新型剪叉式可伸缩可升降机构及其静刚度分析

Static Stiffness Analysis of a New Scissor-type Telescoping and Lifting Mechanism

将Hart直线机构和剪叉机构相结合,提出一种仅含转动副的直线可展单元结构模型,并以此为基础设计得到一种新型剪叉式可伸缩可升降机构,该机构可实现一维方向上的直线伸缩或升降运动。首先,阐述剪叉式可伸缩可升降机构的模块化组成原理,将机构的组成等效为底部模块、中部模块和顶部模块的顺序叠加,3种模块均由直线可展单元构成;其次,建立单个直线可展单元的运动学模型,结合机构的模块化组成原理,推导出任意模块间的运动学递推关系,并以此为基础构建多层模块条件下剪叉式可伸缩可升降机构的整体运动学模型,用以验证该型机构实现精确直线运动的正确性和有效性;最后,以3层2列剪叉式可伸缩可升降机构为例,对其进行静刚度虚拟仿真分析。结果表明,机构沿可伸缩方向具有较好的抵抗变形的能力。

Combining hart straight-line mechanism with scissors mechanism,a new type of deployable model in straight-line motion which consists of revolute joint only is proposed.Corresponding modular system named scissor-type telescoping and lifting mechanism(STLM)is designed for achieving straight-line motion in one dimension.Firstly,modular principle of STLM is explained and the composition of the mechanism is equivalent to the sequential stacking of three kinds of modules including bottom module,middle module and top module.These modules are all composed by the deployable model.Secondly,the kinematics equations of single deployable model is established and introduced into constructing the whole kinematics equations with multi-layer modules which can be used to validate the proposed method for achieving straight-line motion.Finally,taking STLM consisted with three-layer and two-row modules as an example,the structural behavior of static stiffness for this mechanism is analyzed by simulation.Results show a good performance in the stiffness along the deployable direction.