Design and simulation of a normalized fuzzy logic controller for the quadruple-tank process

&lt;p class="MsoNormal" style="margin-top: 6.0pt; text-align: justify;"&gt;Industrial processes include multivariable systems and nonlinearities. These conditions must be effectively controlled to ensure a stable operation. A proportional–integral–derivative controller and other classical control techniques provide simple design tools to designers, but cannot accommodate nonlinearities in industrial processes. In this study, the quadruple-tank process, which is one of the most widely used processes in the chemical industry, was selected as the research object. To examine this process, a fuzzy logic controller, instead of an exact mathematical model, was proposed to ensure the reliability of the experience. A modification was proposed to facilitate the design process. To check the validity of the proposed controller, it was compared with the conventional proportional–integral controller. The former exhibited acceptable performance.&lt;/p&gt;&lt;table class="MsoTableGrid" style="width: 444.85pt; border-collapse: collapse; border: none; mso-border-alt: solid windowtext .5pt; mso-yfti-tbllook: 1184; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt;" width="0" border="1" cellspacing="0" cellpadding="0"&gt;&lt;tbody&gt;&lt;tr style="mso-yfti-irow: 0; mso-yfti-firstrow: yes; mso-yfti-lastrow: yes; height: 63.4pt;"&gt;&lt;td style="width: 290.6pt; border: none; border-top: solid windowtext 1.0pt; mso-border-top-alt: solid windowtext .5pt; padding: 0cm 5.4pt 0cm 5.4pt; height: 63.4pt;" valign="top" width="593"&gt;&lt;p class="MsoNormal" style="margin-top: 6.0pt; text-align: justify;"&gt;&lt;span style="mso-ascii-font-family: 'Times New Roman'; mso-ascii-theme-font: major-bidi; mso-hansi-font-family: 'Times New Roman'; mso-hansi-theme-font: major-bidi; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: major-bidi;"&gt;Industrial processes include multivariable systems and nonlinearities. These conditions &lt;span style="mso-no-proof: yes;"&gt;must be effectively&lt;/span&gt; controlled to ensure a stable operation. A proportional–integral–derivative controller and other classical control techniques provide &lt;span style="mso-no-proof: yes;"&gt;simple&lt;/span&gt; design tools to designers, &lt;span style="mso-no-proof: yes;"&gt;but&lt;/span&gt; cannot accommodate nonlinearities in industrial processes. In this study, the quadruple&lt;/span&gt;&lt;span style="mso-ascii-font-family: 'Times New Roman'; mso-ascii-theme-font: major-bidi; mso-hansi-font-family: 'Times New Roman'; mso-hansi-theme-font: major-bidi; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: major-bidi; mso-bidi-language: AR-IQ;"&gt;-tank process&lt;/span&gt;&lt;span style="mso-ascii-font-family: 'Times New Roman'; mso-ascii-theme-font: major-bidi; mso-hansi-font-family: 'Times New Roman'; mso-hansi-theme-font: major-bidi; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: major-bidi;"&gt;, which is one of the most widely used processes in the chemical industry, was selected as the research object.&lt;span style="mso-spacerun: yes;"&gt; &lt;/span&gt;To examine this process, a&lt;/span&gt;&lt;span style="mso-ascii-font-family: 'Times New Roman'; mso-ascii-theme-font: major-bidi; mso-hansi-font-family: 'Times New Roman'; mso-hansi-theme-font: major-bidi; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: major-bidi; mso-bidi-language: AR-IQ;"&gt; fuzzy logic controller, instead of an &lt;/span&gt;&lt;span style="mso-ascii-font-family: 'Times New Roman'; mso-ascii-theme-font: major-bidi; mso-hansi-font-family: 'Times New Roman'; mso-hansi-theme-font: major-bidi; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: major-bidi;"&gt;exact mathematical model,&lt;/span&gt;&lt;span style="mso-ascii-font-family: 'Times New Roman'; mso-ascii-theme-font: major-bidi; mso-hansi-font-family: 'Times New Roman'; mso-hansi-theme-font: major-bidi; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: major-bidi;"&gt;was&lt;span style="mso-no-proof: yes;"&gt; proposed&lt;/span&gt; to ensure the reliability of the experience. &lt;/span&gt;&lt;span style="mso-ascii-font-family: 'Times New Roman'; mso-ascii-theme-font: major-bidi; mso-hansi-font-family: 'Times New Roman'; mso-hansi-theme-font: major-bidi; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: major-bidi; mso-bidi-language: AR-IQ;"&gt;A modification was proposed to facilitate the design process. To check the &lt;span style="mso-no-proof: yes;"&gt;validity&lt;/span&gt; of the proposed controller, it was compared with the conventional proportional&lt;/span&gt;&lt;span style="mso-ascii-font-family: 'Times New Roman'; mso-ascii-theme-font: major-bidi; mso-hansi-font-family: 'Times New Roman'; mso-hansi-theme-font: major-bidi; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: major-bidi;"&gt;–&lt;/span&gt;&lt;span style="mso-ascii-font-family: 'Times New Roman'; mso-ascii-theme-font: major-bidi; mso-hansi-font-family: 'Times New Roman'; mso-hansi-theme-font: major-bidi; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: major-bidi; mso-bidi-language: AR-IQ;"&gt;integral &lt;span style="mso-no-proof: yes;"&gt;controller. The former exhibited&lt;/span&gt; &lt;span style="mso-no-proof: yes;"&gt;acceptable&lt;/span&gt; performance.&lt;/span&gt;&lt;/p&gt;&lt;p class="MsoNormal" style="margin-top: 6.0pt; text-align: justify;"&gt; &lt;/p&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/tbody&gt;&lt;/table&gt;