Strategies for the Design of a Slide-o-Cam Transmission

TL;DR

This paper explores optimizing the pressure angle in a Slide-o-Cam transmission to improve force transmission efficiency, proposing design strategies involving increasing lobes or cams, aimed at replacing ball-screws in a parallel robot.

Contribution

It introduces specific design strategies to optimize pressure angle in Slide-o-Cam mechanisms, enhancing their performance for robotic applications.

Findings

Increasing the number of lobes reduces the pressure angle.

Adding more cams improves force transmission.

Optimized designs outperform traditional ball-screws in certain metrics.

Abstract

The optimization of the pressure angle in a cam-follower transmission is reported in this paper. This transmission is based on Slide-o-Cam, a cam mechanism with multiple rollers mounted on a common translating follower. The design of Slide-o-Cam, a transmission intended to produce a sliding motion from a turning drive, or vice versa, was reported elsewhere. This transmission provides pure-rolling motion, thereby reducing the friction of rack-and-pinions and linear drives. The pressure angle is a suitable performance index for this transmission because it determines the amount of force transmitted to the load vs. that transmitted to the machine frame. Two alternative design strategies are studied, namely, (i) increase the number of lobes on each cam or (ii) increase the number of cams. This device is intended to replace the current ball-screws in Orthoglide, a three-DOF parallel robot for the production of translational motions, currently under development at Ecole Centrale de Nantes for machining applications.