On direct model reference adaptive controller design for flexible space structures

Direct Model Reference Adaptive Control (DMRAC) and Direct Adaptive Disturbance Rejection (DADR) control methods have recently been developed with control of flexible structures in mind. In this case, the plant model is generally high order since many modes of the structure are needed to faithfully model the response of the structure. DMRAC and DADR control provide a method for adaptively controlling such a high order system and rejecting disturbances from the plant with a much lower order controller. However, DMRAC and DADR theory do not provide many suggestions or guidelines for actually designing and implementing DMRAC and DADR controllers.; A procedural design process is proposed where by the engineer can develop a reference model and adaptive gains for the DMRAC and DADR controller. How to modify a non-minimum phase or non-SPR system so that the augmented system is SPR is also considered. By modifying the output matrix of the system with a nonlinear optimization technique, the system can be made SPR. Within this context, two theorems are stated and proved that show when certain types of systems can be made SPR or when the systems are SPR. It is shown that an appropriate choice of output feedback gain for a single mode, SISO system, will always stabilize the system and make the system SPR. Also, it is shown that a multi-mode, MIMO system is SPR when certain conditions are met. In both cases the satisfaction of the SPR conditions are based on the modal characteristics of the plant model.; The proposed design procedure and theorems are applied to a known illustrative system, a 2-dimentional aeroelastic wing system, and a 79-state model of a space telescope. Each application of the DMRAC and DADR design procedure elucidate different problems that arise when trying to apply DMRAC and DADR control to a given system. The problems encountered are synthesized as design suggestions for engineers hoping to apply DMRAC and DADR control techniques. Namely, if at all possible, design the system so that it is minimum phase. If the system is minimum phase the CuDMRAC software can sometimes be used to design a DMRAC and DADR controller for the system. The reference model and adaptive parameters used in the controller can then be modified to satisfy the required performance specifications.