一种基于D-H参数的7自由度机械臂机构精度综合方法研究

提出了一种基于最佳精度模型的机械臂机构精度综合的方法，利用遗传算法对D-H参数公差优化分配，为机械臂的精度设计提供理论依据。以一种基于双电机伺服驱动关节的7自由度协作机械臂为研究对象，机械臂的几何定位精度的设计目标为1.4 mm,建立该型机械臂末端执行器的几何定位误差模型；对参数误差进行敏感性分析，找出对机械臂末端执行器几何定位误差影响相对较大的参数误差；根据最佳精度数学模型，利用遗传算法对D-H参数公差优化分配；经过对误差仿真计算分析，机械臂的最大几何定位误差为1.226 7 mm,均值为0.485 9 mm,方差为0.216 5 mm,满足设计要求。为该机械臂的制造装配提供了理论参考依据。与基于最小成本模型的精度综合法相比，提出的精度综合方法不需要统计加工制造成本信息，能够确保机械臂的设计精度满足设计要求，可用于单个或者小批量生产制造机械臂的精度设计。

Research on the precision synthesis method of a 7 DOF manipulator based on D-H parameters

A precision synthesis method of manipulator mechanism based on the optimal precision model is proposed. The genetic algorithm is used to optimize the tolerance allocation of D-H parameters, which provides a theoretical basis for the precision design of the manipulator. Taking a 7DOF cooperative manipulator based on the dualmotor servo drive joint as the research object, the geometric positioning accuracy of the manipulator is designed to be 1. 4 mm. The geometric positioning error model of the end-effector of the manipulator is established. The sensitivity analysis of parameter errors is implemented to find out the parameter errors which have a relatively great influence on the geometric position errors of the end-effector of the manipulator. According to the optimal precision mathematical model, the genetic algorithm is used to optimize the tolerance allocation of D-H parameters. After error simulation calculation and analysis, the maximum geometric positioning error of the manipulator is 1. 226 7 mm, with an average value of 0. 485 9 mm and variance of 0. 216 5 mm. This result meets the design requirements and provides a theoretical reference for the manufacturing and assembly of the manipulator. Compared with the precision synthesis method based on the minimum cost model, the precision synthesis method proposed in this paper does not need statistical manufacturing cost information and can ensure that the design precision of the manipulator meets the design requirements. It can be used for the precision design of single or small-batch manufacturing manipulators.