Flexible Switching Control of Aircraft Skin Inspection Robot via Adaptive Dynamic Programming

This article considers the flexible switching control problem of a two-frame aircraft skin inspection robot (TFASIR) with full-state time-varying constraints, input saturation, uncertainty, and unknown disturbance. Initially, this control problem is also treated as a tracking control problem of the dual-coupled adsorption system (DCAS). A novel nonlinear time-varying state-dependent function (NTVSDF) is first designed to tackle the full-state constraint problem. Subsequently, a feedforward tracking control method is designed, that uses the command-filtered backstepping technique, to transform the tracking control problem into an equivalent differential game problem (DGP) of closed-loop systems. Then, a zero-sum game strategy is presented, that uses the idea of adaptive dynamic programming (ADP) algorithm, to determine the DGP. The whole control method ensures that the closed-loop signals are uniformly ultimately bounded (UUB). Furthermore, another problem is that the partial system states are not accessible. To overcome this problem, a high-gain observer is utilized to reconstruct the state vector, and an output feedback controller is developed. The feasibility of the proposed control scheme is demonstrated in simulation.