JPH0782380B2 - Position control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for controlling a robot manipulator, and more particularly to a control apparatus with improved operation performance when the operation time is changed in real time.

(Prior Art) FIG. 6 shows a target position during movement. It is explanatory drawing at the time of changing to. In the conventional method, the target position is temporarily stopped and then updated again. Move to. Generally, the inertia of the manipulator is not small, so accelerate the manipulator from a stationary state to reach the specified maximum moving speed. Acceleration distance to reach up to la, maximum moving speed Requires a rest distance lb from to rest. If the moving distance is longer than the sum of the acceleration distance and the stationary distance, there is a section that moves at a constant speed. There are various methods of determining the characteristics of acceleration / deceleration, but for example, a method of using a cubic velocity pattern with respect to time and making the acceleration distance la and the stationary distance lb equal is used.

(Problems to be solved by the invention) However, the target position before the update When stopped at, there is a problem that the operation time is long due to the acceleration / deceleration operation.

In seam tracking (welding line tracking during welding), for example, the 14th International symposium of Industrial Ro
Proceedings of bots (1984) “A visual seam tracking syste
There is also a control device known in "m for arc welding Robots" that can add an offset via an operation in real time by input from an external sensor, but it is only for temporary offset, and the operation target position is changed. The route cannot be changed significantly.

The present invention solves such a problem. Even when the robot manipulator is in operation, the target position is changed in real time and the operation path is smoothly changed without stopping the manipulator by an external command. It is an object of the present invention to realize a position control device that operates.

(Means for Solving Problems) The present invention that achieves such an object controls the operation of a controlled object in real time by an external command, and
The position control device capable of changing the target position at any time by the command of the target position sent from the outside has the following configuration.

That is, the target position updated from the outside instead of the original target position And a current position of the controlled object at the time of receiving the updated target position. And speed (Vs) and the initial target position Current position storage means (2, 3) for storing the position, and a position for decelerating from this current position and stopping in the direction of the initial target position Using the maximum acceleration (Amax) that occurs when the controlled object moves, A virtual waypoint computing means (4) for computing by the above, the updated target position and this virtual waypoint Change operation end point And a curvilinear trajectory for smoothly connecting the straight line portion from the current position to the virtual via point and the straight line portion from the virtual via point to the updated target position, The connection point between the straight line portions of the curved track is provided with the current position and the track calculation means (6, 7) which is the change operation end point.

Then, the controlled body is moved from the current position to the updated target position along the curved trajectory.

(Operation) The virtual waypoint calculation means determines a virtual waypoint serving as a reference for correcting the trajectory to the updated target position by calculation. The change operation end point calculation means calculates the change operation end point from the updated target position and this virtual waypoint, thereby simplifying the calculation of the curved trajectory. The trajectory calculating means obtains a curved trajectory from the current position and the end point of the change operation, so that even if the target position is updated on the way to the original target position, the trajectory is corrected quickly and smoothly.

(Example) The present invention will be described below with reference to the drawings.

FIG. 1 is a configuration block diagram showing an embodiment of the present invention. In the figure, 1 is a target position instructed from the outside such as a host computer by communication or the like. The target position receiver for storing 2 is 2 and the target position receiver 1 is the initial target position When the target position is updated, the initial target position register 3 that stores the initial target position stores the position information of the robot arm when the target position receiver 1 receives the updated target position. The current position is stored in the current position storage means. And save the moving direction and speed (Vs). Reference numeral 4 is a virtual waypoint calculating means for calculating a position (hereinafter referred to as "virtual waypoint") that decelerates from the present position and stops in the direction of the original target position. Ask for.

Where Dd is the distance required to decelerate and stop, Amax
Is the maximum acceleration that occurs when the robot arm moves.

5 is a change operation end point from the updated target position and virtual waypoint In the change operation end point calculator, the change operation end point means a position smoothly connected to a straight line trajectory connecting the virtual waypoint and the updated target position, and is calculated by the following equation.

