Browse Prior Art Database

Linear Bidirectional Servomechanism

IP.com Disclosure Number: IPCOM000076097D
Original Publication Date: 1972-Jan-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Boll, KF: AUTHOR [+2]

Abstract

Linear bidirectional energization of direct-current motor 1 is achieved from a single-ended power supply 2 by a four-transistor power bridge 3, a differential amplifier 4, a summing amplifier 5 and a motor-current sense amplifier 6.

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Linear Bidirectional Servomechanism

Linear bidirectional energization of direct-current motor 1 is achieved from a single-ended power supply 2 by a four-transistor power bridge 3, a differential amplifier 4, a summing amplifier 5 and a motor-current sense amplifier 6.

The summing amplifier 5 sums a reversible polarity and variable magnitude command signal 7 and an opposite polarity variable magnitude motor-current feedback signal 8 at its inverting input terminal. The polarity of signal 7 indicates the desired direction of rotation of the motor, whereas the magnitude of this signal indicates the desired speed of rotation of the motor.

Output 9 of the summing amplifier is the servo-error signal. This signal is referenced to ground potential and applied as an input to the differential amplifier
4. When the error signal is zero, as when the motor is to remain at rest, the base electrodes of transistors 10 and 11 are both at ground potential. Therefore, the currents flowing through resistors 12 and 13 are equal. The voltage drop across these resistors is adjusted to be equal to one-half motor power supply 2. As a result, the voltage at terminals 14 and 15 is also equal to one-half the motor power supply and the voltage across the motor is zero.

If for some reason an unbalance exists in the power bridge, causing motor current to flow when the motor should be at rest, this current is sensed by amplifier 6 and is fed back to the summing amplifier 5 to cause the differen...