JPH05196B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a gripping device for parts in industrial robots and automatic assembly machines.

(b) Conventional technology In industrial robots and automatic assembly machines that handle parts, the movement of the robot body has become faster and the degree of freedom has increased, but on the other hand, the hand that plays an important role as a point of contact with the parts Due to the diversity of the sizes and shapes of parts and their properties such as hardness, softness, strength, etc., there is a need for a hand with high versatility and intelligence, but there are few hands that are put to practical use. In general, pneumatically driven parallel opening/closing chucks and parallel hands with a parallel ring mechanism are often used, and the current situation is that the hands are replaced depending on the part. Therefore, various hands have been proposed. One is a hand with a multi-jointed structure to increase the degree of freedom of the fingers to provide versatility, and the other is a hand with a turret-shaped rotating head structure equipped with a plurality of grippers.

(C) Problems to be Solved by the Invention As mentioned above, a hand with a multi-joint structure or a rotary head structure with multiple grippers depending on the shape of the part requires a large number of power units such as motors and cylinders. This increases the weight of the hand and increases the complexity of the control system, which places a burden on the robot body, which in turn causes a decline in robot performance. Furthermore, in general, the part to be grasped is usually positioned, and if the center of the hand and the center of the part do not coincide, an unreasonable load may be applied to the arm of the robot.

An object of the present invention is to provide a highly versatile robot hand for handling and assembling parts, which has a simple structure, is lightweight, and can perform gripping operations with simple control.

(d) Means for Solving the Problems The robot hand of the present invention has a two-finger structure with two joints, which is the minimum number of joints in the fingers that come into contact with the grasped part, and the fingertip posture is fixed. It consists of a parallel movement finger mechanism that can be variably set, a finger drive mechanism using wires and pulleys, a restoring force proportional mechanism for a grip release spring, and an operation section, making it possible to grip a variety of parts. There is.

The present invention will be explained based on the drawings. In FIGS. 1 and 2, two movable fingers are rotatably attached to the shafts 8 and 11 on the support member 12, and the movable fingers have two fingertips and two finger bases. They are rotatably connected by shafts 6 and 9 at the tips of the finger bases, respectively. In the first movable finger, the fingertip 1 is fixed to a shaft 6, and is rotatable together with a gear 13 fixed to the shaft 6, to a shaft 7 installed between a shaft 8 fixed to a support member 12 and the finger base 2. It is interlocked with the gear 15 and gear 14 attached to the. Out of the three gears, the gears 13 and 15 at both ends have the same number of teeth, and the intermediate gear 14 is an idler and merely serves to change the direction of rotation. Furthermore, since the gear 15 meshes with the rack 19 that slides on the support member, the fingertip 1 is in a swingable state in conjunction with the movement of the rack 19. The rack 19 is appropriately fixed to the support member 12 with bolts, and the fingertip posture is set to match the shape of the part to be gripped. On the other hand,
The fingertip 3 of the second movable finger is fixed to a shaft 9 in a variably settable state, and the fingertip 3 of the second movable finger is connected to three gears 1 like the first movable finger.
6, 17, and 18, the gear 18 is fixed to a shaft 11 fixed to a support member. The fingertips, which are installed at the tips of the two freely rotatable movable fingers and are interlocked with three gears, have the same oscillation angle as the oscillation angle of the finger mechanism, with the gears 15 and 18 acting as sun gears. Since the rotation is transmitted so as to swing in the opposite direction by the amount of movement angle, the fingertip can continue to maintain the same posture with respect to the support member. Furthermore, attaching an elastic flexible member 5 such as rubber to the surface of the fingertip that comes into contact with the object to be grasped is useful for increasing the adhesion to the object to be grasped and for protecting the object to be grasped. Here, instead of the three gears installed at the finger base, a rotation transmission mechanism may be formed of a transmission element such as a belt or chain.

