Predictive Second Order Sliding Control of Constrained Linear Systems with Application to Automotive Control Systems

TL;DR

This paper introduces a novel predictive second order sliding controller (PSSC) that combines MPC and sliding mode control for constrained linear systems, demonstrated on an advanced automotive engine model, ensuring robust setpoint tracking with minimal error.

Contribution

The paper develops a new PSSC formulation with a virtual reference for feasible setpoint tracking, applied to a high-fidelity RCCI engine model, enhancing control robustness and accuracy.

Findings

Effective tracking of engine load and combustion phasing setpoints.

Minimal steady state error with no overshoot.

Robust performance during engine transients and cyclic variability.

Abstract

This paper presents a new predictive second order sliding controller (PSSC) formulation for setpoint tracking of constrained linear systems. The PSSC scheme is developed by combining the concepts of model predictive control (MPC) and second order discrete sliding mode control. In order to guarantee the feasibility of the PSSC during setpoint changes, a virtual reference variable is added to the PSSC cost function to calculate the closest admissible set point. The states of the system are then driven asymptotically to this admissible setpoint by the control action of the PSSC. The performance of the proposed PSSC is evaluated for an advanced automotive engine case study, where a high fidelity physics-based model of a reactivity controlled compression ignition (RCCI) engine is utilized to serve as the virtual test-bed for the simulations. Considering the hard physical constraints on the RCCI engine states and control inputs, simultaneous tracking of engine load and optimal combustion phasing is a challenging objective to achieve. The simulation results of testing the proposed PSSC on the high fidelity RCCI model show that the developed predictive controller is able to track desired engine load and combustion phasing setpoints, with minimum steady state error, and no overshoot. Moreover, the simulation results confirm the robust tracking performance of the PSSC during transient operations, in the presence of engine cyclic variability.