JPH0514518B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC motor having an automatic gain switching circuit. Also included]
The present invention relates to a position control circuit.

Conventionally, the most common method for controlling the position of a DC motor is a method using a command pulse train.

When used with a microcontroller, the parallel data from the I/O port is used as a position control signal for the DC motor, or this parallel data is first converted into a command pulse train (serial data) and input to the deviation counter. It uses means.

However, a converting circuit from parallel data to serial data is required, and this circuit portion occupies a considerable proportion of the cost, so it has the disadvantage of being expensive.

For this purpose, a method has recently been considered in which the position of a DC motor is controlled by directly inputting parallel data.

However, in this case, if the data is large, problems such as overshoot due to rapid acceleration of the DC motor may occur, so it cannot be said to be an optimal control method.

This is common to the conventional control methods described above, but since the command voltage gain for position control of the DC motor is constant, when the command voltage is increased in order to increase the hold torque of the DC motor, This has the disadvantage that a hunting phenomenon occurs during the rotation of the DC motor. Therefore, the gain of the command voltage cannot be amplified and increased, resulting in a drawback that sufficient hold torque cannot be obtained.

A control circuit shown in FIG. 1 is a position control method using parallel data as a command input, which is one of the position control methods for a DC motor to eliminate such drawbacks.

This will be explained below with reference to the block diagram of a DC motor position control circuit shown in FIG.

1 is the microcomputer (microcomputer) I/
Parallel data 2 obtained from the O port is a presettable up/down counter, which is preset by inputting the parallel data 1 obtained from the outside. 3 is a D/A converter that converts the output of the presettable up/down counter 2 into an analog voltage and inputs it to the adder 4 as a command voltage for the motor 6. The adder 4 inputting the command voltage outputs a predetermined voltage signal to the motor drive circuit, and the output voltage signal of the drive circuit 5 causes the DC motor 6 to rotate in a predetermined direction. When the DC motor 6 rotates, a pulse generator 7 such as an encoder directly connected (or connected) to the motor 6 also rotates at the same time, generating pulses according to the number of rotations. As a result, the pulse generator 7 outputs two-phase signals 7a, 90 degrees out of phase,
7b is output to the direction discrimination circuit 8. When these signals 7a and 7b are input to the direction discrimination circuit 8, the rotation direction of the DC motor 6 is discriminated by the circuit 8, and the speed feedback obtained depending on the case where the DC motor 6 is in the forward rotation direction is determined. A speed feedback pulse signal 8b is obtained depending on the pulse signal 8a and the reverse direction. A speed feedback loop as a minor loop is constituted by an F (frequency)/V (voltage) converter 9, and is subtracted and inputted to the adder 4. Further, the speed feedback pulse signals 8a and 8b are inputted to the up-down counter 2 as count pulses. In this case, it becomes a down count, and the parallel data 1 is subtracted. Furthermore, the DC motor 6 continues to rotate until the content of the up-down counter 2 becomes "0".

In this way, the position control of the DC motor 6 is performed.

However, according to this position control method, since parallel data 1 is input, the rotation speed of the DC motor 6 cannot be determined arbitrarily. This is because when parallel data 1 is input and the number of bits in the D (digital)/A (analog) converter 3 is small, the output of the D/A converter 3 is often saturated. . Therefore, if the weight per count is set to be heavy in the initial settings, the DC motor 6 will start at high speed when data is input.
To accelerate, overshoot occurs.

Therefore, if any inconvenience occurs to the device,
Currently, the output gain of the D/A converter 3 is lowered.

However, when the output gain is lowered, the DC motor 6 may not start even if there is a slight positional deviation depending on the load condition at that time, and a positional error may occur.

The present invention has been made in order to solve the above-described drawbacks of the position control circuit for a DC motor.

In other words, the present invention makes it possible to automatically switch and select the optimal gain for a DC motor in response to parallel data without the need for a conversion circuit for converting parallel data into serial data, thereby preventing sudden changes in the DC motor gain. Even when stopping the motor by lowering the output gain, the motor is stopped while keeping the speed at the optimum value while selecting the optimum gain.
The object of the present invention is to provide a position control circuit for a DC motor that has an automatic gain switching circuit that can ensure accurate stopping accuracy.

