A simple method to design PID controllers in the frequency domain based on a simplified constrained optimization is proposed. The method is based on the use of a single tuning parameter, defined as the quotient between the final crossover frequency and the zero of the controller. The tuning procedure is based on the maximization of the controller gain subject to an equality constraint in the phase margin and an inequality constraint in the gain margin. The main advantage of the proposed method is that, even though the maximization of the controller gain is straightforward, since there is only one parameter to be tuned, the solution is close to the optimal tuning obtained with direct numerical optimization methods. Moreover the method is applicable to any linear model structure, including dead time and non-minimum phase systems.
Versión / Versió:Postprint del autor This paper addresses the state estimation in linear time-varying systems with several sensors with different availability, randomly sampled in time, and whose measurements have a time-varying delay. The approach is based on a modification of the Kalman filter with the negative-time measurement update strategy, avoiding running back the full standard Kalman filter, the use of full augmented order models or the use of reorganization techniques, leading to a lower implementation cost algorithm. The update equations are run every time a new measurement is available, independently of the time when it was taken. The approach is useful for networked control systems, systems with long delays and scarce measurements, and for out-of-sequence measurements.
In this paper we analyse the conditions that produce oscillations in event based PID controllers. A Symmetric SendOn-Delta scheme (SSOD) is assumed, and the describing function is the tool used to address the problem. Once the conditions for oscillations are established, a new robustness to oscillations performance measure is introduced. Then a very simple and intuitive rule of thumb is given about how to tune PID controllers to avoid the limit cycles. The rule presented here entails with the classical concept of phase margin, providing the key to design SSOD based PID by using continuous PID tuning methods. The proposed ideas are tested in simulations with a batch of models widely used in PID design methods testing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.