Human-like walking with straightened knees, toe-off and heel-strike for the humanoid robot iCub

Most humanoid robots don´t walk in a very human-like manner. Their bent knees ensure a constant centre of mass height but this requires high motor torques. Also, humanoids walking without toe-off and heel-strike phases are considered to be considerably less energy efficient. Therefore, it is desirable to design a walking trajectory generator that has both straightened knees and toe-off and heal-strike phases. In this paper, we address this issue by designing pattern generators for varying both the hip height and the feet trajectories (toe-off and heel-strike phases). The dynamic simulation of a child robot “iCub” demonstrates successful gaits in a human-like manner. The knee joint torque required by the proposed strategy is reduced, compared to conventional bent knee walking. Additionally, the simulation also reveals a redistribution of joint torques among the hip, knee and ankle in the human-like walking, which is more energy efficient.