五自由度混联机构运动学分析与参数优化

Kinematic Analysis and Parameter Optimization of 5-DOF Hybrid Mechanism

摘要:

结构参数优化对机构性能有重要影响，本文以一种面向复杂曲面加工的五自由度混联机构为研究对象，对其进行运动学分析及结构参数优化。运用数值迭代法和解析法建立机构运动学模型。采用分层搜索法求解可达工作空间并计算由每层最大内切圆构成的规则工作空间体积。定义全域性能指标并采用正交试验法分析机构尺寸对性能的影响。通过参考目标距离法建立多目标优化模型，采用遗传算法进行优化设计。仿真结果表明，优化后机构尺寸均有所减小，而全域运动性能指标、全域运动性能波动指标以及全域可操作度性能指标分别提高40%、45%和77%。

Abstract:

The optimization of structural parameters had a significant impact on the performance of mechanisms, in this paper, a five-degree-of-freedom hybrid mechanism for complex surface machining was taken as the research object, and the kinematic analysis and optimization of structural parameters were carried out. The forward and inverse kinematic models of the mechanism were established respectively by using the numerical iterative method and the analytical method. The layered search method was used to solve the reachable workspace and calculated the volume of the regular workspace consisting of the maximum internal tangent circle of each layer. The global performance index was defined and the influence of the size parameters of the mechanism on each performance index was analyzed by orthogonal test method. The multi-objective optimization model of the mechanism was established by the reference target distance method and the linear weighting method, and the genetic algorithm was used to optimize the design. The simulation results showed that the size of the optimized mechanism was reduced, while the global motion performance index, the global motion performance fluctuation index and the global operability performance index were increased by 40%, 45% and 77% respectively. To further verify the optimization results, the velocity and acceleration of the models before and after optimization were simulated and compared. It was found that after the mechanism was optimized, the impact and vibration during the motion process could be reduced, making the motion control of the mechanism more precise.