Guidance and obstacle avoidance of passive robot walking helper based on receding horizon control

Along with the coming of the aging society, the passive robot walking helper is introduced for providing safe mobility for the elderly, which features continuous energy dissipation from the system with brakes for steering. When this passive walking helper is applied for guidance and obstacle avoidance, it is crucial to determine proper braking torques in accordance with user-applied force for avoiding the obstacles and reaching the desired location. Motivated by it, in this paper, we propose such an approach based on receding horizon control. The proposed approach is efficient in braking torque derivation and allows the walking helper to stop at the goal with parking control. With the desired location to reach, the proposed scheme first plans a smooth path for the walking helper to follow based on Dubins curve [13]. The process of torque derivation is then formulated into solving an optimization problem with constraints that guarantee system passivity. When the walking helper detects the obstacles, the obstacle avoiding strategy is activated to bring it to deviate from them, which is achieved by including the constraints for obstacle avoidance into the optimization process. Simulations and experiments are performed to demonstrate the effectiveness of the proposed approach.