| Parallel robot is used as Motion Simulator and Micro Manipulator because of its outstanding advantages of high rigidity and great load.There are still areas for improvement.Firstly,the energy consumption is higher when parallel robot working.Secondly,the couplings of motion is very obvious that influences the operation accuracy of the parallel robot.For these problems,the parallel mechanism which has redundant legs has become research hotspot recently.These redundant legs balance gravity to reduce energy consumption.In addition,optimization design of the parallel mechanism can also improve its performance as well as the usage of redundant structure.In the control method,the PID controller,which is used widely in industry,is easier to cause strong coupling among each degree of freedom,so that new control algorithm is needed to improve the motion precision of the parallel mechanism.This thesis take the redundant 6-DOF parallel mechanism as the research object using the MATLAB/Simulink,and the main results of the thesis can be summarized as follows:1.Based on robotics,static coordinate and moving coordinate system for the 6-DOF parallel mechanism were built,and got the coordinate transform matrix.The force balance equation between hydraulic cylinder and load was deduced from orifice flow formula and hydraulic cylinder continuity equation.According to the Newton-Euler equations,this paper analyzed kinematics and dynamics of the mechanism,and got its Jacobi matrix to solve the inverse kinematics.2.Combined with the relationships between the parameters of structure and the peak values of velocity,driven force and power in some typical motions,determine the goals and function to optimize: multi-objective optimization approach based on the peak values of velocity,driven force and power.The parameters of structure and mechanism are optimized by IGA(Immune Genetic Algorithm)to make sure that it can have better performance in kinematics and dynamics and meet the basic requirements at the same time.Compared with a mature product in industry in simulation and analyze the result.3.Built the whole system in MATLAB/Simulink: Built the mechanism model using Sim Mechanics and constructed the models of hydraulic cylinder,inverse kinematics solution and P-controller.Step function and sine function in every degree of freedom were selected to test the response and curve tracking performance of system.The results were observed.And tried to work out the rule of coupled motion in every non-target degree of freedom.4.Analyzed the model characteristics of the redundant 6-DOF parallel mechanism by using mode theory.The expression of computed torque controller in model space were deduced,and designed the controller by this.In the environment of MATLAB/Simulink,simulated the motion in every degree of freedom by this controller,and compared the results of the test before.Observed the inhibitory effect of new controller for coupled motion. |
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