A pulley 20 and a pulley 21 are rotatably attached to the shafts 8 and 11, and a sliding member 22 that can slide back and forth is provided on a vertical line in the middle of the distance between the shafts. A movable pulley 24 is rotatably attached to the fixed shaft 23. One wire 25 is wound around these two pulleys 20 and 21 and the movable pulley 24, and both ends thereof are fixed to the tips of the first finger base 2 and the second finger base 4. stopper 26, 27 and 28,
Reference numerals 29 limit the movable range of the movable fingers, and the stoppers 27 and 29 limit the open position, and the stoppers 26 and 28 limit the closed position, and are set in accordance with the shape and size of the object to be grasped. If particularly necessary, if the open position and the closed position are the same, that is, the movable finger is restrained, it functions as a fixed finger.

Pulleys 30 and 31 are fixed to the shafts 6 and 9 of the movable fingers. Two wires 32 and 33 whose one ends are fixed and wound around the pulleys 30 and 31
The other ends are connected to tension springs 34, 35, respectively, and the other ends of the springs are further engaged with the shafts 8 and 11. Therefore, the restoring force of the spring always acts on the two movable fingers to return them to the open position.

An operating device such as a wire 36 or a cylinder is connected to the sliding member 22 that slides the movable pulley 24, which is a component of the finger drive mechanism. Here, if they are connected by a wire or a shaft, the drive source can be installed at a location remote from the hand, which is advantageous in reducing the weight of the hand.

(E) Operation The operation of grasping an object with the robot hand of the present invention will be explained. The wire 36 is subjected to tension by a drive source such as a cylinder installed at a location remote from the hand, and power is transmitted to the sliding member 22 to which the wire 36 is connected. A wire 25 is wound around a movable pulley 24 rotatably attached to a shaft 23 provided on the sliding member 22. Both ends of the wire are fixed to the tips of the two finger bases, and the first finger base 2 and the second finger base 4 rotate freely around the shafts 8 and 11, respectively, so that the linear movement of the sliding member is 2 pulleys 20, 21
is converted into rotational motion of the two movable fingers.
On the other hand, the first fingertip 1 and the second fingertip 3, which are fixed to a shaft 6 and a shaft 9 rotatably provided at the tips of the first finger base 2 and the second finger base 4, are interlocked with three gears. You can move in parallel while maintaining the initially set posture. Therefore, at this point, the two fingertips begin to grip the object while moving in parallel due to the rotational force of the two finger bases.

When the two movable fingers rotate and one of the two fingertips contacts the object to be grasped first, the reaction force of the fingertip that came into contact first is transmitted to the finger base, and the movement of the wire 25 is restricted. Therefore, the rotation of the movable finger stops. However, since power is further transmitted from the drive source, rotation is continued until the fingertip of the other movable finger makes contact and stops rotation, and the gripping operation is completed.

In this way, the two movable fingers can grip the object by making matching movements as if following the position of the object to be gripped. In addition, at this time, if the stoppers 26 and 28 of the two movable fingers are adjusted appropriately according to the size and shape of the object to be grasped, the second fingertips 3 can be used as a reference plane even after grasping the object to be grasped. The position and posture of can be maintained stably.
Furthermore, the soft material fixed to the surface of the first fingertip is useful for absorbing setting errors in the fingertip posture and for improving closeness to the object to be grasped.

Next, a spring restoring force proportional mechanism for releasing the gripping state will be explained. Generally, a coil spring is used to obtain a restoring force proportional to displacement, but when used for a swinging part, a displacement proportional to the swing angle cannot be obtained. However, when the movable finger swings at an angle θ toward the closing side due to the action of the parallel finger mechanism, the pulleys 30 fixed to the shafts 6 and 9,
31 rotates in the opposite direction by the swing angle of the movable finger. The ends of the wires 32 and 33, one end of which is fixed and wound around the pulleys 30 and 31, are
Rθ becomes shorter, and as a result, the tension spring 34,
35 is extended by Rθ, so that a restoring force proportional to the swing angle of the movable finger can be obtained. Therefore,
By operating the drive source in the opposite direction, the power transmission to the sliding member 22 is reversed, and the two movable fingers are opened by the tension of the two tension springs 34 and 35, and the gripping state is released. Ru.

(f) Embodiment The above description of the grasping operation was related to the case where the object to be grasped was hard or rectangular. The robot hand of the present invention is highly versatile and can be easily applied to cylindrical objects and weak objects.

