Control of a nonlinear continuous stirred tank reactor via event triggered sliding modes

TL;DR

This paper introduces an event-triggered sliding mode control approach for nonlinear CSTRs, ensuring stability and robustness with reduced computational effort by activating control only when necessary.

Contribution

It presents a novel event-driven sliding mode control method with a dynamic triggering rule for efficient regulation of CSTRs under uncertainties.

Findings

Ensures stable operation across multiple points.

Reduces control updates via event-triggering.

Validates effectiveness through simulations.

Abstract

Continuous Stirred Tank Reactors (CSTR) are the most important and central equipment in many chemical and biochemical industry that exhibit second order complex nonlinear dynamics. The nonlinear dynamics of CSTR poses many design and control challenges. The proposed controller guarantees a stable closed loop behavior over multiple operating points even in presence of disturbances and parametric uncertainties. An event driven sliding mode control is presented in this work to regulate the temperature and concentration very close to the equilibrium points of CSTR. The control is executed only when a predefined condition gets violated and hence the controller is relaxed when the system is operating under tolerable limits in terms of closed loop performance. A novel dynamic event triggering rule is presented to maintain desired performance with minimum computational cost. The inter event execution time is shown to be lower bounded by a finite positive quantity to exclude Zeno behavior. Sliding mode control (SMC) combined with event triggering scheme retains the inherent robustness of traditional SMC and aids in reducing computational load on the controller involved. Simulation results validate the efficiency of the proposed controller.