The object of the present invention is to provide a position control means for controlling the position of the DC motor 6 by inputting one parallel data, and to control the feedback pulses 8a and 8b obtained from the pulse generator 7 connected to the DC motor 6. Digital comparator circuits 13-1, . . . , 13- that are equipped with position deviation data 10 obtained as a result of inputting to the up-down counter 2 and compare the position deviation data 10 with a plurality of setting reference data 11-1, . . . , 11-5. 5, and a decoder 14 for decoding the output data of the digital comparator circuits 13-1, . . . An analog switch selection circuit 1 consisting of a plurality of analog switches 15A that selects only one of the plurality of amplifier circuits 12 having different gains depending on the output.
5, and outputs the positional deviation data 10 to D/
The analog switch selection circuit 1 includes an amplifier 12 for outputting a plurality of A-converted gains.
This can be achieved by providing a position control circuit for a DC motor having an automatic gain switching circuit characterized in that it is equipped with means for selecting one of the outputs of No. 5 and energizing the DC motor with the output.

Referring to FIG. 2 below, a position control circuit for a DC motor having an automatic gain switching circuit according to the present invention is as follows.
Position deviation data 10 and setting reference data 11-1,
..., 11-5, the gain of the analog voltage is switched.

First, as in the case of FIG. 1, the parallel data 1 for position control of the DC motor 6 is presettable.
It is input to the up-down counter 2 and preset. Then, the position deviation data 10 obtained by inputting the feedback pulses 8a and 8b of the parallel data 1 to the up-down counter 2 is transferred to the D/A converter 3.
The amplifier 12 outputs a speed command voltage.

In this way, a position deviation calculation circuit is constructed.

At the same time as the command voltage is output, position deviation data 10 and a plurality of setting reference data 11-1,
..., 11-5 is the digital comparator 13-1,
..., 13-5. This comparison data is decoded by the decoder 14, and the analog switch selection circuit 15 selects one of the plurality of analog switches 15A.

Therefore, by setting the output gain of the D/A converter 3 in advance using a plurality of amplifiers 12 according to the amount of deviation, the gain can be automatically switched. For example, when the deviation is large, the gain is lowered to prevent overshoot at startup, and when the deviation is small, the gain is raised to eliminate positional deviation, thereby increasing the stopping torque.

Incidentally, the output of the selection circuit 15 is output to the adder 4, and the subsequent configuration and operation thereof are the same as in the case of FIG. 1, so a description thereof will be omitted.

As is clear from the above, according to the DC motor position control circuit using parallel data input of the present invention,
Compared to the conventional command pulse train input method, there is no need for a conversion circuit from parallel data to serial data, which not only makes it possible to construct it at a lower cost, but also allows the DC motor to be accurately stopped at the optimal position, resulting in high accuracy. There are expensive things that can be easily configured. Furthermore, if the comparison calculation is performed using a microcomputer, it is possible to further reduce costs, and the circuit space can be omitted, allowing the device to be made smaller. Therefore, the present invention as described above,
When used in industrial robots, etc., accuracy can be greatly improved compared to conventional ones.

[Brief explanation of the drawing]

FIG. 1 shows a block diagram of a conventional DC motor position control circuit using parallel data input, and FIG. 2 shows a block diagram of a DC motor position control circuit having an automatic gain switching circuit according to the present invention. 1...Parallel data, 2...Presettable down counter, 3...D/A converter, 4...
Adder, 5...Motor drive circuit, 6...DC motor, 7...Pulse generator, 8...Direction discrimination circuit, 8a, 8b...Speed feedback pulse signal, 9...F/V converter, 10... Position deviation data, 11-1,..., 11-5... Setting reference data, 12... Amplifier, 13-1,..., 13-
5...Digital comparator, 14...Decoder, 15...Analog switch selection circuit, 15A
...Analog switch.

Claims (1)

[Scope of Claims] 1. A position control circuit for a DC motor having an automatic gain switching circuit, characterized by comprising the following components. Equipped with position control means for controlling the position of the DC motor 6 by inputting one parallel data. Feedback pulses 8 obtained from a pulse generator 7 connected to the DC motor 6
It is provided with positional deviation data 10 obtained as a result of inputting a and 8b into the up-down counter 2. Multiple setting standard data 11-1,...,11-
digital comparator circuits 13-1, . Early digital comparator circuit 13-1,
. . , 13-5. The digital comparators 13-1,...,13
Decoder 14 for decoding the output data of -5.
The analog switch selection circuit 15 is provided with a plurality of analog switches 15A for selecting only one of the plurality of amplifier circuits 12 having different gains based on the output of the analog switch 15A. an amplifier 1 for outputting a plurality of gains obtained by D/A converting the output of the positional deviation data 10;
2. A means is provided for selecting the output of the analog switch selection circuit 15 and energizing the DC motor with the output.