolling axis b is inclined at a predetermined angle θ with respect to the vertical direction a of the axis P. However, the rolling axis b is perpendicular to the axis P. The angle formed with the direction a is not limited to a specific value, and is set as appropriate. The specific configuration can be appropriately configured as described in JP-A-08-074843.

  In the above-described embodiment, the torque limiting mechanism using the rotational friction mechanism has been described. However, the torque limiting mechanism is not limited to this, and a known torque limiter may be used.

  In the above-described embodiment, the motor is not explicitly described as the actuator, but it goes without saying that the actuator can be used as appropriate, such as an air motor, an electromagnetic motor, a hydraulic motor, an electromagnetic rotary solenoid, a direct acting actuator such as a power cylinder. Absent.

  In the above-described embodiment, the configuration in which the output of the motor is transmitted to the joint member by the bevel gear and the spur gear as the transmission mechanism is described, but this is not limited to that, and the pulley, the timing belt, the gear train, and the control wire In addition, a known transmission mechanism such as an infinite rotation mechanism such as a belt or a chain can be employed.

  For example, as shown in FIG. 8A, a transmission mechanism that transmits the output of the motor M to the harmonic drive H through a small-diameter bevel gear G10 and a large-diameter bevel gear G20 meshing with the bevel gear G10, FIG. As shown, the small-diameter bevel gear G40 meshes with the small-diameter bevel gear G30, and the bevel gear G40 is a transmission mechanism that transmits the output of the motor M to the harmonic drive H via the spur gear W10, the idle spur gear W20, and the spur gear W30. There may be. By adopting the above-described configuration, the diameter of the joint member J can be reduced.

  Similarly, as shown in FIG. 8C, the joint member J can be made smaller also when the timing pulley / belt B is used instead of the spur gears W10, W30 and the idle spur gear W20.

  In any case, since the joint member J can be made small, the joint device 1 can be made small.

  In the above-described embodiment, the configuration including the harmonic drive reduction mechanism with a high reduction ratio as the reduction mechanism incorporated in the joint portion of the joint device has been described. However, the reduction mechanism is not limited to the harmonic drive reduction mechanism, and may be appropriately selected. By changing the configuration of the joint drive mechanism, it is possible to provide a reduction mechanism such as a planetary gear reduction mechanism, a cyclo reduction gear (registered trademark, hereinafter the same), or the like.

  In other words, the joint device according to the present invention is a joint device in which a pair of link members are connected via a joint member that rotates about a predetermined axis, and the output of a motor assembled to the joint member on one link member. Meshes with an input portion that is transmitted through a transmission mechanism and rotates about the predetermined axis, a fixed portion having a rotating portion that joins with an outer peripheral portion of the input portion, and a tooth portion formed on the rotating portion. A reduction mechanism comprising a tooth portion and an output portion formed on an inner peripheral portion, the fixing portion being fixed to one link member via a torque limiting mechanism, and the output portion being directly connected to the other link member Alternatively, it may be configured to be indirectly fixed.

  Hereinafter, as another embodiment of the joint device, a configuration of the joint device 2 using the planetary gear speed reduction mechanism as the speed reduction mechanism will be described. In addition, about the same structure as the joint apparatus 1 shown in FIG.1 (b), the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 9A, the planetary gear speed reduction mechanism Y includes a sun gear 70 as an input unit, a plurality of planetary gears 71 as a rotating unit meshing with the sun gear 70, and a fixed holding the planetary gear 71. A planetary carrier 72 as a part and an outer ring gear 73 as an output part. As shown in FIG. 9B, the sun gear 70 is fitted and fixed to the rotating shaft of the spur gear G4 of the transmission mechanism T with a set screw 16. Then, the extension shaft 74 is fixed to the planet carrier 72, and the extension shaft 74 is fixed to the link member L1 via the torque limiting mechanism R. A casing 36 is fixed to the outer periphery of the outer ring gear 73, and a link member L2 is connected to the casing 36 to form a joint member J2. When the link member L2 is directly connected to the outer periphery of the outer ring gear 73, the casing 36 is not necessarily provided, and the configuration of the transmission mechanism T is appropriately selected as shown in FIG.

  When the output of the motor M is transmitted to the sun gear 70 via the transmission mechanism T, the rotation shaft of the planetary gear 71 is supported by the planet carrier 72, so that the rotation of the sun gear 70 is transmitted to the planetary gear 71. Then, the rotation of the planetary gear 71 is transmitted to the outer ring gear 73, and the link member L2 rotates relative to the link member L1.

  Here, when an external force greater than the holding torque by the torque limiting mechanism R is applied in the direction opposite to the rotational torque applied to the link member L2 via the joint member J2 by the motor M, the pressure receiving body 41 of the torque limiting mechanism The pressure body 45 starts to rotate relatively, and the output shaft 74 rotates in the direction opposite to the rotational torque along with the external force, thereby avoiding the possibility that the external force damages the planetary gear reduction mechanism Y.

