| In the process of connection and encapsulation of optical waveguide devices,the key problem is how to improve the accuracy,which puts forward the demand for the large stroke and multi degree of freedom(DOF)precision positioning platform.The existed 6-DOF platform was driven by electromagnetic motor and wire rod to achieve alignment between array fiber and optical waveguide device.Because of the long transmission chain,the system stiffness and its response are both slow,and the system precision is difficult to be further improved.The system can only rely on other driving modes to compensate for the higher precision,which makes the system more difficult to control.In addition,the guiding accuracy of the platform is also a key factor to restrict the further improvement of alignment accuracy.In this study,a piezoelectric motor with a wide range of working modes,large stroke,fast response and high precision was proposed as the actuator,which was used in the 6-DOF hybrid precision positioning platform.The specific design objective is to have the ability of large stroke working range and high precision positionin.The translational positioning accuracy is 1?m,and the rotation positioning accuracy is 0.0005°.Firstly,the flexible quadrature actuators,flexible lever actuators and flexible rhomb actuators were developed,and the continuous driving mode and the step driving mode were also proposed,which could meet the requirements of far stroke and accurate positioning,respectively.On the other hand,the new structural parameter?and the flexibility parameter?were pointed out,and the influence mechanism of the parameter?on the compliance of the flexible hinges,and the relationship between the?and the?,were all studied.The optimization design of the three types of piezoelectric actuators were put forward respectively,and the effectiveness of the optimization was verified by various means.The experimental results prove that the three types of piezoelectric actuators improved the resolution of the step motion,and they could be applied directly to the multi DOF precision positioning platform because of the high precision motion resolution and stable macro continuous motion ability.Secondly,after comparing the advantages and disadvantages of the series and parallel mechanisms,the 6-DOF precision positioning platform was constructed by taking use of the 2T1R series platform and the 2R1T parallel platform.The 3-DOF parallel platform adopted 3 symmetrical inclined planes traction parallel branches,a large stroke cylindrical flexure hinge was also designed based on the fuzzy optimization algorithm,and the effectiveness and reliability of the large stroke cylindrical flexure hinge in 3-DOF parallel platform were analyzed by building the stiffness model of the 3-DOF parallel platform.On the other hand,the complete kinematic and dynamic models of the 6-DOF hybrid precision positioning platform were both constructed.With the help of the homogeneous coordinate transformation method,the positive and negative solutions of kinematic posture were analyzed,and the dynamic driving force of the dynamics was given by using the Lagrange dynamic model.The simulation research of the 6-DOF platform was carried out by making use of the ADAMS.The simulation results show that the proposed 6-DOF positioning platform has good kinematic ability and can realize the large travel space range under the given external force(torque)condition.The ability of macro motion and location of each DOF meet the requirements of the motion design.Finally,an experimental system for the 6-DOF hybrid precision positioning platform was set up,and the experiment measurement method was also developed.The experimental results show that the translation step resolution of the X axis,Y axis and Z axis are 1.2?m,1.4?m and 1?m,respectively.As for the rotation step resolution of the three axes are 8.6?rad,11?rad,10?rad,and 3?rad,repectively.On the other hand,in the continuous motion experiment,the translation macroscopic motion velocity of the X axis,Y axis and Z axis are 1.82mm/s,1.89mm/s and 312?m/s.As for the rotation macroscopic motion angular velocity of the X axis,the Y_U axis,the Y_V axis the Z axis is 29000?rad/s,29400?rad/s,28000?rad/s and 26400?rad/s,repectively.The translational resolution and the rotational resolution of each axis has basically reached the desired design goal,and the working stroke range of the translational and rotational axis of each axis has totally realized the expected requriments.At the same time,the analysis of the influence factors of the motion error of the 6-DOF platform was also discussed,and the motion error bar analysis of each axis was given.It has a good guiding significance for further improving the positioning accuracy and the motion performance of the designed 6-DOF platform.The 6-DOF positioning platform designed in this study took the non resonant piezoelectric linear motor directly as the driving mechanism of each axis,significantly shortened the transmission chain,improved the dynamic response speed,simplified the control mode of the system.The 6-DOF platform could achieve high precision micro motion and large stroke macro motion only by taking use of the steping driving mode and the continuous driving mode of the non resonant piezoelectric linear motor.This technology could break the monopoly of technology abroad and realize the leaping development of optical waveguide packaging in China.The research has important theoretical value and practical significance.Therefore,the 6-DOF hybrid positioning platform has broad application prospects. |
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