Descending stairs locomotion and somatosensory control for an erect wheel-legged service robot

In this paper, an erect stair climbing robot, which has been able to ascend stairs, is further developed for descending stairs automatically. The somatosensory control functions are also implemented for a human rider to drive the robot on flat ground as a personal vehicle instinctively. In order to face front whether climbing up or down stairs, the robot is designed with proper mechanical structure and mass distribution. Moreover, the perception and control methods of descending stairs are modified from the methodologies of ascending stairs in our previous works so that the robot can handle both ascending and descending stairs effectively under similar principles. As for the somatosensory control part, the functions of controlling the robot to move back and forth using the rider's body motion is realized, which has more advantages than Segway PT since it can stand still when the rider wants the platform to stop moving, and the robot motion under the control of the human rider is stable enough for indoor applications. In the experiments, the stair-climbing abilities and somatosensory control functions are both successfully demonstrated, which proves that the design and implementation of the robot system are feasible and efficient. We are looking forward for more functions and applications of the robot, including our ultimate goal of carrying a human rider to climb stairs in an erect way with somatosensory control simultaneously.