Trajectory optimization and control for moving handrail based on human dynamical model

Abstract

To reduce the burden of caregivers, we have developed a moving handrail-type device that supports the standing-up motion of a person based on the Assist-As-Needed concept. The trajectory of the moving handrail was optimized to minimize the power of the user’s whole body based on a human dynamical model, using the motion of a person who stands up naturally as a reference. In the Assist-As-Needed method of control, the speed at which the handrail moves along the trajectory is changed according to the force acting on the handrail and the amount of assistance is adjusted so that the handrail provides only the necessary amount of assistance. For this purpose, the control is carried out using a orbit attractor so that the motion is realized without time constraint. Finally, the designed optimal trajectories are implemented in an experimental system with a moving handrail consisting of two-link manipulators and a humanoid robot consisting of four-link manipulators to verify the effectiveness of the control method.