基于迭代估计的三轴加速度计温度模型参数外场标定方法

摘要

为补偿加速度计标度因数和零偏的热漂移误差，设计了一种可估计内场恒温环境下参数变化量的加速度计温度参数模型，并提出了基于迭代估计的温度模型参数外场标定方法。该方法不依赖精密的惯性测量设备和温箱，仅在重力场内对加速度计进行连续多组位置观测，充分利用加速度计冷启动过程产生的热漂移误差进行模型参数辨识，解决了加速度计温度误差特性和启动温度点相关的问题。针对加速度计测量信号为高斯白噪声的特点，建立了关于温度模型参数矢量和多组位置倾斜矢量的非线性准则函数，提出了两步迭代估计方法实现两组参数矢量的分离估计。根据不同位置下三轴加速度计输出信号粗略提取倾斜矢量，解决了迭代估计算法的初值问题。重力场内通过优化分析加速度计温度模型参数对重力值的灵敏度，设计了6组位置观测编排。实验结果表明，温度误差补偿前的重力值测量最大误差为3.62×10-4g，而温度误差补偿后重力值测量误差小于1×10-5g；同时，温度误差补偿前系统3 h纯惯性导航最大定位误差为1186 m，而温度误差补偿后最大定位误差小于600 m，从而表明提出的外场标定方法的有效性。%In order to reduce the thermal drift errors of scale factors and biases, the thermal model of triaxial accelerometers is established whereby the alteration of internal-field constant-temperature parameters is also compensated. An iterative estimation based field calibration method is proposed to solve the thermal parameters. First, no precise inertial test facilities and incubators are utilized in the calibration procedure. Second, the sequential multi-position gravitational observation is implemented on the accelerometers in the after-power-on procedure. Thus, the thermal parameters dependent on the startup temperature is estimated by the above thermal drift. Considering the Gaussian distribution of measurement noise, a nonlinear criterion function with respect to the thermal parameter vector and combined inclination vector is optimally resolved by a two-step iterative estimation method. The initial combined inclination vector is calculated by normalizing the raw outputs of triaxial accelerometers. An optimal six-position observation scheme is derived by maximizing the sensitivity functions of thermal parameters on the gravity. The test results illustrate that the maximum residual gravity error is 3.62×10-4g before the thermal compensation but less than 1.0×10-5g for the case where the thermal errors are considered. The maximum position error in the time span of almost three hours is about 1186 m before the thermal compensation but the position error is reduced to less than 600 m after the thermal compensation. The comparison results prove the effectiveness of proposed field calibration method.