Influence of hip joint axes change of orientation on power distribution in humanoid motion

A lot of humanoid robots have classical orthogonal leg joint kinematics where all pitch, roll and yaw joints are respectively along longitudinal, lateral and vertical axes of the robot´s body. This paper investigates the influence of different rotary joint axis inclination at the hip joints on power distribution and torque versus speed. Dynamics simulations are carried out taking into account double support motions. The rotation of hip axes about longitudinal axis gives interesting results i.e. a better power distribution when the robot flexes its knees with additional load in the hands.