Aeronautics and astronautics – Spacecraft – Attitude control
Patent
1978-04-19
1980-03-18
Kelmachter, Barry L.
Aeronautics and astronautics
Spacecraft
Attitude control
244170, B64G 120
Patent
active
041935705
ABSTRACT:
An apparatus for controlling nutation motion in a spinning body, comprising an angular accelerometer having its input axis perpendicular to the spin axis of the body, a flywheel having an axis of rotation perpendicular to the axis of the accelerometer and to the spin axis of the body, and a motor for driving the flywheel to attenuate or build nutation. The motor is controlled by circuitry that monitors the output of the angular accelerometer and drives the motor clockwise or counterclockwise during predetermined nutation angles synchronized to the zero crossover points of the accelerometer signal and centered about the nutation peaks. In one embodiment, the motor drive is phased to damp nutation motion to zero for stabilization. To increase the noise immunity of the system, when the output of the accelerometer falls below a threshold level, the circuitry operates in an open loop, beat mode wherein data representing the last accelerometer signal that exceeded that threshold level is stored, and the motor drive is controlled by the stored data. In a second embodiment, the motor is controlled to supply a predetermined amount of nutation motion to a body undergoing testing on a spin table for energy dissipation evaluation. In each embodiment, the use of an angular accelerometer rather than a linear accelerometer or gyro to monitor nutation enables placement of the nutation control apparatus at any location relative to the spin axis of the body requiring only crude orientation and no calibration.
REFERENCES:
patent: 3511452 (1970-05-01), Smith et al.
patent: 3591108 (1971-07-01), Perkel et al.
patent: 3643897 (1972-02-01), Johnson, Jr.
patent: 3984071 (1976-10-01), Fleming
patent: 4096427 (1978-06-01), Rosen et al.
Donohue James H.
Hoffman Henry C.
Eisenzopf Reinhard J.
Kelmachter Barry L.
Manning John R.
Marchant Robert D.
The United States of America as represented by the Administrator
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