2010 IEEE International Conference on Robotics and Automation, 2010
We present exploration and mapping strategies for a mobile robot moving among a finite collection... more We present exploration and mapping strategies for a mobile robot moving among a finite collection of convex obstacles in the plane. The obstacles are unknown to the robot, which does not have access to coordinates and cannot measure distances or angles. The robot has a unique sensor, called the gap sensor, that tracks the direction of the depth discontinuities in
Abstract: Within the popular probabilistic roadmap (PRM)framework for motion planning, we challen... more Abstract: Within the popular probabilistic roadmap (PRM)framework for motion planning, we challenge the use of randomization.By applying quasi-random sampling techniques, we illustrateboth experimental and theoretical advantages of using deterministicsamples. Two quasi-random variants of PRM-based planners areproposed: 1) a classical PRM with quasi-random sampling, and 2)a quasi-random lattice-based Lazy roadmap. Both have been implemented,and are shown through experiments to oer some...
Proceedings of International Conference on Robotics and Automation, 1997
We introduce the problem of computing robot motion strategies that maintain visibility of a movin... more We introduce the problem of computing robot motion strategies that maintain visibility of a moving target in a cluttered workspace. Both motion constraints (as considered in standard motion planning) and visibility constraints (as considered in visual tracking) must be satisfied. Additional criteria, such as the total distance traveled, can be optimized. The general problem is divided into two categories, on
ABSTRACT. We consider coordination of multiple robots in a common environment, each robot having,... more ABSTRACT. We consider coordination of multiple robots in a common environment, each robot having,its own,(distinct) roadmap.,Our primary,contribution is a classification of and exact algorithm,for computing,vector-valued,— or Pareto — optima,for collision-free coordination. We indicate the utility of new,geometric techniques,from CAT(0) geometry,and,give an argument,that curvature,bounds,are the key distinguishing feature between,systems,for which,the classification is finite and for those in which it is not.
Given a collection of robots sharing a common environment, assume that each possesses an individu... more Given a collection of robots sharing a common environment, assume that each possesses an individual roadmap for its C-space and a cost function for attaining a goal. Vector-valued (or Pareto) optima for collision-free coordination are by no means unique: in fact, continua of optimal coordinations are possible. However, for cylindrical obstacles (those defined by pairwise interactions), we prove a finite
Computing optimal paths for mobile robots is an interesting and important problem. This paper pre... more Computing optimal paths for mobile robots is an interesting and important problem. This paper presents a method to compute the shortest path for a differential-drive mobile robot, which is a disc, among piecewise smooth and convex obstacles. We consider all trajectories that are composed of a finite number of subpaths inside the free space and on the boundary of obstacle
We address an on-line version of the visibility-based pursuit-evasion problem. We take a minimali... more We address an on-line version of the visibility-based pursuit-evasion problem. We take a minimalist approachinmodelingthecapabilitiesofapursuerrobot. Apointpursuermovesinanunknown,simply- connected, piecewise-smooth planar environment, and is given the task of locating any unpredictable, movingevadersthathaveunboundedspeed. Theevadersareassumedtobepointsthatmovecontinuously. To solve the problem, the pursuer must for each target have an unobstructed view of it at some time during execution. The pursuer is equipped with a range sensor
2007 46th IEEE Conference on Decision and Control, 2007
AbstractWe consider finding a time-optimal trajectory for an airplane from some starting point a... more AbstractWe consider finding a time-optimal trajectory for an airplane from some starting point and orientation to some final point and orientation. Our model extends the Dubins car [15] to have altitude, which leads to Dubins airplane. We assume that the system has ...
Autonomous Observers are mobile robots that cooperativelyperform vision tasks. Their designraises... more Autonomous Observers are mobile robots that cooperativelyperform vision tasks. Their designraises new issues in motion planning, where visibilityconstraints and motion obstructions mustbe simultaneously taken into account. This paperpresents the concept of an Autonomous Observerand its applications. It discusses three problems inmotion planning with visibility constraints: modelbuilding, target finding, and target tracking.1 IntroductionWe are interested in mobile robots which...
The computer-assisted spine surgery system presented in this paper follows the basic ideas which ... more The computer-assisted spine surgery system presented in this paper follows the basic ideas which have been developed for computer-assisted medical interventions (CAMI) in our lab since 1985. There are three steps to insert a linear tool inside vertebral pedicles. First, the surgeon defines an optimal trajectory on pre-operative computed tomography. Second, this trajectory is reported in the operating room coordinate system using an intra-operative sensor and a registration algorithm. Third, a guiding system helps the surgeon follow the selected trajectory. In this paper, we present an implementation of this method that uses only a 3-dimensional optical localizer. Results on cadaver specimens and on the first seven patients are presented.
