Research On The Design And Application Of The Rate-biased Platform

With the development of laser gyro, it has been widely applied in the Inertial Navigation System (INS). But it can't be used in the system until some bias technology is used to overcome the lock-in of the laser gyro. Among all kinds of bias technology, the rate-biased technology can decrease the random walk error and improve the accuracy of laser gyro. In this paper, the hardware and software of the rate-biased platform are designed based on the preliminary study of the rate-biased technology, and experiments of laser gyro scale factor and random walk are conducted on the rate-biased platform.Firstly, the hardware and software of the rate-biased platform's angular measuring system are completed. The angular measuring system using ring inductosyn is designed based on the resolver-to-digital converter of AD2S90, and the errors of the angular measuring system are analyzed. This angular measuring system has effectively improved the anti-jamming, reliability and the integration of the system, reduced the size, and the angular resolution and accuracy can meet the requirements of ratio-biased platform.Secondly, the control and drive system of the ratio-biased platform based on TMS320F2812 digital signal processor is designed. Hardware circuits including peripheral DSP controller, power driver, over-current detector and optoelectronic isolator are designed and implemented. Software including PID digital controller,detection and calculation of the angle-feedback signal, generating of PWM signal, over current protection, serial communication etc are fulfilled. Three closed-loops with position, velocity and current are designed for promoting accuracy.At last, the response characteristics of position command, rate reversing transition and rate smoothness are tested. Experiments of laser gyro scale factor and random walk error are conducted on this platform. The accuracy of laser gyro scale factor test can achieve PPM order of magnitude, which meets the needs of the normal test. Random walk in the mode of rate-biased is smaller than that in the mode of mechanically dithered-biased. Besides, causes of the errors in the mode rate-biased are analyzed.