Kinematic Calibration Research Of A 6-DOF Mechanism In Captive Trajectory Simulation Test In Wind Tunnel

Captive Trajectory Simulation Test is one of the methods used in the special test of wind tunnel,to simulate the movement trajectory of the hanging objects after the separation of the mother machine and ensure the safety of the external hanging objects from the separation of the mother machine.The 6-DOF Mechanism is the core of the Captive Trajectory Simulation system in wind tunnel.The 6-DOF Mechanism implements six degrees of freedom to movement through the control of the controller,and efficiently achieve specified position according to the specified speed accurately to complete captive trajectory simulation test.The movement accuracy of the 6-DOF Mechanism is an important role in promoting the accuracy,reliability in captive trajectory simulation test and need to be calibrated in kinematics.Through the calibration test,the motion data of each degree of freedom is obtained.The motion accuracy of the mechanism is improved by data analyzed and error compensated effectively.Based on the series characteristics of the 6-DOF Mechanism,apply Lagrange label method to the topological structure analysis of the non-tree system.Cut off the independent loop in the non-tree system and get the straight line variable arc mechanism corresponding to the pitching and yaw mechanism.And deduced the formula of the positive and inverse kinematics,and simulations are done in MATLAB.Based on the establishment of the coordinate system of the 6-DOF Mechanism and the direction cosines of each substructure,the positive and inverse solution formula of the terminal position is derived,and simulations are done in MATLAB.Classify and analyze the reasons for the error of the 6-DOF Mechanism,and propose the precision requirements of the mechanism.The error analysis focuses on the errors generated by the linear variable arc mechanism,and the corresponding error calibration model is established to identify the kinematic parameters.Analyze the end position and posture error of the mechanism.The position error analysis is used to study the decoupling and non-decoupling of the mechanism,and the positive and inverse relationship between the end position and the linear drive is derived.Newton iteration method is used to improve the inverse calculation efficiency and obtain the position error compensation formula.The attitude Angle is defined by the generalized Euler Angle,and is obtained by certain rotation sequence.The attitude Angle error is caused by the mismatch between the pitch axis and the axis of rotation.According to the theoretical analysis,the relationship between the pitch Angle and yaw Angle and the corresponding linear sliding block drive is deduced,and the error compensation formula of attitude Angle is obtained.The error of coupling error is mainly studied too.Due to the inability to directly measure the end position of the mechanism,the end data is obtained by a certain calibration method,and the actual terminal position is calculated by posture calculating.A laser tracker is used to calibrate the various degrees of freedom of the mechanism.Analyzes the collected data and fits error curve.The error fitting function is brought into the TwinCAT program for compensation and calibrate the result of compensation once again to improve the precision of the 6-DOF Mechanism,and the accuracy of the theory is verified.