  As shown in FIG. 9 (c), the pressure receiving body 41 may be fixed to the planet carrier 73, and the torque receiving mechanism 41 may be configured by providing the pressure receiving body 41 with an output shaft 74. The specific configuration is designed appropriately. Is done.

  As still another embodiment, a configuration of a joint device 3 using a cyclo reducer as a speed reduction mechanism that constitutes a joint member will be described. In addition, about the same structure as the joint apparatus 1 shown in FIG.1 (b), the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 10A, the cyclo reducer C includes an eccentric cam 80 as an input portion, a curved plate 81 as a rotating portion in which an opening through which the eccentric cam 80 is inserted is formed in the center portion, and a fixed portion. A plurality of inner pins 82 as output pins and a plurality of outer pins 83 as output portions are provided. The curved plate 81 is formed with the same number of inner pin openings 85 as the inner pins meshing with the inner pins 82, and the outer periphery thereof is epitaxial. A trochoidal curved surface is formed and is configured to mesh with the outer pin 83.

  The eccentric cam 80 is fitted and fixed to the rotation shaft of the spur gear G4 of the transmission mechanism T, and the eccentric cam 80 is inserted into the central opening of the curved plate 81. The plurality of inner pins 82 are fixed to the inner pin holding member 84 at predetermined intervals, and each is inserted into the inner pin opening 85 of the curved plate 81. The output shaft 86 is fixed to the inner pin holding member 84, and is fixed to the link member L1 via the torque limiting mechanism R. Further, the casing 36 is fixed to the outer pin holding member 87 that holds the outer pin 83 along the epitrochoid curved surface formed on the outer periphery of the curved plate 81, and the link member L2 is connected to the casing 36. When the link member L2 is directly connected to the outer periphery of the outer pin holding member 87, the casing 36 is not necessarily provided, and the configuration of the transmission mechanism T is appropriately selected as shown in FIG.

  When the output of the motor M is transmitted to the eccentric cam 80 via the transmission mechanism T, the curved body 81 moves eccentrically with the eccentric rotation of the eccentric cam 80, and the epitrochoid curved surface sequentially engages with the outer pin 83 to link member. L2 is rotated relative to the link member L1. At this time, since the inner pin 82 and the inner pin holding member 84 are fixed to the link member L1 via the torque limiting mechanism R, they do not rotate.

  Here, when an external force larger than the holding torque by the torque limiting mechanism R is applied in the direction opposite to the rotational torque applied to the link member L2 by the motor M via the joint member J3, the pressure receiving body 41 of the torque limiting mechanism R. Therefore, the pressure body 45 starts to rotate relatively, and the output shaft 86 rotates in the direction opposite to the rotational torque in accordance with the external force, and the possibility that the external force damages the cyclo reducer C is avoided.

  As shown in FIG. 10 (c), the pressure receiving body 45 may be fixed to the inner pin holding member 84, and the output shaft 86 may be provided on the pressure receiving body 45 to constitute a torque limiting mechanism. It is selected appropriately.

  In the above-described embodiment, the configuration in which one finger unit is configured by three joint devices has been described. However, the number of joint devices configuring the finger unit is not particularly limited, and the finger units are configured by one joint device. It may be configured. Furthermore, the number of finger units constituting the universal robot hand and the number of joint devices constituting the robot arm are not particularly limited.

  The specific structure of the joint device described in the above-described embodiment is merely an embodiment, and the scope of the present invention is not limited thereby, and the configuration may be changed as appropriate within the scope of the same effects. Is possible.

(A) is a front view of the joint device according to the present invention, (b) is a side sectional view of the joint device. Explanatory diagram of rotation operation of harmonic drive according to the present invention It is explanatory drawing of a rotational friction mechanism as a torque limitation mechanism, (a) is a disassembled perspective view, (b) is a principal part explanatory drawing, (c) is explanatory drawing of the arrangement | positioning attitude | position of a roller group, (d) is action explanatory drawing. (A) is a schematic diagram of a universal robot hand according to the present invention, (b) is a schematic explanatory diagram of a finger unit corresponding to an index finger (second finger), and (c) is a finger unit corresponding to a thumb (first finger). Schematic explanatory diagram (A) is a plan view of the finger unit according to the present invention, (b) is a front view thereof. It is operation | movement explanatory drawing of the finger unit by this invention, (a) is explanatory drawing of an initial position, (b) is explanatory drawing of a holding | grip attitude | position. FIG. 2 is an operation explanatory view of a finger unit according to the present invention, where (a) is an explanatory view showing that an external force has been applied during a gripping operation, and (b) is an explanatory view showing that a unique posture is caused by the external force. (A) is explanatory drawing of another embodiment, (b) is explanatory drawing of another embodiment, (c) is explanatory drawing of another embodiment. It is explanatory drawing of another embodiment, (a) is explanatory drawing of a planetary gear reduction mechanism, (b) is sectional drawing of a joint apparatus, (c) is the schematic of a joint apparatus. It is explanatory drawing of another embodiment, (a) is explanatory drawing of a cyclo reducer, (b) is sectional drawing of a joint apparatus, (c) is the schematic of a joint apparatus. Configuration diagram of a robot hand according to the prior art Configuration diagram of a robot hand according to the prior art

