JP2008062335A - Positional error absorbing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positional error absorbing device, exhibiting enough error absorbing function even in the case of causing gravity action due to various attitudes of a robot arm. <P>SOLUTION: In this positional error absorbing device for assembling work or fitting work of members W1, W2, a fixed body 1 fitted to the output end side of a robot and a movable body 2 to which one member W1 is fitted are connected to each other through a plurality of fluid pressure cylinders 3 including a multi-degree of freedom joint at both ends, thereby constructing a parallel mechanism. A positional error between the members W1, W2 is absorbed by motion of the movable body 2 based on the parallel mechanism. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a position error absorbing device (remote center compliance device or floating device) attached to an output end of a robot that performs high-precision assembly work and fitting work, and in particular, various postures of a robot arm. The present invention relates to a position error absorbing device capable of exhibiting a sufficient error absorbing function even when a gravitational action is caused.

  For example, in the assembly robot R, as shown in FIG. 7, the member P1 is held by the tip of the robot hand H, moved horizontally to the guide hole of the counterpart component, and then lowered vertically to move the member P1. Is inserted into the guide hole for assembly. Such an assembly robot includes a position error absorbing device in which a fixed plate 100 and a movable plate 101 are connected via an elastic element 102 having rubber or metal bellows as a component. The plate 100 is attached to the output end side of the robot R, and the robot hand H is attached to the movable plate 101 for use. At this time, a certain amount of positioning is performed by moving the robot arm, and even when there is a slight misalignment between the member P1 and the guide hole, the elastic element 102 has when the member P1 contacts the edge of the guide hole. Since the fixed plate 100 and the movable plate 101 move relative to each other due to elasticity (oscillation motion or translational motion), it is possible to absorb a positional shift between them and guide the member P1 to the center side of the guide hole. (Patent Document 1)

  However, in the actual part assembling operation, not only the part P1 gripped by the robot hand H and the guide hole of the counterpart part are positioned horizontally as described above, but as shown in FIG. In some cases, the assembly work is performed in a vertical state or in various other positions, states, and postures. When the member P1 gripped by the robot hand H and the guide hole of the counterpart component are in a vertical state in this way, the elastic element 102 hangs down in the direction of the arrow in FIG. 8 due to the weight of the member P1 gripped by the robot hand H. There was a case. When attempting to insert the member P1 into the guide hole in such a state, there is a problem that it is very difficult to handle because the robot arm needs to be moved in accordance with the amount of sag and the work efficiency is reduced.

  Note that the rigidity of the elastic element 102 itself can be increased in order to prevent the sagging as described above. However, if the rigidity is excessively increased, the elastic element 102 does not function as an elastic body and cannot absorb a position error. there were.

  Even if the member P1 can be inserted into the guide hole once, there is no means for maintaining the state. Therefore, when an external force such as a welding robot in the welding operation or fixing operation between the inserted members is applied, The element 102 is defeated by the external force, and there is a problem that the position difference between the member P1 and the guide hole and the member P1 are lifted from the guide hole or come off.

Further, even when the assembly work is performed in a horizontal state, the elastic element 102 having too low rigidity causes the parts to shake due to acceleration / deceleration when moving the robot arm to the predetermined guide hole. For positioning, there is a problem that it is necessary to wait until the shaking is settled, and that a quick operation cannot be performed. In addition, the vibration accompanying the acceleration / deceleration and the weight of the parts may also act on the robot side, causing deformation and misalignment.
JP-A-11-138487

  Accordingly, an object of the present invention is to provide a position error absorbing device capable of exhibiting a sufficient error absorbing function even when a gravitational action is caused by various postures of the robot arm. In addition, the present invention can exhibit a sufficient error absorbing function even when gravity action occurs due to various postures of the robot arm, and once the members are assembled and fitted, It is an object of the present invention to provide a position error absorbing device capable of maintaining the above.

  The position error absorbing device of the present invention is a position error absorbing device for assembling work and fitting work between members, and includes a fixed body attached to the output end side of the robot and a movable body to which one member is attached. A parallel mechanism is formed as a whole by connecting through a plurality of fluid pressure cylinders having multi-degree-of-freedom joints at both ends, and a position error between members is absorbed by the movement of the movable body based on the parallel mechanism. It is characterized by doing so.

