JPH0625934B2 - Positioning control device for rotating body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a positioning control device for a rotating body suitable for stopping a spindle of a machine tool or the like at a fixed position, for example.

[Prior Art] FIG. 5 is a schematic configuration diagram of a conventional positioning control device,
In the figure, (1) is a control device that constitutes a feedback control system,
(2) is an electric motor whose speed is controlled by a command from this control device, (3) is an electric motor shaft, (4) is a gear connected to this electric motor shaft (3), and (5) is another one meshing with it. Gear, (6) is gear
A rotating shaft that is combined with (5) and becomes the main axis of the machine tool,
(7) is a small gear connected to the end of the rotary shaft (6), (8) is another small gear that meshes with this, (9) is a position detector connected to the small gear (8) , (10) are pulse encoders which are attached to the electric motor (2) and generate pulses in accordance with the rotation thereof.

FIG. 6 is a block diagram showing a detailed configuration of this positioning control device, and those denoted by the same reference numerals as those in FIG. 5 show the same elements. And (11) other than these are RO
Microcomputer equipped with M, RAM, and buffer, except for switches, whose functions are shown in blocks, (1
In 2), the position detector (9) rotates once and outputs 4 n pulses.
A counter that multiplies, (13) a counter that directly counts the n pulses that the position detector (9) makes one rotation and outputs, and (14) that is based on the count values of the counters (12) and (13). Position control circuit that calculates the speed command of), (15) is a pulse encoder
A speed detection circuit that counts the number of output pulses in (10) and outputs an N-bit, for example, 8-bit speed feedback signal,
(16) is a speed control circuit that calculates the deviation between the speed command output from the position control circuit (14) and the speed feedback signal output from the speed detection circuit (15) and applies the speed control signal to the electric motor (2), (17) is the first speed command for deceleration, (1
8) is the second speed command, (19) is the stop position command, and (20) is the first
When the speed command (17) and the speed feedback signal match, a speed reaching circuit that outputs a signal of "H", (21) is a gear ratio reading circuit that reads the gear ratio setting value, and (22) is a stop position command.
(19) is a position data reading circuit, (23) is a gear ratio setting device, (24) is a position loop gain circuit, and (25) is a position loop gain setting device for setting the gain of this position loop gain circuit. .

Hereinafter, the operation of this conventional positioning control device will be described with reference to FIGS. 3 and 6.

First, when the control device (1) applies a speed control signal to the electric motor (2), the electric motor (2) rotates and rotates at a speed determined by the gear ratio (gear ratio) of the gears (4), (5). The shaft (6) is driven. At this time, the position detector (9) is rotated via the small gears (7) and (8), and the position data of the rotation shaft (6) is fed back to the control device (1). In addition, the pulse encoder (10) is the motor (2)
The number of pulse signals according to the rotation of is applied to the control device (1). Therefore, the control device (1) compares the speed command calculated based on the output of the position detector (9) with the speed feedback signal obtained by counting the pulses of the pulse encoder (10), and the difference is zero. Electric motor (2)
In addition to that, the rotary shaft (6) is stopped at a fixed position.

Here, as shown in FIGS. 3 (b), (c), and (d), the position detector (9) includes n pulses for one rotation of the rotating shaft (6),
A pulse signal (9a) and a pulse signal (9b) whose phases are different from each other,
A pulse signal (9c) containing one pulse for one rotation of the rotating shaft (6) is output. Of these, the pulse signal (9
The counter (12) multiplies the pulse number by 4 for a) and (9b), and the pulse signal (9c) is directly converted to a value corresponding to the voltage by the counter.

Next, as shown in FIG. 3 (a), when a fixed position stop command is applied at time t ₁ , the position control circuit (14) switches the switch SW.
1 and SW2 are closed, and a first speed command (17) smaller than the normal operating speed is added to the speed control circuit (16), and at the same time, the gear ratio reading circuit (21) causes the gear ratio set value (23) ) Is read.
When the electric motor (2) is decelerated and reaches the first speed at time t ₂ , the first speed command (17) and the speed detection circuit (1
Since the speed feedback signals of 5) become equal, the speed arrival circuit (20) outputs a signal of "H", and the switch SW5 is closed at the rising timing of this signal.

When the switch SW5 is closed, the output signal of the counter (13) is applied to the position data reading circuit (22), the forward rotation side of the electric motor (2) rises at the timing when the signal rises, and the reverse rotation side shows its fall. At each timing, the reading of the stop position command (19) and the quadruple counting operation of the pulse signals (9a) and (9b) by the counter (12) are started. And counter (13)
When the count value of reaches the value corresponding to the first deceleration point, the position data reading circuit (22) opens the switches SW1 and SW2 and closes the switches SW3 and SW4. As a result, the second speed command (18) is applied to the speed control circuit (16), and at the same time, the gear ratio set value is read by the gear ratio reading circuit (21). Therefore, the electric motor (2) decreases to the second speed,
Position data reading circuit at time t ₄ when reaching the count value of the second deceleration point (22) to close the switch SW6.

Thus, the speed command calculated based on the stop position command (19) and the pulse signal (9a), (9b) of the position detector (9),
The speed of the electric motor (2) is controlled by the deviation in which the speed feedback signal of the speed detection circuit (15) is matched, and the rotating shaft (6) is stopped at the position of the count pulse of the stop position command (19). FIG. 7 is a flowchart showing the processing procedure of the position data reading circuit (22).

