JP2006198748A - Joint device and mechanical universal hand using joint device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive joint device which completely dispenses with software for controlling the same, and can suitably grip an object which is located in a different location or in a different position, or an object different in shape and dimension depending only on mechanical operation by a mechanical gripper etc. , and to provide a mechanical universal hand using the joint device. <P>SOLUTION: A first joint device 3a is formed of a grip frame 30, shafts 33, 34 rotatably pivoted on the grip frame 30, a link plate 38 connected to the shafts via a torque control mechanism 36, and a driving mechanism 31 for driving the shafts for rotation. Then a finger unit 2 is formed by linking the grip frame 30 of a second joint device 3b to a front end of the link plate 38, and providing a drive link mechanism 39 for driving and linking the shafts 33 of the respective first and second joint device 3a, 3b together. Further the finger units 2 thus formed are connected together at their proximal ends to constitute the mechanical universal hand. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mechanical universal hand, a joint device suitable for the mechanical universal hand, 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.

In order to solve such problems, 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 joints having a plurality of joints imitating a human hand Universal robot hands composed of fingers have been researched and developed.
Japanese Patent No. 3174848 Edited by Ichiro Kato, “Illustrated Mechanical Hand” Industrial Research Society, 1979, p. 127 Shigeo Hirose “Interference Drive of Multi-Freedom Robot”, Journal of the Robotics Society of Japan, Vol. 7, no. 2, p. 128-135

  The robot hand imitating the human hand described above is still under development, and the problem of mechanical design, how to incorporate a complex joint drive mechanism in a limited hand shape, and how to control many joints These control software problems have not yet been sufficiently solved, and all of them are extremely complicated and expensive, so that a universal robot hand that can be put to practical use at a production site has not been realized.

  In view of the above-described problems, the present invention appropriately controls objects having different positions / postures and shapes / dimensions of a gripping object only by a mechanical operation such as a mechanical gripper without requiring any software control. An inexpensive joint device that can be gripped and a mechanical universal hand using the joint device are provided.

  In order to achieve the above-mentioned object, the first characteristic configuration of the joint device according to the present invention is, as described in claim 1 of the claims, a gripping frame and a pivotally supported by the gripping frame. A shaft, a link plate connected to the shaft via a torque limiting mechanism, and a drive mechanism for rotationally driving the shaft, so that another gripping frame can be connected to the tip of the link plate. There is in point.

  According to the above-described characteristic configuration, the shaft that is rotationally driven by the drive mechanism and the link plate that is connected via the torque limiting mechanism rotate integrally around the rotation axis of the shaft, and are connected to the tip of the link plate. Other connected gripping frames also rotate together. When the other gripping frame or link plate comes into contact with the gripping object, for example, the reaction force torque acts on the torque limiting mechanism due to the reaction force from the object, and when the set value is exceeded, the link plate and the shaft slip, Other gripping frames or link plates continue to contact the object with a constant contact force. If the rotation direction by the drive mechanism is reversed in this state, the other gripping frame or link plate is separated from the object. In other words, even if there is no complicated software control algorithm, it is possible to construct a joint that can apply a stable pressing force to an object by appropriately setting a set value for the reaction torque by the torque limiting mechanism. It is.

  According to the second characteristic configuration, as described in claim 2, in addition to the first characteristic configuration described above, the torque limiting mechanism is configured such that the rolling shaft has a predetermined inclination angle with respect to the radial direction of the shaft. It is composed of a rotational friction mechanism that holds a roller group held by a holding body along a rotation orbit of the shaft with a predetermined tightening force between opposed surfaces of the shaft and the link plate. In the point.

  According to the above configuration, when the shaft is rotated with an axial load applied, each roller rolls while contacting the shaft and the link plate. At that time, each roller moves along the rotation path of the shaft while being restricted by the holding body so as to roll in a direction inclined by a predetermined angle with respect to the rotation path of the shaft. A friction force proportional to the axial load is generated between the plate and the plate. 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, by appropriately setting the axial load, it is possible to construct a joint that can give a very stable pressing force to the object.

  According to the first characteristic configuration of the finger unit of the present invention, as described in the third aspect, the joint device according to the first or second characteristic configuration described above is connected in a plurality of stages, and the drive is connected to the shaft of each joint device. A drive transmission mechanism that sequentially transmits the rotational driving force from the mechanism is provided.

