标准 Stewart 平台对负载的苛刻要求使其无法实现完全动态各向同性，而基于复合单叶双曲面的广义 Stewart 平台以解析形式给出了其满足局部完全动态各向同性的参数约束条件，打破了对负载特性的限制． 为进一步衡量广义 Stewart 平台在大运动范围下的模态频率特性，文中基于模态分析理论，提出了一种新的全局动态各向同性指标;以此为优化目标，以局部完全动态各向同性解析条件为约束，提出了满足局部完全动态各向同性且在全域工作空间内具有最优全局动态各向同性的结构优化方法． 设计实例表明，该方法为大运动范围 Stewart 并联平台的设计提供了新路线．

The traditional Stewart platform cannot achieve complete dynamic isotropy due to its strict payload re-quirement，while the generalized Stewart platform based on a pair of circular hyperboloid of one sheet gives the ana-lytical form of parameters constraint conditions satisfying local complete dynamic isotropy，and breaks the limit of payload characteristics． In this paper，for the purpose of measuring the modal frequency characteristics of general-ized Stewart platform in large workspaces，a new global dynamic isotropy index is proposed based on the modal a-nalysis． By using this index as the optimal goal and by taking the analytical form of local complete dynamic isotropy as the constraint condition，a structural optimization method，which satisfies the local complete dynamic isotropy and the best global dynamic isotropy in workspace，is proposed． Design example shows that the proposed method provides a novel approach to designing Stewart parallel platform in large workspaces．