Optimized Design Method Based on Parallel Stepwise Hierarchical Constraints and its Application for 1-DOF Six-Bar Finger

The function and adaptability of the manipulator is critical in specific operational tasks such as gripping, plugging, screwing, and shearing, among which gripping is a prerequisite for performing other functions. This article proposes a linkage design method based on parallel stepwise hierarchical constraints (PSHC) that satisfies the design requirements of complex linkages while improving design efficiency and optimizing accuracy. By taking advantage of the simple control and high rigidity of one-DOF linkage, constraints such as reference point, closed-loop rotational angle, and envelope angle were applied by using the PSHC method to efficiently design multiple sets of Watt I linkage fingers with envelope angles greater than 180^◦ in about 20 min. A case in this article achieved an envelope angle of 213.47^◦, which is currently the largest among linkage fingers, and demonstrated a human-like appearance and great grasping performance. This study has good reference significance for the design of other single degree-of-freedom mechanisms and subsequent flexible hand designs for single-finger/multi-finger systems.