Singularity Analysis and Dimensional Optimization on a Novel Serial-parallel Leg Mechanism

A novel series-parallel hybrid mechanism is presented to overcome the limitations of serial robots and parallel robots caused by the mechanism characteristics, and using it as the leg, a serial-parallel quadruped robot is structured. Based on vector method and differential transform method, velocity Jacobian matrix of the hybrid leg mechanism is gained, and singularity of the leg is analyzed ulteriorly. In order to evaluate the kinematic dexterity of the hybrid leg, dexterity evaluation indexDh is proposed, further more, dimensional optimization has been taken according to index Dh, and results show that, when angle between driving shaft of the hip and vertical direction is 50.5 degree and the ratio of the thigh and the calf is 0.72, index Dh is maximum, that is, the hybrid leg has best dexterity. In accordance with the results of the optimization, prototypes of the hybrid leg and the serial-parallel quadruped walking robot have been successfully trial-produced. This research helps lay a solid foundation for a series of further studies of the novel series-parallel quadruped robots.