Singularity-inducing compliant toggle linkage mechanism for large clamping range

Abstract

Finger Clamping Units (FCU) are widely used in industries to clamp flat-shaped objects such as steel panels of car bodies. Generally, FCUs have rigid toggle linkage mechanisms to amplify torque input, and this is possible because the torque amplification ratio becomes large at a near-singular configuration (in proposed FCU, when every link is on the same straight line with each adjacent links, 3(f)). However, such FCUs have limitations that they cannot clamp various thicknesses of panel without change of settings due to the rigidity of the linkage mechanism. In this study, a new type of FCU is proposed with a compliant link that can be compressed to adapt to various thicknesses of panel without any additional calibration. First, static analysis was performed to predict the behavior of a compliant toggle linkage mechanism. Second, the dimension and compliance characteristics were optimized to ensure a large clamping range. Third, verification experiments were performed using FCU prototype.