GB817671A - Improvements in and relating to electrical control systems - Google Patents

Abstract

817,671. Automatic steering control systems. ENGLISH ELECTRIC CO. Ltd. Nov. 4, 1955 [Nov. 5, 1954], No. 32149/54. Class 38 (4). [Also in Group XL (c)] In a guided missile control system, the actual and required positions of the missile are compared and the resultant signal used to bring the missile to the required position. The actual position is determined by a doubly integrating accelerometer 41, Fig. 6, and the required position is derived from a signal storage device 40, in the missile. The outputs from both the accelerometer and the storage device are electrical pulse trains, and the number of pulses produced in a period of time represent a distance travelled in that time. The two trains are compared in a pulse discriminator 43, and the output signal is developed at either one of two lines 45, 46 according to which of the input trains is the more rapid. Each line is associated with a ratchet release mechanism 47 which together move a cam-operated variable resistance 49, 50 controlling the missile positioning device 52. The pulse discriminator has no output when the two input trains apply the same number of pulses to the discriminator in a specified period. In one embodiment, Fig. 2, the two pulse trains are applied, at 12 and 13, respectively, to the switches 10, 11. These are normally at position a but on receiving a pulse each switch is moved to position b for the duration of the pulse. If the moving contacts of 10 and 11 are connected to the battery 15 then output pulses will appear at 18, 19. However, the moving contacts of 10, 11 are connected to 15 through the arm of switch 17 and this is moved to contacts c or d accordingly as 17 is pulsed from 12 or 13. Hence, a pulse from 12 moves 17 to c and 10 to b and similarly a pulse from 13 moves 17 to d and 11 to b. Thus if alternate pulses are received at 12, 13 to above sequence is effected continually and no signals appear at 18, 19 as the action of 17 lags the movements of 10 and 11 due to the short period delay line 20. This condition corresponds to the required and actual missile positions being the same. Should the two positions not correspond, the pulses will appear at 12, 13 in groups and consecutive pulses at 12 or 13 will move 17 to the corresponding position and then pulses will appear at 18 or 19 due to the movements of 10 or 11 under the action of its controlling pulses. Should pulses at 12, 13 be rear coincidence, the system does not operate accurately and in a further embodiment, Fig. 4 (not shown), rear coincident pulses are eliminated. A coincidence detector closes a gate preceding each switch 10. 11 when pulses in the trains at 12 and 13 are at rear coincidence. Specification 817,672 is referred to.