Trajectory Generation and Control of a Quadrotor with Slung Payload Considering Swing Suppression and Cable Collision Avoidance

Abstract

In this thesis, a trajectory generation algorithm is proposed for a quadrotor with slung payload. There exist two major issues of the slung payload: cable collision and payload swing. Previous studies tried to circumvent cable collision effect by performing conservative payload lifting, that is by placing the quadrotor at the top of the payload and lifting it gently. In this paper, the state jump occurs at cable collision is limited to its magnitude by aligning the velocity vector of the quadrotor with the position vector between the vehicle and the load. Therefore, the trajectory can be generated without dividing it into several discrete modes. Swing of the payload should be suppressed to avoid undesirable potential instabilities throughout the mission. Therefore, trajectory suppressing the swing is generated by minimizing the derivative of the tension over the whole mission. The reference trajectory suppressing the payload swing is generated. Rapidly-exploring Random Tree algorithm is used for generating intermediate waypoints between initial position and final position. By planning the path in advance, limitations on sensor and controller of the system can be relieved. The proposed method can make quadrotor follow the reference trajectory without knowing the current state information of the payload, thereby the payload can also follow the swing suppressing trajectory. Numerical simulation is performed to demonstrate the performance of the proposed algorithm.