Modified A* Algorithm for Optimal Motion Trajectory Generation of Rotary Cranes

Abstract

This paper presents an optimal trajectory generation method to achieve smooth and fast motion of rotary cranes in the presence of obstacles. The proposed trajectory is generated by a combination of the A* algorithm and a time-optimal scheme. The first approach is obtained by modifying the A* algorithm based on joint coordinate frames to improve the motion-time of the two rotational boom angles and rope motion with obstacle avoidance. Different weight values are assigned to provide varied priorities for each joint motion in the crane system. Next, the time-optimal approach is applied to the path generated by the proposed A* under crane dynamics and loadsway constraints. The proposed trajectory is represented by a polynomial function to provide practical and smooth motion. Simulation results illustrate the effectiveness of the time-optimal trajectory with load-sway suppression and obstacle avoidance.