A new biped mechanism with two 7-DOFs legs and a double spherical hip joint

The conventional biped mechanism is uniquely fixed when its poses of feet and waist have been specified, and the humanoid robot with it has to walk with bending knees. To overcome these disadvantages, this paper proposes a new biped mechanism with two 7-DOFs legs and one double spherical hip joint. There are two primary advances compared with the conventional one. First, the humanoid robot with two 7-DOFs legs can adjust the lower limb in a manner similar to what human does even that poses of feet and waist have been set. Second, the double spherical hip joint can implement the functions of both hip and waist without introducing waist joint, which means that it is possible for humanoid robots to act knee-stretch walking. In this paper, kinematic analysis and motion pattern generation of the proposed biped mechanism are discussed in detail. And the effectiveness of this new mechanism has been validated by experimental results.