Rigid-body load control and transportation by multiple UAVs with improved sliding mode based extended state observer compensation

Abstract In the past decade, the use of multiple drones to transport rigid loads, such as precision instruments and easily spilled medical agents, has attracted significant attention in both industry and academia. However, controlling the position and orientation of rigid loads remains challenging due to their indirect control characteristics. To address this, this paper derives a dynamic model for a multi-quadrotor system transporting a rigid load using Hamilton’s principle and the Lagrangian method. An ESO-based IBSMC active disturbance rejection algorithm is then designed to ensure quadrotor formation stability by controlling quadrotor positions, attitudes, cable swing angles, and load attitude. The control structure integrates the laws to achieve fast response, strong robustness, and minimal steady-state error, generating smooth trajectories using the system’s differential flatness properties. Simulations and experiments validate the proposed method, demonstrating its effectiveness and superiority in load transportation tasks.