Robust temperature control of a diesel oxidation catalyst using continuous terminal sliding mode with extended state observer

Abstract

Robust temperature control is essential for the diesel oxidation catalyst (DOC) in modern diesel engines to realize efficient and reliable thermal regenerations in real driving cycles. This paper investigates the design and validation of an improved robust control solution for the DOC-outlet temperature control by applying the error-based active disturbance rejection control (ADRC) method and the non-singular terminal sliding mode (TSM) scheme along with a second-order sliding mode approach. The second-order TSM scheme is introduced to substitute the proportional–derivative (PD) control in the conventional ADRC framework. A finite-time convergence of the sliding mode dynamics is consequently guaranteed and the tracking errors are driven to zeros asymptotically, which accordingly implies that a faster temperature response is expected. Moreover, the undesired chattering effect is eliminated, resulting in an inherently continuous control input signal. The extended state observer (ESO) is synthesized as a feedforward compensator to estimate and reject the total disturbance. Theoretical convergence and stability of the proposed control strategy are analyzed based on the Lyapunov approach. Selection of the controller parameters is further discussed as well. The effectiveness and robustness are finally examined through an extensive comparative study using simulation and experimental tests. Results demonstrate that the proposed continuous TSM control achieves superior temperature control performance, including faster disturbance suppression, more accurate set-point tracking, and greater robustness against internal model uncertainties and external disturbances compared to the conventional ADRC controller.