JPS623301A - Pulse width modulation method - Google Patents

Abstract

PURPOSE:To eliminate the offset and to omit the need for control with a modulation system for pulse width by performing the down-count operation with the oscillation output of a fixed level for a counter which stores the addition/ subtraction value between the command value for drive of the load and the feedback signal and producing a pulse according to the counted time. CONSTITUTION:A command signal A of a command controller 1 is stored in a storage device 2. The output B of the device 2 undergoes an operation through a parallel binary adder/subtractor 3 with the signal H obtained by binary-coding the output signal G of a speed detector 8 by an A/D converter 10. The output C of the adder/subtractor 3 is stored in a down-counter 4 and then subtracted by a down-counter pulse D of an oscillator 5. The output of the counter 4 is turned into a pulse width modulated pulse E and supplied to a power amplifier. The output of the power amplifier is turned into a motor driving signal F and drives a motor 7.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pulse width modulation method for controlling the pulse width input to a drive circuit that drives a load.

Conventional technology In recent years, a load such as a motor can be arbitrarily driven, and the rotation of the motor can move, for example, a robot arm, and the movement of the robot arm can grasp an object with a robot node attached to the tip of the robot arm. Nowadays, robots are provided that assemble the objects. The motor drive method for positioning the robot arm in the desired position is a method in which the input signal to the drive circuit that drives the motor according to the command value is a pulse width modulation method to generate control pulses. is used. An example of a conventional pulse width modulation method will be described below with reference to the drawings. Second
The figure shows a block diagram of a conventional pulse width modulation method. Reference numeral 21 in FIG. 2 indicates a command controller 22 which outputs a command to rotate the motor 2o.
A storage device 23 performs digital-to-analog conversion (hereinafter referred to as an A converter) of the output of the recorder 22, an A converter, and 25 an amplifier that fully amplifies the D-A converter e. , 27 is a comparator that compares the output f of the amplifier 26 and the output k of the triangular wave oscillator 28, 2 is a power amplifier that amplifies the pulse width modulation signal q of the comparator, and 20 is the power amplifier 29. 31 is a speed detector which inputs the rotational speed of the motor as a feedback signal i to the feedback adder 24 at the connection point 25; 32 is a motor driven by a signal from the motor white 0;
The output from the position detector is a position feedback signal i to the command controller 21.
sent as. The pulse width modulation method configured as above will be explained below.

The command value & output from the command controller 21 is stored in the memory 22. The output of the memory 22 is converted into an analog value by the A converter 23 and sent to the connection point 26 as the output C. At the connection point 25, the output signal ii of the speed detector 31 and the output d of the feedback calculator 24 are added or subtracted. The output e of the coupling point 26 is amplified by the amplifier 26 and sent to the triangular wave oscillator 2.
A comparator 27 compares the signal with the output of 8 to obtain a pulse width modulation signal q. The pulse width modulation signal q is a pulse obtained by comparing the signal a from the command controller 21 and the signal i from the speed detector 31 with the output of the triangular wave oscillator 28 according to the value of the output d of the feedback adder 26. It becomes a modulated signal. The pulse width of the pulse modulation signal q increases or decreases depending on the value of the output f of the amplifier 26.

The pulse width modulation signal q is amplified by the power amplifier 29 and rotates the motor 30.

Problems to be Solved by the Invention However, in the above configuration, if the offset adjustment of the D-A converter 23 and the triangular wave oscillator 28 is not performed correctly, the pulse width modulation signal q of the comparator 27 will not match the value of the command value a. This causes the problem that pulse width modulation cannot be performed correctly. In other words,
When the command value a becomes a positive or negative value, the pulse width of the positive pulse width modulation and the pulse width of the negative pulse width modulation are different, and the rotation speed of the motor 30 differs depending on the direction of forward or reverse rotation. .

The present invention eliminates the need for offset adjustment of the D-Ai converter 23 and the triangular wave generator 28, and the motor 30 is controlled by the command controller 2.
This method performs pulse width modulation to rotate the motor at the same speed regardless of forward or reverse rotation with respect to a command value a of 1, and eliminates the need for pulse width modulation adjustment.

