| With a new round of scientific and technological revolution and industrial change in the world,modern optical system is developing rapidly in the direction of large aperture,high precision,high resolution and high power.Therefore,higher requirements are put forward for robot equipment manufacturing optical mirror.For a piece of optical element to be processed,it is necessary to make the robot grind and polish according to the predetermined processing trajectory.In this process,it is also necessary to maintain a relatively constant grinding contact force,so as to ensure a higher processing accuracy.This paper takes the optical mirror machining robot as the research object,analyzes and tests the robot polishing mode,Cartesian space trajectory planning method,forward and inverse kinematics of hybrid robot,mathematical model of pneumatic servo polishing control system and impedance control strategy of robot polishing compliance control strategy are studied.Finally,a prototype is built to verify the above theory.The main research contents can be summarized as follows:(1)The trajectory planning method and kinematics of the robot are studied.Firstly,this section introduces the tool path mode of robot polishing finishing,and analyzes the path generation principle of line cutting method and ring cutting method.Secondly,this section studies the interpolation principle of Cartesian spatial trajectory planning methods(linear trajectory interpolation method and arc trajectory interpolation method).Thirdly,this section establishes the world coordinate system on the bottom support of the workpiece,solves the rotation matrix from the world coordinate system to the robot's fixed coordinate system,connects the Cartesian space with the robot's fixed coordinate system space,and uses the closed-loop vector method and RPY coordinate transformation method to analyze the forward and inverse kinematics of the whole robot including parallel module and series module.Finally,according to the mathematical model obtained by theoretical analysis,the corresponding control program is written in Matlab software to verify the correctness of forward and inverse kinematics of the optical mirror processing robot,and the trajectory of the grinding point at the end of the robot in Cartesian space is transformed into the trajectory of each joint branch chain.(2)The control system of pneumatic servo polishing is analyzed.Firstly,this section introduces the working principle of pneumatic servo polishing control system,and briefly analyzes the function of each component.Secondly,the working principle of the electrical proportional valve is introduced,and the flow continuity equation of the proportional valve,the flow equation of the valve port and the model of the connecting pipe of the proportional valve are established.Thirdly,the force balance equation of the cylinder is established and the general transfer function model of the pneumatic servo polishing control system is deduced.Finally,according to the specific parameters of each component in the pneumatic servo polishing control system,the transfer function is solved and analyzed in Matlab software.The simulation results verify that the system is stable.(3)The control strategy of robot polishing compliance is studied.Firstly,the impedance control strategy in compliance control is introduced,the impedance control principle is analyzed,and the position based impedance control model is established.Secondly,the control variable method is used to study the influence of each target impedance coefficient in the impedance control system,and the simulation is carried out.Thirdly,the reason of the steady-state error of impedance control is analyzed theoretically,and the calculation formula of the steady-state error of impedance control is deduced.Aiming at the shortage of common impedance control,an adaptive impedance control method is studied.Based on Lyapunov stability principle,an indirect adaptive impedance controller is designed and its expression is derived.Finally,the adaptive impedance control model is built in the Matlab/Simulink simulation environment,and the simulation results verify the robustness of the adaptive impedance control method.(4)The above theories are analyzed by experiments.Firstly,the polishing experiment platform of optical mirror machining robot is built,and the hardware components of robot motion control system and pneumatic servo polishing control system are introduced respectively.Secondly,the relevant electrical components are calibrated.Thirdly,the control process of robot constant force polishing is introduced Finally,the robot contact force control experiment and constant force polishing aluminum plate experiment are carried out.The experimental results verify the effectiveness of Cartesian space trajectory planning for the optical mirror processing robot and the good adaptability and robustness of the adaptive impedance control algorithm,which can achieve the control goal of robot flexible constant force polishing workpiece.In this thesis,there are 56 pictures,2 tables and 93 references. |
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