基于凝结物覆盖率的露点仪自适应PID温控算法

Adaptive PID Temperature Control Algorithm of Dew Point Meter Based on Condensate Coverage

在露点仪的测量过程中,露点温度是由控制器经过二阶振荡逼近得到的。但是在整个露点测量范围内,水汽凝结速度会有20000倍的差别,固定的控制参数并不适用于整个露点测量范围,会使露点仪的响应速度以及稳定性不理想。为了提高露点仪在整个露点测量范围内的测量速度以及系统测量的稳定性,提出了基于镜面凝结物覆盖率的自适应调整参数的温度控制算法。设定与凝结物覆盖率和镜面温度有关的反馈参数,根据反馈参数的变化来触发PID控制。另一方面,镜面凝结图像的熵值在有无凝结物时会有相当明显的差异。设定图像结露熵值作为阈值,将实时熵值与熵值阈值之差作为PID控制算法的输入,实现控制参数的自适应调节。结果表明,测量速度有了较大提高,同时兼顾了系统稳定而振荡小的特点。

During the measurement of the dew point meter,the dew point temperature is obtained by the controller through the second-order oscillation approximation.However,within the entire dew point measurement range,the condensation speed of water vapor will be 20000 times different.The fixed control parameters are not suitable for the entire dew point measurement range,which will make the dew point meter’s response speed and stability unsatisfactory.In order to improve the measurement speed of the dew point meter in the entire dew point measurement range and the stability of the system measurement,a temperature control algorithm based on the adaptive adjustment parameters of the mirror condensate coverage is proposed.The feedback parameters related to the condensate coverage and mirror temperature were set,and the PID control was triggered according to the change of the parameters.On the other hand,the entropy value of the mirror condensation image would be quite different with or without condensation.The image dew entropy value was set as the threshold,and the difference between the real-time entropy value and the entropy value threshold was used as the input of the PID control algorithm to realize the adaptive adjustment of control parameters.The results show that the measurement speed has been greatly improved,while taking into account the stability of the system and the small oscillations.