Study On The Analysis And Optimization For Anti-bias Load Of Capacitance Weighing Sensor

Capacitance weighing sensor is a cell that converts the change of measured loadto the change of capacitance, It is payed more attentions and widely used by peoplebecause of its advantage of high sensitivity, low energy consumption, the simplestructure and strong adaptability. However, in the working process of capacitanceweighing sensor, especially in the application of high precision micro force measuringsystem, capacitance weighing sensor has some significant disadvantages, such as poorlinearity. Due to the high nonlinear of input/output characteristic curve, the sensor ishighly susceptible to the nonlinearity. In addition, the existence of eccentric load inthe working process brings many errors to the measurement of precise capacitanceweighing sensor. The modern measurement system puts forward higher request forprecision and linearity of sensor. In order to reduce the nonlinear error and themeasurement error caused by eccentric load in the working process, it is necessary tooptimize the structure of capacitance weighing sensor elastic element to improve itslinearity and eccentric resistance. Based on this background, deep research was madeon these two aspects. The main contents are as follows:(1) Describe the working principle of capacitance weighing sensor in detail, Thestatic technical indicator, such as sensitivity, linearity, resolution as well as theinfluence mechanism exist between eccentric and capacitance weighing sensor arealso analyzed, it set a well theory stage for the analytical calculation and the structureoptimization of sensor in the future research.(2) Establish the relationship between sensitivity, linearity of the capacitanceweighing sensor and oriented capability, and the calculation formula between orientedcapability, the capacitance of resistance to bending or distortion and the structureparameters of elastic element. Take the capacitance weighing sensor that with200gmeasuring range and0.001g measuring precision as object for researching, thechanging principle between performance and structure parameters of elastic elementhas been analysed.(3) Finite element analysis of elastic element has been carried out in ABAQUS,the accuracy of calculation result is verified. On base of the result, Establish themathematical model of multi-objective optimization, the objective function andconstraint condition of model is derived from oriented capability, the capacitance of resistance to bending or distortion of elastic element. NSGA-II algorithm integrated inISIGHT is applied to solve the mathematical model of multi-objective optimization,then get the Pareto optimal solution set. Finally, finite element analysis is made toverify the method and result of optimization in ABAQUS.