Explanation of symbols

1: Joint device 2: Joint device 3: Joint device 13: Stopper mechanism 14: Screw 15: Set screw 16: Set screw 31: Wave generator 32: Flex spline 33: Extension shaft 34: Circular spline 35: Bearing 36: Casing 37: Tooth part 38: Tooth part 40: Rotary friction mechanism 41: Pressure receiving body 43: Holding body 42: Roller 45: Pressurizing body 44: Holding hole 50: Fixing mechanism 51: Nut 52: Set screw 53: Spring washer 60: Base 70: Sun gear 71: Planetary gear 72: Planetary carrier 7
73: Outer ring gear 74: Extension shaft 80: Eccentric cam 81: Curved plate 82: Inner pin 83: Outer pin 84: Inner pin holding member 85: Inner pin opening 86: Output shaft 87: Outer pin holding member 90: Holding Object 91: External force B: Timing pulley / belt C: Cyclo reducer F1: Mother finger (first finger)
F2: Index finger (second finger)
F3: Middle finger (third finger)
F4: Ring finger (fourth finger)
F5: Little finger (fifth finger)
G1: Bevel gear G2: Bevel gear G3: Spur gear G4: Spur gear G10: Bevel gear G20: Bevel gear G30: Bevel gear G40: Bevel gear H: Harmonic drive H21: Harmonic drive H22: Harmonic drive H24: Harmonic drive J: Joint member J2: Joint member J3: Joint member J11: First joint member J12: Second joint member J13: Third joint member J14: Fourth joint member J21: First joint member J22: Second joint member J23: Third joint member J24: Fourth Joint member L1: Link member L2: Link member L11: Link member L12: Link member L13: Link member L14: Link member L15: Link member L21: Link member L22 (L22a, 22b): Link member L23 (L23a, 23b): Link member L24 (L24 , L24b): link member L25: link member P: shaft center P11: first shaft center P12: second shaft center P13: third shaft center P14: fourth shaft center P21: first shaft center P22: second shaft center P23: Third axis P24: Fourth axis R: Torque limiting mechanism M: Motor M21: Motor M22: Motor M23: Motor T: Transmission mechanism T21: Transmission mechanism T22: Transmission mechanism T23: Transmission mechanism T24: Transmission mechanism U : Universal robot hand W10: Spur gear W20: Idle spur gear W30: Spur gear Y: Planetary gear reduction mechanism a: Radial direction b: Rolling axis θ: Angle

Claims (6)

A joint device in which a pair of link members are connected via a joint member that rotates around a predetermined axis,
The joint member includes a wave generator in which an output of a motor assembled to one of the link members is transmitted via a transmission mechanism and rotates around the predetermined axis, and an inner peripheral portion joined to an outer peripheral portion of the wave generator. And a harmonic drive (registered trademark, hereinafter the same) reduction mechanism comprising a flexspline and a circular spline having a tooth portion meshing with a tooth portion formed on an outer peripheral portion of the flexspline on the inner peripheral portion, A joint device in which a flexspline is fixed to one link member via a torque limiting mechanism, and the circular spline is fixed directly or indirectly to the other link member.   The torque limiting mechanism includes a ring-shaped pressure receiving body fixed to one link member and a circumferential direction of the pressure receiving body in a posture in which a rolling axis is inclined at a predetermined angle with respect to a radial direction of the pressure receiving body. A plurality of rollers arranged in a row, an annular holding body that holds each roller so as to roll freely at a predetermined interval, and an annular pressure body that is disposed so as to face the pressure receiving body with the roller interposed therebetween. An annular rotational friction mechanism externally fitted to the extension shaft of the spline, and fixing for fixing the extension shaft and the pressure receiving body directly or indirectly with a predetermined tightening force via the pressure body. The joint device according to claim 1, further comprising a mechanism.   The joint device according to claim 2, further comprising an actuator that dynamically adjusts a tightening force between the extension shaft and the pressure receiving body by the fixing mechanism.   When an external force greater than the holding torque by the torque limiting mechanism is applied in the opposite direction to the rotational torque applied to the other link member by the motor via the joint member, the torque limiting mechanism causes the joint member to be 4. A stopper mechanism is provided on one of the link members so that the link member is configured to rotate in a direction opposite to the rotational torque, and the pair of link members are held in a unique posture that is linearly positioned. The joint device according to any one of the above.   A robot arm incorporating the joint device according to claim 1.   A finger unit that is used in a universal robot hand and includes a plurality of joint devices, wherein the joint device according to any one of claims 1 to 4 is incorporated.