Design and analysis of a two-DOF coupling motion robotic joint
In this paper, a robotic joint with a two-DOF coupling motion is proposed for higher payload ability, power density and speed. With these advantages the joint is ideal for use in robots, especially multi-DOF manipulators. The entire robot manipulator composed of these joints is not involved in this paper. It will be reported in detail in a future publication. Here we just focus on the robotic joint. This robotic joint which is configured as a series-parallel hybrid structure can be called as angular swivel joint. And the joint can move on a spherical surface whose apex angle is 100° by the coupling motions of two independent motor-reducer drive systems. Details of the mechanism design, kinematics analysis and differential kinematics will be depicted. In addition, all motions of the joint can be divided into two modes: mode 1 is that the two motor-reducer systems work in the same speed and with the opposite direction (SSOD); and mode 2 is that the two motor-reducer drive systems work in the same speed and with the same direction (SSSD). Moreover, a unique control strategy based on these two basic motion modes are presented. Finally, simulations and experiments are implemented to verify the feasibility and performance of the joint.