Time domain synthesis of robust controllers for space nuclear power systems

Many control problems demand hard constraints on system variables because of physical limitations related to safety. Although results relating to energy bounds and probabilistic bounds are numerous, corresponding results on hard constraints are scattered and have not been adequately treated in the literature. Work specifically dealing with hard constraints is research on the unknown-but-bounded (UBB) description of uncertainty for linear systems, pioneered by F.C. Schweppe (1973). Schweppe´s ellipsoid bounds are extended to account for system parameter variations. An algorithm is presented for the time domain synthesis of control systems which inherently exhibit robustness to system parameter variations. The theoretical results are applied to the regulation of a simplified model of a gas-cooled space nuclear power system, which exhibits uncertainty in its reactivity coefficients. Results indicate that appropriate selection of the uncertain system parameter bounds allows design of regulators that exhibit desired stability and performance characteristics-compliance with the imposed constraints-throughout the range of the parameter uncertainty