JPH01252386A - Robot hand - Google Patents

Abstract

PURPOSE:To make a device simple in structure and light in weight as well as to enable holding operations to be simply controlled be letting two movable fingers with two joints be driven by a pulley type finger driving mechanism and a parallel moving finger mechanism maintaining the finger attitude which can be set variable, constant. CONSTITUTION:When a cylindrical article is held, the adjustment of stoppers 26 and 27 of No.2 movable finger allows the finger to erected against a supporting member 12 so that the finger base section 4 is not rotated but is stationary. On the other hand, when finger tips are set in such a way that the finger tip 1 of No.1 movable finger and a finger base section 2 are formed into a V-shape configuration, the cylindrical article can be held while being gripped by means of three point contacts on the basis of No.2 movable finger. In the second place, when a force feeling sensor is mounted in order to control holding force, a rack 19 is elastically supported in such a way as to be in a half stationary condition. And the reaction of the finger tip when the article is held acts on a holding force detector so as to let a parallel spring be strained. This permits the output from a strain gauge element 38 to be inputted into a control device via an amplifier so as to control driving apparatus such as motors and the like so that articles which are weak in strength can be safely held without bringing the articles to destruction.

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 has increased the degree of freedom. Due to the diversity of component sizes, shapes, and properties such as hardness, softness, strength, etc., there are only a few Hunts that are put to practical use despite the need for highly versatile and highly intelligent Hunts. In general, pneumatically driven parallel opening/closing chucks and parallel grips using parallel link mechanisms are often used, and work is currently carried out by replacing the grips depending on the parts. For this reason, various hunts have been proposed. One is a multi-joint structure that increases the degree of freedom of the fingers to increase versatility, and the other is a hunt with a turret-shaped rotating head structure equipped with multiple grippers.

(c) Problems to be solved by the invention As mentioned above, the hunt with a rotary head structure that has a multi-joint structure and multiple grippers depending on the shape of the parts 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 puts a strain on the robot body, which in turn causes a decline in robot performance. Furthermore, in general, the part to be gripped 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.

SUMMARY OF THE INVENTION 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, the minimum number of joints in the fingers that come into contact with the grasped part, and has a fingertip posture. It consists of a parallel moving finger mechanism that can be variably set, a finger drive mechanism using wire and pulleys, a restoring force proportional mechanism for a grip release spring, and an operating device, making it possible to grip a variety of parts. There is.

The present invention will be explained based on the drawings. 1 and 2, the support member 12 has two movable fingers, a shaft 8 and a shaft 11.
2, which is a component of the movable finger, is rotatably attached to the
The two fingertips and the two finger bases are each rotatably connected by a shaft 6.9 at the tip of the finger base. In the first movable finger, the fingertip 1 is fixed to the shaft 6,
A gear 13 fixed to the shaft 6 and a support member 12
It is linked to a gear 15 and a gear 14 rotatably attached to a shaft 8 fixed to a shaft 8 and a terauchi 7 installed in the middle of the finger base 2. Gears at both ends of the three gears 13.15
have the same number of teeth, and the intermediate gear 14 is an idler wheel that merely serves to change the direction of rotation. Furthermore, gear 15
is engaged with the rack 19 that slides on the support member, so 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 tip 3 of the second movable finger is fixed to the shaft 9 in a variably settable state, and
Like the movable finger, it is linked to three gears 16, 17, 18, but the tooth 4 [18] is fixed to the shaft 11 fixed to the support member. The fingertips, which are installed at the tips of the two movable fingers that can rotate freely in this way and are linked to three gears,
Gears 15 and 18 act as sun gears and the rotation is transmitted so that they swing in the same direction as the swing angle of the finger base, so the fingertip continues to maintain the same posture with respect to the support member. be able to. 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 composed of a transmission element such as a belt or a chain may be used.

◆A pulley 20 and a pulley 21 are rotatably attached to the shaft 8 and the shaft 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, and the sliding member A movable pulley 24 is rotatably attached to a shaft 23 fixed to the shaft 23 . A single ear 25 is wound around these two pulleys 20, 21 and the movable pulley 24, and its both ends are fixed to the tips of the first finger base 2 and the second finger base 4. Stoppers 26.27 and 28.29
The stoppers 27 and 29 limit the movable range of the movable fingers, and the stoppers 26 and 28 limit the closed positions, and are set in accordance with the shape and size of the object to be grasped. If particularly necessary, the open position and the closed position are the same, that is, the movable finger is restrained so that it functions as a fixed finger.

Pulleys 30, 31 are fixed to the shafts 6 and 9 of the movable fingers. The other ends of the two g-wheels 32.33, one end of which is fixed and wound around the pulley 30.31, are connected to tension springs 31L and 35, respectively, and the other ends of the springs are further engaged with the shafts 8 and 11. are combined. Therefore, the restoring force of the spring always acts on the two movable fingers to return them to the open position.

Slide the movable pulley 24, which is a component of the finger drive mechanism.
An operating device such as a wire 36 or a cylinder is connected to the moving member 22 . Here, if the drives are connected by a wire or a shaft, the drive source can be installed at a location remote from the hunt, which is useful for reducing the weight of the hunt.

