JPH01128102A - Locus control method for robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a robot trajectory control method based on a speed plan, and in particular to smooth speed change in response to an external speed change command during trajectory control. Regarding countermeasures.

(Prior Art) Conventionally, as a general motion control method for robots, when a movement command signal for the arm tip is input, an optimal speed plan for the movement of the arm tip is drawn up in advance based on the movement command signal. However, a method is known in which interpolation points on the trajectory are calculated based on the basic speed plan and the arm tip is controlled to move between the interpolation points.

(Problem to be Solved by the Invention) However, in the case of the above conventional method, a speed change command signal is input from the outside while the robot arm is moving on a trajectory based on a basic speed plan that has already been created. However, it was extremely difficult to recreate the speed plan in an extremely short period of time, and in practice, it was nearly impossible to change the speed.

The present invention has been made in view of these points, and its purpose is to change the speed plan by changing only the arrival time of the interpolation point when a speed change command is issued while the arm tip of the robot is moving. The goal is to change the speed of the arm tip without changing the trajectory.

(Means for Solving the Problem) In order to achieve the above object, the solving means of the present invention is to formulate a basic speed plan in a speed planning section (2a), and to move on a trajectory to be moved based on the speed plan. After calculating each interpolation point sequentially at a predetermined period, a target position command signal corresponding to each interpolation point is output, and in response to the command signal, the control unit (6) controls the arm tip (A) of the robot (R). ) is assumed to be a robot trajectory control method that controls the movement of the robot.

At the same time as the target position command signal, the required time signal at each interpolation point is input into the control unit (6) in advance, and when a speed change command signal is input from the outside, the calculation cycle of each interpolation point is The purpose is to perform interpolation processing by keeping constant and changing only the required time input in advance in accordance with the speed change command signal.

(Operation) According to the above method, in the present invention, each interpolation point on the trajectory to be moved is sequentially calculated at a predetermined period based on the basic speed plan drawn up by the speed planning section (2a), and each interpolation point is calculated at a predetermined period. A target position command signal corresponding to the interpolation point is output. Then, in accordance with the target position command signal, the control unit (6) controls the arm tip (A) of the robot (R) to move on a trajectory.

In that case, the required time signal at each interpolation point is input into the control unit (6) in advance at the same time as the target position command signal,
When a speed change command signal is output from the outside, the calculation cycle of each interpolation point remains constant and only the pre-input required time is changed, so the robot (
Even if a change command is issued when the speed planning has already been completed during the operation of R), the speed at each interpolation point will be changed at a rate corresponding to the change rate of the required time. Therefore, the speed can be easily changed without re-creating the basic speed plan.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 shows an outline of a robot control device to which the present invention is applied, in which (R) is a robot that performs automatic assembly work etc. with the tip of the arm (A), and (C) is a robot that controls the operation of the robot (R). A controller to control, (D) is the controller (C)
This is an input device for giving commands to change the speed of the robot (R) while it is moving.

FIG. 2 shows the signal system of the controller (C).
1) is an interpreter that translates commands from the input device (D) and executes them according to the interpretation, and (2) is a plan for optimal movement of the robot (R) in response to commands from the interpreter (1). A planner who creates a speed plan for (3)
) is a feedback loop unit for comparing the position command signal based on the speed plan drawn up by the planner (2) with the actual position of the arm tip (A) of the robot (R) to feedback control its movement; (4) receives the control signal from the feedback loop section (3) and the robot (
A driver section (5) outputs a pulse signal for driving the arm end (A) of arm R), and (5) is a mechanism section that moves in accordance with the output of the driver section (4).

Then, in the feedback loop section (3),
(A) calculates the algebraic difference between the target position command signal based on the speed plan from the planner (2) and the position signal of the arm tip (A) from the compensator (15), which will be described later.
A) is the first summing point that detects the positional deviation; (8) is the first loop gainer that multiplies the position gain by 1 to the calculation result of the first summing point (7); and (9) is the first summing point. A second summing point (10) is the second summing point (9) that calculates the algebraic difference between the multiplication result of the loop gainer (8) and the velocity signal of the arm tip (A) from the compensator (15). ) is multiplied by the speed gain by 2 to output a torque signal for driving the arm end (A). Further, (12) is a first differential element that receives a position signal of the arm tip (A) and calculates the actual speed, and (13) further calculates the velocity of the arm tip (A) calculated by the first differential element. A second differential element (14) that calculates acceleration by differentiation is calculated using the position signal of the arm tip (A), the velocity calculated by the first differential element (12), and the second differential element (13). The fourth addition point (15) is the fourth addition point (15) that calculates the so-called PID component of velocity by adding the
This is a compensator for compensating the gain of the PID signal from ).

Next, in the driver section (4), (17) calculates the algebraic difference between the torque signal from the second summing point (10) and the current feedback signal for driving the mechanism section (5). The third summing point (18) that calculates and compensates for the phase delay is a signal converter that converts the torque signal from the third summing point (17) into a pulse signal and outputs a so-called PWM signal. The above feedback loop section (3
) and the driver section (4) constitute a control section (6) that controls the arm tip (A) of the robot (R).

