Department of Automation and Control Engineering, Faculty of Applied Informatics, Tomas Bata University in Zlín, nám. T. G. Masaryka 5555, 760 01, Zlín, Czech Republic.
Department of Technical Studies, College of Polytechnics Jihlava, Tolstého 1556/16, 586 01, Jihlava, Czech Republic.
Sci Rep. 2022 Jun 3;12(1):9290. doi: 10.1038/s41598-022-13182-5.
The focus of this contribution is twofold. The first part aims at the rigorous and complete analysis of pole loci of a simple delayed model, the characteristic function of which is represented by a quasi-polynomial with a non-delay and a delay parameter. The derived spectrum constitutes an infinite set, making it a suitable and simple-enough representative of even high-order process dynamics. The second part intends to apply the simple infinite-dimensional model for relay-based parameter identification of a more complex model of a heating-cooling process with heat exchangers. Processes of this type and construction are widely used in industry. The identification procedure has two substantial steps. The first one adopts the simple model with a low computational effort using the saturated relay that provides a more accurate estimation than the standard on/off test. Then, this result is transformed to the estimation of the initial characteristic equation parameters of the complex infinite-dimensional heat-exchanger model using the exact dominant-pole-loci assignment. The benefit of this technique is that multiple model parameters can be estimated under a single relay test. The second step attempts to estimate the remaining model parameters by various numerical optimization techniques and also to enhance all model parameters via the Autotune Variation Plus relay experiment for comparison. Although the obtained unordinary time and frequency domain responses may yield satisfactory results for control tasks, the identified model parameters may not reflect the actual values of process physical quantities.
本研究的重点有两个方面。第一部分旨在对一个简单时滞模型的极点轨迹进行严格而完整的分析，该模型的特征函数由一个具有非时滞和时滞参数的拟多项式表示。所得的频谱构成了一个无限集，使其成为即使是高阶过程动态的合适且足够简单的代表。第二部分旨在将简单的无限维模型应用于基于继电器的换热器加热-冷却过程更复杂模型的参数识别。这类结构的过程在工业中被广泛应用。该识别过程有两个实质性步骤。第一步采用具有低计算复杂度的简单模型，使用饱和继电器，该继电器提供比标准开/关测试更准确的估计。然后，使用精确的主导极点轨迹分配，将此结果转换为对复杂无限维换热器模型初始特征方程参数的估计。该技术的优势在于可以在单个继电器测试下估计多个模型参数。第二步尝试通过各种数值优化技术来估计其余的模型参数，并通过 Autotune Variation Plus 继电器实验进行增强以进行比较。虽然所得到的非寻常的时域和频域响应可能会对控制任务产生令人满意的结果，但所识别的模型参数可能无法反映过程物理量的实际值。
