Prescribed Performance Event-Triggered Control for Nonlinear Multiquadrotor Slung-Load Transportation

This paper presents an event-triggered control strategy that integrates a relative threshold mechanism with prescribed performance constraints for multi-quadrotor slung-load transportation systems. The proposed approach addresses the challenges posed by strong nonlinearities and limited onboard computational resources. A dynamic model that explicitly considers load geometry and cable tension constraints for a multi-quadrotor slung-load transportation system is obtained through the application of the Udwadia-Kalaba equation. This model effectively captures the coupled nonlinear dynamics between the slung-load and the quadrotors during transportation maneuvers. Based on consensus theory, a cooperative control architecture is designed for the multi-quadrotor formation. Leveraging an adaptive backstepping control framework, a prescribed performance function is implemented to map the tracking error into a constrained domain. This mapped error signal is further integrated into a relative threshold event-triggered mechanism that dynamically adjusts the control signal update frequency based on the current error state, thereby reducing computational resource consumption while ensuring precise tracking. Simulation experiments, including complex scenarios like load landing and unloading, were conducted. The results demonstrate that the proposed control method significantly reduces the number of control updates and computational burden, while also improving tracking accuracy and dynamic response.