STEERING COMMAND COMPUTER FOR NAVIGABLE CRAFT

1293780 Automatic steering control SPERRY RAND CORP 19 April 1971 [2 March 1970] 22249/71 Heading G3R In an automatic steering system for a marine vessel, e.g. wherein a heading error signal # e from a gyro compass system results in a rudder order signal applied to a rudder positioning servo 60, a potentiometer 23 provides a range of thresholds corresponding to a range of yaw angles, and a low gain mode is effective within the preset yaw zone whilst a high gain mode is effective outside the yaw zone. The heading error signal # e from source 10 is applied to an operational amplifier 11, with a low pass filter 12, 13, and limiter 14, and then to the threshold circuit 21 including the potentiometer 23 the circuit 21 providing a bipolar threshold. Source 10 also provides the heading error signal to an integrator 24 including amplifier 25, integrating capacitor 26 and integrating resistor 27. The signal is applied via a fiveposition integrator gain controlling switch 30 positioned in accordance with the vessel 10 characteristics and loading. A field effect transistor 35 functions as the gain controlling element of the integrator. The integrator has a limiter circuit 36 and is reset to a reference condition by a signal on a reset line 37 when a change in course is commanded. Source 10 also enables the heading error rate to be obtained through a differentiator 40. Signal # e is applied via a rate adjust potentiometer 41 to a tapped voltage divider 45-49, with taps connected to the wiper arm of a five-position switch 52 gauged with switch 30. Switch 52 selects the gain of differentiator 40 in accordance with the vessel 10 loading and dynamic characteristics. The signal from switch 52 is applied via a differentiating capacitor 44 and an adjustable low pass filter 53 to the amplifier 42 across which the differentiating resistor 43 is connected, as well as a limiter 54. The amplified and filtered heading error signal provided by amplifier 11, the integrated heading error signal from integrator 24 and the differentiated and filtered heading error signal from differentiator 40 are applied to a mixer circuit 55 including a conventional summing network. A limiter circuit 66 limits the amplitude of the rudder order signal, limiting the bipolar signal output of amplifer 56 and providing a single adjustment to vary simultaneously the opposite polarity reference voltages.