  According to the above configuration, the same joint device is connected to the tip of each link plate, and the finger unit is configured so that the shaft of each joint device can be transmitted through the drive transmission mechanism. The rotational driving force can be transmitted to the shaft of the joint device on the distal end side. Therefore, the grip frame of the second joint device connected to the link plate of the first joint device on the proximal end side comes into contact with the target object, and the torque limiting mechanism is activated by the reaction force from the target object to link. When the plate and the shaft slip, the gripping frame of the second joint device keeps contacting the object with a constant contact force by the rotational driving force of the first joint device, and the shaft provided on the gripping frame The grip frame of the third joint device, which rotates in the same way via the drive connection mechanism and is connected to the link plate of the second joint device, contacts the object. When the torque limiting mechanism of the second joint device is actuated by the reaction force from the object and the link plate and the shaft slip, the gripping frame of the third joint device is moved by the rotational driving force of the second joint device. With a constant contact force. By repeating such an operation, the object is supported by a plurality of points.

  As described in the copper claim 4, the second characteristic configuration includes, in addition to the finger unit according to the first characteristic configuration described above, another joint connected to the grip frame of the joint device and the link plate of the joint device. A stopper mechanism for preventing the device from rotating in the reverse direction at a predetermined position is provided.

  According to the above-described characteristic configuration, by reversing the rotation direction of the actuator, the link plate is driven to rotate in the reverse direction in conjunction with the shaft rotating in the reverse direction, and each grip frame in contact with the object is Separate from the object. After that, the stopper mechanism prevents the other joint devices from rotating in the reverse direction at a predetermined position, so that in the opening operation after the gripping operation, the predetermined position is surely returned to a certain initial posture. Will be able to.

  The characteristic configuration of the mechanical universal hand according to the present invention includes the joint device according to the first or second characteristic configuration described above or a plurality of the finger units described above, and grips the object. The point is that they are arranged opposite to each other.

  According to the above-described configuration, a plurality of points can be obtained by a plurality of joint devices or finger units arranged to face an object, without recognizing the specific shape of an object of various shapes. Since it is supported by contact with a stable pressing force, it can be securely gripped. In this case, since it is not necessary to control the driving of each joint by a complicated control algorithm, a flexible mechanical universal hand can be configured at a very low cost.

  As described above, according to the present invention, it is not necessary to control the software at all, and only the mechanical operation such as the mechanical gripper is used to appropriately detect the object with different position / posture and shape / size. An inexpensive joint device that can be gripped and a mechanical universal hand using the joint device can be provided.

  Embodiments of a joint device and a finger unit and a mechanical universal hand using the joint device according to the present invention will be described below. As shown in FIGS. 1 and 5, the finger unit 2 includes a first joint device 3a disposed on the proximal end side, and a second joint device 3b coupled to the distal end side of the link plate 38a of the first joint device 3a. The third joint device 3c is connected to the distal end side of the link plate 38b of the second joint device 3b, and the distal end grip portion 4 is connected to the distal end side of the link plate 38c of the third joint device 3c.

  As shown in FIG. 2, the first joint device 3 (3a) is supported by a gripping frame 30 composed of side plates 300 and 301 and a base plate 302, and rotatably supported by the gripping frame 30 via a bearing mechanism 30a. A rotary shaft 32, a pair of shafts 33, 34 fitted into the rotary shaft 32, a link plate 38a sandwiched between the shafts 33, 34 via a torque limiting mechanism 36, and the shafts 33, 34. And a drive transmission mechanism 39 that transmits the driving force of the driving mechanism 31 to the joint devices 3b and 3c in the subsequent stage.

  The drive mechanism 31 rotates the shaft 33 with power from an output shaft 52 of an air motor 51 as an actuator mounted on a motor bracket 50 frame-connected to the base end side of the first joint device 3 (3a). The mechanism comprises a second bevel gear 31 that rotates in mesh with a first bevel gear 53 fitted and fixed to the output shaft 52.

  The drive transmission mechanism 39 is constituted by a pulley 39a and a timing belt 39b that are attached so that the second bevel gear 31, the shaft 33, and the rotating shaft 32a rotate integrally, and are fixed to the rotating shaft 32.

  As shown in FIGS. 4A, 4B, and 4C, the torque limiting mechanism 36 is configured such that the rolling axis b can roll at a predetermined inclination angle α with respect to the radial direction of the shaft 33, and A group of rollers 36b held by a holding body 36a along the rotation path of the shaft 33 is composed of a rotational friction mechanism that is sandwiched between opposing surfaces of the shaft 33 and the link plate 38 with a predetermined tightening force. Yes. These are the minimum members constituting the rotational friction mechanism, and the shaft 33, the link plate 38 and the holding body 36a are actually assembled to a housing or the like (not shown) so as to maintain a coaxial state.

