Abstract: For a switching of a magnitude of system gain in the driving of a load by a control system, a method of inhibiting formation of switching transients has a step of distinguishing between an estimate of a plant state, such as the attitude of a spacecraft, and an integral control state which allows the control system to provide actuation in response to long term disturbances, such as solar pressure, in operation of the system. In the case of a feedback configuration to the system with controller in a forward branch and an estimator in a feedback branch, a loop error signal serves to drive an actuator of the load via the controller. The method includes a further step of evaluating a portion of a controller input signal which is exclusive of an integral control state and which comprises a difference between a desired state and an estimate of the plant state.

Abstract: An active attitude control system for a spacecraft having first, second, and third mutually perpendicular axes utilizes four flywheels, at a minimum, which can selectively provide options of fully redundant momentum bias, 3/4 redundant momentum bias, or fully redundant zero momentum bias. A plurality of reaction wheels are mounted on the spacecraft and rotatable on spin axes in a fixed configuration for together maintaining full three-axis control of the spacecraft to a predetermined attitude. A momentum wheel is also rotatable on the spacecraft about the first axis for maintaining gyroscopic stiffness. In the event of a failure of the momentum wheel, the reaction wheels may have a combined angular momentum sufficient to maintain the gyroscopic stiffness lost by the failure of the momentum wheel while maintaining full three-axis control of the spacecraft to a predetermined attitude.

Abstract: An air bag module and steering wheel assembly includes an air bag module and a steering wheel. The air bag module includes a base plate, an air bag attached to the base plate, and a cover having downwardly extending side walls loosely connected to the base plate while leaving the cover free for manual removal from the base plate, yet being sufficiently sturdy for transporting and storing of the module. The steering wheel includes an upstanding capture plate forming a vertically extending wall surrounding a receiving area. The capture plate engages the side walls of the cover when the module is inserted into the receiving area and captures the side walls of the cover between the base plate and the capture plate such that the cover is anchored to the base plate for withstanding the forces of air bag inflation.

Abstract: An automatic, on-board system for orbiting spacecraft that controls yaw excursions caused by solar torques and thruster firings, which system combines inputs indicative of roll and yaw momentum increases and inputs containing information comprising the unbiased roll error from the earth sensor, yaw momentum measured from the wheel speeds, and commanded yaw momentum output from the wheel controller, and produces therefrom output signals indicative of the yaw estimate and the yaw momentum estimate. These output signals are combined and processed in a controller with a mimimum yaw error and roll thrust yaw controller gain and a miminmum yaw error and roll thrust yaw momentum controller gain, and a signal is produced therefrom for commanding roll thruster firings to change roll momentum, and, in turn, control yaw attitude and yaw excursions.