Patent GB-1133658-A (GB)
Title: A method and apparatus for guiding a vehicle automatically and asymptotically into a predetermined path
IPC: G05D1/02
Filed: 1966-05-27
Abstract: 1,133,658. Vehicle guidance computer. LITTON INDUSTRIES Inc. 27 May, 1966 [28 May, 1965], No. 24047/66. Heading G4G. In apparatus for guiding a vehicle e.g. an aircraft 12 into a desired predetermined path 10 (Fig. 1), along alternative high speed and low speed approach paths 24, 22 wherein the displacement of the initial point from the predetermined path is D OT , the heading of the vehicle is # TA , the velocity of the vehicle is #V g , the northing and easting velocity components are #V x , #V y ; the velocity component normal to the path is #V CT , the bearing of the required path is # TD  and the azimuth of the vehicle relatively to that of the required path is #; signals representing #V x , #V y  are derived; e.g. from a gyro carrying northing and easting accelerometers followed by integrators, or from corresponding velocity meters, or from a radio navigation system; and applied to a dual sin/cos potentiometer 28 (Fig. 2), developing signals representing #V x  cos # TA  and #V y  sin # TA , which are summed at 30 to control the gain amplifier 32, while other signals representing - #V x  sin # TA  and #V y  cos # TA  are summed at 32; the output of which controls a velocity stabilized servomotor 34, 36 regulating potentiometer 28, so that the output of amplifier 30 represents the velocity Vg of the vehicle over the earth's surface and the shaft position of 34 represents the azimuth # TA  of the velocity referred to north. A sin potentiometer 40 receives  signals representing #V 0  and motor 34 drives a mechanical differential 42 also receiving a manually adjustable shaft rotation representing the azimuth of the desired path referred to north, # TD , so that its output represents the azimuth # of the vehicle relative to the desired path, which drives potentiometer 40 and control transmitter 44. The latter energizes a receiver 46 and the potentiometer output represents velocity #V cr  of the vehicle normal to the required path, which is applied over resistor 48 to an RC integrator 50 also receiving a zero set input over resistor 54 from a switch 56 normally spring biased to disconnect and operable to pick up  voltages from source 62; a switch 64 ganged to 56 energizing relay 66 to insert resistor 70 increasing the integration speed during zero set. The integrator output representing the distance D OT  is displayed on measuring instrument 72, is limited by a T connected resistor/Zener diode circuit, and is applied to summation amplifier 82 also receiving a #V CT  signal from potentiometer 40 and a retroactive signal from potentiometer 84 driven by velocity stabilized servomotor 86, 88 energized from the amplifier output; the motor shaft driving receiver 46 to develop a steering signal representing # + K 1  DOT + K 2  V CT  applied at 114 to the autopilot (not shown). For test, switches 92, 94, 96 are operable to apply standard V x  V y  signals from source 102, 104 to potentiometer 28 and connect the resultant steering signal to comparator circuit 106, also receiving a predetermined adjustable voltage from potentiometer 110, which energizes an indicator lamp or other signal device to indicate inequality and malfunction. In operation, # TD  is inset manually and switches 56, 64 are operated until the known distance from the required path at a check point is set on meter 72 by voltage 62, and the switches are then released, after which the meter reads continuously the distance of the vehicle from the required path, and a steering signal is generated to bring the vehicle on to such path; the limiter restricting the angle of approach to  90 degrees.