Abstract

This paper aims at developing a control technique using Variable Structure control [VSC] methodology for a pH control plant. The VSC involves both SLIDING MODE CONTROL (SMC) and DYNAMIC SLIDING MODE CONTROL (DSMC). The pH control process involves a prototype model in which acidic and alkaline streams are mixed into a Continuous Stirred Tank Reactor [CSTR] in proper proportions so as to control the pH of the plant. The control mechanism involved controls the flow rate of the acid and alkaline solutions. Sliding Mode Control and Dynamic Sliding Mode control are types of nonlinear control. As the neutralization process is also non linear, VSC serves as a better solution. SMC suffers a problem called chattering, to overcome this, Dynamic Sliding Mode controller is implemented and the results are compared. Apart from this, both PID control and fuzzy control are incorporated on the same process and the results are furnished. The unique feature of this paper is that all the control methods are implemented using LabVIEW Software. LabVIEW stands for Laboratory Virtual Instrumentation Workbench. The programming done with this software is applied to the prototype model and the results of PID, Fuzzy, SMC and DSMC are compared and it is found that SMC AND DSMC controllers are better suited than PID and fuzzy controllers.