Anti-saturation prescribed-time control for multi-quadrotor transportation system with collision avoidance

Multi-quadrotor cable-suspended transport systems face multiple practical challenges, including unmeasurable payload states, actuator faults, input saturation, and collision risks. To simultaneously address these issues, an integrated anti-saturation prescribed-time control strategy is proposed in this paper. First, a novel asymmetric saturation function is introduced to approximate the control input subject to saturation constraints. Second, a prescribed-time extended state observer is designed to estimate the unmeasurable states of the payload and compensate for external disturbances, which guarantees that state estimation errors converge within a prescribed time. Then, a prescribed-time sliding mode control strategy integrated with the repulsive potential function is constructed, which achieves precise trajectory tracking and collision avoidance between quadrotors. The convergence time of the entire transport system can be manually designed and is independent of initial values and system parameters. Finally, the effectiveness and superiority of the proposed control strategy are verified on the Robot Operating System (ROS) and Gazebo platforms.