GB864751A - Improvements relating to control means employing gyroscopes - Google Patents

Abstract

864,751. Radar; aerials. ELECTRIC & MUSICAL INDUSTRIES Ltd. June 26, 1957 [June 26, 1956], No. 19816/56. Class 40(7) [Also in Group XX] Control means for aiming a component mounted for rotation about two axes of freedom comprises two gyroscopes mounted on the component so that their spin vectors are mutually cancelling, and having precessional motors for imparting torque to the respective gyroscopes about orthogonal axes. The system is shown applied to a guided missile, part of which is shown at 1, which is controlled by a radar system having an aerial 2 with a reflector 3 mounted on a plate 7, which is carried by gimbals 4 on the missile 1. The gimbal axes constitute the pitch axis C and the yaw axis D of the aerial. Two gyroscopes 5, 6, with their spin axes parallel to the axis of the reflector, are mounted on plate 7 in gimbals pivoted on axes A, B parallel with axes C, D respectively. The gyroscopes have torque motors 8, 9 and pick-offs 10, 11, and torque motors 12, 13 act on the gimbals 4. If there is an error between the line of sight of the target and the axis of the reflector about the yaw axis D, an error signal produced by the radar apparatus operates torque motor 8. The torque generated causes gyroscope 5 to precess and turn the aerial about the yaw axis D to reduce the error. The reaction torque on the aerial tends to turn it about the pitch axis C, but this is resisted and effectively prevented by gyroscope 6, which precesses about axis B. Since the spin vectors of the gyroscope are equal and opposite, the torques applied are equal and opposite. Similar considerations apply when the error appears about the axis C. Since the gimbals 4 cannot be entirely frictionless, a torque arises whenever the aerial moves with respect to the missile. The torque will tend to move the aerial, but will be opposed by the reaction torque due to the precession of one or both of the gyroscopes. As a result, the gyroscope spin axes wander from parallelism with the reflector axis, whereupon signals derived from pick-offs 10, 11 actuate torque motors 12, 13 to precess the gyroscopes to restore their spin axes to their original direction.