  More specifically, the shaft 33 is formed in an annular shape, and the surface facing the link plate 38 is formed on a plane. Each roller 36 b has a cylindrical shape extending uniformly in the axial direction, and is arranged at equal intervals in the circumferential direction of the shaft 33. Further, both end surfaces of each roller 36b are formed in a convex spherical shape in order to reduce friction with the holding body 36a. The link plate 38 is also formed with an annular flat surface facing the shaft 33.

  The holding body 36a is also formed in an annular shape, and its axial thickness is smaller than the outer diameter of the roller 36b. The holding body 36a is provided with a number of holes 36c for holding the rollers 36b, and the rollers 36b are rotatably accommodated in the holes 36c. Each hole 36c is formed such that the rolling shaft b of each roller 36b is inclined by a predetermined angle α with respect to the radial direction a of the shaft 33, as shown in FIG.

  Therefore, as shown in FIG. 4 (d), when the shaft 33 is rotated with an axial load applied, each roller 36b rolls while contacting the shaft 33 and the link plate 38. Following this, the holding body 36a also rotates. At that time, each roller 36b moves along the rotation path of the shaft 33 while being restricted by the holding body 36a from rolling in a direction inclined by an angle α with respect to the rotation path of the shaft 33. Therefore, a frictional force proportional to the axial load is generated between each roller 36b and the shaft 33 and link plate 38.

  At that time, since each roller 36b generates sliding friction while rolling, a stable resistance force is always obtained by dynamic friction without generating static friction, and even if static friction is generated at the initial stage, the roller 36b is rotated. It moves to dynamic friction instantly by movement. As described above, according to the above-described rotational friction device, an arbitrary resistance force proportional to the axial load can be applied to the rotational motion of the shaft 33 by the tightening force of the tightening bolt 37 shown in FIG. By adjusting the tightening force, the resistance force of the shaft 33 can be controlled very easily. At that time, since the sliding friction is accompanied by rolling of each roller 36b, a stable resistance force can always be obtained without generating a static friction causing stick-slip.

  As shown in FIGS. 1 and 3, the second joint device 3 b and the third joint device 3 c are similar to the first joint device described above, and the holding frame 30 including the side plates 300 and 301 and the base plate 302, A rotary shaft 32b, 32c rotatably supported by the grip frame 30 via a bearing mechanism 30a, a pair of shafts 33, 34 fitted into the rotary shafts 32b, 32c, and a torque between the shafts 33, 34. Link plates 38b and 38c sandwiched via a limiting mechanism 36 and a drive mechanism 31 that rotationally drives the shafts 33 and 34 are configured. The second joint device 3b is driven by the drive mechanism 31. A drive transmission mechanism 39 that transmits force to the joint device 3c in the subsequent stage is provided. The second joint device 3b and the drive mechanism 31 of the second joint device 3c are constituted by a pulley 39c that is driven via a drive connection mechanism 39 of the joint device on the proximal end side.

  The distal ends of the link plates 38a, 38b, and 38c are bolted to the base plate 302 of the second joint mechanism 3b, the base plate 302 of the third joint mechanism, and the base plate 402 of the distal end grip portion 4, respectively. Therefore, when the first joint device 3a rotates around the rotation shaft 32a, the second joint device 3b rotates around the rotation shaft 32 integrally with the link plate 38a, and the second joint device 3b rotates around the rotation shaft 32b. When rotated, the third joint device 3c rotates around the rotation shaft 32b together with the link plate 38b.

  According to the above-described finger unit 2, similar joint devices 3 b, 3 c can be connected to the tips of the link plates 38 a, 38 b, and the shafts of the joint devices 3 a, 3 b, 3 c can be transmitted through the drive transmission mechanism 39. Thus, the rotational driving force applied to the drive mechanism 31 of the joint device 3a can be transmitted to the shafts 33 and 34 of the joint devices 3b and 3c on the distal end side.

