Eduardo André Perondi

Cascade controlled pneumatic positioning system with LuGre model based friction compensation

This paper proposes a cascade controller with friction compensation based on the LuGre model. This control is applied to a pneumatic positioning system. The cascade methodology consists of dividing the pneumatic positioning system model into two subsystems: a mechanical subsystem and a pneumatic subsystem. This division allows the introduction of friction compensation at force level in the pneumatic positioning system. Using Lyapunovs direct method, the convergence of the tracking errors is shown under the assumption that the system parameters are known. Experimental results illustrate the main characteristics of the proposed controller.

Modeling and simulating the controller behavior of an Automated People Mover using IEC 61850 communication requirements

Automated People Movers (APM) are systems for passenger transport with fully automated operation and high frequency service. Trains controllers are traditionally centralized and based on wired circuits, although they generally have serious difficulties in the installation and maintenance. As there is increased demand on the system, there are advantages in choosing an open architecture, with a simple communication system and distributed. These concepts are largely addressed in the development of IEC 61850. In this study we proposed the adaptation of the standard IEC 61850, design to be used in electric power systems to be applied in an APM system named Aeromovel installed in Porto Alegre, Brazil. Aeromovel is a nonconventional Automatic People Mover whose operation principle is based on pneumatics. A model, based on timed automata formalism, is proposed for IEC 61850 communications requirements and respective simulation results are presented.

Using timed automata for modeling, simulating and verifying networked systems controller's specifications

Abstract The development of dependable controllers can be a very complex task. For this purpose, some synthesis and analysis modern computational techniques can be used. In this paper, simulation and formal verification analysis techniques are used in a concurrent way in order to validate formal communication requirements of generic object oriented substation event and sample value communication protocols from the IEC 61850 standard. Because these techniques are used in a complementary way, the formalism and tools used for both are the same: timed automata for modeling, and UPPAAL model checker for performing simulation and formal verification tasks. Also, we show that the use of timed automata formalism is suitable for modeling the controllers’ specifications, specifying the time requirements for information exchanging taking into account networked controllers, and, as it is a non-deterministic formalism, for analyzing the plant behavior. The concepts developed in this study were successfully tested in an application in the control system of an automated people mover.

A Formal Methodology for Accomplishing IEC 61850 Real-Time Communication Requirements

Reliability is extremely important for control systems of energy distribution and generation. The IEC 61850 standard specifies an open architecture and communication protocols for such applications. The standard defines an open control architecture for networked control systems composed by intelligent electronic devices, stating some requirements that must be accomplished when developing reliable controllers for such systems. In this paper, we present a systematic and formal methodology to be adopted to achieve the correct implementation of the communication requirements of this standard. The methodology consists in five steps: modeling of real-time communication requirements defined by the standard; simulation of the obtained model; formal verification of the model, improved in the previous step; translation of the global model (simulated and verified) into the input language of the real controller; and finally, application of conformance testing technique to the computational routine implemented in the real controller. Presented research deals with the proposition of a strategy to synthesize and validate models of systems developed under IEC61850 real-time requirements (GOOSE and SMV) through simple operational conditions cases that, once validated, can be used in performance and conformance testing of more complex systems. The proposed methodology allows designers to synthesize reliable systems under IEC61850 real-time communication requirements.

A continuous version of the LuGre friction model applied to the adaptive control of a pneumatic servo system

Abstract This work presents the application of a friction compensation scheme to the trajectory-tracking control of a pneumatic servo actuator. Such scheme is based on a continuous approximation of the LuGre friction model, developed so as to allow complete Lyapunov stability analyses without resorting to assumptions that are difficult to satisfy in practice due to their physical meaning. By using adaptive estimation, extensive identification procedures are also avoided for determining friction parameters. Experimental results illustrate the most significant advantages and potential limitations of the proposed scheme in real applications.

OPTIMAL PLACEMENT OF PIEZOELECTRIC MACRO FIBER COMPOSITE PATCHES ON COMPOSITE PLATES FOR VIBRATION SUPPRESSION

This work presents a new methodology for the parametric optimization of piezoelectric actuators installed in laminated composite structures, with the objective of controlling structural vibrations. Problem formulation is the optimum location of a Macro Fiber Composite (MFC) actuator patch by means the maximization of the controllability index. The control strategy is based on a Linear Quadratic Regulator (LQR) approach. For the structural analysis, the modeling of the interaction between the MFC and the structure is made taking into account the active material as one of the orthotropic laminate shell layers. The actuation itself is modeled as an initial strain arising from the application of an electric potential which deforms the rest of the structure. Thereby, modeling the electric field and the electromechanical coupling within the actuator is avoided because these effects are considered analytically. Numerical simulations show that the structural model presents good agreement with numerical and experimental results. Furthermore, the results show that optimizing the location of the actuator in the structure helps the control algorithm to reduce induced structural vibration.

Design Methodology of a Dual-Halbach Array Linear Actuator with Thermal-Electromagnetic Coupling

This paper proposes a design methodology for linear actuators, considering thermal and electromagnetic coupling with geometrical and temperature constraints, that maximizes force density and minimizes force ripple. The method allows defining an actuator for given specifications in a step-by-step way so that requirements are met and the temperature within the device is maintained under or equal to its maximum allowed for continuous operation. According to the proposed method, the electromagnetic and thermal models are built with quasi-static parametric finite element models. The methodology was successfully applied to the design of a linear cylindrical actuator with a dual quasi-Halbach array of permanent magnets and a moving-coil. The actuator can produce an axial force of 120 N and a stroke of 80 mm. The paper also presents a comparative analysis between results obtained considering only an electromagnetic model and the thermal-electromagnetic coupled model. This comparison shows that the final designs for both cases differ significantly, especially regarding its active volume and its electrical and magnetic loading. Although in this paper the methodology was employed to design a specific actuator, its structure can be used to design a wide range of linear devices if the parametric models are adjusted for each particular actuator.

O controle em cascata de sistemas pneumáticos de posicionamento

This work deals with the control of pneumatic positioning systems and propose a cascade strategy that alow us to overcome several obstacles to the trajectory tracking in pneumatic systems. The exponential convergence of the closed loop trajectory tracking errors in the ideal case is demonstrated using Lyapunovs method. The robustness properties of the closed loop system are also presented. An experimental implementation attests the effectiveness of this strategy.

Cascade Control of a Pneumatic Servo Positioning System Using Neural Networks

This paper deals with the nonlinear control of pneumatic servo positioners. It is proposed the use of a neural network technique associated with a nonlinear cascade control strategy, as a means of bypassing strong difficulties common to the practical implementation of model based strategies in pneumatic systems control. Such difficulties are associated to the precise plant identification that, in the case of pneumatic servo positioners, is usually very complex and hard to find. The experimental results of position tracking control presented in the paper allow us to conclude that the neural network technique applied in this work can avoid the need of execution of time expensive experiments usually required to perform precise identification of the plant characteristics used in model based control strategies for pneumatic servo positioners.

A continuous extension of the LuGre friction model with application to the control of a pneumatic servo positioner

This work presents a novel continuous approximation of the LuGre model, with the aim of improving its applicability in the control of a class of systems that include fluid-driven servo positioners. The main attractive of the proposed approximation is the preservation of the properties of boundedness and passivity that are inherent to the original LuGre model, a feature that is not guaranteed in the approximate models that are usually encountered in the specialized literature. The most relevant properties of the proposed approximation are demonstrated analytically, and its applicability is illustrated both analytically and experimentally in the case of a pneumatic servo positioner.