JPS6059407A - Position control method - Google Patents

Abstract

PURPOSE:To control smoothly the speed of an object to avoid an evil effect to a machine mechanism by controlling the gain of a position control loop so that the speed changing factor is reduced when the object passes through points between two specific points. CONSTITUTION:The signal of a resolver 2 synchronizing with a motor 1 is converted into a pulse by a converter 3. These pulses are counted by a counter 4. A shift amount is delivered from a position command output part 5, and the difference between this shift amount and the output of the counter 4 is delivered by an integration counter 6. This difference is supplied to a speed control part 9 through an amplifier 7 and an A/D converter 8, and the value of the counter 6 is controlled to zero. The position command values V2 and V1 are extracted from the part 5 by a position command part 10. Then V2/V1 is calculated by an arithmetic unit 11, and the gain of the amplifier 7 is switched at the place near a passing point. The gain of the amplifier 7 is reset to the original amplification factor after passing the point. Thus it is possible to perform smooth control of speed when an object passes through points between two specific points and to avoid an evil effect to a machine system.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for controlling the position of a robot or automatic machine having a servo motor.

[Technical background of the invention and its problems]

In a robot, etc., p from point A to point B as shown in Figure 1.
'rp method (connect specified points and do not care about the route)
If you want to specify a pseudo route between two points when trying to move the tip of the arm, there is a method of specifying point 0 as a waypoint between points A and B. At this time, high positioning accuracy at the 0 point is not required, and the positioning completion range at the 0 point (hereinafter referred to as in-position zogon) is widened in order to shorten the time and smooth the movement of the arm tip. There is. However, in order to maintain accuracy at a certain level, there is a limit to the size of the in-position zone, and when the arm tip enters in-position, the speed decreases, and B
It must accelerate again to the speed towards the point. That is, the X direction.If you think about it, the first command to move from point A to point 0, as shown in Figure 2, and the command from point 0 to B, which is output after the tool enters the 0 point position zone, are shown in Figure 2. In response to the second command to move to a point, the speed decreases once between the two commands, as shown in FIG. 3, and then increases again. Therefore, Fig. 3 1. The speed change in the vicinity becomes large.

[Object of the Invention] It is an object of the present invention to provide a position control method that improves the above-mentioned drawbacks, minimizes changes in speed at waypoints such as point C in Figure 1, and smoothes the movement of the arm. With the goal.

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides, in the vicinity of a waypoint,
This is a position control method in which the gain of the position control loop is adjusted so as to reduce the speed change rate.

[Embodiments of the invention]

The present invention will be explained below based on one embodiment of the accompanying drawings.

The paths A-, C-, and B in FIG. 1 are controlled by a device that performs positioning within the xy plane using the ``2'' axis that moves in the X direction and the ``2'' axis that moves in the X direction. At this time, the two axes are controlled to start and stop at the same time (synchronous control).

FIG. 5 shows a block diagram of a position control system embodying the present invention. In the figure, a signal from a resolver 2 synchronized with a motor 1 is converted into pulses by a converter 3, and counted by a counter 4. This counter 4 is read out and cleared every sampling time Δ. The position command output unit 5 outputs the amount of movement between Δ and the difference from the output of the counter 4 is input to the integral counter 6. The output of the integral counter 6 is amplified by an amplifier 7 and inputted to a speed control section 9 through a D/A converter 8, and is controlled so that the value of the integral counter 6 becomes 0. The above control is performed for both the ■ and II axes. Further, the position command output section 5 monitors the output of the integral counter 6, and starts outputting a position command for the flame after entering the in-position. Therefore, when controlling the operation shown in FIG. 1, the two commands A-, C, and CB become as shown in FIG. Therefore, in the present invention, the position command reading unit 10 extracts the position command values V and ■ from the position command output unit 5, the arithmetic unit 11 calculates v2/vI, and the gain adjuster 12 calculates the value shown in FIG. The gain of the amplifier 7 is switched at time t, as shown in FIG. Then, at time t3, the amplification factor is returned to the original amplification factor GO.

[Operations and Effects of the Embodiment] When the control method described above is used, in controlling the operation shown in Fig. 1, the speed response near the way point C becomes as shown in Fig. 4, and the speed change when applying force at the C point becomes as shown in Fig. 4. It becomes less. In this embodiment, the case of V2/V14-Pl was described as shown in Fig. 2, but even when vv/V1 becomes a negative value, the gain of the position loop becomes high as shown in Fig. 6. Therefore, from the first command (A → C) to the second command (C,
You can quickly move to B). GO indicates normal loop gain.

This can prevent adverse effects on the robot, automatic machine itself, or workpiece. Further, by providing a large number of route points close to each other and applying the present control method to each point, the route between two points can be controlled in a pseudo manner.

〔Effect of the invention〕

As explained above, the present invention has the following effects.

Since it is possible to smoothly control the speed when passing through a point or a plurality of waypoints provided between two points, it is possible to prevent adverse effects on the mechanical system and to cope with work that requires controlling the route between two points.

[Brief explanation of the drawing]

Figure 1 shows the in-position zone, Figure 2 shows the movement amount command in the X direction (■ axis) when passing through the route shown in Figure 1, and Figure 3 shows the conventional response to the movement amount command. FIG. 4 is a characteristic diagram showing the response when the present invention is applied to FIG. 2, FIG. 5 is a block diagram showing the control method of the present invention, and FIG. 6 is a characteristic diagram showing v, /v, FIG. 3 is a diagram showing the relationship between gain and gain. 1... Servo motor 2... Resolver 3... Pulse conversion i 4... Pulse counter 5... Position command output section 6... Integral counter 7... Amplifier 8...
D/A converter 9...Speed control unit 1o-...Position command reading unit 11...Arithmetic unit 12...Gain adjuster (7
317) Agent: Patent Attorney Noriyuki Chika (and 1 others)
Name) Figure 2 → FJ! tP t2 '3 t□fl) Figure 5 Figure 6

Claims (1)

[Claims] When a device that controls the position of a robot, automatic machine, etc. that operates based on a series of position data passes through a specified waypoint while moving from the current location to the next target point, the position is determined near the waypoint. A position control method characterized by smoothly controlling the motion of a controlled object by adjusting the gain of a loop.