Simplified filtered Smith predictor for high-order dead-time processes.

This paper proposes a control structure suitable for high-order non-minimum phase (NMP) processes. In general, dead-time compensators (DTCs) firstly predict the process output with zero error at a steady-state and then a primary controller with an integrator is designed based on the delay-free model. The main advantage of the proposed structure is that the primary controller is only a state feedback gain with no integrators. This leads to fewer parameters to tune and lower order filters, while a robustness filter is used to reject disturbances and guarantee zero error at a steady state. Simulation results show better or equivalent performance compared to other recently published works, even kept the controller design simplicity.

New simple approach for enhanced rejection of unknown disturbances in LTI systems with input delay.

This work proposes the extension of the simplified filtered Smith predictor (SFSP) for state-space systems to improve rejection of matched and unmatched unknown disturbances in LTI systems with input delay. The proposed structure is simpler than others recently proposed in the literature and can be applied to continuous-time or discrete-time systems. Furthermore, it allows improving rejection of both matched and unmatched disturbances, while also enhancing noise attenuation and robustness characteristics. Finite spectrum assignment (FSA) based implementation is used in order to guarantee the internal stability of the proposed controller. Simulation and experimental results are used to show the usefulness of the proposal.

Tuning of a dead-time compensator focusing on industrial processes.

This paper proposes tuning rules for the Simplified Dead-Time Compensator (SDTC), which is intended to deal with stable, unstable and integrative dead-time processes. The main contribution is the proposal of new guidelines for the tuning of the robustness filter. The new set of rules allow for the use of lower order filters which are able to simultaneously account for closed-loop robustness and noise attenuation. Through illustrative examples, it is shown that the proposed approach provides enhanced disturbance rejection and noise attenuation in the control of industrial processes when compared with other recently published works. Furthermore, the internal temperature of an in-house thermal chamber is controlled to evaluate the applicability of the strategy on real processes.