Generating whole-body motion keep away from joint torque, contact force, contact moment limitations enabling steep climbing with a real humanoid robot

Abstract

For humanoid robots to perform whole-body motions, a motion planner should generate feasible motions satisfying various constraints including joint torque limitation, friction, balancing, collision, and so on. Furthermore, for life-size humanoid robots to perform higher-load motions, such as climbing ladders, safely, it is important to generate motions which requirements are not too close to the limitations. In this paper, we propose a humanoid motion planner based on Body Retention Load Vector (BRLV), which is a novel index for representing severity of physical constraints: limitation of joint Torque, contact Force, and contact Moment (TFM limitations). By minimizing the norm of BRLV, we obtain humanoid motions that are farthest from TFM limitations. Finally, we evaluate the proposed motion planner in simulation and confirm the effectiveness of the planner through experiments in which a life-size humanoid robot climbs a ladder and a car.