Reference numeral 6 is a change operation parameter calculator for calculating a curved trajectory that smoothly connects the current position to the end point of the change operation, and obtains the following equation which is, for example, a quartic spline curve.

Reference numeral 7 denotes a target change trajectory generator that calculates the position to move the robot arm from the current position to the updated target position via the curved trajectory of equation (3), and calculates the case where the robot arm exists on the curve. Reference numeral 8 is a normal trajectory generator that calculates the position of the robot arm with respect to the normal trajectory that performs linear motion, and 9 is a control unit that controls the robot arm by switching between the target change trajectory generator 7 and the normal trajectory generator 8.

The operation of the apparatus thus configured will be described below. Second
FIG. 3 is a plan view of the trajectory of the robot arm moving, and FIG. 3 is an explanatory view of the moving speed of the robot arm.

Initially the robot arm is the starting point From the initial target position It starts moving to reach a predetermined maximum speed Vmax. When the target position is updated on the way , Virtual changes Is calculated to obtain a quartic spline curve that smoothly connects the first movement and the updated movement.
On this curved trajectory, the robot arm first decreases its speed and then accelerates to move so as to be the same before and after the connecting point (t = 0, Tp). After that, the robot arm stops at the updated target position.

4 and 5 are explanatory views when the update command is issued at a place near the first target position. Since the updated target position is close to the virtual waypoint, it will decelerate with the update command and then And a virtual waypoint Position between To a curved orbit. Although it moves according to the equation (3) on the curved track, the speed is smaller than the maximum speed vmax. Then change operation end point Causes linear movement, decelerates and stops at the updated target position.

Although the robot arm has been described as an example in the above embodiment,
The present invention is not limited to this, and may be a numerical control device, an XY stage, a plotter, or the like as long as it controls at least two axes.

Also, the positional relationship on the plane is shown, but the same applies to a three-dimensional space.

(Effects of the Invention) As described above, the present invention has the following effects.

(A) Since the target position and route can be changed in real time by sensor input or commands from the interrupt processing program,
Robot motions that flexibly respond to changes in external conditions can be realized.

(B) Being able to change the target position in real time, when applied to a robot, is useful for a wide range of applications of the robot.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of the present invention, and FIG.
The figure is a plan view of the moving track, FIG. 3 is an explanatory view of the moving speed, FIGS. 4 and 5 are explanatory views of other usage states of the present invention, and FIG. 6 is a case where the target position is changed on the way. FIG. 1 ... target position storage means, 2, 3 ... current position storage means,
4 ... Virtual waypoint calculation means, 5, 6 ... Trajectory calculation means, 7,
8,9 …… Control means.

Continuation of the front page (56) Reference JP 61-97708 (JP, A) JP 59-38811 (JP, A) JP 58-51305 (JP, A) JP 58-211211 (JP , A) JP 59-45506 (JP, A) JP 57-21602 (JP, A)

Claims (1)

[Claims] 1. A position control device capable of controlling the operation of a controlled object in real time by an external command and changing the target position at any time by a command of a target position sent from the outside, wherein an initial target from the external device is provided. Target position updated instead of position And a current position of the controlled object when the updated target position is received. And speed (Vs) and the initial target position A current position storage means (2, 3) for storing the current position, and a position for decelerating from this current position and stopping in the direction of the initial target position Using the maximum acceleration (Amax) that occurs when the controlled object moves, A virtual waypoint computing means (4) for computing by the above, the updated target position and this virtual waypoint Change operation end point A means (5) for calculating, a straight line portion from the current position to the virtual waypoint, and a curved path that smoothly connects the straight line portion from the virtual waypoint to the updated target position, and The connection point between the straight line portions of the curved track is provided with the current position and the track operation means (6, 7) which is the change operation end point, and is updated from the current position to the curved track. A position control device for moving the controlled object to a target position.