Problems in Control System Design for Hypersonic Vehicles

Abstract

The unique problems to be encountered in the design of systems for the precise control of hypersonic vehicles are to be presented and discussed. These problems pose significant research challenges if successful guidance and control systems are to be developed for this new class of vehicle. These challenges will be shown to arise due to the stringent mission requirements on the vehicle, and the highly integrated configuration designs being considered. In this paper, the mission requirements and operational goals of these vehicles will be frrst reviewed, and in particular, the heating problems and trajectory performance issues highlighted. Then the presence of critical coupling between several vehicular subsystems will be clearly exposed, and the dynamic interactions between these subsystems will be presented while considering a selected generic hypersonic configuration. This vehicle configuration, similar to the X-30 vehicle, is shown to be an unstable, highly-coupled, aeropropulsive/aeroelastic system, with large variations in its attitude-dynamic characteristics over its extensive flight envelope. The genesis of these interactions is explored, the magnitudes quantified, and their significance in the context of control system design presented. Since these issues may ultimately limit the feasibility of some configurations, the flight-dynamic modeling and analysis must be performed early in the design cycle such that critical dynamics and control issues associated with a candidate configuration may be exposed. Therefore, such dynamics and controls analysis cannot be postponed until detailed numerical models are available, because configuration changes may then be too expensive.