基于FPAA与序贯双卡尔曼滤波信息融合的PCR温控

传统PCR(polymerase chain reaction)仪对样品反应池壁温度进行接触式测量与温控,存在测量迟滞大、无法直接控制试剂温度的缺点。研制的电化学实时定量PCR温控系统采用红外温度传感器、热源温度传感器以及环境温度传感器分别测量试剂表面热辐射、热源与反应池壁温度与环境温度,并提出序贯双卡尔曼滤波估计算法对三点温度数据进行信息融合从而估计出试剂表面温度真实值。该算法中迭代卡尔曼滤波器(iterated extended Kalman filter,IEKF)与线性卡尔曼滤波器(Kalman filter,KF)顺序运行,结合了IEKF非线性估计收敛快与KF实时性高的优点,克服了红外测温噪声大,易受环境、被测物热辐射率等因素影响的缺点。试剂温度的估计值作为反馈输入到基于FPAA(field programmable analog array)的可动态配置PID控制器中构成闭环控制,同时微控制器根据不同温控阶段的控制要求对PID控制器进行配置,从而提高温控效率。实验表明,滤波估计后红外测温精度由2℃提高至0.3℃;试剂表面温度监控与可动态配置PID使得PCR温控更加准确高效;PCR产物测试结果优于市面上PCR仪、恒温时间设置更加合理。

Multipoint temperature information fusion using sequential dual Kalman filter for temperature control system of portable RT-PCR instrument

Traditional PCR instrument detects the temperature of reagent with contact measurement,which has several limitations such as thermal hysteresis,reagent contamination and point-measurement.Thus an infra red thermometer is applied to contactlessly measure the temperature of reagent.But infra red thermometer has the defect of relatively high measurement noise.Therefore,we propose a sequential dual Kalman filter(Seq-DKF) algorithm that uses an iterated extended Kalman filter(IEKF) and a linear Kalman filter(KF) to remove the measurement noise from infra red thermometer signals in real-time.In this algorithm,IEKF and KF are executed sequentially.The former filter rapidly identifies the parameter of heat exchange model with a small number of observations.The latter one filters the temperature signal based on the identified model.After specifying the heat exchange model and the Seq-DKF,we apply the algorithm to the PCR instrument for testing.Finally,the other three filters are employed for comparison to demonstrate the effectiveness of the Seq-DKF algorithm.