Study On 3-axis Mems Gyro Digital Control System Based On Sopc Multi-core Technique

This dissertation introduces a novel 3-axis MEMS gyro system based on SOPC multi-core technique. Firstly three gyros are made to work on the resonant frequency of their own by means of frequency closed-loop control. Then the amplitudes of the drive vibration are set to the desired values by means of amplitude closed-loop control. At the same time the signals of sensing vibration are demodulated. At last 3-axis real-time angular rate message is transmitted to pc. In this dissertation some topical techniques like multi-core synchronous computation, multi-bus control, digital closed-loop control etc. are discussed. A one-chip FPGA multi-core system is architected which has three computing cores and several auxiliary cores. Compared with the FPGA+DSP method in traditional digital control system the new one is smaller, cheaper, and more flexible with completely re-architected ability and parallel computation ability. We also consider it as a foundation of ASIC in the future. It has high value and broad prospect in application.The states of digital MEMS gyroscope research and worldwide SOPC multi-core technique are summarized firstly. Based on the summarization, analysis and comparison of the main schemes and the relative technologies for digital multi-core system are stated, and then the research scheme is determined, which is constructing a SOPC with one FPGA and accomplishing drive, sense and data communication of the three MEMS gyroscopes. Furthermore, the key points of the scheme based on multi-core technique are brought out.Based on the main scheme a one-chip FPGA with three soft cores (MicroBlaze) embedded integrative scheme is brought out. There is an auxiliary IP core which generates accurate digital sin signal for each MicroBlaze via FSL bus. There're also IP cores designed as ADC driver, DAC driver, RS422 interface, EEPROM interface, interrupts controller via OPB bus. In order to realize the synchronation of the data from three channels two universal registers via OPB are added. The volume is smaller and the designation is more flexible than traditional systems in hardware. Algorithms in this dissertation contain LMSD ( least mean square demodulation), digital filters, control loops and transmission protocol. At first of this part a new 64-bit multiplication's accuracy is analyzed. The theory and realization of algorithm are introduced. The functions and effects of closed loops are discussed. Finally the transmission protocol with pc is decided. An UART GUI is designed for this system to help the user get the real-time data easily.At last measurement data with this system is shown. It's mainly about the synchronation ability of the three channels and the bias stability of each gyroscope. According to the results the digital system can work normally from -40℃to +85℃, achieving industrial performance.