In this paper, we propose a compliant—parallel mechanism that enables a wide working area and a high accuracy. The compliant—parallel mechanism is a parallel mechanism that all joints are composed by largely deformable springs. Designing the compliant joints for the mechanism let us explore new challenges: The joints should be elastic for the desired direction, but also rigid for non-desired direction to be deformed. The stress applied during the deformation must not exceed the yield stress to prevent the fatigue failure. The processing method should be carefully considered to minimize the individual variability of spring characteristics. The energetic efficiency also must be taken into account for designing the mechanism. Considering these issues, we developed a new compliant joint structure - alternate side slits structure to be applied to the mechanism. We conducted FEM analysis to clarify the effectiveness of the proposed spring, and the spring was implemented to a prototype, that was designed based on a well known parallel mechanism, DELTA within 50×50×5[mm] of working area. The evaluation tests conducted on the prototype showed 0.46[μm] of repeatability in average and 94.3[N/mm] of rigidity in Z axis, that are promising to be applied for an optical parts assembly system.
