Study on kinematical modeling, control and experiment of a differential waist mechanism

Some biped or wheeled-base humanoid robots have waist mechanism in their body structures. Humanoid robots with waist mechanism have large workspace and high agility. A novel waist configuration with parallel driving motor was introduced in this paper. This waist mechanism is driven by the differential-gear closed transmission. It can realize its pitch and yaw motion separately and composite motion of pitch and yaw. The direct and inverse kinematic model of the waist mechanism was built and the Rosolved Motion Rate Control Strategy based on the kinematic model of the waist mechanism was designed in this paper. The experimental research on the kinematic characteristic of the waist mechanism was also finished. The result shows the response speed of the waist mechanism is fast and the lowest space position tracing error is 0.1 degree.