Aspect] is a simple and practical aspect-oriented extension to Java With just a few new constructs, AspectJ provides support for modular implementation of a range of crosscutting concerns. In AspectJ's dynamic join point model, join points are well-defined points in the execution of the program; pointcuts are collections of join points; advice are special method-like constructs that can be attached to pointcuts; and aspects are modular units of crosscutting implementation, comprising pointcuts, advice, and ordinary Java member declarations. AspectJ code is compiled into standard Java bytecode. Simple extensions to existing Java development environments make it possible to browse the crosscutting structure of aspects in the same kind of way as one browses the inheritance structure of classes. Several examples show that AspectJ is powerful, and that programs written using it are easy to understand.

An overview of AspectJ

A new nonlinear disturbance observer (NDO) for robotic manipulators is derived in this paper. The global exponential stability of the proposed disturbance observer (DO) is guaranteed by selecting design parameters, which depend on the maximum velocity and physical parameters of robotic manipulators. This new observer overcomes the disadvantages of existing DOs, which are designed or analyzed by linear system techniques. It can be applied in robotic manipulators for various purposes such as friction compensation, independent joint control, sensorless torque control and fault diagnosis. The performance of the proposed observer is demonstrated by the friction estimation and compensation for a two-link robotic manipulator. Both simulation and experimental results show the NDO works well.

/pdf/a-nonlinear-disturbance-observer-for-robotic-manipulators-8kcsekd4de.pdf

A nonlinear disturbance observer for robotic manipulators

During the last decade, a big progress has been achieved in the analysis and numerical treatment of Initial Value Problems (IVPs) in Differential Algebraic Equations (DAEs) and Ordinary Differential Equations (ODEs). In spite of the rich variety of results available in the literature, there are still many specific problems that require special attention. Two of such, which are considered in this work, are the optimization of order of accuracy and reduction of cost of functional evaluations of Explicit Runge - Kutta (ERK) methods.

Traditionally, the maximum attainable order p of an s-stage ERK method for advancing the solution of an IVP is such that
p(s)
 4
 
In 1999, Goeken presented an s-stage ERK Method of order p(s)=s +1,s>2.
However, this work focuses on the design of a new approximation algorithm that reduces the cost of functional evaluations and yet increases the attainable order higher 
U n and Jonhson [94]; and the classical ERK methods. The order p of 
the new scheme called Multiderivative Explicit Runge-Kutta (MERK) Methods is such that p(s) 2. The stability, convergence and implementation for the optimization of IVPs in DAEs and ODEs systems are also considered.

Numerical solution of initial value problems in differential - algebraic equations

''Model-free control'' and the corresponding ''intelligent'' PID controllers (iPIDs), which already had many successful concrete applications, are presented here for the first time in an unified manner, where the new advances are taken into account. The basics of model-free control is now employing some old functional analysis and some elementary differential algebra. The estimation techniques become quite straightforward via a recent online parameter identification approach. The importance of iPIs and especially of iPs is deduced from the presence of friction. The strange industrial ubiquity of classic PID's and the great difficulty for tuning them in complex situations is deduced, via an elementary sampling, from their connections with iPIDs. Several numerical simulations are presented which include some infinite-dimensional systems. They demonstrate not only the power of our intelligent controllers but also the great simplicity for tuning them.

https://hal-polytechnique.archives-ouvertes.fr/hal-00828135/document

Model-free control

Computer Controlled Systems: Theory and Design

http://cats-fs.rpi.edu/~wenj/ECSE446S06/astrom_friction.pdf

Friction Models and Friction Compensation

Experiments have shown that the time is now ripe for a new generation of interactive learning tools for control. The tools are based on objects which admit direct graphical manipulation. During manipulations, objects are updated instantaneously, so that relations between objects are maintained all the time. The tools are natural complements to traditional education, and allow students to quickly gain insight and motivation. A high degree of interactivity has been found to be a key issue in the design. Together with a high bandwidth in the man-machine interaction, this enhances learning significantly. Another nice feature is the possibility to hide minor issues and focus on the essentials. It is not easy to describe the power of these tools adequately in text. The best way to appreciate them is simply to use them. We believe that there is a strong pedagogical potential for the type of tools that we have described. We are also of the opinion that we are only at the very beginning in the development of learning tools of this type. The addition of sound and animation are interesting avenues that should be pursued.

Interactive tools for education in automatic control

Optimization is becoming a standard methodology in many engineering disciplines to improve products and processes. The need for optimization is driven by factors such as increased costs for raw materials and stricter environmental regulations as well as a general need to meet increased competition. As model-based design processes are being used increasingly in industry, the prerequisites for optimization are often fulfilled. However, current tools and languages used to model dynamic systems are not always well suited for
integration with state of the art numerical optimization algorithms. As a result, optimization is not used as frequently as it could, or less efficient, but easier to use, algorithms are employed.

This paper reports a new Modelica-based open source project entitled JModelica, targeted towards dynamic optimization. The objective of the project is to bridge the gap between the need for high-level description languages and the details of numerical optimization algorithms. JModelica is also intended as an extensible platform where algorithm developers, particularly in the academic community, may integrate new and innovative methods. In doing so, researchers gain access to a wealth of industrially relevant optimization problems based on existing Modelica models, while at the same time facilitating industrial use of state of the art algorithms. The JModelica project rests upon three pillars, namely a language extension of Modelica for optimization entitled Optimica, software tools, and applications. In this paper, these three topics will be highlighted.

/pdf/jmodelica-an-open-source-platform-for-optimization-of-5f9bmdot8h.pdf

JModelica---an Open Source Platform for Optimization of Modelica Models

This article presents a semi-empirical combined-slip tire model including transient behavior. It is assumed that the transient behavior is a result from the dynamic deformation of the tire carcass and that the interaction between the lateral and longitudinal slip, and forces can be explained by the deformation of the rubber treads. The deformation of the tire carcass makes the tread slip deviate from the wheel-rim motion in a way that may be described by differential equations. A method based on brush-model tire mechanics is used to construct the combined-slip forces as nonlinear scalings of corresponding pure-slip forces.

A semi-empirical dynamic tire model for combined-slip forces

This project is part of the Swedish IVSS program. The aim of IVSS is to stimulate research and development for the road safety of the future. Road conditions with low friction have been identified as a frequent cause of traffic accidents. Therefore, technology to automatically
detect changes in road conditions and alert the driver or take proper actions with active driver support systems would be a key contribution to increased road safety.
The aim of this project was to investigate the possibilities to estimate the tire to road friction.
Three different approaches have been developed and evaluated, from concept to early prototypes in test vehicles. In the first method, the estimation of the coefficient of friction is based on the forces and torques that are produced at the front tires at cornering maneuvers.
The second method is based on a physical model of the tire behavior and estimates road friction from information on the forces that are produced at straight driving. The third method is based on an optical sensor that classifies the road surface ahead of the vehicle.
The three methods have been successfully evaluated in proving ground and public road tests in summer and winter conditions with different tires, and have been compared with reference measurements. The conclusion is that all three methods can be used for tire to road friction
estimation and are recommended for further development and industrialization.

Magnus Gäfvert

Papers

Friction Models and Friction Compensation

Interactive tools for education in automatic control

JModelica---an Open Source Platform for Optimization of Modelica Models

A semi-empirical dynamic tire model for combined-slip forces

Road Friction Estimation