Design of a miniature bi-directional non-back drivable mechanism with high retaining torque

Ensure the safe operation of a mechanical system that involves motion is essential; some traditional ways to achieve this goal are mechanical devices such as breaks or clutches. This paper presents the design, manufacturing, and test of a bi-directional non-back-drivable mechanism for its application in miniature mechanical systems, like prostheses, robotics, or micro-machine tools. The bi-directional non-back-drivable mechanism operates as a locking device, limiting the torque transmission from the output into the input axle. Application of Design for X methods served to identified and prevent the main drawbacks of the mechanisms used for locking tasks, namely wear and backlash, to make the novel mechanism less sensitive to such factors, keeping high transmission performance in a tight space and with minimum parts. The presented set of design equations and selection graphs are for ABS plastic. A unified approach for the design of the bi-directional non-back-drivable mechanism is presented. The final section of the paper is devoted to the manufacturing and test of a sample of the mechanism.