Research On Parameter Optimization And Dynamic Performance Of Magnetic Levitation Stylus Displacement Sensor

The development of precision manufacturing,medical equipment and microelectronics industry has promoted the improvement of surface measurement technology.Contact measurement is widely used for its advantages of large range,simple structure,strong anti-interference ability and high resolution,etc.With a large range of parts,the demand for high-precision measuring instruments is becoming more and more urgent.Although the rigidity of the mechanical support is high at the support point of the traditional profilometer,the series of contact problems caused by the friction at the fulcrum are also not easy to control.With the maturity of the magnetic levitation control technology,it is possible to use the magnetic levitation support for the stylus to move in the vertical direction and measure in the vertical direction.Therefore,based on the contact measurement theory,this paper puts forward a magnetic control model and plan,and makes a critical explanation of the magnetic levitation mode and support theory.Through the theoretical analysis and discussion of the dynamic characteristics of the magnetic levitation in two directions,the magnetic levitation technology is used to control the suspension of the stylus shaft.And support stiffness to comprehensively analyze the sensor's parameter performance.The main research content of the magnetic suspension support surface topography measurement sensor placed vertically and directly measured in the vertical direction is as follows:1.Analysis of stylus measurement parametersEstablish the static contact model of the stylus,the dynamic model of the stylus mechanism and the movement model of the needle tip,simulate the contact situation of dynamics and kinematics,obtain the surface contour trajectory and the actual motion trajectory error,and analyze the source and influence factors of the error,namely The relationship between error and damping,natural frequency,preload displacement and other parameters puts forward requirements on supporting and measuring forces.2.Magnetic suspension radial supporting parameters and magnetic control methodFor the control of the magnetic levitation radial electromagnetic force,due to the insufficient prevention of the swing caused by the measurement force,according to the calculation theory of the air bearing support,the radial support force requirements are calculated.A mathematical model and a control model are established for the magnetic levitation stylus spindle to analyze the diameter.To support the way,establish the magnetic control model and determine the initial parameters.Analyze the relevant characteristics of the radial guidance magnetic field,analyze the support force-air gap characteristics of the guidance magnetic field,determine the bias current and current control method,consider the disturbance of the shaft,add an eddy current sensor for feedback closed-loop control,so the corresponding circuit must be designed Control,perform dynamic error compensation when the axis is laterally offset.3.Measuring force control and parameter optimization analysis of the stylus shaftAccording to the requirements of measuring force and supporting force,analyze the current,determine the Maxwell suspension coil parameters,optimize the coil parameters through experimental or theoretical analysis,analyze the influence of the energizing current on the measurement result,and obtain the optimal parameter relationship.Analyze the influence of the suspension current and measurement speed after the optimization of the coil on the measurement,and consider obtaining the best measurement speed under these parameters through the experimental method.4.Finally,completing the sensor dynamic experiment testCombined with the stylus kinematics and dynamics theory,combined with the dynamic performance of the lever profiler in the measurement direction,the magnetic suspension stylus measuring mechanism is dynamically tested.Similarly,by comparing the air bearing,the dynamic response curve of the shaft under different control currents is measured,the dynamic parameters of the sensor are obtained,and the dynamic characteristics of the sensor are analyzed.