(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 driving source such as a cylinder installed at a location remote from the hand,
Connected I! of wire 36! (Power is transmitted to the moving member 22. A single wire A 25 is wound around a moving pulley 24 rotatably attached to a shaft 23 provided on the sliding member 22. Both ends of the wire is fixed to the tips of the two finger bases, and the first finger base 2 and the second finger base 11 each rotate freely around the axis 8.11, so that
The linear movement of the sliding member is carried out by two pulleys 20 and 21.
It is converted into a rotational motion of the book's movable fingers.

On the other hand, No. IF! The first fingertip 1 and the second fingertip 3 fixed to a shaft 6 and a shaft 9 rotatably provided at the tips of the base 2 and the second finger base 4 are attached to three gears. ! It is possible to 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. However, since power is transmitted from the drive source, the rotation continues until the fingertip of the other movable finger makes contact and stops rotating, completing the gripping operation. .

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. Also at this time, the two movable finger stoppers 26.
If 28 is adjusted appropriately according to the size and shape of the object to be held w1, 111! can be achieved using the second fingertip 3 as a reference plane even in the state after gripping. The position and posture of your belongings can be maintained stably.

Furthermore, the soft material fixed to the surface of the tip is useful for absorbing errors in setting the fingertip posture and for increasing the 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 closed side due to the action of the parallel finger mechanism, the pulley 30.31 fixed to the shaft 6.9 rotates in the direction of the swing angle of the movable finger. The end of the wire 32.33, which is wound around the pulley 30.31 with one end fixed thereto, becomes shorter in Rθ when the radius of the pulley is R. As a result, the tension spring 34.35 is extended by Rθ, which reduces the swing of the movable finger. A restoring force proportional to the moving angle 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 2
The tension of 34.35 tension springs causes 2 ml
The upper fingers are opened and the grasping state is released.

(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 hunt of the present invention is highly versatile and can be easily applied to cylindrical objects and weak objects.

FIG. 3 shows an example of gripping a cylindrical object. By adjusting the stoppers 26 and 27 of the second movable finger, the finger can be made to stand vertically with respect to the support member 12 and the finger base Bk! 4 can be made into a fixed finger that does not rotate. On the other hand, the fingertip 1 and the finger base 2 of the first movable finger
If the fingertips are set so as to form a single-shape, a cylindrical object can be gripped with three points of contact based on the second movable finger.

Next, FIG. 4 shows an example of mounting a force sensor for controlling the gripping force. A rack 19 meshed with a gear 15 in a mechanism that can variably set the fingertip posture of the first movable finger is coupled to one end of a gripping force detector configured by fixing a distortion element 38 to a parallel spring block 37, The other end of the roughly gripping force detector is appropriately fixed to the support member with bolts. Therefore, the rack 19 is in an elastically supported semi-fixed state. The reaction force from the fingertips when gripping acts on the gripping force detector and distorts the parallel spring. The outputs of the strain meter elements 38b) are input to the control device via an amplifier to control a drive source such as a motor, thereby making it possible to grasp 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 joints, and is a pulley-type fff using a movable pulley and wire.
Since the fingers are driven by a drive mechanism and a parallel movement finger mechanism that allows the fingertip posture to be variably set and the posture for setting the amount of paddy to be kept constant, the following unprecedented effects are achieved.

In addition to the function of the two movable fingers as a parallel opening/closing chuck, the two movable fingers perform adaptive motions using one drive source as if following the position of the object to be held, so no unreasonable load is placed on the robot arm.

The weight can be reduced because the drive source can be installed away from the hand via wires or shafts.

By fixing one finger, it is possible to grasp the object through three-point contact with the object to be grasped, so it can be applied to cylindrical objects as well.

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 has a great effect of increasing the versatility of industrial robots and automatic assembly machines.
This can help improve productivity.

[Brief explanation of the drawing]

1 and 2 are a normal Wi view and a cross-sectional view of essential parts showing a pulley type tm drive mechanism, a parallel movement finger mechanism, and a restoring force proportional mechanism for grip release, which constitute the robot hunt of the present invention. FIG. 3 shows an example of grasping a cylindrical object, and FIG. 4 shows an example of attaching a force sensor.

Claims (4)

[Claims] (1) Two movable fingers with 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 finger base, which is attached to the finger base joint axis. It is wrapped around a movable pulley that slides on a vertical line midway between the two finger base joint axes, and the other end passes through a pulley that freely rotates on the second finger base joint axis, and then the second finger base joint axis is wrapped around the movable pulley that rotates freely on the second finger base joint axis. 2
A pulley-type finger drive unit that is fixed at the tip of the finger base to form an open loop and swings the two fingers by moving the movable pulley forward or backward, and the fingertip posture of the two movable fingers is variable. It consists of a parallel moving finger mechanism that can be set and keeps the initial setting constant, and an operating device that moves a movable pulley on which a wire is hung in a straight line.The two movable fingers are used for positioning. A robot hand characterized by having a pulley type finger drive mechanism that performs an adaptive operation as if imitating the position of a grasped object, and a parallel movement finger mechanism that can variably set the fingertip posture. (2) The robot hand according to claim 1, wherein the restoring force of the spring that releases the gripped object from the gripping 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 fingertip that contacts the object to be gripped. The robot hand described in . (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.