Adaptive Trajectory Tracking Control for Unmanned Airships With Input Saturation and Quantization

This article proposes a novel adaptive robust nonlinear trajectory-tracking control strategy for an unmanned airship subject to actuator saturation, input quantization, unknown time-varying disturbances, and model uncertainties. An auxiliary system is first developed to solve the actuator saturation. Then, an adaptive nonsingular terminal sliding mode controller is designed based on the barrier function. The utilized adaptive law eliminates the need to assume disturbance upper bounds, avoids overestimating control gains, reduces chattering, and allows for a stable zero neighborhood of predefined sliding variables. Due to limitations in communication bandwidth, a quantizer is used to quantize the control commands. The key feature of this method is its strong capability for saturation compensation and precise trajectory tracking. Finite-time stability is theoretically proven using the Lyapunov method, and the superiority of the control algorithm is demonstrated through numerical simulations.