  This paper presents a continuous optimization approach to DCOC and its
application to spacecraft high-precision attitude control. The approach
computes a control input sequence that maximizes the time-before-exit by
solving a nonlinear programming problem with an exponentially weighted cost
function and purely continuous variables. Based on results from sensitivity
analysis and exact penalty method, we prove the optimality guarantee of our
approach. The practical application of our approach is demonstrated through a
spacecraft high-precision attitude control example. A nominal case with three
functional reaction wheels (RWs) and an underactuated case with only two
functional RWs were considered. Simulation results illustrate the effectiveness
of our approach as a contingency method for extending spacecraft's effective
mission time in the case of RW failures.
