Design of the power transmission lines inspection robot based on the modular joint with 2 degrees of freedom

This paper proposes a modular joint with 2 degrees of freedom (2DOF) for power transmission lines inspection robot. The proposed 2DOF joint improves the movement ability and has advantage of obstacles avoidance. The joint adopts the modular design concept and can be assembled simply and maintained easily. What's more, it reduces the coupling with other mechanical structures. The differential transmission principle is used to design the joint and three orthogonal bevel gears are used to realize the joint's pitch motion and the rotary motion which make the joint more flexible. The modular joint has a double reduction with 860 reduction ratio. There are two motors as the power source and the driving moment is the synthesis of the two motor torques, which makes the joint a strong load capacity. There are two position sensors at the pitch freedom and rotation freedom for position detection to improve joint's detection precision and control precision. The joint integrates mechanical, electrical and control system and having the characteristics of high integration.