Proceedings 2007 IEEE International Conference on Robotics and Automation, 2007
This paper characterizes the information space of a robot moving in the plane with limited sensin... more This paper characterizes the information space of a robot moving in the plane with limited sensing. The robot has a landmark detector, which provides the cyclic order of the landmarks around the robot, and it also has a touch sensor, that indicates when the robot is in contact with the environment boundary. The robot cannot measure any precise distances or
2010 IEEE International Conference on Robotics and Automation, 2010
We present exploration and mapping strategies for a mobile robot moving among a finite collection... more We present exploration and mapping strategies for a mobile robot moving among a finite collection of convex obstacles in the plane. The obstacles are unknown to the robot, which does not have access to coordinates and cannot measure distances or angles. The robot has a unique sensor, called the gap sensor, that tracks the direction of the depth discontinuities in
Abstract: Within the popular probabilistic roadmap (PRM)framework for motion planning, we challen... more Abstract: Within the popular probabilistic roadmap (PRM)framework for motion planning, we challenge the use of randomization.By applying quasi-random sampling techniques, we illustrateboth experimental and theoretical advantages of using deterministicsamples. Two quasi-random variants of PRM-based planners areproposed: 1) a classical PRM with quasi-random sampling, and 2)a quasi-random lattice-based Lazy roadmap. Both have been implemented,and are shown through experiments to oer some...
Proceedings of International Conference on Robotics and Automation, 1997
We introduce the problem of computing robot motion strategies that maintain visibility of a movin... more We introduce the problem of computing robot motion strategies that maintain visibility of a moving target in a cluttered workspace. Both motion constraints (as considered in standard motion planning) and visibility constraints (as considered in visual tracking) must be satisfied. Additional criteria, such as the total distance traveled, can be optimized. The general problem is divided into two categories, on
ABSTRACT. We consider coordination of multiple robots in a common environment, each robot having,... more ABSTRACT. We consider coordination of multiple robots in a common environment, each robot having,its own,(distinct) roadmap.,Our primary,contribution is a classification of and exact algorithm,for computing,vector-valued,— or Pareto — optima,for collision-free coordination. We indicate the utility of new,geometric techniques,from CAT(0) geometry,and,give an argument,that curvature,bounds,are the key distinguishing feature between,systems,for which,the classification is finite and for those in which it is not.
Given a collection of robots sharing a common environment, assume that each possesses an individu... more Given a collection of robots sharing a common environment, assume that each possesses an individual roadmap for its C-space and a cost function for attaining a goal. Vector-valued (or Pareto) optima for collision-free coordination are by no means unique: in fact, continua of optimal coordinations are possible. However, for cylindrical obstacles (those defined by pairwise interactions), we prove a finite
Computing optimal paths for mobile robots is an interesting and important problem. This paper pre... more Computing optimal paths for mobile robots is an interesting and important problem. This paper presents a method to compute the shortest path for a differential-drive mobile robot, which is a disc, among piecewise smooth and convex obstacles. We consider all trajectories that are composed of a finite number of subpaths inside the free space and on the boundary of obstacle
We address an on-line version of the visibility-based pursuit-evasion problem. We take a minimali... more We address an on-line version of the visibility-based pursuit-evasion problem. We take a minimalist approachinmodelingthecapabilitiesofapursuerrobot. Apointpursuermovesinanunknown,simply- connected, piecewise-smooth planar environment, and is given the task of locating any unpredictable, movingevadersthathaveunboundedspeed. Theevadersareassumedtobepointsthatmovecontinuously. To solve the problem, the pursuer must for each target have an unobstructed view of it at some time during execution. The pursuer is equipped with a range sensor
2007 46th IEEE Conference on Decision and Control, 2007
AbstractWe consider finding a time-optimal trajectory for an airplane from some starting point a... more AbstractWe consider finding a time-optimal trajectory for an airplane from some starting point and orientation to some final point and orientation. Our model extends the Dubins car [15] to have altitude, which leads to Dubins airplane. We assume that the system has ...
Autonomous Observers are mobile robots that cooperativelyperform vision tasks. Their designraises... more Autonomous Observers are mobile robots that cooperativelyperform vision tasks. Their designraises new issues in motion planning, where visibilityconstraints and motion obstructions mustbe simultaneously taken into account. This paperpresents the concept of an Autonomous Observerand its applications. It discusses three problems inmotion planning with visibility constraints: modelbuilding, target finding, and target tracking.1 IntroductionWe are interested in mobile robots which...
The computer-assisted spine surgery system presented in this paper follows the basic ideas which ... more The computer-assisted spine surgery system presented in this paper follows the basic ideas which have been developed for computer-assisted medical interventions (CAMI) in our lab since 1985. There are three steps to insert a linear tool inside vertebral pedicles. First, the surgeon defines an optimal trajectory on pre-operative computed tomography. Second, this trajectory is reported in the operating room coordinate system using an intra-operative sensor and a registration algorithm. Third, a guiding system helps the surgeon follow the selected trajectory. In this paper, we present an implementation of this method that uses only a 3-dimensional optical localizer. Results on cadaver specimens and on the first seven patients are presented.
Proceedings 2007 IEEE International Conference on Robotics and Automation, 2007
This paper characterizes the information space of a robot moving in the plane with limited sensin... more This paper characterizes the information space of a robot moving in the plane with limited sensing. The robot has a landmark detector, which provides the cyclic order of the landmarks around the robot, and it also has a touch sensor, that indicates when the robot is in contact with the environment boundary. The robot cannot measure any precise distances or
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Papers by Steven Lavalle