Theoretical Study On Crank- Group Parallel Mechanism And Its Accuracy Analysis

The theory and the accuracy of the crank-group drive mechanism are researched in this topic based on related research of the crank and parallel mechanism. The feasibility of the agency is analyzed according to the theory and the research methods of parallel mechanism, and kinematic analysis and studying topology structure of this agency was completed. What’s more, the error analys is model of the agency is established and the error calculation method was proposed under the condition of the rod length error and joint clearance. The main works of this thesis as follows:(1)The feas ibility of the crank- group drive mechanism is demonstrated by mathematical methods. Crank- group drive mechanism is a kind of special parallel mechanism, and this topic give the concept of crank- group parallel mechanism. The degree of freedom of this agency is 1, which calculated by degree of freedom analysis methods of parallel mechanism based on screw theory. It has cracked its statically indeterminate problem. According to geometrical conditions, considering rod length error, clearance of movement pair and elastic deformation of the rod, this thesis get the crank group condition presence crank group of crank-group drive mechanism.(2) Kinematic for crank-group drive mechanism in this topic is analyzed. Through the influence coefficient method, the kinematic of parallel double crank mechanism is analyzed. On this basis, the kinematic of crank- group drive mechanism can be divided into crank movement and frame truss rod movement, the kinematic of this agency is described.(3) From the perspective of topological to explore the topological structure of crank- group drive mechanism. Crank drive mechanism is pointed out that this mechanism is a kind of special planar parallel mechanism. this topic also give the symbolic representation of the topological structure of this institution, and its POC collection, analys is the multi-loop characteristics of this agency, and calculate its degree of coupling.(4) Error model of crank- group drive mechanism is established, in order to analyze the precision of this agency. According to the basic unit the agency, deduce the error of a point of link. Analysis the discrete structures first, and then analys is the overall structure. Solve the difficult problem of its coupling error calculation. Point out that the impact of the initial angle error, the rod length error and rod length relative error for the overall error of this agency. And how to control the effect of these error sources to overall error of this agency.The innovation of this topic:(1) Point out that crank-group drive mechanism is a kind of special group from agency deformation and structure two aspects.(2) Prove the feasibility of this agency, analys is the kinematic of this agency and research its topological property, which extends theoretical study of this agency.(3) Error model is established. Aim to the difficult problem which caused by coupling error calculation, analysis the accuracy of crankgroup drive mechanism. This topic provides the credible theoretical basis for the application of the mechanism.