Spatial Trajectory Tracking of a Stratospheric Airship with Constraints

This paper addresses the spatial trajectory tracking problem of a stratospheric airship in the presence of state constraint. A constrained Laguerre-based model predictive control (MPC) method integrated with sliding mode control (SMC) is proposed as the main control framework. First, by approximating the predicted control signal with Laguerre orthonormal basis functions, a linear MPC controller which is capable of dealing with the constraints explicitly is presented to track the predetermined trajectory based on the kinematic model of airship. Second, based on the dynamic model of airship, an SMC controller with a fast power rate reaching law (FPRRL) is designed to track the desired velocity calculated by the MPC controller. Furthermore, a command filter is employed to estimate the derivative of desired velocity. Stability analysis implies that the tracking error will converge to a small neighborhood of zero. Simulation validates the effectiveness of the proposed control scheme.