Browse Prior Art Database

Servo Control With Microprocessor

IP.com Disclosure Number: IPCOM000034711D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Decker, WC: AUTHOR

Abstract

Improved accuracy of velocity and position control in a motor-driven servo loop is obtained by using a microprocessor to regulate acceleration and position. In Fig. 1, DC motor 1 is driven by a signal from velocity control circuit 2 powered at 3. The motor drives tachometer 4 whose velocity signal is continuously compared at velocity control circuit 2 with a position error value from digital position control unit 5 changed by digital-to-analog converter (DAC) 6 to an analog value. Motor 1 also drives position emitter 7 that produces an output pulse for each predetermined unit of displacement traveled, such as 0.001 revolution. The difference between a command value of displacement and actual value is determined at position control unit 5 and monitored by microprocessor 8.

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Servo Control With Microprocessor

Improved accuracy of velocity and position control in a motor-driven servo loop is obtained by using a microprocessor to regulate acceleration and position. In Fig. 1, DC motor 1 is driven by a signal from velocity control circuit 2 powered at
3. The motor drives tachometer 4 whose velocity signal is continuously compared at velocity control circuit 2 with a position error value from digital position control unit 5 changed by digital-to-analog converter (DAC) 6 to an analog value. Motor 1 also drives position emitter 7 that produces an output pulse for each predetermined unit of displacement traveled, such as 0.001 revolution. The difference between a command value of displacement and actual value is determined at position control unit 5 and monitored by microprocessor 8. The microprocessor also receives input instructions and provides output position values through timer 9 or directly to logic circuits 10 to govern the servo system motor. During acceleration or deceleration, microprocessor 8 receives input instructions as to velocity change. The microprocessor first locates the current velocity in a profile table and examines the position error at position control 5 and waits, if necessary, for the error to become less than an error threshold that the system can handle. When below the threshold, the next velocity value from the table in the direction of the desired acceleration is placed in timer 9

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for transmission through logic 10 to position control unit 5. The microprocessor waits for a period of time for errors to accumulate and then examines position error. While the error is above the th...