Means for Solving the Problems In order to solve the above problems, the present invention converts a command value for driving a load and a feedback signal for driving the load into an analog-to-digital converter (hereinafter referred to as an A or D converter). ), the feedback signal is binarized by an adder/subtracter, the output of the calculator is stored in a counter, and the value stored in the counter is subtracted using a constant repetition signal. Pulse width modulation is performed by generating pulses in accordance with time, and pulse width modulation can be made without adjustment, except for offset adjustment of the AD converter.

Function The present invention performs pulse width modulation using the above configuration? This allows correct pulse width modulation regardless of the plus or minus value of the command value, and eliminates the need for pulse width modulation adjustment.

EXAMPLE Below, a pulse width modulation method according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a memory that stores block signals of the pulse width modulation method of the present invention, B is the output of the memory, and 3 is the output of a speed detector 8 that detects the rotational speed of the motor 7 GQA-D converter 10 C is the output of the adder/subtracter; 4 is a down counter that counts the output C of the adder/subtracter 3; 55 is the down counter of 4; D with an oscillator that counts the value
is the down count “′・( ,゛pulse, E is output by the count value of the down counter.
, ], steam) output pulse width modulated pulse, 6 is the count
Pulse width modulated output pulse Ei amplification from 4″・+1°
, , 1 power amplifier, F is the signal outputted from the power amplifier to drive the motor 7, 9 is the rotation of the motor 7 7--,-, -4,1-880
This is the position feedback signal from the □−]゛□ device.

The operation of the pulse width modulation method configured as described above will be explained using FIG. 1.

The command signal A of the command controller 10 is stored in the memory 2. The memory output B is parallel to the signal H obtained by converting the speed detector output signal G from the speed detector 8 into a binary value by the A-D converter 10. 2
The calculation is performed by the decimal adder/subtractor 3. The adder/subtracter output C of the adder/subtracter 3 is stored in a down counter 4 and subtracted by the down count pulse D of the oscillator 5. The output of the down counter becomes a pulse width summer tone pulse E and is input to the power amplifier. The output of the power amplifier is the motor drive signal F
The motor 7 is rotated as follows.

Effects of the Invention As described above, according to this embodiment, pulse width modulation according to the command value can be obtained arbitrarily by the value set in the down counter without adjusting the offset of the A converter and the triangular wave oscillator. At the same time, pulse width modulation can be made unadjusted.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional pulse width modulation circuit. 1...Command controller, 2...Memory device, 3
... Adder/subtractor, 4... Down counter 16... Oscillator, 6... Power amplifier, 7... Motor, 8... ...Speed detector, 9...Position detector, 10...A, D
Converter, A...Command signal, B...Memory output, C...Adder/subtractor output, D...
Down count pulse, E... Pulse width modulation pulse, F... Motor drive signal, G...
Speed detector output, H...binarized signal, engineering...
...Position feedback signal, 21...Command controller, 22...Memory device, 23...D
, A converter, 24...feedback adder,
26...Connection point, 26...Amplifier, 2
7... Comparison calculator, 28... Triangular wave generator, 29... Power amplifier, 30...
・Motor, 31...Speed detector, 32...
...Position detector, a...Command value, b...
・Memory output, C...D, A converter output, d・
...Feedback signal, e...Connection point output, f...Amplifier output, q...Pulse width modulation signal, h...Power amplifier , i...
...Feedback signal, j...Position feedback signal, k...Triangular wave oscillator output. Name of agent: Patent attorney Toshio Nakao and 1 other person3-
Egg-A military base key-r) η→〉Ku 5- 1 section number 6--No 1 + Kuanfu 0 7--death-gay 0--6υki E1 fusion-1 reference A--4 + signal 6-・Revised 4 Asahi Hata Hiroshi Ka Co-ka 19 nights ￥ device f: η D--92 Yushifu Yuntino Lχ E--No 1°rus? 1 katou no zengshisu F=-71 ta kangin (the name e-t4

Claims (1)

[Claims] A storage device for storing a command value, a means for converting the feedback signal into binary data, a means for calculating the storage device and the binary data, and a counter for storing the calculation result, A pulse width modulation method in which the calculation result stored in a counter is subtracted by the output pulse of an oscillator, and the pulse width is controlled according to the subtraction time.