  The gripping operation of the finger unit 2 adopting such a configuration will be described in detail. When the finger unit 2 is opposed to the object to be grasped and the air motor 51 is driven in the forward rotation direction, each joint device 3a, 3b, 3c is rotationally driven in the grasping direction. When the grip frame 30 of the second joint device 3b connected to the link plate 38a of the first joint device 3a on the base end side comes into contact with the object, the reaction force from the object is received and the value is a predetermined value. When the above is reached, the torque limiting mechanism 36 operates. That is, the link plate 38 a sandwiched between the shafts 33 and 34 slips with respect to the shafts 33 and 34. At this time, while the grip frame 30 of the second joint device 3b keeps contacting the object with a constant contact force by the rotational driving force of the first joint device 3a, the shaft 33 provided on the grip frame 30 It rotates in the same way via the drive coupling mechanism 39. Next, when the grip frame 30 of the third joint device 3c connected to the link plate 38b of the second joint device 3b comes into contact with the object, the torque of the second joint device is limited by the reaction force from the object. The mechanism 36 operates and the link plate 38b and the shafts 33 and 34 slip. At this time, the grip frame 30 of the third joint device 3c comes into contact with the object with a constant contact force by the rotational driving force of the second joint device 3b. By repeating such an operation, the object can be supported by contact at a plurality of points. This operating state is shown in FIG.

  Further, as shown in FIGS. 5 and 6, the gripping frame 30 of the joint devices 3b and 3c is reverse to other joint devices or gripping frames connected to the link plates 38b and 38c of the joint devices 3b and 3c. A plate-like body serving as a stopper mechanism 40 that prevents rotation in a direction at a predetermined position extends from the upper end portion of the grip frame 30 in the same direction as the extension direction of the link plate. It is configured to always return to a certain posture during the opening operation.

  That is, after the above-described gripping operation performed by rotating the air motor 51 in the forward direction, the link plate 38 (38a) is interlocked with the shaft 33 rotating in the reverse direction by rotating the air motor 51 in the reverse direction. , 38b, 38c) are rotationally driven in the opposite directions, and the respective gripping frames 30 that are in contact with the object are separated from the object. Thereafter, the rotation of the joint device in the reverse direction is prevented by the stopper mechanism 40 at a predetermined position, so that the rotational friction mechanism as the torque limiting mechanism 36 is activated, the link plate is idled, and is released after the gripping operation. Thus, the operation can surely return to a certain initial posture with the predetermined position as the initial position.

  A plate-like body as the stopper mechanism 40 is arranged to extend from the upper end portion of the grip frame 30 in the same direction as the extension direction of the link plate, and the other joint device or the grip frame is rotated in the reverse direction. A plate-like body serving as a stopper mechanism 40 extends from the upper end of the gripping frame 30 in a direction opposite to the direction in which the link plate extends and is in contact with the gripping frames of other joint devices. It may be configured to prevent rotation of the own grip frame in the reverse direction at a predetermined position, and the specific configuration can be changed as appropriate.

  According to FIG. 5, the stopper is configured so that the posture in which the finger units are aligned in a straight line is taken as the initial posture, and the stopper mechanism 40 is returned to such an initial posture. The present invention is not limited to this, and the torque limiting mechanism 36 may be configured by a mechanism that applies a load to the link plate indirectly or directly so that the torque limiting mechanism 36 operates in a predetermined posture. Note that it is not always necessary to provide the stopper mechanism 40 in all the joint devices.

  By providing a plurality of finger units 2 as described above, opposingly arranged so as to be gripped with respect to the object, and driving the drive mechanism of the joint device on the proximal end side by a single or a plurality of actuators, Correspondingly, a mechanical universal hand that can perform an appropriate gripping operation is configured. For example, as shown in FIG. 7, a mechanical universal hand 1 can be configured in which two finger units 2 are arranged so as to face each other and hold an object so as to sandwich and hold the object. In this case, the driving directions with respect to the joint device on the proximal end side need to be opposite to each other. When driving with a single actuator, a reversing mechanism that reverses the driving direction is required. Moreover, as shown in FIG. 8, the mechanical universal hand 1 that can be gripped more reliably than in two directions by connecting three finger units 2 opposed to the object from three directions on the base end side. It can also be configured. In this case as well, the actuator arranged on the base end side may be either a single or a plurality of actuators, but it is the same in that the actuator is driven so that the joints are actuated to the opposite sides.

