Design And Research Of An Intelligent Electrostatic Driven Capacitance Pressure Sensor

This thesis mainly studies the measurement structure and software and hardware design of pressure sensors.Based on the previous classic design and theory,a capacitive measurement scheme is developed with reference to various force measurement methods.A capacitive pressure sensor with differential structure based on MEMS technology is designed.A model is established for the sensor measurement structure,and the pull-in voltage algorithm and data fitting algorithm are studied.Most of all peripheral hardware circuits and software systems are designed according to system requirements.The intelligent electrostatic drive capacitor pressure sensor is composed of a hard-ware circuit module and a software system.The hardware circuit module is composed of a power module,a capacitor pressure measuring structure,a capacitance measuring module,a main controller module,a data transmission module,a digital-to-analog conversion module,a program downloading module and a serial debugging mode.The software system consists of embedded program and host conputer software.The embedded program is written in MDK5 and keil uVision4 programming environment.The capacitive pressure conversion algorithm and DAC conversion algorithm are written in the STM32 main controller.The STM32 processes the capacitance data measured by the PS021 capacitance measuring chip and outputs the electrostatic driving voltage signal.Data transfer program is written in the USB chip to output measurement data The host conputer software uses the USB driver written in C++for LabVIEW to call,and the application interface is written by Lab VIEW to realize data display and storage functions.After the design is completed,the intelligent electrostatic drive capacitive pressure sensor is calibrated using an intelligent high-precision balance and the input-output characteristic curve of the sensor is analyzed.According to the principle of least squares method,the fitting algorithm is written by MATLAB,the fitting polynomial is calculated,and the fitting error curve is drawn.The fitting parameters are input into the STM32 main controller,and the output data is re-measured.The performance indexes of the sensors are analyzed through the accuracy experiment,and the performance indicators are determined to meet the design requirements.At the same time,this thesis also analyzes the causes of system errors,and proposes solutions.According to the actual application and test conditions of the sensors,the direction of the next work is clarified.