  Further, the position error absorbing device of the present invention is a position error absorbing device for assembling work or fitting work between members, and a fixed body attached to an arbitrary place other than the output end side of the robot, and one member The movable body to be attached is connected via a plurality of fluid pressure cylinders having multi-degree-of-freedom joints at both ends to constitute a parallel mechanism as a whole, and the movement of the movable body based on the parallel mechanism moves the members between them. It is characterized in that the position error of is absorbed.

  Here, the parallel mechanism is a general term for a closed link mechanism in which a fixed body and a movable body are connected by a plurality of leg link mechanisms arranged in parallel. The link mechanism is a mechanical mechanism configured by combining a plurality of links. The link is a structure (rigid body) whose shape does not change. In the present invention, a fluid pressure cylinder is used as the link. ing.

  In such a parallel mechanism, even if a force in any direction is applied to the fixed body and the movable body, only a tensile stress or a compressive stress is applied to the fluid pressure cylinder, and a bending stress is applied. It has a feature that it is easy to ensure sufficient rigidity according to the purpose of use.

  In the position error absorbing device, the fluid pressure cylinder has at least six, and both ends of each fluid pressure cylinder are connected to the fixed plate and the movable plate via a universal joint or a ball joint, respectively. The parallel mechanism may have a total of six degrees of freedom: three axes in the XYZ axis direction and three axes in the rotation direction of each axis.

  The position error absorbing device may include a lock mechanism that can lock the movement of the movable body based on the parallel mechanism in a timely manner as necessary.

  Here, as the locking mechanism, by supplying fluid pressure to the fluid pressure cylinder and restraining the expansion and contraction movement of the piston rod, the movement of the movable body based on the parallel mechanism can be locked in a timely manner as necessary. You may be able to do it.

  Further, as the locking mechanism, a lock member may be installed between the fixed body and the movable body so that the movement of the movable body based on the parallel mechanism can be locked in a timely manner as necessary. .

  As described above, the position error absorbing device according to the present invention is a position error absorbing device for assembling work and fitting work between members, and a fixed body attached to the output end side of the robot and one member are attached. Are connected to each other via a plurality of fluid pressure cylinders having multi-degree-of-freedom joints at both ends, thereby forming a parallel mechanism as a whole, and the movement of the movable body based on the parallel mechanism allows the members to move between the members. Since the position error is absorbed, it is possible to provide a position error absorbing device capable of exhibiting a sufficient error absorbing function even when gravity action occurs due to various postures of the robot arm.

  In addition, since the position error absorbing device is provided with a lock mechanism that can lock the movement of the movable body based on the parallel mechanism in a timely manner as necessary, gravity action due to various postures of the robot arm can be achieved. Provided is a position error absorbing device that can exhibit a sufficient error absorbing function even when it occurs, and that can maintain the state once the members are assembled and fitted. it can.

  Hereinafter, the present invention will be described with reference to the drawings shown as embodiments.

  1 is a perspective view of a position error absorbing device of the present invention, FIG. 2 is a front view thereof, FIG. 3 is a top view thereof, and FIG. 4 shows a state before the position error absorbing device of the present invention absorbs the position error. FIG. 5 is a state diagram showing a state during a position error absorbing operation by the position error absorbing device of the present invention. FIG. 6 is a state diagram showing a state after the position error absorbing operation of the position error absorbing device of the present invention. It is.

  As shown in FIGS. 1 to 3, this position error absorbing device is formed by connecting a fixed body 1 and a movable body 2 via a plurality of fluid pressure cylinders 3 each having a multi-degree-of-freedom joint. As a whole, it constitutes a parallel mechanism. And the movable body 2 moves according to the attitude | position of the other party member by this parallel mechanism, and the relative position error of the one member attached to the movable body 2 and the other party member shall be absorbed.

  Although not shown, the fixed body 1 and the movable body 2 may be provided with male / female connectors for connecting paths such as electricity, air, oil, and water. When properly connected, or when one member attached to the movable body 2 and the counterpart member are appropriately connected, the path may be turned on.