  That is, according to the mechanical universal hand described above, the object can be gripped so as to be wrapped. Therefore, even if the shape and size of the object slightly change, Even if the position and posture of the object are different, the object can be gripped extremely accurately and easily. Further, it is possible to cope with this by simply adjusting the tightening force by the above-described tightening bolt 37 according to the hardness of the object to be grasped. Moreover, only the control for the actuator on / off signal and the driving direction signal is required at the time of operation, and development of expensive control software is unnecessary, and the control circuit and control for the conventional industrial robot control device are unnecessary. The software is very economical because it can be used almost as it is.

  The structure of the above-described finger unit and mechanical universal 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 gripping frame with an elastic resin cover so that the gripping object can be protected from impact.

  Hereinafter, another embodiment of the joint device and the finger unit using the joint device and the mechanical universal hand according to the present invention will be described. In the above-described embodiment, the description has been given of the rotational friction mechanism disposed on both surfaces of the pair of shafts and the link plate as the torque limiting mechanism. However, the rotational friction mechanism is disposed only on one facing surface and on the other facing surface. May be provided with a thrust bearing. Further, a plurality of link plates or a plurality of link plates whose base end side branches into a plurality may be sandwiched by a plurality of shafts via a rotational friction mechanism.

  In the above-described embodiment, the torque limiting mechanism 36 is configured such that the rolling axis b is rollable at a predetermined inclination angle α with respect to the radial direction of the shaft 33 and is attached to the holding body 36 a along the rotation trajectory of the shaft 33. In the above description, the roller 36b group that has been held is constituted by a rotational friction mechanism that is sandwiched between the opposed surfaces of the shaft 33 and the link plate 38a with a predetermined tightening force. The angle formed with the radial direction a of the shaft 33 is not limited to an appropriate value, and is appropriately set. The specific configuration may be appropriately configured as described in Japanese Patent Application Laid-Open No. 08-074843. Is possible.

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

  In the above-described embodiment, an actuator using an air motor has been described. However, the present invention is not limited to this, and a linear motion actuator such as an electromagnetic motor, a hydraulic motor, an electromagnetic rotary solenoid, and a power cylinder can be used as appropriate. Needless to say. In addition, although a description has been given of using a bevel gear as a drive mechanism, this is not limited to that, and a known drive mechanism can be used as appropriate.

  In the above-described embodiment, the drive transmission mechanism is configured by a pulley and a timing belt. However, an infinite rotation mechanism such as a gear train, a control wire, a belt, or a chain can be adopted as the drive transmission mechanism.

  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 mechanical universal hand is 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.

Plan view of finger unit according to the present invention Plan view of the joint device according to the present invention FIG. 3 is a plan view of the main part of the finger unit 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 plan view of the finger unit according to the present invention, (b) is a front view thereof. Operational diagram of finger unit according to the present invention Operational explanatory diagram of mechanical universal hand according to the present invention Operational explanatory drawing of the mechanical universal hand according to the present invention showing another embodiment

Explanation of symbols

1: mechanical universal hand 2: finger units 3, 3a, 3b, 3c: joint device 4: tip gripping part 30: gripping frame 31: drive mechanism (second bevel gear)
32, 32a, 32b, 32c: Rotating shaft 33, 34: Shaft 36: Torque limiting mechanism (rotational friction mechanism)
36a: Holding body 36b: Roller 36c: Holes 38, 38a, 38b, 38c: Link plate 39: Drive transmission mechanism 40: Stopper mechanism

Claims (5)

  The link includes a gripping frame, a shaft rotatably supported by the gripping frame, a link plate connected to the shaft via a torque limiting mechanism, and a drive mechanism that rotationally drives the shaft. An articulated device configured such that another gripping frame can be connected to the tip of the plate.   The torque limiting mechanism includes a roller group in which a rolling axis is held by a holding body along a rotation trajectory of the shaft such that a rolling axis is rotatable at a predetermined inclination angle with respect to a radial direction of the shaft. The joint device according to claim 1, wherein the joint device comprises a rotational friction mechanism that is clamped between opposing surfaces of the link plate with a predetermined tightening force.   A finger unit in which the joint device according to claim 1 or 2 is connected in a plurality of stages, and a drive transmission mechanism for sequentially transmitting a rotational driving force from the drive mechanism to a shaft of each joint device.   The finger unit according to claim 3, wherein a stopper mechanism is provided on a gripping frame of the joint device to prevent a rotation of another joint device connected to a link plate of the joint device in a reverse direction at a predetermined position.   A mechanical universal hand comprising a plurality of the joint devices according to claim 1 or 2 or a plurality of finger units according to claim 3 or 4 and arranged so as to be gripped with respect to an object.