1,721,073 research outputs found
Discussion on: "State feedback fuzzy adaptive control for active shimmy damping"
No full textThe paper by Pouly et al. addresses modeling
and control design for a classical physical system,
an elastic rotating wheel with a vertical steering
axis, which can be found in many vehicles
characterized by critical safety issues, aircrafts
and motorcycles above all. the aim of this discussion paper is to
highlight the key points, in the paper by Pouly et
al., that could be of interest for further investigation
by the same authors and by other research
groups working on similar topics. The rest of
the paper presents the points of discussion following
the sequential order in which fundamental
steps of any control project are typically addressed:
modeling, control design, realisation
Formal Methods for Manufacturing Systems Control Design
No full textThe aim of this thesis is to propose a formal methodology for the design and verification of industrial
control systems, with particular regard to the domain of manufacturing machines. The methodology is
driven by an approach derived from Software Engineering concepts and is supported by the definition of
a set of specification languages, derived from the semi-formal notation of UML [UML01], that permit to
describe all the aspects related to the design of a complete machine control system, both architectural
and behavioral.
In particular, the underlying approach of the development process is oriented to the modularization
and encapsulation of control tasks, in order to obtain a system architecture composed of independent
and reusable components, as is suggested by Object-Oriented design techniques. Because of the hybrid
nature of Manufacturing Systems, the control system may be partitioned into logic control modules
and continuous control modules. Ideally, the architecture specification language proposed in this thesis
would permit to describe both kind of components, together with their interactions. However, since the
proposed methodology is mainly oriented to the solution of logic control problems, which are those less
supported by formal methods in the industrial practice, the behaviour specification language adopted,
derived from Statecharts [Har87], is basically event-oriented, with extensions that permit the description
of simple data-processing operations. With regard to behavioral design, the suggested approach is that of
direct design, which means that operational specifications on the desired behaviour of the manufacturing
machine (or its components) are explicitly mapped into an operational model for each control module
defined in the architecture specification.
Formal verification of the control system design model can be performed, by means of a translation
into a formal language. In particular, the technique suggested is model checking, in order to prove desired
properties expressed in a form of temporal logic. For example, a model checking tool that can serve the
purpose is SMV [McM93], which uses the temporal logic dialect CTL [CA81].
The rest of the thesis is organized as follows:
- Chapter 2 presents a review of the most important formalisms and techniques to model and control
Discrete Event Systems, with particular regard to their applicability in the manufacturing industry.
- Chapter 3 describes a number of Software Engineering techniques that have been successfully applied
to the domain of Real-Time software design, even if they are principally supported by semiformal
languages. In particular, the techniques adopting Statecharts for behavioral specification
are described in depth and with emphasis on the different semantical interpretations.
- Chapter 4 describes the design methodology for industrial control systems proposed by this thesis,
including the underlying approach, the specification languages adopted and the relationships with
the features of the application domain.
- Chapter 5 presents the definition of formal procedures to verify the correctness of industrial control
systems, designed and modeled with the methods proposed in Chapter 4, and briefly describes how
the design models can be implemented on real controllers.
- Chapter 6 summarizes the features of the proposed approach to Manufacturing Systems control
design, that aim to introduce the use of formal methods in the industrial practice, and ends with
proposals for future work.
- The thesis ends with an illustrative example of control system design and verification, described in
Appendix A, referred to a machine component quite common in the packaging industry
Mechatronic objects encapsulation in IEC 1131-3 norm
No full textThis paper concerns with the definition and use of 'mechatronic objects' for the design of complex manufacturing system as large machinery. In particular the programming languages and structures defined under the IEC 1131-3 norm are considered regarding the software encapsulation of the mechanical system. The paper reports about a real application example of the proposed concepts showing effectiveness of the object-oriented framework for industrial applications
Discussion on "A comparison of sliding mode and unknown input observers for fault reconstruction" by Christopher Edwards and Chee Pin Tan
No full textThe paper by Christopher Edwards and Chee Pin Tan
represents an interesting contribution to the important
area of the fault diagnosis of dynamic systems.
