JPH06104313B2 - Anti-vibration device for manipulator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel vibration preventive device for a manipulator used in a robot, and more specifically, a mass damper is installed at the tip of the manipulator to prevent vibration, thereby achieving accuracy in tracking the trajectory of a hand. The present invention relates to a vibration preventive device for a manipulator, which can contribute to energy saving, because the robot can be improved in weight, speed and weight can be reduced, and size can be reduced.

[0002]

2. Description of the Related Art Conventionally, it has been known that when a manipulator of a robot is suddenly stopped, vibration is generated to make it difficult to position a hand. May occur when a large acceleration is applied due to a speed change, when a large torque is applied to a joint in torque control, when a torque fluctuation occurs due to tooth contact of the reducer, or when an external force such as an earthquake or wind is applied. Are known.

As described above, when the hand of the manipulator vibrates, the trajectory tracking accuracy of the hand cannot be maintained, and the settling time until positioning becomes long, so that the function of the robot cannot be fully exerted. Further, the fatigue strength of the arm structural member is reduced, and there is a risk of damage such as cracks. In order to avoid the risk of this deterioration of function and damage, an increase in the rigidity of the arm structural member causes an increase in the weight of the arm, and an actuator (motor, etc.) of the joint is used to drive the heavy arm. It is necessary to increase the ability of the robot, and as a result, the weight and size of the entire robot increase, which inevitably increases the size of the robot. Further, it is possible to reduce the change in speed of motion to suppress the occurrence of vibration, but in this case, there is a disadvantage that the speed cannot be increased.

[0004]

Under the circumstances described above, the present invention can improve the accuracy of tracking the trajectory of the hand of a manipulator used in a robot, and can reduce the weight and speed of the robot. At the same time, the object of the present invention is to provide a vibration preventing device for a manipulator, which can be downsized and contribute to energy saving.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies to develop a vibration preventing device for a manipulator having the above-mentioned preferable properties, and as a result, the mass damper is composed of a specific mass damper and a control device. Has found that the object can be achieved by a vibration preventing device having a structure installed on the wrist of the manipulator or an arm near the wrist, and has completed the present invention based on this finding.

That is, the present invention comprises a mass damper consisting of a damping mass for generating an inertial force for preventing vibration and an actuator for driving the damping mass, and a control device for controlling the damping mass according to a sensor for detecting the vibration. And a vibration damper for a manipulator, characterized in that the mass damper is installed on a wrist portion or an arm portion near the wrist portion of the manipulator.

The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a perspective view of an example of a robot manipulator in which the vibration preventing device for a manipulator of the present invention is installed. The manipulator 1 is subjected to external force fluctuations such as acceleration, joint torque, and earthquake during operation, and produces vibrations indicated by a dotted line. Therefore, the free end 2 of the manipulator and the wrist 3 vibrate in a plane perpendicular to the axial center of the uppermost arm 4 and vibrate at amplitudes a ₁ and a a perpendicular to each other.
_The vibration mode has ₂ . In order to prevent such vibration, a mass damper 5 is mounted on the arm 4 near the wrist.

FIG. 2 is an arrangement diagram of an example of mass dampers for preventing in-plane vibration perpendicular to the cross section of the arm portion. Two mass dampers 5'and 5 "are attached to the arm portion 4 by the pedestal 6. The vibration components a ₁ and a ₂ are detected by the vibration sensor 7, and the mass damper 5'corresponding to their vibration directions.
And 5 "are arranged orthogonally to each other. Since the mass dampers 5'and 5" are separated from the axis of the arm portion, when the torsional vibration is expected to be generated by the mass damper operation, the dotted line in FIG. As shown in FIG. 5, 5'a and 5 "a dampers (operating in the same direction as 5'and 5", respectively) may be added on the opposite side across the axis.

FIG. 3 is a principle diagram for actively operating the mass damper, in which the manipulator 1 is equivalent to the mass mass at the mass damper installation position according to the vibration mode.
It can be converted into a spring system and is represented by an oscillating mass M, an equivalent spring K, and a damping coefficient C. On the other hand, the mass damper 5 has a mass m for damping inside, and the mass m is generated by the damping force U generated by an actuator (linear motor, hydraulic cylinder, etc.).
To drive. The vibrating mass M is excited by an external force F.
The vibration of the vibrating mass M is detected by the vibration sensor 7.
The detected vibration information is fed back by the control law G and converted into the control force U. The inertial force of the mass m is always in balance with the control force U, and is in the form of a reaction force reception of the vibration-preventing control force U of the vibrating mass M, and the mass m is necessary for damping. The control law G is determined from control theory such as pole arrangement and optimal regulator. When the mass damper is effective in the direction in which gravity acts such as in the vertical direction, a force for gravity compensation is added to the control force U. When two such mass dampers are arranged as shown in FIG. 2 and acted in directions orthogonal to each other,
In-plane vibration perpendicular to the axis of the arm 4 is prevented, and as a result, vibration of the hand 2 is rapidly reduced.

FIG. 4 is an explanatory view of an example of operating a manipulator equipped with the vibration prevention device of the present invention, which uses a manipulator with a two-degree-of-freedom arm having a length of 600 mm and a hand on a vertical surface. Move the part to 200 mm x 50
The case where a 0 mm rectangular figure is drawn is shown.

FIG. 5 is a graph showing an example of the effect of the vibration prevention device of the present invention, in which the hand of the manipulator is represented by a figure A.
The change in the amount of flexure of the hand portion when the trajectory is followed and stopped in the order of BCDA is shown. In the figure, the solid line shows the case of the manipulator in which the vibration prevention device of the present invention is installed, and the dotted line shows the case of the manipulator in which the vibration prevention device is not installed.

As can be seen from this figure, in the manipulator in which the vibration preventing device of the present invention is installed, there is little vibration, and the vibration disappears promptly after stopping.

[0013]

The anti-vibration device for a manipulator according to the present invention (1) has a vibration-preventing effect on the hand portion only by being installed on the manipulator, and it is not necessary to remodel the control system or the mechanical portion of the manipulator main body. It can be easily attached to an operating robot, (2) it can improve the tracking accuracy of the hand part, and can shorten the settling time of positioning, and (3) reduce the weight and size of the entire robot. It is possible to contribute to energy saving, and (4) high-speed movement is possible, and work speed can be increased.

[Brief description of drawings]

FIG. 1 is a perspective view of an example of a robot manipulator in which a vibration prevention device of the present invention is installed.

FIG. 2 is a layout view of mass dampers for preventing in-plane vibration perpendicular to the arm section.

FIG. 3 is a principle diagram of an example for actively operating a mass damper.

FIG. 4 is an explanatory diagram of an example of operating a manipulator provided with the vibration prevention device of the present invention.

FIG. 5 is a graph of an example showing the effect of the vibration prevention device of the present invention.

[Explanation of symbols] 1 Manipulator 2 Hand part 3 Wrist part 4 Arm part 5 Mass damper 6 Pedestal 7 Vibration sensor M Manipulator vibration mass F External force m Vibration suppression mass G Control law U Control force

Claims (1)

[Claims] 1. A mass damper composed of a damping mass for generating an inertial force for preventing vibration and an actuator for driving the damping mass, and a control device for controlling the damping mass according to a sensor for detecting the vibration. A vibration preventive device for a manipulator, wherein a mass damper is installed on a wrist of the manipulator or an arm near the wrist.