GB592405A - Improvements in automatic steering systems - Google Patents

Abstract

592,405. Magnetic compasses. GENERAL MOTORS CORPORATION. May 3,1944, No. 8315. Convention date, July 30, 1943. [Class 97 (ii)] [Also in Groups XXXIII and XXXV] An automatic steering system for a ship or other craft or body steered by a magnetic compass is provided with a tilt compensating coil 92 mounted adjacent to the compass needle 2 and energized by a current proportional in sign and strength to the direction and extent of the direct actuation of the steering gear. The coil 92 is connected electrically across a resistance bridge circuit and in series with the contact arm 78 of a potentiometer resistance 80, the arrangement being such that when the craft is on course the arm 78 is in its midposition and no current flows through coil 92. The steering wheel 46 is connected to the arm 78 by a coupling shaft 70, whereby the resistances in the two arms of the bridge formed by potentiometer 80 are varied in accordance with the actuation of the steering-wheel, and coil 92 is energized to create a magnetic field which neutralizes the effect of the vertical component of the earth's field upon the' compass needle, more especially when the rudder is forced hard over. The compass needle 2 is pivoted about a vertical axis within a horizontally trunnioned gimbal ring 3 which is weighted at the bottom so that it tends to retain a vertical position within a housing 4 that provides a support for the compensating coil 92. The craft is maintained on a set course by an automatic control system comprising a light-sensitive device 10 located below the compass needle and influenced in accordance with the deviation of the needle (see Group XXXV).