基于灵敏度变化机理的双传感器称重系统在位标定方法

称重系统传感器安装完成后,会由于传感器安装面的形位误差使得传感器受力面不一定水平,对于所承受的重力或出现偏载,灵敏度系数安装前后不再相同,一般需在位标定后方可使用。对于双传感器系统,由于各传感器安装情况不同,灵敏度系数不仅安装前后不同,而且彼此也不相同；另一方面,由于标定时加载重心位置有一定随机性,不能保证两传感器的平均受力,因而加载重量未知。偏载和加载位置随机性相互作用,使得双传感器系统灵敏度系数标定变得困难。目前常用方法是在处理电路上附加电位器等元件,通过改变原信号放大倍数使各路灵敏度相同,然后再加载标准重量完成标定。该方法需改变原电路,可能带来未知的影响,而且对于集成型的处理电路难以实现。针对上述问题,首先建立了传感器受力模型,通过受力分析明确偏载和重心位置变化对灵敏度系数的影响机理,推导了灵敏度标定算法,将双传感器系统灵敏度系数分解为耦合系数和转换系数两部分,标定时用同一标准重物在不同位置加载两次,即可完成在位标定,解决了双传感器系统灵敏度系数的标定问题,保证偏载情况下系统的测量精度。经实验验证,该方法不改变原测量电路和机械结构,标定后系统误差小于0.03%。

In-situ Calibration Method for Dual-sensor Weighing System Based on Sensitivity Change Mechanism

The sensitivity coefficient is no longer the same before and after the installation of weighing system sensor due to the unbalance loading resulting from the shape error of the sensor mounting surface. Thus, it need to be re-calibrated before use. For dual-sensor systems, due to the different installation conditions of each sensor, the sensitivity coefficient is not only different before and after installation, but also not the same as each other, on the other hand, due to the randomness of load center when calibrating, there is no guarantee that the two sensor bear the same force, so the load weight is unknown.The stochastic interaction between unbalance loading and randomness of loading position makes it difficult to calibrate the sensitivity coefficient of the dual-sensor system.At present, the common calibration method is to attach potentiometer and other components to the processing circuit to changing the magnification of the original signal to make the sensitivity of each path be the same, and then load standard weight to complete the calibration.This method needs to change the original circuit, which may bring unknown influence, and it is difficult to realize for integrated processing circuit.Aiming at the above problem the sensor force model was established, the influence mechanism of unbalance loading and gravity position on sensitivity coefficient was defined by force analysis, the sensitivity calibration algorithm was deduced. The sensitivity coefficient of dual sensor system was decomposed into two parts, coupling coefficient and conversion coefficient, and calibration could be completed after loading two times in different positions with the same standard weight. This new calibration method could ensure the measurement accuracy of the system under unbalance loading. The experimental results show that the new method did not change the original measuring circuit and mechanical structure, and the system error is less than 0.03%.