초록 ▼

A dual-spin spacecraft having a momentum wheel spinning relative to a platform to provide bias momentum utilizes cross products of inertia (POI) existing in the platform between the spinning axis and the transverse axes to achieve nutation damping. When the platform is rotating or is displaced from

A dual-spin spacecraft having a momentum wheel spinning relative to a platform to provide bias momentum utilizes cross products of inertia (POI) existing in the platform between the spinning axis and the transverse axes to achieve nutation damping. When the platform is rotating or is displaced from a reference the cross products of inertia are also rotating or are displaced causing thereby degradation of the optimum nutation damping time constant. Two or more phase shifting networks are provided to be sequentially coupled into a control loop to shift nutation signals to effect optimum nutation damping at selected positions of the rotating or displaced platform without substantial nutation damping time constant degradation.

대표청구항 ▼

A method of stabilizing an orbiting spacecraft of the dual-spin type having a spin axis and a characteristic nutation frequency, and further having a platform which can spin relative to a motor-driven spinning wheel, said wheel spinning about the spin axis of the spacecraft, said spin axis being com

A method of stabilizing an orbiting spacecraft of the dual-spin type having a spin axis and a characteristic nutation frequency, and further having a platform which can spin relative to a motor-driven spinning wheel, said wheel spinning about the spin axis of the spacecraft, said spin axis being common to said platform and said wheel, a control loop including a motor for driving said wheel and consequently by reaction torques between said wheel and said spacecraft rotating said spacecraft and further including a first sensor and a second sensor, said first sensor oriented to sense motion of said spacecraft about a given geodetic reference lateral axis, and said second sensor oriented to sense pitch errors manifested by rotation of the platform of the spacecraft about the spin axis from a given reference to control the speed of said motor to reduce pitch errors towards said reference, said spacecraft further having cross products of inertia existing on said platform between at least one of the lateral axes and the spinning axis, comprising the steps of: a. driving said wheel at a speed to thereby rotate said spacecraft about said spin axis; b. sensing by said first sensor the geodetic referenced lateral motion of the spacecraft about one of said geodetic referenced lateral axes; c. generating a signal corresponding to the sensed geodetic referenced lateral motion having a cyclic component at the nutation frequency for controlling the torque of the motor; d. phase shifting the cyclic component of the generated signal by said first sensor at the nutation frequency of said spacecraft by an amount such that the signal from said first sensor is shifted in phase by a first angle such that the first sensor signal is equivalent to a sensor signal of a sensor located on a lateral axis wherein substantially optimum nutation damping is achieved at one angular position of said spacecraft about said spin axis as said spacecraft rotates through a first angular displacement; e. applying the phase shifted signal to said control loop to control the torque of said motor; f. phase shifting the cyclic component of the generated signal by said first sensor at the nutation frequency of said spacecraft by an amount such that the signal from said first sensor is shifted in phase by a second angle such that the first sensor signal is equivalent to a sensor signal of a sensor located on a lateral axis wherein substantially optimum damping is achieved at a second angular position of said spacecraft about said spin axis as said spacecraft rotates through a second angular displacement; and g. applying the second-mentioned phase-shifted signal to said control loop to control the torque of said motor. A nutation control system for a dual-spin stabilized device having a platform, a wheel, a motor, a nutation sensor and a pitch sensor, in which the invention comprises at least two phase shifting networks selectively coupled to said nutation sensor and to said motor to cause said motor to apply a torque to said device to reduce the amount of nutation, and further, said pitch sensor being coupled to said motor to control the rotation of said device about the axis of said motor.