Motoshi Ohno

A bio-inspired compliant parallel mechanism for high-precision robots

In this paper, a compliant parallel mechanism with high precision and a wide working area is presented. A compliant parallel mechanism is a parallel mechanism in which all of the joints are deformable elastic joints. The presented mechanism is composed of circular compliant joints that have been inspired by Drakaea, which is an orchidaceous species. From our analytical and experimental tests, it was revealed that these circular compliant joints have desirable characteristics for composing a compliant parallel mechanism. Based on these primary experimental results, we developed a 3-DOF compliant parallel mechanism for an optic component positioning machine. The prototype evaluation tests revealed the mechanisms advantageous characteristics.

Compliant-parallel mechanism for high precision machine with a wide range of working area

In this paper, we introduce a further optimization of morphology of compliant joint based on FEM analysis for a compliant-parallel mechanism with a wide working area and a high accuracy. Compliant-parallel mechanism is the mechanism that all joints are composed by compliant joints in a parallel structure. In the integration of compliant and parallel mechanism, the motion of compliant joints can be guided by mechanical constraints from the parallel structure; thus the mechanism can be precisely driven. However, since compliant joints generally have a limited working area due to limitation in their structural deformation, the working area is commonly limited in micrometer-scale. Designing the compliant joints within a wide range of working area presents us a new challenge: the joints should be elastic for the desired direction, but also rigid for non-desired direction to be deformed. From these requirements, the morphology of the compliant joint was optimized by FEM analysis, and newly serially layered-flat spring compliant joint was developed. The developed compliant joint was implemented on a parallel mechanism as a high precision micro-assembly system for optical components. The prototype enabled 50×50×5 mm of working area within 0.71 mm of repeatable accuracy. From these results, the effectiveness of the morphological optimization for compliant joint was shown.