Patent GB-775133-A (GB)
Title: Punch card controlled aircraft navigation computer
IPC: G01C21/00
Filed: 1954-10-28
Abstract: 775,133. Electric analogue calculating systems. COLLINS RADIO CO. Oct. 28, 1954 [Nov. 23, 1953], No. 31191/54. Class 37. [Also in Group XL (c)] The lateral deviation G, Fig. 2, of an aircraft C from any desired course (bearing #3) passing through an arbitrary point E, i.e. the " way point," and the distance F of the aircraft from said point E measured along said course are determined by an electro-mechanical analogue computer into which are fed the bearings #1 and 62 from the craft C of two radio phase beacons A and B, Fig. 1, the rectangular components Xs, Ys of the separation D of said beacons, the distance d of the way point E from the master beacon A, the bearing #4 of E from A and the bearing 63 of the desired course through E. The bearings 61 and #2 are determined by two radio receivers 10 and 21, Fig. 3, automatically tuned to a selected pair of beacons by means of a unit 11 controlled by a punch card reader of the type disclosed in U.S.A. Specification 2,662,944 and unit 11 also supplies the corresponding beacon separation co-ordinate voltages Xs and Ys, Figs. 4-6 (not shown). As described the values of d and #4 are set in manually but alternatively the rectangular coordinates X2, Y2 of the point E relative to the beacon A may be supplied by the control unit 11. The first step comprises the determination of the distance p and the corresponding rectangular components X1, Y1 of the craft C from the master station A by using the following relationships between p, X1, Y1, Xs, Ys, #1 and 02: As shown in Fig. 3, receiver 10 tuned to beacon A produces an electrical output proportional to 01 which is converted to a corresponding angular position of an output shaft 19 by means of amplifier 17, servomotor 18 and resolver 13; similarly the angular position of shaft 29 is adjusted to 02 by receiver 21. An A.C. voltage having an amplitude equal to a trial value of p is applied from an adjustable tapping 64 on an auto-transformer 66 to a resolver 33 controlled by the #1 shaft 19 giving outputs X1 and Y1 which are combined in the control unit 11 with Xs and Ys voltages, the resultant voltages (X1-Xs) and (Y1-Ys) being applied to the stators 57, 58 of a resolver 35 which has two orthogonal rotors 54, 55 controlled by the #2 shaft 29. The output E3 (equation (5)) from rotor 54 is applied through servo amplifier 51 to control a motor 62 which adjusts the position of tapping 64 on auto-transformer 66 such that E3 is reduced to zero and the amplitude of the voltage at the tapping 64 is then exactly equal to p; this voltage is also applied to a resolver 32 controlled by the #1 shaft 19 to give outputs proportional to X1 and Y1. Since (#1-#2) changes sign as the aircraft crosses the line AB (or an extension thereof) the phase of the output from amplifier 51 will reverse accordingly and this is prevented by inserting a phase-reversing relay (not shown) in the output of amplifier 51 said relay being controlled by a phase-sensitive amplifier 49 whose input is coupled to the rotor of a control selsyn 34 whose stators are coupled to the stators of a selsyn transmitter 31, the rotors of selsyns 31 and 34 being mechanically coupled to shafts 19 (#1) and 29 (02) respectively. The bearings #1 and #2 are measured relative to the magnetic meridians at beacons A and B and in order to compensate for any difference # in the magnetic deviation at A and B an output: from the rotor 55 of resolver 35 is multiplied by a factor K in control unit 11 and the resultant signal E4 is combined in the input of amplifier 51 with the signal E3 applied directly from the rotor 54 of resolver 35 so that the resultant signal applied to amplifier 51 is: where # = tan<SP>-1</SP>k which shows that the effective value of 62 has been increased by #. The rectangular components XT, YT of the position of the craft C relative to the point E, Fig. 2, are then computed by using the following relationships: The tapping 81 on auto-transformer 80 is set manually to give an A.C. voltage of amplitude proportional to d which is applied to the rotor 77 of a resolver 76 and the angular position of rotor 77 is set manually to #4 so that voltages proportional to X2 and Y2 are induced in stators 84 and 83 respectively and are combined therein with X1 and Y1 voltages from resolver 32 giving output voltages X T  and Y T  which are applied to the stators of a resolver 86. The rotor of resolver 86 comprises two orthogonal coils 91, 92 and is set manually to the required value of #3 by a knob 94. The A.C. output from coil 92 is then proportional to G and is applied to an indicator 104 through a phase-sensitive rectifier 103 and the A.C. output from coil 91 corresponding to F is converted to a corresponding angular position of shaft 102 by means of servo 95, 96, the value of F being indicated by a pointer 101. Specification 660,939, [Group XXXVIII], is referred to.