Westinghouse Electric Corporation

Space Industries Partnership, L.p.

Donald J Schmidt

In an attitude control system for a spacecraft having a frame which is to be maintained in a desired orientation relative to a selected set of reference axes, which system includes an electromechanical actuator mechanically coupled to the spacecraft frame for applying to the frame a mechanical torque which opposes deviations from the desired orientation relative to at least one reference coordinate, the actuator including an electric motor and an element connected to be rotated by the motor, and a torque command signal generator connected to the motor for applying a torque command signal which is a function of such deviations and which drives the motor in a manner to control the torque being produced by the actuator, there is included an energy desaturating system composed of: a unit coupled to the element for producing a signal representative of element motion; a signal modifying circuit connected to produce a control signal having a magnitude which is a function of the signal representative of element motion; and signal coupling components including a switch connected for applying the control signal to the actuator with a polarity for effecting actuator desaturation only during the times that the switch is closed.

Energy desaturation of electromechanical actuators used in satellite

A guided missile subsystem including a Kalmanized radar track loop driven by acceleration signals of the missile generated by an inertial measuring unit (IMU), and a missile control loop driven by estimates of the relative kinematics of the missile and target computed by the radar track loop is disclosed. The IMU driven Kalmanized radar track loop accommodates the use of a high performance radar, like a synthetic aperture radar, for example, which operates to measure radar data at a low rate on the order of 1 Hz, to generate estimates of relative target and missile kinematics to drive the control loop at rates compatible with high performance missile kinematics. The Kalmanized track loop effects an exchange of IMU errors for 'dynamic lag' errors of conventional track loops which cannot be modeled very well, and can change very rapidly. In contrast, the IMU errors can be modeled well, and in addition change very slowly which is what permits the Kalmanization function to work well in the track loop at reduced rates. Because of the dynamic exactness of the track loop, very good estimates of the relative kinematics of the missile may be supplied to the control loop to effect more accurate computations of maneuver commands which drive the controls of the missile. Moreover, the Kalmanized track loop does not let large amounts of angle glint noise into the control loop prior to missile impact. An effective bandwidth decrease as glint noise increases is provided without incurring a dynamic lag error penalty.

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Ellicott City, MD, United States of America

Donald J Schmidt