GB693506A - Improvements in remote position control systems - Google Patents

Abstract

693,506. Electric follow-up systems. BRITISH THOMSON-HOUSTON CO., Ltd., and STOKES, J. A. Sept. 25, 1951 [Oct. 27, 1950], No. 26278/50. Class 40 (i). In a remote control system using coarse and fine Selsyn systems, wherein both coarse and fine error signals are applied to a common control channel, and the coarse error voltage is blocked by normally non-conductive means until it reaches a predetermined value, a stabilizing voltage derived from a feedback channel from the receiver driving motor is mixed directly with the coarse error voltage, but is passed through a further network before mixing with the fine error voltage. As shown, the control member 11, Fig. 1, operates the controlled member 10 through coarse and fine Selsyn systems 14-18, 15-19, the coarse and fine error voltages developed in the respective transmitter rotors being applied over lines h-g, a-b by way of a common control channel f-e to an amplifier and demodulator 25 which controls the magnitude and sense of the energization of the field of a motor driven generator 13 which drives the servomotor 12, and with it the load 10 in the follow-up sense. The coarse error voltage is applied over a transformer 32 and rectifiers 34, 35, Fig. 2, to the grids of triodes 28, 29, coilnected reversely in parallel. For small deviations from correspondence of the members 10, 11, the triodes are blocked by the bias applied by batteries 30, 31, and the fine error voltage applied over high impedances Z to the line f-e controls the servo-motor 12. Hunting of the system is prevented by a feedback voltage derived from the motor circuit in known manner and applied through a channel 26 and a network 27 across one of the impedances Z. When the deviation reaches a predetermined value the triodes 28, 29, conduct on alternate half-cycles, and apply an amplified version of the coarse signal to the common channel f-e over the transformer secondary 33, in series with the anti-hunt feed back voltage in channel 26. At the same time the shunting action of the conducting triodes across the line a-b attenuates the fine error signal to render it innocuous. The stabilizing negative feedback voltage derived from the channel 26 is a simple function of velocity and, or acceleration, whereas the network 27 produces a more complex function of these values. Specification 576,117 is referred to.