Patent GB-1247735-A (GB)
Title: Automatic electric pilot for rudder-controlled craft, in particular ships
Inventor: KUNDLER WALTER
IPC: G05D1/02
Filed: 1968-09-25
Abstract: 1,247,735. Automatic steering control. ANSCHUTZ & CO. G m.b.H. Sept. 25, 1968, No.45550/68. Heading G3R. An automatic electric pilot for rudder-controlled craft, such as ships, of the type including a compass-controlled signal converter 12 for producing a D.C. voltage corresponding to the course error and having an adjustable dead zone (dead band) in the band of error signals, has inserted between the signal converter 12 and the steering gear an averaging device 16, having a dead zone with adjustable limits, a P.I.D. (Proportional Input Derivative) controller 18, and a control circuit 20 operating the steering gear via relays, the signal converter 12 supplying two auxiliary signals to circuit 20 via lines 30, 31, with voltages proportional to the positive and negative amounts of course deviation, respectively. Instead of control circuit 20, a servo-amplifier (not shown) may be provided, the output signal of the amplifier causing the rudder of the craft to move at proportional angular velocity. Averager 16 comprises a voltage divider R 2 , R 2 <SP>1</SP>, Fig. 2, the central point 14 of which is connected to an earthed capacitor C 2  constituting the output end of the averager; its input end 15 is connected through rectifying diodes D, D<SP>1</SP>, to each of the ends of the voltage divider, and an adjustable voltage source U is arranged in parallel to the divider. A low-pass filter R 1 , C 1  is inserted in front of the averager 16 and/or another low-pass filter R 3 , C 3 , behind it. A single control knob varies source U and resistor R 3  simultaneously. The P.I.D. controller 18, Fig.4, contains an operational amplifier RV, with resistance R 4  and capacitor C 4  generating the proportional and derivative components, while the integral component is produced by the rudder supplying a feedback signal which is uncoupled by a capacitor C 5  discharging slowly through a resistor R 7 . The feedback signal is supplied by a sensor 21 comprising a potentiometer with a wiper displaceable by the rudder motor 22 simultaneously with the rudder. Alternatively, the signal is supplied by a low-pass filter simulating the rudder angle, Fig. 9, and Fig. 10 (not shown) the filter being connected to a second output line of control circuit 20. The control circuit 20 includes amplifiers V 1 , V 2 , Fig. 5, controlling windings 32, 33, of two relays operating the steering gear to apply rudder to port (via terminals BB) or starboard (via terminals St B), the relays also operating respectively contacts S1 and S2 in the low-pass filter, Fig. 9, comprising resistors R B , R s , and capacitor C 31  . This filter is alternatively an operational amplifier S3, Fig. 10 (not shown), fed back by a capacitor C 32  and resistor R 42  in parallel. Control circuit 20 provides positive feedback at the input side of amplifiers V 1 , V 2 , in accordance with the voltages applied to lines 30, 31, via resistors R 12 , R 22 , and contacts of the "port" and "starboard" relays. When the course error exceeds a definite amount, e.g. 10 degrees, the capacitor C 5 , Fig.4 is shortcircuited by switch S 1  automatically, to switch off the integral component. In place of S 1  a relay D, Fig.11 (not shown), is used. A push-button switch 23, Fig.9, allows for quick setting of the integral component by disconnecting amplifier RV from trigger circuit 20 and earthing the terminals of capacitor C 5  at the amplifier end. Capacitor C 5  is charged instantaneously up to the voltage supplied by sensor 21. At this instant, the correct rudder angle previously produced by a course error αm is co-related to the integral action. Release of push-button 23 causes the ships bow to be brought to the set course and the error signal αm to become zero. A variable resistor R 6  allows for adjustment of the I-component without varying R 7  or C 5  .