Antiswing Control Strategy for Quadrotor Transporting a Cable-Suspended Payload: A Two-Stage ADRC Approach

In order to deal with the control problem of a quadrotor with a cable-suspended payload, a novel antiswing control strategy based on a two-stage active disturbance rejection control (ADRC) is proposed in this article. The process of lifting the payload from the ground is considered, and the whole control can be divided into three stages accordingly, which is different from most existing works. The ADRC-based control algorithm is applied at each stage to attenuate the effect of unknown external disturbances, and a step-extended state observer is introduced specially to ensure tracking performance during the transient stage. Furthermore, the concept of virtual position is introduced to deal with the swing motion of the suspended payload generated during the quadrotor's trajectory tracking. Based on the virtual position, a novel quadrotor position controller is designed, which can improve the antiswing performance and disturbance rejection capabilities simultaneously. Numerical simulations and experiments have validated the effectiveness of the proposed method at the end of the article.