Stewart并联机构运动失控性研究

RESEARCH ON LOSS OF CONTROLLABILITY OF STEWART PARALLEL MECHANISM AT BIFURCATION POINTS

为了确定机构在分岔点附近的运动行为,利用同伦法和静态分岔条件,构造了一种能够获得Stewart机构全部构型分支曲线及其分岔点的算法。基于提出的构型分岔分析和最大失控域概念,研究了分岔点附近的机构失控自由度。结果表明,增大输入参数的控制精度可以有效地提高机构在奇异位置附近的运动可控性。

In order to investigate the concrete moving behaviors at bifurcation points, based on the homotopy method and the static bifurcation condition, the algorithm, which is capable to detect all the configuration branches and bifurcation points, is constructed. With the aid of the concept of maximum uncontrollable domain, uncontrollable orientation components of manipulators at singular points are analyzed. The study shows that the uncontrollable orientation components have relations with both characteristics of the bifurcation curves of configurations and control precision of input parameters. It is found that increasing the control precision of input parameters will reduce uncontrollable regions of manipulators at singularities. By this way, the controllability of manipulators near by singular points is enhanced.