In the mechanism section (5), (19) is a power amplifier for amplifying the PWM signal from the signal converter (18), and (20) is for amplifying the PWM signal from the power amplifier (19). A servo motor (
21) is an integral element as joint dynamics driven by the servo motor (20).

FIG. 3 shows the flow of signals in the control system. Commands such as the movement path of the arm tip (A) of the robot (R) are translated by the interpreter (1), and based on the translated commands, The trajectory planning section (2a) as a speed planning section of the planner (2) creates a basic trapezoidal speed plan consisting of an acceleration section (■), a constant speed section (■), and a deceleration section (■) as shown in Fig. 4, for example. Once the speed plan is created, the interpolation processing unit (2b) of the planner (2) calculates, as shown in FIG. 5, according to the speed plan.
Each point on the trajectory that the arm tip (A) should move, that is, the interpolation point, is calculated at each time of the so-called parametric variable pet (%) (distance traveled during the movement divided by the total distance). An interpolation process is performed to find the value at . At that time, the period to be calculated is a certain period of time To. Then, based on the data of each interpolation point obtained in the interpolation process, the interpolation process unit (2b) sends the robot (
The trajectory along which the arm end (A) of arm R) should move, that is, the value of the parameter pct at each fixed period TO, is output as a target position command signal. Further, within the control section (6), a control signal is outputted in the feedback loop section (3) according to the deviation between the target position command signal (1) and the actual position of the arm tip (A), and then a control signal is output to the driver. In section (4), the control signal is PW.
The signal is converted into an M signal to drive the mechanism section (5), and the movement of the arm tip (A) of the robot (R) is controlled.

Further, when a speed change command signal is input from the input device (D), the command signal is read by the speed change signal reading section (1a) of the interpreter (1) and then controlled as a required time change signal. The information is inputted into the section (6).

As a feature of the present invention, the interpolation processing section (2b)
When outputting the target position command signal from the controller (6),
A signal regarding the time required to reach that position, that is, the time T' at each interpolation point indicated by the horizontal axis in FIG. 5, is simultaneously input to the control unit (6), and the speed change signal is When a speed change command signal (required time change signal) is output from the reading section (1a) to the control section (6), the interpolation processing section (2b) first inputs the signal according to the signal. The required time T' for each interpolation point is newly changed.

Therefore, in the above embodiment, when it becomes necessary to change the speed while the arm tip (A) of the robot (R) is moving, when the speed change signal is output from the input device (D), the speed change signal is outputted from the input device (D). The signal reading section (1a) converts it into a modified signal of the required time T' at each interpolation point. For example, while the calculation period To remains constant, the required time T' is converted to T'+n. That is, in the control unit (6), the actual moving speed of the arm tip (A) of the robot (R) is changed from the initial setting to T'/T' 10n, and the speed change command signal is After the output time t○,
The moving speed will be changed as shown by the broken line (■) in FIG.

Therefore, even when the robot (R) is in operation and the speed plan has already been created, the speed can be easily changed in response to an external speed change command without having to re-devise the speed plan. It is possible to do this.

Also, as a result, the arm hand of the robot (R) (
It is possible to efficiently create an application program that takes into account the change in speed during movement in A).

(Effects of the Invention) As described above, according to the present invention, as a trajectory control method for a robot, when instructing the control unit to provide a position command signal for each interpolation point corresponding to the trajectory of the arm tip, each interpolation point is The required time at each interpolation point is also commanded at the same time, and when a speed change command is issued from the outside, the required time at each interpolation point is changed according to that command signal.
Speed changes can be easily made without having to redesign the speed plan. Furthermore, application programs can be created efficiently.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a block diagram showing the flow of control signals within the controller, FIG. 2 is a perspective view showing the outline of the entire device, and FIG. 3 is a block diagram showing the configuration of the controller. 4 is a speed diagram based on the speed plan, and FIG. 5 is a change characteristic diagram of parameter variables corresponding to the speed diagram of FIG. 4. (2a)...Trajectory planning section (speed planning section), (2b)...
...Interpolation processing unit, (6)...Control unit, (A)...Arm hand, (R)...Robot, (D)...Input device. Agent Patent Attorney Former 1) Hiroshi 1
1. ''J4. ．． □“−゛〈f

Claims (1)

[Claims] (1) The speed planning unit (2a) creates a basic speed plan, calculates each interpolation point on the trajectory to be moved sequentially at a predetermined period based on the speed plan, and then corresponds to each of the above interpolation points. The control unit (
In the robot trajectory control method in which the movement of the arm tip (A) of the robot (R) is controlled in step 6), the control unit (6) sends the required time signal at each interpolation point in advance at the same time as the target position command signal. When a speed change command signal is input from the outside, the calculation cycle of each interpolation point above remains constant, and only the required time input in advance is changed according to the speed change command signal. A robot trajectory control method characterized by performing interpolation processing.