Jixie chuandong (Apr 2020)
Type Synthesis of Mobile Mechanisms with Multiple Modes based on Single-loop Kinematic Chains
Abstract
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 single-loop 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.
