Accuracy Analysis And Compensation And Research On Control Strategy Of 6-DOF Electric Motion Platform

With the rapid development of the aerospace industry,therequirement ofprecision of inertial components and IMU was continuously improved.As one of the important dynamic test equipment of IMU,the dynamic accuracy and performance of the three-axis swing table is directly related to the authenticity and validity of the test results,so its performance requirement is also increasing.The traditional three-axis swing table usually adopts serialmechanism,which is composed by three mutually perpendicularframeworks and driving mechanism.The drawback of this serial mechanism islow stiffness.The dynamic accuracy,dynamic characteristics and bandwidth of the system cannot meet the requirements at many appli cations,and cannot be used to achieve the six degrees of freedom test of IMU.Therefore,its application has some limitation.6-DOF motion platform is a typical parallel mechanism with high positioning accuracy,stiffness,structural stability,strong bearing capacity,small movement inertia,good dynamic characteristics and other characteristics.As a motion system of parallel machine tools(also known as virtual axis machine),automobiles,tanks,ships,flight simulators,shaking tablesand other large-scale simulation and test equipment,it has been widely used at home and abroad in many fields.6-DOF motion platform is an importantsimulation test device forthe research of system performance and reliability of aircraft,ships,aerospace and automotive equipment,as well as effectivetraining methods for simulation training,ship navigation simulation training and vehicle driving simulation of pilots,flight crew and the vehicle driver,has become an important tool of modern aviation,ships,aerospace and auto motive industry.The high-precision 6-DOF motion platform applied to the dynamic characteristics of the test is used to set up a new technology developed in recent years.Especially sine rocking motion of its six degrees of freedom motion capability used to set the desired dynamic test provides a good solution.Dynamic testing using six degrees of freedom electric motion platform semi-physical simulation method used to set the real-time simulation of aircraft position during the flight,the attitude,the group is used to provide a realistic flight environment for product testing and performance assessment of inertia group.This study used to set dynamic test rig consists of six degrees of freedom electric motion platform,real-time measurement composition and part of the control system,data acquisition systems and user monitoring systems.To be able to effectively simulate the aircraft position during the flight,the attitude of the kinematics and dynamics of six degrees of freedom electric motion platform and precision made high demands.Therefore,it is necessary to kinematics,dynamics and characteristics of six degrees of freedom electric motion platform for analysis,modeling.Based on this analysis focus on the accuracy of motion compensation and control strategy platform,thereby improving the accuracy and dynamic performance sports six degrees of freedom electric motion platform to meet the dynamic characteristics of the test used to group needs.Kinematics is a six degree of freedom electric motion pl atform design,workspace analysis,basic singularity analysis,precision analysis and motion control.Through inverse kinematics kinematics get on the platform pose,velocity and acceleration with six electric cylinder movement.By studying the kinematics algorithm,six degrees of freedom electric motion platform of positive solutions for Newton-Taylor expansion method and the Newton-Raphson algorithm for real-time positive solutions,and establish a relationship based on kinematics simulation model visualization electric six degrees of freedom motion platform,analyzes the up space on the platform at the singularity and structural design is reasonable.Newton-Raphson algorithm positive solutions for real-time,so as a result of the positive solutions platform pose indirect feedback to achieve six degrees of freedom electric motion platform closed-loop control as possible.Dynamic performance is an important indicator of the six degrees of freedom electric motion platform,directly related to the fidelity of the six degrees of freedom electric motion platform motion simulation,and therefore need to be studied in depth in order to design a reasonable structure,superior dynamic performance six degrees of freedom electric motion platform to meet the needs of th e dynamic characteristics of the test used to group.Meanwhile,the basic dynamics of electric motion platform is six degrees of freedom as well as other relevant characteristics of the control strategy.This paper analyzes the dynamics of six degrees of freedom electric motion platform,the establishment of a system of first use Newton-Euler method for a single rigid body dynamics model,and then were Lagrange method and Kane method to establish multi-DOF electric motion platform rigid body dynamics model;mathematical model derived vector control AC servo motor on the basis of a dynamic model of a full six degrees of freedom electric motion platform;use the full dynamic model established for six degrees of freedom electric motion platform coupling between the degree of freedom is analyzed and experimentally verify the correctness of the analysis results.Pose Accuracy DOF electric motion platform is directly related to the accuracy of the test used to group dynamics.Therefore,the accuracy of this article DOF electric motion platform error analysis and generate electric cylinders were Compensation.First,the use of single-branched modeling established monobranched error model,summarized 42 sources of error.Then the error model established six degrees of freedom electric motion system based on inverse kinematics equations,the accuracy of the system are analyzed and integrated.On this basis,further analysis of the passive movement spiral additional electric cylinder group generated in the usual course of the campaign dynamic test bench,and the motion compensation algorithm is studied.Through the error passive spiral movement of additional quantitative analysis,the results indicate that the presence of additional movement of passive spiral very significant impact on the group dynamic inertia pose accuracy test bench.Using Lab VIEW graphical programming language for the compensation algorithm,and applied to real-time control system used to set the dynamic test bench.Experimental results show that after the compensation algorithm,the positional accuracy of the inertia group dynamic test rig has reached the design requirements.Six degrees of freedom electric motion platform is a multi-degree of freedom,multivariable,highly nonlinear,multi-parameter coupling of complex systems,which control strategy including control strategies hinge point in space and control strategy based on dynamic model.The former is a traditional control method,the six electric servo position as an independent platform for distributed control systems,for each position servo system is time-varying load characteristics.Controller designed to handle this load characteristics into an equivalent quality and equivalent disturbing force,however,on the platform is in a different pose,great quality and equivalent equivalent disturbance force change,this design out of control has a great conservative,can only accommodate lower performance requirements.Control strategy based on dynamic model is considered dynamics DOF electric motion platform and the dynamic characteristics of the various electric servo mechanism to design,which can improve overall system performance.This article first feedforward control method,repetitive control theory and control theory synovial briefly discussed.After that,for six degrees of freedom electric motion platform not only system model parameter uncertainty and friction nonparametric uncertainties,and there is the controlled object,thrust fluctuations non-parametric uncertainties and unknown external disturbance characteristics,based on fuzzy basis function network an adaptive repetitive learning control methods to ensure the robust stability and the tracking performance of the system.Simulation and experimental results of surface,using the above method can effectively improve the six degrees of freedom electric motion platform system bandwidth and dynamics.Research to solve the above problems,to further improve the 6-DOF electric motion platform theoretical analysis,to improve the accuracy and the development and application of control systems,etc.,has important theoretical and practical value.This is not only the need for the "six degrees of freedom inertial test electric motion platform," the research,but also for the general theory o f parallel mechanism analysis,design and application have important reference significance and practical value.