Experiment And Research On 6-DOF Measurement Of Rigid Body Realized By Total Station Free Leveling

The study of mechanical mechanics often involves establishing a mathematical model of rigid body dynamics,and the 6-DOF pose parameters in the global coordinate system are obtained by solving the model.Whether the model is accurate requires experimental verification,which generally requires the use of specialized measuring instruments to carry out the experiment.At present,the commonly used measurement test equipment system consists of photoelectric vision,photoelectric scanning,etc.These instruments often have high requirements on the working environment and high cost.Therefore,a 6-DOF measurement of rigid body based on universally applicable equipment is explored.The method has become an inevitable trend.As a general engineering measuring instrument in the field of photoelectric scanning,the total station has high measurement accuracy,low cost and simple operation.However,the general total station can only measure the three-dimensional position of the control point in the total station instrument coordinate system,and generally requires a cumbersome leveling operation when used.Therefore,how to establish a rigid body 6-DOF measurement platform based on the rapid and accurate measurement of the total station,and verify the accuracy of the 6-DOF parameter of the total station without leveling measurement has become an urgent problem to be solved.In order to further improve the measurement efficiency of the 6-DOF of the rigid body,it is feasible to provide a feasible experimental method for the 6-DOF measurement and verification of the position and attitude of the rigid body.In this paper,a method for measuring the 6-DOF of rigid body in the global coordinate system based on the total station-free leveling measurement is proposed.The 6-DOF measurement technology based on the total station-free measurement method is developed.This research mainly carried out the following work:(1)Feasibility analysis of the 6-DOF of rigid body measurement for the total station.The theoretical analysis of the rigid body kinematics model,the rigid body 6-DOF is an important parameter of the mechanical system,its measurement can be applied to the verification of the theoretical model of kinematics and dynamics,as well as the constraint reaction force of the known condition solving system.Dynamic analysis,which shows the importance of the 6-DOF of rigid body to the kinematics of rigid body.To explore the cumbersome steps in the general leveling operation of the total station,and to propose the actual operation methods and steps of the total station without leveling measurement.The 6-DOF measurement principle and the configuration diagram principle are used to establish a 6-DOF model for measuring the rigid body without the flatness of the total station,and the corresponding coordinate system conversion relationship of the total station without the flat is listed,thus proving that the total station is free to measure the rigid body.The theoretical feasibility of six degrees of freedom.(2)Solving the 6-DOF measurement model based on MATLAB.Through the Gauss-Newton iterative algorithm and the detailed introduction of the DLT(direct linear transformation)method,combined with the SVD(singular value decomposition)method,the solution of the coordinate system transformation matrix can be realized,and the 6-DOF measurement result of the rigid body can be obtained.In this study,the DLT is combined with the SVD method to solve the transformation matrix between coordinate systems.And use MATLAB to write the corresponding program to solve the unknown parameters,so as to obtain the accuracy of the measurement method proposed in this paper.(3)The multi-function three-axis turntable was used to verify the 6-DOF model of the total station.The verification experiment uses a precision three-axis multi-function turntable to realize different reference positions and postures of the rigid body,thereby establishing a 6-DOF measurement model in two cases.The 6-DOF of the rigid body centroid relative to the global coordinate system are solved by solving the transformation matrix of the local coordinate system to the global coordinate system.(4)The 6-DOF measurement method based on the total station is applied to the paddy fielder.Based on the paddy field leveler developed by South China Agricultural University,the total station is used to measure the position of the shovel relative to the fuselage,measure the position of multiple control points on the shovel,and use the total station to complete the same group control at different positions.Point measurement to obtain the 6-DOF parameter of the shovel.Next,the position of the control points on the grader shovel was calculated and analyzed by the binocular measurement using the translation of a single high-speed camera.Establish a global coordinate system on the grader gantry and a local coordinate system on the shovel.The TEMA is used to process the captured image,and the global coordinates of the control points are obtained.The known local coordinates are used to solve the conversion relationship between the coordinate systems,and the Euler angle of the rigid body and the global coordinates of the centroid are obtained,and the obtained 6-DOF result is obtained.Compare with a high speed camera to verify the accuracy of the total station.Based on the basic theory of 6-DOF measurement,this paper establishes a total station-free leveling measurement model.The method theory of 6-DOF of rigid body measurement based on total station is not summarized,and the theoretical verification is carried out on the three-axis turntable.The results of the turntable experiment show that the total station measures the 6-DOF parameter of the rigid body and rotates around the Z axis.The Euler angle error is 2.349°,the Euler angle measurement error is 3.085° around the Y axis,and the Euler angle error is 0.931° around the X axis.The three translations on the central axis are 0.004 m and 0.003 respectively according to the XYZ axis order.m,0.006 m,the measurement error of all three displacements is less than 0.010 m.The result is a normal value within the range of the total station angle and distance measurement error,that is,the measurement accuracy meets the requirements.The measurement method was applied to the high-speed camera and total station comparison test developed on the paddy field leveler.The comparison experiment results of the high-speed camera measurement value as the true value showed that the total station measured the 6-DOF result of the shovel and the absolute of the camera.The error is 0.778° Euler angle around the Z-axis,0.760° Euler angle around the Y-axis,and Euler angle-6.725° around the X-axis.The absolute error of the three translations is-0.004 m along the X-axis.It is-0.099 m along the Y-axis and 0.019 m along the Z-axis,which meets the accuracy requirements of the total station for 6-DOF measurement.This method proposes a 6-DOF measurement method and procedure based on total station unleveling,and provides a feasible experimental method for the 6-DOF measurement and verification of the position and attitude of rigid body of mechanical system.