[Problems to be Solved by the Invention] The conventional positioning control device for a rotating body is configured as described above, and has a position loop gain from the second deceleration point until stopping at a fixed position and a position loop during stopping at the fixed position. Since the gain and the gain must be set to the same value, there is a problem that the positioning accuracy is low during the fixed position stop and the rigidity with respect to the deviation is inferior.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a positioning control device for a rotating body that can significantly improve the stop position accuracy of the rotating body and increase the rigidity due to deviation. And

[Means for Solving Problems] The positioning control device for a rotating body according to the present invention starts operation at a predetermined point where the rotating body has started deceleration, and the deviation between the stop position of the rotating body and the stop position command is A timer circuit that generates a signal at the time after the value completely becomes zero and position loop gain switching means that can switch and set the position loop gain to a higher one in response to the signal from the timer circuit are provided.

[Operation] According to the present invention, by setting the position loop gain to a high setting at a time point after the deviation between the stop position of the rotating body and the stop position command is completely zero, the stop position accuracy and the deviation can be reduced. Increase rigidity.

[Embodiment] FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, in which the same reference numerals as those in the conventional apparatus shown in FIG. 6 denote the same elements. Then, the operation is started by the output of the position data reading circuit (22), and when the deviation between the stop position of the electric motor (2) and the preset stop position command is assumed to be completely zero, the time is up and the signal is output. And a timer circuit (26) that outputs
6 is different from FIG. 6 in that a position loop gain switching circuit (27) capable of setting a high gain of the position loop gain circuit (24) is newly added after the time elapses. Before explaining the operation of this embodiment, the signal output timing from the timer circuit (26) will be described. In general, when decelerating a rotating body such as an electric motor to position it at a stop position, a position overshoot may occur during the period until the actual position of the rotating body reaches the target stop position and stabilizes at the target stop position. There is.

Therefore, if the position loop gain is set high when the target stop position is reached, the gain becomes too high in the overshoot period, which may induce vibration. Therefore, in the present embodiment, when the overshoot period has passed, the timer circuit (26) times out and outputs a signal to the position loop gain switching circuit (27).

Hereinafter, the operation of this embodiment will be described below with reference to FIGS. 2 to 4 with a focus on a portion to which a new element is added.

As shown in FIG. 2 (a), when the position data reading circuit (22) outputs a signal indicating that the second deceleration point has been entered, it enters the linear zone of the position loop gain setter (25) and the motor ( 2)
Starts decelerating and stops at the target stop point. Timer circuit (2
2) Start operation at time t ₅ slightly earlier than the target stop point as shown in Fig. 2 (b) and Fig. 3 (f), and set from the time when the overshoot period seems to pass. The stop completion signal is output after the lapse of the set time, and the gain switching signal (27a) is added to the position loop gain circuit (24) after the stop completion signal is output. Then, while stopped, position loop gain setter (25)
The position loop gain becomes larger than the value set by, and the stop position accuracy and the rigidity against deviation during stop can be increased. FIG. 4 is a flowchart showing this processing procedure.

It should be noted that, in the above-described embodiment, the one in which the spindle of the machine tool is stopped at a predetermined position has been described, but it goes without saying that the present invention can be applied to stop position control of a general rotating body driven by an electric motor.

[Effects of the Invention] As described above, according to the present invention, after the rotating body starts to operate at a predetermined point where deceleration has started, the deviation between the stop position of the rotating body and the stop position command becomes completely zero. Since the timer circuit that generates a signal at time and the position loop gain switching means that can switch and set the position loop gain to the higher side in response to the signal of this timer circuit are provided, the change of the speed command due to the gain switching is minimized. It is possible to suppress the occurrence of vibration and overshoot, and it is possible to improve the stopping accuracy and the rigidity while preventing the vibration and overshoot.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention,
FIGS. 2 (a), (b), and (c) are time charts for explaining the operation of the same embodiment, and FIGS. 3 (a) to (f) show the operation of the same embodiment as a conventional device. A related time chart, FIG. 4 is a flow chart for explaining the operation of the embodiment, FIG. 5 is a schematic configuration diagram of a conventional rotary body positioning control device, and FIG. 6 is a detailed configuration of the device. FIG. 7 is a block diagram showing the operation of the apparatus, and FIG. 7 is a flow chart for explaining the operation of the apparatus. In the figure, (1) is a control device, (2) is an electric motor, (6) is a rotating shaft as a rotating body, (9) is a position detector, (14) is a position control circuit, and (24) is a position loop gain. Circuit, (26) timer circuit, (27) position loop gain switching circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A rotating body is stopped at a fixed position based on a position detection signal for detecting a position of a rotating body driven by an electric motor and a stop position command obtained by setting a stopping position of the rotating body. In the positioning control device of the rotating body,
A timer circuit that starts operation at a predetermined point where the rotating body has started decelerating, and generates a signal at a time after the deviation between the stop position of the rotating body and the stop position command becomes completely zero,
A positioning control device for a rotating body, comprising position loop gain switching means capable of switching and setting the position loop gain to a higher one in response to a signal from the timer circuit.