Study On Data Acquisition Technology For Parameters Of Inertial Navigation Components Based On USB Interface

The data measuring and recording system is designed in this paper. In the system, all signals from inertial navigation products are collected by a circuit board which is mainly composed of a USB microcontroller and a FPGA logic device.The collected data are transferred to the host computer by USB interface.Firstly, the development of USB technology and its features are introduced in the paper. Then, USB specification and types of transfer are explained in detail. The feasibility of the data acquisition system based on USB interface has been analyzed in theory. Inertial navigation products and design requirements of the system are introduced and then followed by the solution of the system design.The system design can be devided into two parts which are hardware design and software design. The main works of the hardware design are to complete the functional module design and the interface circuit design. The hardware platform of the system is constructed by Altera FPGA device of FLEX10K series and USB microcontroller of Cypress EZ-USB FX2LP series. Several functional circuit modules are designed in FPGA, such as Positive/Negative Polarity Selection, Turn-on Time Measurement, Digital Circuit Filter for Pulse Signal of Inertial Navigation Products. FIFO structure in FX2LP and design methods of GPIF interface are also explained in detail. Software design includes the firmware programming for EZ-USB FX2LP microcontroller and application programming of the host computer. Firmware responds to any specific user defined requests and takes correspondent actions, data buffering and actions of interface are also controlled by firmware. The application program is compiled by VC++6.0. User can make command to USB controller in circuit board through interface of application. It can match the data package size defined in firmware to finish the task of collecting, saving and computing. In order to meet the need of user, it provides a user-friendly interface.Finally, the data measuring and recording system was tested and the measurement accuracy was analyzed. The results show that two inertial navigation products can be sampled at the same time and it improves efficiency of the system. The function of pluse polarity selection is realized. Specific noise signals can be filtered according to the output of inertial navigation products.All functions of this system and system stability are tested to meet the design requirements.