  As shown in FIG. 1, the parallel mechanism includes six fluid pressure cylinders 3. The fluid pressure cylinders 3 can be pneumatic or hydraulic fluid cylinders. Each fluid pressure cylinder 3 is arranged such that its cylinder body 30 is located below and the piston rod 31 is located above, and the lower end of the cylinder body 30 is connected to the fixed body 1 via the universal joint 4. The upper end portion of 31 is connected to the movable body 2 via the ball joint 5. Each fluid pressure cylinder 3 is connected to a fluid supply source 6 through a fluid supply line, and a pressure supply valve 7 and a SOL valve 8 are arranged in the middle thereof. Thereby, each fluid pressure cylinder 3 receives supply of fluid pressure from the fluid supply source 6 or discharges fluid pressure from a discharge port (not shown). By repeating these operations, the piston rod 31 has its length. Stretching in the vertical direction is performed. Note that a fluid pressure cylinder 3 having a built-in lock mechanism (for example, a cylinder with a lock manufactured by SMC Corporation or CKD Corporation) is adopted, and according to the supply of fluid pressure to the fluid pressure cylinder 3. The piston rod 31 can be freely locked at an upper limit position (a state where the piston rod is fully extended), a lower limit position (a state where the piston rod is fully contracted), or an intermediate position thereof.

  With the above-described configuration, the parallel mechanism can perform parallel motion based on the universal joint 4, rotational motion of the movable body 2 based on the ball joint 5, and vertical motion based on the expansion and contraction motion of the piston rod 31. 1 has a total of 6 degrees of freedom, 3 degrees of freedom in the XYZ axis direction and 3 degrees of freedom in the direction of rotation of each axis as shown in FIG. 1, and the movable body 2 is free to correspond to the position, posture and state of the counterpart member. It is assumed that the position error between the members is absorbed by high-precision movement.

  In FIG. 1, the fluid pressure cylinders 3 are attached in a state of being substantially upright at a predetermined interval. However, the present invention is not limited to this. For example, the two fluid pressure cylinders 3 are arranged at 120 ° intervals. Alternatively, the upper end of the piston rod 31 may be connected to three ball joints so that the fluid pressure cylinder 3 has an angle. Further, instead of the parallel mechanism of 6 degrees of freedom as described above, a parallel mechanism of 2 to 5 degrees of freedom may be used as necessary. In this case, the degree of freedom of the fluid pressure cylinder 3 is set to a required number of degrees of freedom. By suppressing it, the structure can be simplified and the cost can also be suppressed.

  4 to 6 show the above-described position error absorbing device connected to an industrial robot in which the robot arm is in a vertical state. The fixed body 1 is fixed to the output end of the robot arm, and the movable body 2 is attached to the movable body 2. The attached member W1 is combined with the counterpart member W2 in an arbitrary position and posture.

  By the way, in this embodiment, the fixed body 1 is fixed to the output end of the robot arm as described above. However, the present invention is not limited to this, and the fixed body 1 can be fixed to an arbitrary place such as the ground. It is.

  In the position error absorbing device of the present invention, even when the robot arm is in a vertical state, the actuator (fluid pressure cylinder 3) is attached to the movable body 2 by adjusting the hardness of each actuator (fluid pressure cylinder 3) by air pressure, hydraulic pressure, spring force, etc. The displacement of the movable body 2 and the fixed body 1 due to the gravitational action from the member W1 and the gravitational action accompanying the change in the posture of the robot arm, the deviation of the core, and the change in softness can be canceled.

  In the present embodiment, the member W1 attached to the movable body 2 is combined with the counterpart member W2. However, the present invention is not limited to this, and a member attached to the movable body 2 and gripped by the robot hand. The combination of W1 and the counterpart member W2 may be performed, or the combination may be performed by inserting the pin P provided on the movable body 2 into the guide hole provided on the counterpart member.

  FIG. 4 shows a state before the member W1 attached to the movable body 2 is combined with the counterpart member W2. In this state, the piston rod 31 of each fluid pressure cylinder 3 is strongly locked at the lower limit position by the lock mechanism. ing. As a result, it is possible to prevent the movable body 2 and the member W1 from shaking due to acceleration / deceleration when the robot arm moves, thereby enabling quick work.

