A Compliant-Parallel Mechanism with Bio-Inspired Compliant Joints for High Precision Assembly Robot

In this paper, we describe a study on compliant-parallel (C-P) mechanism with high precision and wide range of working area using bio-inspired compliant joints. C-P mechanism is a parallel mechanism in which all of joints are composed by wide deformable compliant joints. In the integration of the compliant joint and the parallel mechanism, a deformation of the compliant joint can be guided by mechanical constraints from the parallel mechanism; thus C-P mechanism can be precisely driven. C-P mechanism has no back-lash, requires no lubrication, and is free from machine noise and abrasion power. And, unlike conventional mechanisms, C-P mechanism can be integrated into compact, lightweight, and simple structure. From these backgrounds, we developed a widely deformable circular compliant joint inspired by Drakaea, which is an orchidaceous species. The circular compliant joint was implemented on a 3-DOF (rotational 2 and translational 1 DOF) parallel mechanism as a first prototype. Then, our second prototype was developed to realize further wide range of working area. A serially layered-flat spring compliant joint was developed based on the bio-inspired circular compliant joint, and was implemented on a traditional 3-DOF DELTA mechanism, as the second prototype. From the evaluation tests of these prototypes, the feasibility of C-P mechanism was shown positive to be applied to a high precision assembly robot within a wide range of working area.