Julio E. Normey-Rico

Robust Predictive Control Strategy Applied for Propofol Dosing Using BIS as a Controlled Variable During Anesthesia

This paper presents the application of predictive control to drug dosing during anesthesia in patients undergoing surgery. The performance of a generic predictive control strategy in drug dosing control, with a previously reported anesthesia-specific control algorithm, has been evaluated. The robustness properties of the predictive controller are evaluated with respect to inter- and intrapatient variability. A single-input (propofol) single-output (bispectral index, BIS) model of the patient has been assumed for prediction as well as for simulation. A set of 12 patient models were studied and interpatient variability and disturbances are used to assess robustness of the controller. Furthermore, the controller guarantees the stability in a desired range. The applicability of the predictive controller in a real-life environment via simulation studies has been assessed.

Improving the robustness of dead-time compensating PI controllers

Abstract This paper describes a PI controller with dead-time compensation that presents robust behaviour. The formulation is based on a Smith predictor structure plus the addition of a filter acting on the error between the output and its prediction in order to improve robustness. The controller is very simple, and the filter needs no adjustment, since it is directly related to the plant dead-time. Simulations and experimental results show that this controller can improve the performance of related algorithms.

A Predictive Controller for Autonomous Vehicle Path Tracking

This paper presents a model predictive controller (MPC) structure for solving the path-tracking problem of terrestrial autonomous vehicles. To achieve the desired performance during high-speed driving, the controller architecture considers both the kinematic and the dynamic control in a cascade structure. Our study contains a comparative study between two kinematic linear predictive control strategies: The first strategy is based on the successive linearization concept, and the other strategy combines a local reference frame with an approaching path strategy. Our goal is to search for the strategy that best comprises the performance and hardware-cost criteria. For the dynamic controller, a decentralized predictive controller based on a linearized model of the vehicle is used. Practical experiments obtained using an autonomous ldquoMini-Bajardquo vehicle equipped with an embedded computing system are presented. These results confirm that the proposed MPC structure is the solution that better matches the target criteria.

Robust tuning of dead-time compensators for processes with an integrator and long dead-time

Presents a simple criterion for tuning a dead time compensator for plants with an integrator and long dead time. The criterion is based on the definition of a closed-loop performance and considers that the model of the process is not precisely known. Using an estimation of the dead time and velocity gain of the plant, the proposed control law has only one tuning parameter that determines the closed-loop performance and robustness. By tuning this parameter it is possible to attain some robust performance specifications. In order to compare the proposed criterion with previous algorithms proposed in the literature, a comparative analysis of robustness is presented. Some simulation examples demonstrate the good properties of the proposed compensator.

Mobile robot path tracking using a robust PID controller

Abstract This paper presents a simple and effective solution for the path tracking problem of a mobile robot using a PID controller. The proposed method uses a simple linearized model of the mobile robot composed of an integrator and a delay. The synthesis procedure is simple and allows the PID controller to be tuned considering the nominal performance and the robustness as control specifications. Experimental results demonstrate the good performance and robustness of the proposed controller.

A Smith-predictor-based generalised predictive controller for mobile robot path-tracking

Abstract This paper shows how to improve the robustness of mobile robot path tracking when predictive control algorithms are used. When uncertainties in a mobile robot are considered, it is shown how the classical generalised predictive controller (GPC) may lead to an unstable behaviour of the mobile robot. The equivalence between the GPC and a structure composed by an optimal predictor and a classical controller is given, and it is shown that use of a Smith predictor instead of an optimal predictor increases the robustness of the system. A new strategy, the Smith-predictor-based GPC, is proposed. Experimental tests carried out on a LABMATE mobile robot validate the performance of the proposed controller.

Robust Nonlinear Predictive Control Applied to a Solar Collector Field in a Solar Desalination Plant

This brief presents the application of a robust nonlinear predictive controller to the distributed collector field of a solar desalination plant. The main purpose of the controller is to manipulate the water flow rate to maintain the collector outlet-inlet temperature gradient constant in spite of disturbances. The controller uses a robust dead-time compensation structure and a nonlinear model predictive control to cope with time delay uncertainties and system nonlinearities, respectively. Simulation and real experimental results are shown to illustrate controller performance.

OPC based distributed real time simulation of complex continuous processes

Abstract This paper presents a methodology for the development of distributed process simulation using OPC (OLE for Process Control). The distributed components operate as OPC servers enclosing continuous simulations developed with the simulation language EcosimPro. The paper presents the problems related to data interchange and synchronisation in real time and the solutions adopted and gives results about the performance of OPC in this kind of applications. The methodology has been applied to a large process simulator of a beet sugar factory used for control room operator training. This includes a process simulation operating in a network of six computers, a SCADA system for operation on the process, an instructor console and the corresponding software for real time communication and synchronisation. The main advantages of this approach are: (i) independence of the development of the simulation from the communication mechanisms, (ii) access to the simulations by a wide range of applications, due to the standard provided by OPC, (iii) use of low cost conventional equipment and (iv) support for large scale simulations.

A Robust Adaptive Dead-Time Compensator with Application to A Solar Collector Field 1

Abstract This paper describes an easy-to-use PI controller with dead-time compensation that presents robust behaviour and can be applied to plants with variable dead-time. The formulation is based on an adaptive Smith predictor structure plus the addition of a filter acting on the error between the output and its prediction in order to improve robustness. The implementation of the control law is straightforward, and the filter needs no adjustment, since it is directly related to the plant dead-time. An application to an experimentally validated nonlinear model of a solar plant shows that this controller can improve the performance of classical PID controllers without the need of complex calculations.

A Smith Predictor Based Generalized Predictive Controller for Mobile Robot Path-Tracking

Abstract This paper presents the application of a Smith predictor based generalized predictive controller (SPGPC) to the path-traking problem of a mobile robot. The equivalence between the generalized predictive controller (GPC) and a structure composed by an optimal predictor and a classical controller is given and it is shown that using a Smith predictor instead of an optimal predictor, increases the robustness of the system. Some results concerning the influence of the new predictor structure on the closed loop robustness are presented. Simulation and experimental tests carried out on a Labmate mobile robot validate the performance of the proposed strategy.