Much has been written about theory and practice in the law, and the tension between practitioners and theorists. Judges do not cite theoretical articles often; they rarely "apply" theories to particular cases. These arguments are not revisited. Instead the Essay explores the working and interaction of theory and practice, practitioners and theorists. The Essay starts with a story about solving a legal issue using our intellectual tools - theory, practice, and their progenies: experience and "gut." Next the Essay elaborates on the nature of theory, practice, experience and "gut." The third part of the Essay discusses theories that are helpful to practitioners and those that are less helpful. The Essay concludes that practitioners theorize, and theorists practice. They use these intellectual tools differently because the goals and orientations of theorists and practitioners, and the constraints under which they act, differ. Theory, practice, experience and "gut" help us think, remember, decide and create. They complement each other like the two sides of the same coin: distinct but inseparable.

Of Theory and Practice

Leader-follower formation control of nonholonomic mobile robots based on a bioinspired neurodynamic based approach

Most tools and resources developed for natural language processing of Arabic are designed for Modern Standard Arabic (MSA) and perform terribly on Arabic dialects, such as Egyptian Arabic. Egyptian Arabic differs from MSA phonologically, morphologically and lexically and has no standardized orthography. We present a linguistically accurate, large-scale morphological analyzer for Egyptian Arabic. The analyzer extends an existing resource, the Egyptian Colloquial Arabic Lexicon, and follows the part-of-speech guidelines used by the Linguistic Data Consortium for Egyptian Arabic. It accepts multiple orthographic variants and normalizes them to a conventional orthography.

A Morphological Analyzer for Egyptian Arabic

In this paper, the distributed formation control problem for multiple nonholonomic mobile robots using consensus-based approach is considered. A transformation is given to convert the formation control problem for multiple nonholonomic mobile robots into a state consensus problem. Distributed control laws are developed for achieving the formation control objectives: a group of nonholonomic mobile robots at least exponentially converge to a desired geometric pattern with its centroid moving along the specified reference trajectory. Rigorous proofs are provided by using graph, matrix , and Lyapunov theories. Simulations are also given to verify the effectiveness of the theoretical results.

Distributed consensus-based formation control for multiple nonholonomic mobile robots with a specified reference trajectory

ENGLISH) xiv ABSTRACT (ARABIC) xvARABIC) xv 1 CHAPTER

Stabilization of networked control systems with random delays

The note combines (weak) control Lyapunov function-based nonlinear receding horizon control, with randomized optimization. This approach is applied to the problem of robot navigation in the presence of state and input constraints. It is shown that under certain conditions, relaxing the definiteness requirements on the terminal cost function allows one to select control inputs through a Monte-Carlo optimization scheme in a way that preserves the stability and convergence properties of the closed loop system. While the particular randomized optimization scheme used here can be substituted for the nonlinear optimal control method of choice, the introduction of randomization in receding horizon optimization is anticipated to offer additional trade-offs between performance and computation speed compared to the fixed-overhead nonlinear optimal control strategies typically employed.

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Randomized Receding Horizon Navigation

The paper suggests a new approach to navigation of mobile robots, based on nonlinear model predictive control and using a navigation function as a control Lyapunov function. In this approach, the nonlinear optimal control problem is treated using randomized algorithms. The advantage of the proposed combination of navigation functions for robot motion planning with randomized algorithms within an MPC framework, is that the control design offers stability by design, is platform independent, and allows the designer to trade-off performance for (computation) speed, according to the application requirements.

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Randomized model predictive control for robot navigation

In this paper we expose experimental issues faced in a closed-loop networked control system. We also propose some compensation actions, and evaluate their performance for different experimental setups, focusing specifically on time delays.

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Practical issues in networked control systems

This technical note tackles the problem of constructing state-feedback stabilizers that guarantee good transient closed-loop performance when applied to general unknown nonlinear multiinput state-feedback stabilizable systems. An adaptive Control Lyapunov Function-based control scheme is proposed in order to address this problem. Mathematical analysis establishes that the proposed control scheme guarantees good closed-loop transient performance outside the regions where the system is uncontrollable, provided the controlled system admits a controllability-like property.

CLF-Based Control Design for Unknown Multiinput Nonlinear Systems With Good Transient Performance

In this paper we introduce the notion of Finite Time Mode Abstraction to relate a hybrid automaton to a timed automaton that preserves the stability and reachability properties of the former. The abstraction procedure discards the continuous dynamics of each mode in the hybrid automaton completely, keeping only the information about the maximum time in which the continuous state makes a discrete jump. This information is used to construct a timed automaton, based on the original hybrid automaton, and to prove that the stability and reachability properties of the original system are retained in the abstract timed automaton. In the process of abstracting a hybrid to a timed automaton we introduce a new notion of hybrid distance metric, which provides information about both the number of discrete transitions that a system would have to make to go from one hybrid state to another, and the distance between the continuous parts of such hybrid states.

/pdf/discrete-asymptotic-abstractions-of-hybrid-systems-4eq64zn6ly.pdf

Jorge L. Piovesan

Papers

Randomized Receding Horizon Navigation

Randomized model predictive control for robot navigation

Practical issues in networked control systems

CLF-Based Control Design for Unknown Multiinput Nonlinear Systems With Good Transient Performance

Discrete Asymptotic Abstractions of Hybrid Systems