Cooperative walk control of paraplegia patient and assistive system

Abstract

This paper introduces a cooperative control algorithm that designs a stable biped walk satisfying a wearer's intention relating to his/her walk such as a timings to start and stop walking, walking speed and waking direction. Using this algorithm an exoskeletal walking support system could help a paraplegia patient walking comfortablly. At first, a pair of gloves with several DOFs is developed to convey a wearer's intention to the walking support system. He/she swings both his/her index fingers as to simulate foot motions of his/her walking. The amplitude and period of the swing corresponds to a step length and period of the walk, respectively. Pronation/supination of the wrist joint of his/her right arm corresponds to a walk direction. The cooperative control algorithm based on a cart-table model designs trajectories of each joint for stable walking pattern that satisfies the intention expressed by the wearer's hand motion and then the designed walking pattern is executed in realtime by the walking support system. As the first trial, a small humanoid robot “HRP-2m” is used for safety as a control target that will be a combination of a wearer and the walking support system in the final situation. Through some experiments we confirm that our proposed algorithm enables the humanoid robot to start and stop stable walk with variable step length in the desired walking direction according to operator's intentions.