JPH02219481A - Potation control circuit for rotating body - Google Patents

Abstract

PURPOSE:To eliminate a discretization phenomenon of speed data at the time of a low speed and a pulse vanishing phenomenon at the time of a high speed by decreasing the multiple of a multiplication signal from 4 to 1 in the range where a control according to a quadrupling signal exceeds a possible speed. CONSTITUTION:A comparator 13 receives a signal 19 being actual value data of a speed, judges whether said data is more of less than a certain threshold value, and outputs a signal 15 being 1-bit information. A latch circuit 12 clocks the signal 15 from said comparator 13 by a sampling pulse signal 17 and sends its output signal 16 to a speed detector 7, a position transducer 8 and a selector circuit 9. Said selector circuit 9 receives the signal 16 and outputs the output pulse of a rotary concorder 5 selectively to a quadrupling circuit 10 or a multiplying circuit 11. That is, when the actual value data of said speed is larger than the change-over speed of the multiple of a multiplied signal, said monoploid circuit 11 operates to input said data to said speed detector 7 and position transducer 8 to perform the operation of said speed and position.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a control circuit that controls the rotation of a rotating body using a rotary encoder.

[Conventional technology]

7. A method of using a rotary encoder to detect the speed and position of a rotating body is known. There is. A control circuit for a servo motor using a conventional row encoder has a configuration as shown in FIG. In the figure, l is APC (position adjuster)
, 2 is an ASR (speed regulator), 3 is an ACR (current regulator) system, 4 is a servo motor, 5 is a rotary encoder attached to the rotating shaft of the servo motor 4, and 6 is a pulse output from the rotary encoder 5. A pulse shaper shapes the waveform of the signal, 7 is a speed detection section, and 8 is a position detection section. From the low-resolution encoder 5, approximately 9 as shown in Fig. 4 is output.
Two signals, an A-phase pulse and a B-phase pulse, with a phase difference of 0@ are output. The duty ratio of both signals is approximately 50%, and the frequency is proportional to the rotation speed of the servo motor 4, so if you know the frequency of this pulse, you can know the rotation speed of the servo motor 4, and by integrating it, you can also know the position of the servo motor. It is. By the way, there are generally two methods for detecting frequencies: (b) A method of counting the number of pulses within a certain sampling time and detecting the frequency through digital processing. (II) A method of detecting the frequency by analog processing through an F/V circuit. In both methods (a) and (0), in order to increase the detection resolution, the A-phase and B-phase pulses are shaped into one pulse at the edge of each pulse as shown in Figure 5, and then the signal (4
(transfer signal). The pulse shaping circuit 6 shown in FIG. 3 performs this conversion. That is, in the method (A), the frequency is detected by counting the number of pulses of this quadrupled signal, and in the method (TI), this signal is passed through an F/V circuit, converted into a voltage equivalent, and the frequency is detected. Detected.

[Problem to be solved by the invention]

Now, in order to control the rotating body with high precision using the conventional control method, it is necessary to increase the number of output pulses of the rotary encoder, but if a multi-pulse encoder is used and high-speed operation is performed, as shown in Figure 5. A phenomenon occurs in which the pulses of the quadrupled signal shown in the diagram are connected. Possible causes of this phenomenon are as follows. (b) Time from edge to edge of A-phase and B-phase pulses (5th
Xi) in the figure is the pulse width of the quadruple signal (X in Figure 5).
(D) When the transmission path from the rotary encoder to the control circuit extends over a long distance, the transmission path becomes a distributed constant circuit, and the phase difference between the A-phase pulse and the B-phase pulse is equal to or shorter than 2). If the deviation is greater than 90° (for example, as shown in Figure 6, x3 becomes X2
(C) When the accuracy of the low-resolution encoder itself is poor and it does not output A-phase and B-phase pulses with a duty ratio of 50% and a phase difference of 90°. When this phenomenon occurs, it becomes impossible to control the motor, and the maximum rotational speed of the motor is thereby automatically limited. Furthermore, in order to eliminate this phenomenon, if the multiplier of the pulse shaper 6 shown in FIG.
There is a problem in that speed information is discretized at low speeds and rotational unevenness increases.

[Means to solve the problem]

In order to solve this problem, the A-phase and B-phase pulses are multiplied by 4 in the speed range that can be controlled by a 4-multiply signal.
In a range exceeding that speed, the motor is controlled by automatically switching the multiplier to a one-multiply signal as shown in FIG.

[For use]

Since the multipliers of the A-phase and B-phase pulses, which are the output pulses of the low-resolution encoder, are switched at a certain speed, the phenomenon of discretization of speed data at low speeds and the pulse disappearance phenomenon at high speeds are eliminated.

【Example】

An embodiment of the rotation control circuit according to the present invention will be described below with reference to the drawings. However, it is assumed that the speed detection section and the phase detection section of this embodiment perform digital processing. FIG. 1 is a block diagram of a control circuit for a servo motor incorporating a rotation control circuit according to the present invention, in which the same reference numerals as in FIG. 3 indicate the same components. FIG. 2 is a signal timing chart showing the operation of the control block circuit of FIG. 1. Comparator 13 receives signal 19 (actual value data of speed) and determines whether the data is above or below a certain threshold (the value indicated by the broken line in Figure 2 at the switching point of the multiplier). and outputs 1-bit information (signal 15). The latch circuit 12 receives the signal 15 from the comparator 13.
is clocked using a sampling pulse (signal 17) and its output (signal 16) is sent to the speed detection section 7, position detection section 8, and selector circuit 9. Selector circuit 9 receives signal 16
The receiver selectively outputs the output pulses (human phase, B-phase pulses) of the low reconcoder 5 to a quadrupling circuit 10 or a one-multiplying circuit 11. That is, if the actual value data of the speed is smaller than the switching speed of the multiplier (that is, the above-mentioned threshold value D), the 4 multiplier circuit 10 operates and performs the same control calculation as the conventional one, and when it is larger, the 1 multiplier circuit 11 operates. operates and inputs the signal to the speed detection section 7 and position detection section 8 to calculate speed and position. Furthermore, the latch circuit 12 is inserted to synchronize with the sampling pulse since the speed detection section 7 and the position detection section 8 perform sampling control.

【Effect of the invention】

As described above, according to the present invention, it is possible to control speed over a wide range without rotational unevenness, especially high-speed operation, using a multi-pulse low-return encoder.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a rotation control circuit for a rotating body according to the present invention, FIG. 2 is a timing chart of the embodiment of the present invention shown in FIG. 1, and FIG. 3 is a diagram of a conventional servo motor. Block diagram of the control circuit, Figure 4 is the timing chart of the output pulse of the rotary encoder, Figure 5 is the timing chart of the signal after pulse shaping (4-week signal), Figure 6 is the low reencoder during high-speed operation. FIG. 7 is a timing chart of the human phase and B-phase pulses which are the outputs of the 1-multiple signal. 4-motor, 5--rotary encoder, 7--speed detection section, 8-position detection section, 9--selector circuit, 10
-4 multiplier circuit, 11-1 multiplier circuit, 12-latch circuit, 13-- comparator.

Claims (1)

[Claims] 1) A rotary encoder that outputs a pulse signal as the rotating body rotates, and a switching circuit that switches the multiplier of the pulse signal according to the speed of the rotating body detected based on the pulse signal. A rotation control circuit for a rotating body.