Discrete sliding mode controller with reaching phase elimination for TITO systems.

Area of Science:

• Control Engineering
• Automation Systems
• Process Control

Background:

• Sliding Mode Control (SMC) offers robust control but suffers from chattering and lacks robustness during the reaching phase.
• Physical constraints like actuator saturation can impede the reaching phase in traditional SMC systems.
• Existing methods often fail to provide guaranteed robustness throughout the entire control process.

Purpose of the Study:

• To propose a novel chatter-free discrete sliding mode controller (DSMC) that eliminates the reaching phase.
• To address the limitations imposed by physical constraints, such as actuator saturation, on the reaching phase.
• To validate the controller's effectiveness and applicability on a real-world interacting two-tank liquid level system.

Main Methods:

• Decoupling a two-input-two-output (TITO) system into two single-input-single-output (SISO) systems using an ideal decoupler.
• Designing discrete sliding mode controllers (DSMCs) independently for each decoupled SISO system.
• Ensuring system stability using the Lyapunov stability approach.

Main Results:

• The proposed DSMC successfully eliminates the reaching phase, mitigating associated robustness issues.
• The controller effectively handles physical constraints like actuator saturation.
• Both simulation studies and experimental results on an interacting two-tank liquid level system confirm the controller's performance.

Conclusions:

• The developed chatter-free DSMC provides a robust and effective solution for process control, overcoming limitations of conventional SMC.
• The method of decoupling TITO systems and applying independent DSMCs is a viable strategy for complex control problems.
• The controller's practical applicability is demonstrated through successful experimentation on a real-world system.