JPS59175390A - Positioning control circuit of dc motor - Google Patents

Abstract

PURPOSE:To prevent the vibration after positioning by completely interrupting a control input during the period less than positive and negative pulses including zero at the output of an error counter. CONSTITUTION:An error counter 2 compares an input pulse to be positioned as a target with a shaft rotating input pulse. When both inputs are equal, a detector 8 is started, an FF circuit 10 is set, and a power switch circuit 11 is opened. A control circuit of a motor 5 is interrupted due to the opening of the switch circuit 11, and a motor shaft is stopped. In this case, a detector 9 does not operate unless the pulse from a sensor 7 side due to overrun is less than two. Accordingly, inputs from controllers 3, 4 are interrupted as long as the output of the counter 2 is two pulses including zero.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a positioning control circuit for a DC motor driven by a negative feedback servo circuit.

(b) Background of the Technology In machine tools that use motors as drive sources, it is widely practiced to extract the movements of the movable parts of two machines using rotation information of the motor shafts.

The present invention proposes a control circuit that prevents the motor from being photographed especially after positioning with a predetermined accuracy.

(c) Prior Art and Problems FIG. 1 is a circuit block diagram of automatic feedback control for a motor drive source.

In the figure, 1 is a controller with digital input settings for motor control, 2 is an error counter that inputs the input of the controller 1 and the rotation information of the controlled motor M example, 3 is a digital-to-analog converter B (DA converter), and 4 is the DA converter. A servo amplifier for driving a motor that amplifies the analog output of the converter 3, 5 is a controlled motor M, and 6 is an encoder that outputs the rotation information directly connected to the motor shaft. Furthermore, 7 is a sensor 1 that detects the rotational direction of the motor. The line attached to the output line of sensor 7 is a clockwise direction, and cch is a counterclockwise sign.

The sensor feeds back motor shaft information to the error counter for each rotation direction. That is, the error counter 2 compares the input (pulse) of the sensor 7 based on the set amount (target amount) of the controller 1, and when the difference count becomes zero, the output of the servo motor 4 becomes zero.

By the way, in the conventional block circuit shown in FIG. 1, even if the error counter output becomes zero, the motor does not stop due to the inertia of the motor, but overruns in the opposite direction. Along with this, the encoder 6 goes to the error counter 2, which had previously had zero output.
By sending out a rotation pulse in the opposite direction from the sensor 7 and the sensor 7, a motor drive pulse in the opposite direction to the rotation direction mentioned above is output. However, even when the motor rotates in the reverse direction, overrun occurs again, and this is repeated. This causes vibration when the motor is stopped, which is extremely inconvenient.

(d) Purpose of the invention The present invention is to solve the above-mentioned disadvantages.

That is, a switch circuit is added that disables (cuts off) the servo amplifier output for a certain period of time after the error counter detects zero.

(e) Structure of the Invention The above-mentioned object is to provide an error counter that compares an output on the controller side to which a digital input is set and an output on the encoder side for detecting the amount of motor shaft rotation, performs OA conversion on the output of the error counter, and converts the output of the error counter into an OA converter. In a control circuit in which a motor is driven by a servo amplifier output that amplifies a converted analog quantity, the error counter outputs a detection circuit that stops motor control during a predetermined cycle pulse period of positive and negative output pulses in which the error counter output includes zero. This can be achieved by providing it on the side.

(f) Embodiments of the Invention The present invention will be described in detail below with reference to FIG. 2, which shows an embodiment of the present invention.

In the circuit block diagram of FIG. 2, in comparison with the previous version, the part with a double border is the vibration control circuit section after motor positioning, which is the main part of the second invention.

In the figure, 8 is a detector (hereinafter abbreviated as DET) that detects the zero output of the error counter 2, 9 is a DET that detects two period sections of positive and negative output pulses of the error counter 2, and 10 is a detector that detects the zero output pulse of the error counter 2. A flip-flop (FF circuit) operated by the detection output, and 11 a power switch circuit (23 circuits) inserted between the servo amplifier 4 and the motor 5.

Next, the operation of the circuit shown in FIG. 2 will be explained.

The error counter 2 is a comparator that compares and counts inputs of the target input pulse for positioning on the 1 side and the shaft rotation input pulses on the 6 and 7 sides. For example, if the setting input is 20, the input from sensor 7 operates to reduce the setting value. And when the output is zero or the human power of both is equal.

DET8 on the rear stage side starts up first, and the cent of the F-F circuit (
Activate the S) side terminal. As a result, F-F circuit 1
0 makes the output line on the side of the 1PS circuit 11, for example, H level;
During the level period, 23 circuits are opened.

By opening the PS circuit 11, the motor control circuit is cut off and the motor shaft stops rotating. In this case, as long as the number of pulses from the sensor 7 side due to overrun is less than 2, the DET 9 will not operate, and therefore there will be no input from the reset terminal (R3) of the FF circuit 10.

For this reason, the power switch circuit (circuit 23) maintains the cut-off state.

That is, during the two-pulse interval in which the output of the error counter 2 includes zero, the inputs from the control circuits 3 and 4 to the positioning motor shaft are completely cut off.

Next, if the input for sequential motor control is manually applied on at least two sides from the controller 1 side, two sections of the pulse can be detected.
ET 9 is activated to activate the reset terminal (terminal R3 in the figure) of the rear-stage FF circuit 10 to close the open ps circuit.

By closing the PS circuit 11, the motor control input circuit becomes a circuit similar to that shown in FIG. For example, when a clockwise (or) rotational digital input is sent to the motor 5 from the controller 1, the motor rotation is started in proportion to the input via the D^ converter 3 and the servo amplifier 4. The same applies when instructing the motor 5 to rotate counterclockwise (CCW).

The feedback of rotational information from the encoder 6 and sensor 7 to the error counter upon starting the motor rotation is also the same as in FIG.

When the number of feedback pulses becomes equal to the number of input pulses, the DET 8 is activated again, and the motor rotation is stopped following the same process as described above.

In other words, once the motor has been positioned by zero detection, the motor input becomes invalid unless there is a control input equal to or greater than either positive or negative nivals.

Although it is difficult for such a motor positioning control circuit to control positioning at the minimum resolution, i.e., the amount of movement per pulse, the control circuit of the present invention uses double the accuracy of the minimum resolution to provide accurate positioning control when the motor is stopped. 1.Dialogue is prevented, and 2.the problems of the conventional system are solved.

(g) Effects of the Invention According to the positioning control circuit for a DC controller of the present invention, which has been explained in detail with reference to the embodiments, the control input is completely cut off during the period in which the output of the error counter 2 includes zero and is less than the positive and negative nivals. This has the advantage of preventing vibration after the first positioning.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional motor control circuit, and FIG. 2 is a block diagram of the same motor control circuit showing an embodiment of the present invention. In the figure, 1 is a controller and 2 is an error counter. 3 is a DA converter, 4 is a signal amplifier, 5 is a motor, 6 is an encoder, and 8 is an output zero detector (0-DET). 9 is 2 two-period pulse section detector (±2 DET)
.

Claims (1)

[Claims] It is equipped with an error counter that compares the output on the controller side, where the digital input is set, and the output on the encoder side, which detects the amount of rotation of the motor shaft. The DC motor is characterized in that, in the control circuit to be driven, a detection circuit is provided on the output side of the error counter for stopping morph control during a predetermined cycle pulse period of positive and negative output pulses in which the error counter output includes zero. positioning control circuit.