Figure 3 shows an example of grasping a cylindrical object. By adjusting the stoppers 26 and 27 of the second movable finger, the finger can be made to stand perpendicularly to the support member 12, making it a fixed finger in which the finger base 4 does not rotate. On the other hand, if the fingertips of the first movable fingers are set so that the fingertips 1 and the finger bases 2 form a V-shape, it is possible to grip a cylindrical object with three-point contact based on the second movable fingers.

Next, FIG. 4 shows an example of mounting a force sensor for controlling the gripping force. In the mechanism that can variably set the fingertip posture of the first movable finger, the rack 19 that meshes with the gear 15 is connected to the parallel spring block 37 by the distortion element 3.
8, and the other end of the gripping force detector is appropriately fixed to the support member with a bolt. Therefore,
The rack 19 is in an elastically supported semi-fixed state. When supported, the reaction force from the fingertips acts on the supporting force detector and distorts the parallel spring. The output from the strain meter element 38 is taken into the control device via an amplifier,
By controlling a drive source such as a motor, it is possible to grip a weak object without destroying it.

(G) Effects of the Invention The robot hand of the present invention is composed of two movable fingers with two interstices, and has a pulley-type finger drive mechanism using a movable pulley and wire, and a fingertip posture that can be variably set. Since the fingers are driven by a parallel finger mechanism that can maintain a constant posture, there are the following unprecedented effects.

In addition to functioning as a parallel opening/closing chuck, the two movable fingers move in a manner that follows the position of the object to be grasped using a single drive source, so that no undue load is placed on the robot arm.

The drive source can be installed away from the hand via a wire or shaft, making it possible to reduce weight.

By fixing one finger, it is possible to grasp the object with three points of contact, so it can also be applied to cylindrical objects.

A force sensor is installed to grip weak objects without destroying them, and the gripping force can be easily controlled using a reversible motor as the drive source.

The robot hand of the present invention having the above advantages,
The effect of increasing the versatility of industrial robots and automatic assembly machines is significant and can contribute to improving productivity.

[Brief explanation of the drawing]

FIGS. 1 and 2 show a pulley type finger drive mechanism, a parallel displacement finger mechanism, and
FIG. 2 is a front view and a sectional view of a main part of a restoring force comparison mechanism for grip release. Figure 3 is an example of grasping a cylindrical object, Figure 4
The figure shows the installation diagram of the force sensor. 1, 3: fingertip, 2, 4: finger base, 5: flexible member, 6, 7, 8, 9, 10, 11: shaft, 12: support member, 13, 14, 15, 16, 17, 18:
Gear, 19: Rack, 20, 21: Pulley, 22:
sliding member, 23: shaft, 24: movable pulley, 25: wire, 26, 27, 28, 29: stopper, 30,
31: Pulley, 32, 33: Wire, 34, 35:
Tension spring, 36: wire, 37: parallel spring block, 38: strain meter element.

Claims (1)

[Scope of Claims] 1. Two movable fingers having joints at two locations, one at the fingertip and the other at the base, and one wire with one end fixed at the tip of one of the finger bases, and the finger base joint axis. The pulley is wrapped around a movable pulley that slides on a vertical line midway between the two finger base joint axes via a freely rotating pulley provided at the base, and whose other end rotates freely about the second finger base joint axis. A pulley-type finger drive unit that is fixed again at the tip of the second finger base to form an open loop and swings the two fingers by moving the movable pulley forward or backward, and the two movable fingers. It consists of a parallel movement finger mechanism that allows the fingertip posture to be variably set and to keep the initial setting constant, and an operating device that moves a movable pulley on which a wire is hung in a straight line. A robot hand characterized by having a pulley-type finger drive mechanism in which the fingers make an adaptive motion as if following the position of a positioned object to be grasped, and a parallel movement finger mechanism in which the posture of the fingertips can be variably set. 2. The robot hand according to claim 1, wherein the restoring force of the spring that releases the grasped object from the grasped state generates a force proportional to the swing angle of the movable fingers. 3. Claim 1, characterized in that a force sensor unit that detects the gripping force is included in the parallel movement finger mechanism unit that can variably set the posture of the fingertips that come into contact with the object to be gripped. Robot hand to be described. 4. The robot hand according to claim 1, characterized in that an elastic flexible member is attached to the fingertip that contacts the object to be grasped.