An Integrated Joint for Cooperative Robots

This paper proposes a high-power density integrated joint for the novel cooperative robots. The design trends to be a more compact mechatronical integrated joint with high reliability and accuracy. To achieve this, the main components inside the joint are a harmonic drive, a permanent magnet torque motor, an incremental encoder, a single turn absolute encoder, a brake and a servo drive. This combination of components inside the joints leads to lower weight and smaller outer envelope size. The entirety of the motor shaft and harmonic drive cam can reduce the axial length of the joint. The wires arranged inside the hollow shafts is the critical way to achieve the mechatronical joints. Double encoders configuration inside the joint (incremental encoder feedbacks the motor position and single turn absolute encoder feedbacks the joint position) will achieve the absolute position accuracy less than 0.05mm. Finally, a simulation result is shown to verify the reliability of the designed joint.