Energetically Efficient Ladder Descent Motion With Internal Stress and Body Motion Optimized for a Multilocomotion Robot

Energy efficiency of locomotion is a significant issue for autonomous mobile robots. This paper focuses on the pace gait ladder descent motion that has a closed kinematic chain formed by the robot links and the environment. To reduce the energy cost in the closed kinematic chain, we propose an optimal control strategy by optimizing the internal stress and motion trajectories in parametric form. As the main contributions of this paper, three types of energetically efficient ladder descent motions are generated with different motion-mode assumptions. Critical factors, including cycle time, horizontal distance between the robot and the vertical ladder, and value of internal stress, are analyzed theoretically. Simulation and experimental results indicate that the proposed control strategy is effective for planning an energetically efficient ladder descent motion.