Design Of Digital Accelerometer Based On FPGA

The acceleration sensor is an important electronic device used to measure the acceleration of the object.It is widely used in automatic control,seismic monitoring,inertial navigation and other fields.With the rapid development of digital processing technology,digital circuits gradually have the characteristics of high stability and high anti-interference.Therefore,acceleration sensors are also widely used in various digital systems.At present,in China,the research of accelerometer is mainly focused on analog signal,but the research on digital accelerometer is less.The technology and experience of developing digital accelerometers with high precision and wide measurement range are less.These reasons directly limit the development and application of digital accelerometers in China.Based on the reasons above,this paper takes an existing analog acceleration sensor as an example to analyze and study some key technologies in the process of digitizing the sensor.Based on the comparison and analysis of various digital processing schemes,a digital system solution based on FPGA is proposed,and the tasks of the hardware circuit and software algorithm are determined.On this basis,the specific implementation of the scheme is carried out.Finally,a three-axis digital accelerometer is designed based on the sensor.The main work,research methods and results of this paper include:(1)This paper analyzes the parameters and characteristics of the output electrical signal of the analog acceleration sensor,determines the design tasks and principles of the system according to the specific requirements of the subject.This paper puts forward the overall design scheme of the system,and divides the system into different modules.The system is composed of hardware circuit and software systems.The hardware circuit is used to adjust and collect the signal.The software is used to analyze and process the acceleration data,the motion mode detection and the serial communication interface.(2)The hardware circuit of the system is designed and developed with Proteus.The signal conditioning circuit carries on the voltage transformation and the filter to the analog voltage signal of the sensor output according to the system requirement.The temperature measurement circuit provides temperature parameters for the system.The analog-to-digital conversion circuit is used to acquire the acceleration signal and temperature signal.FPGA control circuit is used to control other circuits,data analysis and processing,motion mode detection and serial communication.(3)The software system is designed and implemented by Verilog HDL,including control program,data processing program and serial communication program.The control program controls the working mode of the hardware circuit and other modules in the software system according to the contents of the control registers set up in the software system.The data processing software is used for digital filtering and temperature compensation of the acceleration data obtained by the analog-to-digital conversion,which is used to improve the accuracy of the output data of the system.At the same time,the software realizes the functions of tap detection,free fall detection,motion and static detection by analyzing the acceleration data.Serial communication software is used to exchange data and commands between the system and the user's processor.After the design of the system,the hardware circuit is simulated by Proteus.The results show that the conditioning circuit can transform the voltage of the signal from the sensor and filter the noise in the signal.Matlab and Modelsim are used to verify the control program,data processing program and serial communication program,and the whole software system is verified at board level.The results show that the designed software system can effectively improve the accuracy of the system and reduce the influence of temperature change on the system.The system can also complete the motion mode detection and serial communication according to the design requirements.Finally,the verification results show that the functional modules meet the requirements of the system design.