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惯性平台系统是一种框架系统,主要包括平台本体、电路箱和电源箱。平台系统精度主要靠安装在平台本体的三浮陀螺和加速度计来保证。通常惯性平台的工作环境比较严酷,惯性传感器对温度有很高的敏感度,在系统正常工作时,平台内部有二级温控来保证仪表有良好的工作环境,但内部空间温度梯度变化会影响惯性传感器的精度。在温度采集过程中,铂电阻存在非线性、自热效应及热电动势等电气干扰的精度影响。采用阻值比较法,通过引入恒定激励电流来抑制温度采集电路的自热效应,并基于FPGA设计并行多通道温度采集电路。给出了系统总体设计方案、测温电路参数设计、序列激励电流控制和数字滤波补偿的具体实现方式,测试结果表明该系统可实现64路温度采集,在一定范围内测温精度能达到±0.02℃,满足精度要求。
Inertial platform system is a kind of frame system, mainly including platform body, circuit box and power box. The platform system accuracy is mainly guaranteed by the three-floating top and accelerometer installed on the platform body. In general, the working environment of the inertial platform is rather harsh. The inertial sensor has a high sensitivity to temperature. When the system is working normally, the temperature inside the platform has two levels of temperature control to ensure that the instrument has a good working environment, but the temperature gradient in the internal space will change Inertial sensor accuracy. In the process of temperature acquisition, platinum resistance exists nonlinear, self-heating effect and thermal electromotive force and other electrical interference accuracy. The resistance comparison method is adopted to suppress the self-heating effect of the temperature acquisition circuit by introducing a constant excitation current, and a parallel multi-channel temperature acquisition circuit is designed based on the FPGA. The overall design of the system, the design of the temperature measurement circuit, the sequence of excitation current control and the digital filter compensation are given. The test results show that the system can achieve 64 temperature acquisition, within a certain range of temperature measurement accuracy of ± 0.02 ℃, to meet the accuracy requirements.