Miguel A. Davó

Reset control of a liquid level process

The aim of this work is to present an experiment of liquid level process controlled by a reset PI+CI compensator. The results are compared with a well tuned linear PI compensator, showing that the reset compensator improves the performance in both setpoint tracking and disturbance rejection. The experiment validates the simulation results obtained for a tuning rule proposed in a previous work.

Delay-dependent stability of reset control systems with input/output delays

This work presents results on the stability of time delay reset control systems, extending previous results of reset control systems to deal with input/output delays. The stability results are derived by using a more general Lyapunov-Krasovskii functional, obtaining LMI (Linear Matrix Inequality) conditions. In addition, a less conservative result is obtained by relaxing the conditions over the L-K functional for systems with some constraints over the time intervals.

PI+CI tuning for integrating plus deadtime systems

The PI+CI is a reset compensator that has been shown to be effective in a number of practical applications. In this work, a simple PI+CI tuning method for integrating systems with time delay is proposed. It is a direct method, with only a tuning parameter to balance between closed-loop robustness and performance. A tuning rule for the reset ratio parameter of the PI+CI compensator is proposed in order to improve the disturbance rejection. Finally, the proposed compensator is compared with some well-tuned PI compensators.

An impulsive dynamical systems framework for reset control systems

ABSTRACT Impulsive dynamical systems is a well-established area of dynamical systems theory, and it is used in this work to analyse several basic properties of reset control systems: existence and uniqueness of solutions, and continuous dependence on the initial condition (well-posedness). The work scope is about reset control systems with a linear and time-invariant base system, and a zero-crossing resetting law. A necessary and sufficient condition for existence and uniqueness of solutions, based on the well-posedness of reset instants, is developed. As a result, it is shown that reset control systems (with strictly proper plants) do not have Zeno solutions. It is also shown that full reset and partial reset (with a special structure) always produce well-posed reset instants. Moreover, a definition of continuous dependence on the initial condition is developed, and also a sufficient condition for reset control systems to satisfy that property. Finally, this property is used to analyse sensitivity of reset control systems to sensor noise. This work also includes a number of illustrative examples motivating the key concepts and main results.

Performance analysis of PI and PI+CI compensation for an IPDT process

In this work, it is performed a comparison between the performance of PI and PI+CI compensators, in terms of a balanced index (servo/regulatory) based on the integrated absolute error (IAE). The plant is modelled by an integrating plus dead time (IPDT) process. The purporse of this work is to provide insight into the benefit of reset compensation both in servo and regulatory problems. This is accomplished by providing a tuning rule for the PI+CI, that allows to analyze the performance index in the compensator parameter space. The analysis done is independent of the process parameters.

Tuning rules for a reset PI compensator with variable reset

Abstract The PI+CI compensator is a simple reset compensator, its base system is a PI, which has been shown to be effective in a number of practical applications. One fundamental parameter to be tuned is the reset ratio; for lag dominant systems or systems with integrators it is known to give good results overcoming PI compensation. In this work, a systematic method for the tuning of a variable reset ratio (variable at the reset instants) is developed for first and second order plants.