Research On Motion Complexity Of Mechanical Systems With Clearance Based On The Entropy Theory

Joint is an important part of mechanism. Whether it is in the aerospace field just like space truss and solar panel substrate or other space structure, or in the general machinery field like earth moving machinery and even small slider-crank mechanism, using joints to connect. When it is connecting two elements, the clearance exist.And it has influence on the performance of the mechanism movement. So is a key problem urgently to be solved in mechanical theory and engineering field. To research the influence of clearance, the paper tried to analyze the force theory, do the simulation and carry out experiments, even more study on evaluation index. The study will offers method and theoretical basis of actual mechanical system structure design and analysis method about kinematics behavior.Based on the theory of dynamics system with clearance, the paper analyzes geometrical characteristic and mechanical properties of three dimensional joints with clearance systematically. Focusing on the clearance, the geometry model and mechanical model are built. Combining with the analysis of the nonlinear characteristics of clearance system, it established the system dynamics model. For further study on the response signal of the system, it set up singular-spectrum entropy, power-spectrum-entropy and wavelet-energy-spectrum entropy model based on the field of signal. And used entropy theory to analyzing the kinematics response of system.According to the theoretical model of clearance, it built the simulation of four-bar linkage model based on ADAMS simulation platform. And called procedure of joints with clearance model written by Fortran-language. Loading on the rotating joint and establishing the kinematics model of four bar linkage containing 3 d clearance eventually. The simulation researched effects on the kinematics of four bar linkage with initial speed and clearance size. Exporting simulation data to MATLAB software, and using procedures of singular-spectrum entropy, power-spectrum entropy and wavelet-energy-spectrum entropy models to analysis and processing data. It concluded that the initial motivation and the clearance size had influence on organization’s movement complexity.Carrying out the experiment of four bar linkage with clearance, and analyzing the changes of displacement, velocity and acceleration characteristics with the motivation and the size of clearance. And studying the changes of entropy. It proved that clearance had important influence on organization’s movement complexity. Finally compared the experiment with simulation results to verify the feasibility of information entropy model.