Controls design challenge - A variable structure approach

The purpose of this paper is to investigate variable structure control as a tool for the design of flight control systems. Variable structure control allows the direct incorporation of model uncertainties and nonlinearities in the design process, yielding a piecewise continuous structure for the compensator that maintains the system dynamics along specified stable trajectories (sliding hypersurfaces). Under mild restrictions, the resulting control law is robust with respect to unknown but bounded parameter variations and other uncertainties. A linearized model of an aircraft is used for the design, and a flight control system is synthesized, which gives desired response to initial conditions and tracks a commanded altitude. The control synthesis and simulation are performed using computer-aided software on a personal computer.