Design and experiments of a humanoid torso based on biological features

Among the components of a humanoid robot, a humanoid torso plays a vital role in supporting a humanoid robot to complete the desired motions. In this paper, a new LARMbot torso is developed to obtain better working performance based on biological features. By analyzing the anatomy of a human torso and spine, a parallel cable-driven mechanism is proposed to actuate the whole structure using two servo motors and two pulleys. Analysis is conducted to evaluate the properties of the proposed parallel cable-driven mechanism. A closed-loop control system is applied to control the whole LARMbot torso. Experiments are performed using the manufactured prototype in three modes to evaluate the characterizations of the proposed design. Results show that the proposed LARMbot can complete the desired motions properly, including two general human-like motions and a full rotation motion. When completing two general human-like motions, the maximum bending angle is 40 degrees. The maximum cable tension is 0.68 N, and the maximum required power is 18.3 W. In full rotation motion, the maximum bending angle is 30 degrees. The maximum cable tension is 0.75 N, and the maximum power required is 20.5 W. The proposed design is simplified and lightweight, with low energy consumption and flexible spatial motion performance that can meet the requirements of the humanoid robot torso's application in complex scenarios and commercial requirements.