基于单环运动链的多模式移动机构型综合

Type Synthesis of Mobile Mechanisms with Multiple Modes based on Single-loop Kinematic Chains

针对移动机构多运动模式的功能需求,提出基于单环运动链的设计方案。首先,根据单环自由度公式,确定满足闭环且能活动的条件,并分析得到单环运动链的约束螺旋系阶数、杆件数目、运动副数目、自由度之间的组合关系;其次,以螺旋理论为基础,运用虚功原理得到满足不同约束螺旋系阶数下的各种运动副轴线存在的几何条件,以R副、P副为设计单元,群举出所有可能的不同自由度下的单环运动链组合方式,再以所构造的单环运动链作为本体或分支,从而构造出一类多模式移动机构;最后,给出多模式移动机构的构型综合的步骤及部分设计案例,验证了提出的设计理论和设计方法的可行性和实用性。

Aiming at the functional requirements of mobile mechanisms with multiple modes,a design scheme based on single-loop kinematic chains is proposed.Firstly,according to the single-loop freedom formula,the conditions satisfying the single-loop and can be active are determined,and the combination relationships among the order of the constrained screw system,the number of bars,the number of kinematic pairs and the degree of freedom of the single-loop kinematic chains are obtained.Secondly,based on the screw theory,the geometric conditions of the axis of kinematic pairs under different constrained screw orders are obtained by using the virtual work principle.Taking the R and P pairs as the design units,all the possible combinations of the single-loop kinematic chains under different degrees of freedom are enumerated,and then the constructed singleloop kinematic chains are used as the body or branch to construct a kind of mobile mechanisms with multiple modes.Finally,the steps of type synthesis of mobile mechanisms with multiple modes and some design cases are given,which verifies the feasibility and practicability of the proposed design theory and design method.