Gyro North Seeker Structure

The gyro north seeker belongs to the field of inertial measurement technology or geophysical experiments and instruments, and specifically relates to a dynamic rotation modulation gyro north seeker. The purpose is to provide a gyro north seeker device using continuous rotation modulation sigma seek north. Including: pedestal, high-precision single-axis turntable system, gyroscope, accelerometer, conductive slip ring, torque motor, constant speed control circuit, power conversion/filter circuit, signal conditioning circuit, high-speed signal acquisition/processing device, high-speed north seek Solve the computer control display device; Torque motor drive high-precision single-axis rotary table system rotates relative to the base; Gyroscope, accelerometer, and constant-speed control circuit, power conversion/filter circuit, signal conditioning circuit, high speed on single-axis rotary table system Signal acquisition/processing device, high-speed north-seeking computer electrical connection.

Next, we will introduce the structure and function of the north finder in detail. North seeker structure diagram

As shown in the figure, the fiber optic gyro north-seeking system mainly consists of the following parts: The precision electronically controlled turntable system includes inertial components, namely flexible quartz accelerometers and fiber optic gyros, signal processing circuits, motor control circuits, FPCA microprocessors, and Results storage and display unit.

The motor control circuit is composed of a motor and a rotation positioning circuit. It first receives the indexing command through the microcontroller to make the stepper motor rotate a certain number of steps. At the same time, the motor feeds back its in-position signal to FGPA.

The FGPA microprocessor has many functions in the north-seeking system, which mainly include the following functions: such as signal sampling, processing of sampled signals, calculation of north-seeking results, rotation control, and judging whether to turn to position, etc. Among them, signal sampling is used to receive the output signals of single-axis fiber optic gyroscopes and single-axis quartz accelerometer at four different positions, and put them into the database. Filtering models and outliers elimination model will be used in the signal processing of sampling. Eliminate the model to filter and eliminate the sampled signal, calculate the average value at each position and store it in the memorizer. The calculation of the north-seeking result includes a mathematical model of the north-seeking solution. By passing the measured sampling signal values at four different locations through this model, the angle between the carrier and the north direction can be calculated, which is the azimuth angle, and the calculation result is Through the digital tube display; the rotation control is performed by the FGPA issuing an indexing command to the micro controller. It is also responsible for receiving the in-position interrupt request sent by the micro controller to determine whether it is in place. This can complete the sampling of the output signals of the fiber optic gyroscope at four different measured positions.

DSP, accesses the FPGA through control lines, address lines and data lines to obtain the sensor information required for azimuth angle calculation. Fast and reliable data communication between DSP and FPGA is the key to the design of north seeker data acquisition unit.

Interfaces play a vital role in the north-seeking system. The entire north-seeking system can collect and transmit data through various interfaces. We divide it from the perspective of data flow transmission nodes: it can be divided into A/D interface module and serial interface module. The A/D interface module is the most important part of the entire system interface module. Its function is to realize the signal acquisition function of the fiber optic gyroscope. The serial interface module includes serial port interrupt initialization, serial port baud rate and parity bit settings, serial port data transmission and serial port data interrupt reception, etc. The serial interface is used to connect to external devices and transmit north-finding and attitude results to them.

Based on these theoretical technologies, Ericco Company has continued to refine its research on north seekers, and has developed ER-FNS-01, ER-FNS-02 and ER-FNS-03 in the fiber optic north seeker series. The advantage of the utility model is that under the condition that the carrier has a large attitude angle and does not need to be leveled and the latitude of the measuring point does not need to be known, a rapid and accurate north-seeking measurement is realized, and the speed of the geodesic operation is improved.

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