Development of coaxial wire reduction gear for manipulator robots

A coaxial cable drive mechanism is proposed to implement a high reduction gear ratio. The cable drive mechanism has great advantages such as lightweight, zero backlashes and high degrees of freedom in terms of mechanical design. However, it is restrictively utilised in robotic applications because it is difficult to implement a high reduction gear ratio of more than 10:1 due to the complexity of adjusting tension components, which causes the mechanical structure to be rather bulky and heavy to be mounted. To overcome this, in the present author´s previous work a multi-level reduction mechanism, by adopting a seamless winding method which links the previous output axis to the next input axis, was developed. The performance of the previous work, by adopting a coaxial mechanism to drive the multi-level reduction system is improved. Significantly, the proposed mechanism reduces the overall size due to efficient integration of mechanical parts. On the basis of the proposed mechanism, a three-dimensional computer-aided design is provided and the prototype is manufactured, where the usability of the prototype is verified by experimental results.