Multi-task Trajectory Synthesis Method of Single-DOF Stephenson Mechanisms Based on Sensitivity Analysis

doi:10.3901/JME.2024.05.059

Abstract

Abstract: Single-degree-of-freedom (single-DOF) mechanisms are simple to control and have good stability, yet they can only realize one specific motion. Hereby a design method for multi-mode single-DOF six-bar Stephenson mechanisms is proposed, which retains the advantages of single-DOF mechanisms while enabling the realization of multiple target trajectories through a selected adjustable parameter. The kinematic analysis of a single-DOF Stephenson mechanism is conducted, and based on its kinematic equations, sensitivity analysis is conducted on nine link length design parameters to determine the impact of variations in different design parameters on the resulting trajectory of the end effector. Based on the comparison of the trajectory variation, the cost function is constructed, and an analysis method with different adjustable parameters is proposed. Taking the synthesis of multiple lower-limb gait trajectories from various populations as the example, through sensitivity analysis and evaluation function value comparison, l₆ is determined as the optimal adjustable design parameter for multi-mode Stephenson six-bar mechanism in multi-objective trajectory synthesis and parameter design. The results show that by adjusting the length parameter of the l₆ link, three target trajectories can be well achieved on this single-DOF mechanism. Further analysis of this multi-mode single-DOF Stephenson mechanism shows that its kinematic performance is good. Using this mechanism as an actuator to design a lower limb gait rehabilitation device not only provides a simple structure and convenient control, but also has good adaptability for different target populations.

Key words: single-DOF mechanism, sensitivity analysis, trajectory synthesis, rehabilitation mechanism design

CLC Number:

TP242

ZHAO Ping, ZHANG Yating, CHENG Yue, XU Hongwei, ZI Bin. Multi-task Trajectory Synthesis Method of Single-DOF Stephenson Mechanisms Based on Sensitivity Analysis[J]. Journal of Mechanical Engineering, 2024, 60(5): 59-69.

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