Boumediene Belkhouche

Line of sight robot navigation toward a moving goal

In this paper, we consider the problem of robot tracking and navigation toward a moving goal. The goals maneuvers are not a priori known to the robot. Thus, off-line strategies are not effective. To model the robot and the goal, we use geometric rules combined with kinematics equations expressed in a polar representation. The intent of the strategy is to keep the robot between a reference point, called the observer, and the goal. We prove under certain assumptions that the robot navigating using this strategy reaches the moving goal successfully. In the presence of obstacles, the method is combined with an obstacle avoidance algorithm. The robot then moves in two modes, the navigation mode and the obstacle avoidance mode. Simulation of various scenarios highlights the efficiency of the method and provides an instructive comparison between the paths obtained for different reference points.

Modeling and controlling a robotic convoy using guidance laws strategies

This paper deals with the problem of modeling and controlling a robotic convoy. Guidance laws techniques are used to provide a mathematical formulation of the problem. The guidance laws used for this purpose are the velocity pursuit, the deviated pursuit, and the proportional navigation. The velocity pursuit equations model the robots path under various sensors based control laws. A systematic study of the tracking problem based on this technique is undertaken. These guidance laws are applied to derive decentralized control laws for the angular and linear velocities. For the angular velocity, the control law is directly derived from the guidance laws after considering the relative kinematics equations between successive robots. The second control law maintains the distance between successive robots constant by controlling the linear velocity. This control law is derived by considering the kinematics equations between successive robots under the considered guidance law. Properties of the method are discussed and proven. Simulation results confirm the validity of our approach, as well as the validity of the properties of the method.

A method for robot navigation toward a moving goal with unknown maneuvers

This paper deals with a method for robot navigation towards a moving goal. The goal maneuvers are not a priori known to the robot. Our method is based on the use of the kinematics equations of the robot and the goal combined with geometrical rules. First a kinematics model for the tracking problem is derived and two strategies are suggested for robot navigation, namely the velocity pursuit guidance law and the deviated pursuit guidance law. It turns out that in both cases, the robots angular velocity is equal to the line of sight angle rate. Important properties of the navigation strategies are discussed and proven. In the presence of obstacles, two navigation modes are used: the tracking mode, which has a global aspect and the obstacle avoidance mode, which has a local aspect. In the obstacle avoidance mode, a polar diagram combining information about obstacles and directions corresponding to the pursuit is constructed. An extensive simulation study is carried out, where the efficiency of both strategies is illustrated for different scenarios.

Direct implementation of abstract data types from abstract specifications

The development of correct specifications is a critical task in the software development process. An alternative approach for the development of specifications is described. The approach relies on a specification language for abstract data types and synthesis system. The system is capable of translating in abstract data type specification into an executable program. This process defines an alternative methodology that provides the necessary tools for the early testing of the specifications and for the development of prototypes and implementation models.

Multi-robot hunting behavior

In this paper we consider the problem of hunting an unpredictably moving prey using a group of robots. We elaborate a mathematical model for the tracking-navigation problem based on geometric rules. This model consists of systems of two differential equations describing the relative motion of the prey with respect to the robots. The control laws are decentralized and the robots move in different modes, namely: navigation-tracking mode, obstacles avoidance mode, cooperative collision avoidance, and circle formation. In the tracking-navigation mode, we use the deviated pursuit strategy, which consists of a closed loop control law based on geometric rules. The properties of this strategy are explored briefly. For obstacles and cooperative collision avoidance, a collision cone approach is used. Our method is illustrated using simulation.

Plagiarism detection in software designs

Detecting plagiarism in software is a computationally complex process. At the same time it is critical, for the lack of a deterrent through detection may result in various losses. Several systems to detect plagiarism have been proposed. However, their lexically-based analysis is not powerfull enough and can be foiled with minimal efforts. To address their shortcomings, we have devised a detection framework with the following salient features: (1) designs, instead of code, are compared; (2) multi--level abstractions of the design are generated; and (3) comparison follows a stepwise process according to the abstraction levels. A comparison with existing systems shows that this strategy results in simpler algorithms and more accurate analyses.

Wheeled mobile robot navigation using proportional navigation

We present a method for wheeled mobile robot navigation based on the proportional navigation law. This method integrates the robots kinematics equations and geometric rules. According to the control strategy, the robots angular velocity is proportional to the rate of turn of the angle of the line of sight that joins the robot and the goal. We derive a relative kinematics system which models the navigation problem of the robot in polar coordinates. The kinematics model captures the robot path as a function of the control law parameters. It turns out that different paths are obtained for different control parameters. Since the control parameters are real, the number of possible paths is infinite. Results concerning the navigation using our control law are rigorously proven. An extensive simulation confirms our theoretical results.

Parallel navigation for reaching a moving goal by a mobile robot

In this paper, we present a method for robot navigation toward a moving object with unknown maneuvers. Our strategy is based on the integration of the robot and the target kinematics equations with geometric rules. The tracking problem is modeled in polar coordinates using a two-dimensional system of differential equations. The control law is then derived based on this model. Our approach consists of a rendezvous course, which means that the robot reaches the moving goal without following its path. In the presence of obstacles, two navigation modes are integrated, namely the tracking and the obstacle-avoidance modes. To confirm our theoretical results, the navigation strategy is illustrated using an extensive simulation for different scenarios.

ROBOT FORMATION MODELLING AND CONTROL BASED ON THE RELATIVE KINEMATICS EQUATIONS

This paper deals with the problem of modeling, initialization, and control of mobile robots formation. We suggest to use a new family of methods that consists of a combination between classical guidance laws and kinematics rules. These methods allow modeling and controlling a dynamic robotic formation using sets of differential equations that give the relative motion between the robots. These differential equations give the range rate and the visibility angle between leaders and followers. Graph theory is used to store the relationship leader-follower and plan the formation by using three different matrices. The configuration of the formation is based on these matrices. Initialization of formation is also considered, where different approaches are suggested. Because of the nature of the kinematics laws, it is easy to model, initialize, and keep any formation shape. Simulation is provided to illustrate the method.

Kinematics-based characterization of the collision course

The problem of collision course between a mobile robot and a moving object is modeled in polar coordinates using the kinematics equations. A model of the relative motion of the moving object as seen by the robot is then derived. This model consists of the relative velocities along and across the visibility line, and gives the range rate and the turning rate of the moving object with respect to the robot. The conditions for the collision course are derived in terms of the robots and the moving objects states. We define two types of collision course: the exact collision course and the weak collision course. The exact collision course always results in a collision, and is clearly characterized by a given set of equations. The weak collision course may become an exact collision course near collision and allows an early detection of the collision course in various scenarios. Several examples and scenarios illustrating the theory are shown using simulation.