Patent GB-762301-A (GB)
Title: Gyroscopic reference apparatus for dirigible craft
Inventor: VACQUIER VICTOR
IPC: G01C21/16
Filed: 1954-03-12
Abstract: 762,301. Electric indicating systems. SPERRY RAND CORPORATION. March 12, 1954, No. 7271/54. Class 40 (1). In a system in which three or more gyroscopes stabilize the position of a structure mounted with freedom about three mutually perpendicular axes in a moving craft, each of the gyroscopes is stopped and reversed in turn. In Fig. 2 gyroscopic apparatus carried on a craft produces electrical signal outputs 132, 133, 134 corresponding to roll, pitch and yaw of the craft, which may be used for example to control an automatic pilot for the craft. Accelerometers on a platform 30 pivoted about the vertical axis of an azimuth ring 23 are responsive to horizontal motions of the craft in respective mutually perpendicular directions. A.C. signals obtained from these accelerometers are applied through amplifiers to inductive-type resolvers R4, R5 to produce integrated signals representative of motion of the craft in latitude and about the polar axis of the celestial sphere. These signals control servomotors 35 and 45 to maintain a spherical casing 10 fixed in space when the craft is in a predetermined attitude on a predetermined course. A further signal is produced by the resolvers to control an A.C. servomotor 55 moving platform 30 so as to eliminate errors due to change of longitude or the centrifugal effect of the earth's rotation. Servomotor 35 also operates a latitude indicator (not shown) and servomotor 45 co-operates with a siderial clock (not shown) to indicate longitude. Casing 10 contains four gyroscopes (not shown) respectively responsive to movement of the craft about axes approximately 109.5 degrees to each other. Inductive pickoffs associated with these gyros produce A.C. signals upon attitude or course deviation of the craft and cam-operated contacts controlled by a timing mechanism (not shown) apply three of them at a time to a converter which produces three signals P, S and T representative of deviation of the craft about three mutually perpendicular axes one of which is the celestial polar axis. With a view to eliminating gyro drift, each gyroscope is thus periodically taken out of service and its direction of spin and its pick-off connections reversed automatically. Change of connections to reverse the threephase induction motor gyro drive is effected by further cam-operated contacts of the timing mechanism when the frequency of supply has been reduced to zero by a frequency changer introduced by the timing mechanism and driven by an electric motor the speed of which is cyclically varied by the timing mechanism. While each gyro is out of service its pick-off output is maintained at zero by the timing mechanism connecting the pick-off to an electric torque motor precessing the gyroscope. Signals P, S and T are applied to inductive-type resolvers R1, R2, R3 which derive signals representative of the motion of the craft about the roll, pitch and yaw axes to control A.C. servomotors 128, 129, 122 maintaining ring 23 in the local vertical plane and rings 25 and 26 in the local horizontal plane. Pick-offs VR, VP, VZ associated with the rings then produce signals representative of roll, pitch and yaw of the craft. Each servomotor drives a feedback generator so that its speed corresponds to its controlling signal. Specification 762,346 is referred to.