Patent EP-0048212-A1 (EP)
Inventor: KROGMANN UWE DIPL-PHYS
IPC: G01C21/18
Filed: 1981-08-22
Abstract: 1. Heading attitude reference system comprising a two-axis attitude gyro (10) having a spin axis (14), a first input axis (16) and a second input axis (18), which is perpendicular to the first input axis (16), a first (24) and a second position pick-off (26) on the first (16) and the second input axes (18) of the attitude gyro (10), respectively, a first (28) and a second torquer (30) on the first (16) and the second input axis (28) of the attitude gyro (10), respectively, characterized in that (a) a housing (12) of the attitude gyro (10) is arranged on an inner gimbal (32), the spin axis (14) and the first input axis (16) of said attitude gyro (10) being substantially horizontal, (b) the inner gimbal (32) is rotatably mounted in an azimuth gimbal (36) about a pivot axis (34), which is parallel to the first input axis (16), (c) the azimuth gimbal (36), in turn is rotatably mounted about an instrument-fixed substantially vertical azimuth axis (38), (d) a first inclination sensor (40) is arranged on the inner gimbal (32) and responds to deflection of the inner gimbal (32) relative to the horizontal about an axis, which is perpendicular to the pivot axis (34) of the inner gimbal (32) and to the azimuth axis (38), (e) a second inclination sensor (42) is arranged on the inner gimbal (32) and responds to deflection of the inner gimbal (32) relative to the horizontal about the pivot axis (34) of the inner gimbal (32), (f) a third and a fourth inclination sensor (44, 46) are arranged in a housing-fixed manner and respond to deflection of the housing (48) about axes (y**G , x**G ), which are mutually orthogonal and perpendicular to the azimuth axis (38), (g) an azimuth angle indicator (54) is arranged on the azimuth axis (38), (h) a first servomotor (50) is arranged on the pivot axis (34) of the inner gimbal (32), which servomotor (50) is adapted to rotate the inner gimbal (32) relative to the azimuth gimbal (36), (i) a second servomotor (52) is arranged on the azimuth axis (38), which servomotor (52) is adapted to rotate the azimuth gimbal (38) relative to the housing (48), (j) the signal from the first position pick-off (24) of the attitude gyro (10) or the signal from the second position pick-off (42) optionally is applied to the first servomotor (50) through switching means (58), (k) the signal from the second position pick-off (26) of the attitude gyro (10) is applied to the second servomotor (52), (l) the signal from the second inclination sensor (42) is applied to the second torquer (30) of the attitude gyro (10), (m) signal processing means (fig. 4) are provided, to which the signal psi C from the azimuth angle indicator (54) and the signals from the first, third and fourth inclination sensors (40, 44, 46) Ly **C , Lx **G , and Ly **G , respectively, are applied, and which signal processing means comprise (m1 ) means (68 to 92) for forming sin theta B , cos theta B , sin phi B , cos phi B , sin phi A and cos phi A , theta B being the pitch angle of the instrument, to which the third inclination sensor (44) responds, phi B being the roll angle of the instrument, to which the fourth inclination sensor (46) responds, and phi A being the roll angle of the inner gimbal (32), to which the first inclination sensor (40) responds, (m2 ) means (94) for forming the true directional psi B by means of the relation tan psi B (t) = - tan psi C (t) (cos theta B (t)/cos phi B (t)) + tan phi B (t) sin theta B (t) and (m3 ) means (98) for generating a signal Uz **C (t) = - cos phi A (t) OMEGA E sin PHI (t), wherein OMEGA E is the angular rate of the rotation of the earth and PHI is the geographic latitude, and (n) the signal Uz **C (t) is applied to the second torquer (30) of the attitude gyro (10).