The work under discussion compares a diagnosis
method based on sliding mode observers for fault
reconstruction [1] with the linear technique relying on
unknown input observers (UIOs) [2].Bot h the
schemes described in the mentioned references exploit
their robustness properties to overcome uncertainty
acting on the system under diagnosis.In particular,
Tan and Edwards in Ref.[1] suggested an observer
design method, based on the solution of a linear
matrix inequality (LMI), which seeks to minimize the
L2 gain between the uncertainty and the fault reconstruction
signal.In terms of the UIO literature, the
work of Saif and Guan has been chosen because
the problem it tackles is the closest to the one
associated with the sliding mode scheme and because
the assumptions in Ref.[2] are similar to those
from Ref.[1].On the basis of this hypothesis and using
also the results achieved from other related works
by the same authors, the links between the two
approaches are recalled and investigated, even if the
details of the methods are quite different.These
methods are finally compared by exploiting a nonlinear
dynamic model of a crane system affected by
simulated faults
Data Driven Approach for Wind Turbine Actuator and Sensor Fault Detection and Isolation
No full textIn order to improve reliability of wind turbines, it is important to detect and isolate faults as fast as possible, and handle them in an optimal way. An important component in modern wind turbines is the converter, which for a wind turbine control point of view normally provides the torque acting on the wind turbine generator, as well as measurement of this torque. In this work, a diagnosis strategy based on fuzzy prototypes is presented, in order to detect these faults in the converter, and isolate them either to be an actuator or a sensor fault. The fuzzy system is used since the model under investigation is nonlinear, whilst the wind speed measurement is highly noisy, due to the turbulence around the rotor plane. The fuzzy system consists of a set of piecewise affine Takagi Sugeno models, which are identified from the noisy measurements acquired from the simulated wind turbine. The fault detection and isolation strategy is thus designed based on these fuzzy models. The wind turbine simulator is finally used to validate the achieved performances of the suggested fault detection and isolation scheme
A non linear fuzzy PID controller for robotic visual-servoing
No full textThis paper presents a very simple fuzzy pid non linear algorithm used to control a Puma 260 robot arm. On the end effector of the robot is mounted a CCD b/w camera, and by means of this camera the system performs the tracking of an object moving on a plane parallel to the CCD. The paper presents the results of practical experiments and the comparison between the fuzzy algorithm and a previous non linear PID algorithm
Formal Verification of Hybrid Models for Physical Systems
No full textIndustrial automation is an application field in which logic controllers play a dominant role. These controllers typically interact with an heterogeneous physical system, composed by mechanical parts, electrical drives, chemical processes and so on, which means that the overall system's behavior should be represented and analyzed with tools derived from hybrid systems theory. This paper proposes a modeling approach that aims to provide a unified framework, based on the cardinal principles of object orientation, for the specification and verification of logic controllers for multi-domain physical systems. The proposed modeling methodology allows to describe both control software and physical components using the same basic concepts and the same modeling notation, based on the UML language. Moreover, the paper describes how to analyze the behavior of the closed-loop system with formal verification techniques for hybrid systems, in order to prove the correctness of the designed logic controller
Online Smooth Trajectory Planning for Mobile Robots by Means of Nonlinear Filters
No full textThe paper presents a nonlinear filtering technique that can be adopted to generate smooth trajectories for mobile robotic applications. The proposed trajectory planner can be fully executed online by the robot control system, thanks to its inherently discrete-time behavior and to its limited computational requirement. The outputs of the nonlinear filter used as a trajectory planner include the derivatives of the desired position in the cartesian plane up to the third order. This allows the implementation of feedback linearization control schemes that can transform the dynamics of a mobile robot in a double chain of three integrators, exploiting the highest derivative of the filter’s output as a feedforward action. Finally, the paper reports experimental results obtained by the full implementation of the proposed trajectory planning and control scheme on a real unicycle-like robot
Unified modeling of control software and physical plants
No full textThe aim of this paper is to provide a unified language for modeling both
control software and physical plants in real time control systems. This is done by
embedding the bond graph modeling language for physical systems into the UMLRT
framework, widely used to model distributed real-time software
Motorised Digital Level: development and applications
No full textA low-cost motorisation of the Leica DNA03 digital level was designed to enable the automatic
monitoring of deformations without compromising its manual use in levelling. The upgrade of the
instrument and its electronic control system are described together with laboratory tests carried
out to study the effects of ambient temperature on the level. A simple model for the correction of
measurements as a function of the temperature is proposed. The detection of vertical movements
with sub-millimetre accuracy was obtained in a simulated permanent monitoring system. The
operational advantages of the instrument are shown in a field test. Despite the encouraging
results, research is still needed to find a reliable model for the correction of the staff readings
under changing temperature conditions
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