Reconfigurable Inner Loop Control of a Space Maneuvering Vehicle

Abstract

The development of an inner-loop control law for a reusable launch vehicle is described in this paper. The control design is based upon a dynamic inversion control law developed for a lifting body with six control surfaces. The commanded body rates constitute the input to a dynamic inversion control law that forms the inner-loop control structure. This provides the control system the ability to track roll, pitch, and yaw rates. In addition to these three inner-loop variables, a velocity control loop has been developed. This velocity loop provides limited control over the vehicle’s velocity, utilizing only the drag produced by the control surfaces. As a result, instead of using a typical three-axis control allocator, a four-axis control allocation algorithm was developed (three bodyaxis rotation rates and one linear acceleration). The outputs of the dynamic inversion algorithm, namely the commanded body angular acceleration vector and linear longitudinal acceleration, serve as the inputs to a linear programming based control allocator. A method for improving the perfor