Comparison of ARMAX Model Identification Results Based on Least Squares Method
Publication Date : 11/10/2015
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Abstract :
In this paper, process simulator which carried out wireless temperature control was modelled with linear parametric single input-single output (SISO) model by using the system identification technique. To achieve the data transfer between computer in Process Control Laboratory and the process simulator in Unit Operations Laboratory, wireless communication system established and wireless experiments were performed on-line by means of MATLAB/Simulink program. Wireless data transfers during the experiments were carried out using radio waves at a frequency of 2.4 GHz. ARMAX model parameters were calculated by using three least squares parameter estimation methods including heater capacity and heater output temperature were selected as input and output, respectively. Square wave signal was performed as input signal and model parameters were estimated by using Recursive Least Squares (RLS), Filtered Least Squares (FLS) and Extended Least Squares (ELS) methods by input-output values were collected from the system. In order to the test the model validation, two successive step changes were applied and heater output temperature changes compared with the obtained values from these three least squares methods. According to the results best representing ARMAX model of the system was determined with FLS method and results of RLS and ELS methods close to each other. Keywords—System identification, MATLAB/Simulink, ARMAX model, parameter estimation, least square method, wireless measurement and control
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