Double spherical joint and backlash clutch for lower limbs of humanoids

In this paper, we develop two mechanisms for improving humanoid robot motions. The double spherical joint is a six DOF mechanism whose axes intersect in one point. This mechanism is used for humanoid hip joints with a waist joint function without increasing the actuator. The backlash clutch realizes a high torque driving and a free joint using backlash mechanisms is used for knee joints. The free mode will play a role in humanoid behavior that is dynamically coupled with the environment. The humanoid robot with these two mechanisms is developed and results of preliminary experiments are shown.