Unspecified final-time nonlinear suboptimal guidance of aerobatic aircraft in air race

This paper presents a new suboptimal nonlinear guidance design for aerobatic aircraft in air race. This guidance design needs to ensure several stringent terminal conditions at the specified race gates, and to satisfy various path inequality constraints dependent on state and input throughout the flight trajectory such as bounds on control, altitude, velocity as well as structural load factor limits. It also requires to be robust in presence of uncertainties in aerodynamic parameters as well as external disturbances due to wind gust, which makes this guidance design more challenging. To meet these demanding requirements, the guidance commands are generated using an innovative extension of the generalized model predictive static programming (G-MPSP) technique for incorporating both state and input inequality constraints in unspecified final time framework. This formulation readjusts final time depending on online performance of the system. In addition, to ensure various state and input inequality bounds throughout the trajectory, a penalty function approach is followed with this unspecified final time G-MPSP formulation. The effectiveness of this guidance design approach is validated in an air race scenario, while comparing with the Chebyshev pseudospectral method. Simulation results by considering a large number of simulations indicate that the proposed approach is successful under parameter uncertainties and disturbances, demonstrating its robustness aspect.