  FIG. 5 shows that the parallel mechanism of the position error absorbing device of the present invention is operated by pressing the member W1 against the counterpart member W2 by the robot arm, and the movable body 2 is moved so that the member W1 follows the position and posture of the counterpart member W2. The state in which the position error between the member W1 and the counterpart member W2 is absorbed is shown. In this state, as described above, the piston rod 31 that has been strongly locked at the lower limit position is kept in a soft and flexible state by adjusting the pressure. Thereby, the fluid pressure cylinder 3 and the movable body 2 based on the universal joint 4 are swung, the movable body 2 is rotated based on the ball joint 5, and the fluid pressure is supplied to and discharged from the fluid pressure cylinder 3. Combination with the expansion and contraction motion of the movable body 2 based on the expansion and contraction of the piston rod 31 is possible, and the position error between the member W1 and the counterpart member W2 can be absorbed.

  In this embodiment, the member W1 is combined with the position and posture of the counterpart member W2 by pressing the member W1 against the counterpart member W2 by the robot arm, but the position and posture of the counterpart member W2 By inputting various information such as the inclination of the contact surface to the robot in advance, the robot automatically applies fluid pressure to the fluid pressure cylinder 3 even before the member W1 contacts the counterpart member W2. The position error may be absorbed by adjusting the supply amount of. Alternatively, a sensor is attached to the tip of the robot arm or the movable body 2 to detect the position and posture of the counterpart member W2, the inclination of the contact surface, etc., and the robot automatically performs a position error absorbing operation based on the information. It may be done.

  FIG. 6 shows a state where the position error absorbing operation by the position error absorbing device of the present invention is completed and the member W1 attached to the movable body 2 and the counterpart member W2 are combined. In this state, the piston rod 31 that has been in a soft and flexible state for absorbing the position error is strongly locked again by the lock mechanism to maintain its posture. Thereby, after combining the members, even when an external force from a welding robot or the like acts when welding or fixing the members, it is possible to prevent the positional deviation or the disconnection between the member W1 and the counterpart member W2.

  In this embodiment, the piston rod 31 is locked by the locking mechanism built in the fluid pressure cylinder 3, but the locking member 9 combined with a joint as shown in FIG. The movable member 2 may be constrained by the lock member 9 and the movement of the movable body 2 may be restricted by the locking member 9 to prevent the positional deviation or the disconnection between the member W1 and the counterpart member W2. This lock member 9 is configured by a combination of a rotary joint and a swing joint so that it can move freely with the movable body 2 when absorbing the position error, and stops its rotational and swing movements as necessary. It can be fixed. Thereby, after the members are combined, even when an external force from a welding robot or the like is applied when the members are welded or fixed, the locking member 9 is locked and the positional deviation between the member W1 and the counterpart member W2 is reduced. It can be prevented from coming off.

  In the first embodiment, the member W1 attached to the movable body 2 and the counterpart member W2 are combined. However, the position error absorbing device of the present invention is an industrial robot (for example, Japanese Patent Laid-Open No. 4-101996, FIG. 4). ) Can also be used for connecting / separating a tool change coupler.

  Usually, an arm type industrial robot is provided with a tool changing function, and has a tool changing coupler at the tip of the arm. This tool changer coupler is composed of a first housing attached to the robot side and a second housing on the workpiece side to which the tool is attached, and a number of second housings having different tools are prepared, When one process is completed and the process proceeds to the next process, the second housing used so far is removed from the first housing, and the second housing having another type of tool is coupled. In order to properly connect the first housing and the second housing, a taper pin whose diameter is reduced toward the tip is made upright on one of the joint surfaces, and the taper pin on the other joint surface. A guide hole is provided for guiding.

  Therefore, in the arm type industrial robot as described above, the fixed body 1 of the position error absorbing device of the present invention is fixed to the output end of the robot, and the first housing is attached to the movable body 2 to connect the coupler. When the work is performed, even if the joint surface of the first housing and the joint surface of the second housing are not parallel, the joint mechanism described above can make both joint surfaces parallel without bringing the housings into contact with each other. Furthermore, even if the teaching position of the first housing and the position where the second housing is placed are slightly misaligned, the first housing moves relative to the robot arm in such a manner that the taper pin is guided to the guide hole by the parallel mechanism. And a 1st housing and a 2nd housing can be connected appropriately.

  As described above, in the position error absorbing device of the present invention, an accurate position error can be obtained by the parallel mechanism even when the gravitational action due to various postures of the robot arm occurs or regardless of the posture, position and state of the counterpart member. Absorption can be performed, and the welding operation after the combination can be easily performed by a lock mechanism that can maintain the posture at the time of absorbing the position error.

The perspective view of the position error absorption apparatus of this invention. The front view of the position error absorption apparatus of this invention. The top view of the position error absorption apparatus of this invention. The robot arm is in a vertical state, and is a state diagram showing a state before the position error is absorbed by the position error absorbing device of the present invention. FIG. 3 is a state diagram showing a state in which the robot arm is in a vertical state and the position error is absorbed by the position error absorbing device of the present invention. FIG. 3 is a state diagram showing a state after the robot arm is in a vertical state and the position error is absorbed by the position error absorbing device of the present invention. The state diagram which showed the state after absorbing a position error with the position error absorption apparatus with which the locking mechanism was provided separately. FIG. 5 is a state diagram showing a state where the robot arm is in a horizontal state and a position error is absorbed by a conventional position error absorbing device. FIG. 6 is a state diagram showing a state where the robot arm is in a vertical state and a position error is absorbed by a conventional position error absorbing device.

Explanation of symbols

W1 member W2 counterpart member 1 fixed body 2 movable body 3 fluid pressure cylinder 4 universal joint 5 ball joint 6 fluid supply source 7 pressure supply valve 8 SOL valve 9 lock member 30 cylinder body 31 piston rod

Claims (7)

  A position error absorbing device for assembling work and fitting work between members (W1) and (W2), and a movable body to which a fixed body (1) attached to the output end side of the robot and one member (W1) are attached. The body (2) is connected through a plurality of fluid pressure cylinders (3) each having a multi-degree-of-freedom joint at both ends to constitute a parallel mechanism as a whole, and the movable body (2 based on the parallel mechanism) ) To absorb the position error between the members (W1) and (W2).   A position error absorbing device for assembling work and fitting work of members (W1) and (W2), a fixed body (1) attached to an arbitrary place other than the output end of the robot, and one member (W1). By connecting the movable body (2) to be attached via a plurality of fluid pressure cylinders (3) each having a multi-degree-of-freedom joint, a parallel mechanism is formed as a whole, and the movable mechanism based on the parallel mechanism is movable. A position error absorbing device characterized in that a position error between members (W1) and (W2) is absorbed by movement of a body (2).   The fluid pressure cylinder (3) has at least six, and at least one of the multi-degree-of-freedom joints provided at both ends of the fluid pressure cylinder (3) includes a universal joint (4) or a ball joint (5). The position error absorbing device according to claim 1 or 2, wherein the parallel mechanism has a total of six degrees of freedom: three axes in the XYZ-axis direction and three axes in the rotation direction of each axis.   The position error absorbing device according to any one of claims 1 to 3, further comprising a lock mechanism that can lock the movement of the movable body (2) based on the parallel mechanism as needed.   As the locking mechanism, by supplying fluid pressure to the fluid pressure cylinder (3) and restraining the expansion and contraction movement of the piston rod (31), the movement of the movable body (2) based on the parallel mechanism is performed as necessary. The position error absorbing device according to claim 4, wherein the position error absorbing device can be locked in a timely manner.   As the lock mechanism, a lock member (9) is installed between the fixed body (1) and the movable body (2), so that the movement of the movable body (2) based on the parallel mechanism can be performed as needed. The position error absorbing device according to claim 4, wherein the position error absorbing device can be locked.   7. The position error absorbing device according to claim 1, wherein one of the members (W1) and (W2) is movable as one of housings constituting a coupler of a type in which a taper pin is integrated into a guide hole. A position error absorbing device which is attached to the body (2) and absorbs a position error between the taper pin and the guide hole by the movement of the movable body (2) based on the parallel mechanism.

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