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Andrew M. Ladd

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

4 papers

1 author row

IROS Conference 2003 Conference Paper

Multiple query probabilistic roadmap planning using single query planning primitives

Kostas E. Bekris
Brian Y. Chen
Andrew M. Ladd
Erion Plaku
Lydia E. Kavraki

We propose a combination of techniques that solve multiple queries for motion planning problems with single query planners. Our implementation uses a probabilistic roadmap method (PRM) with bidirectional rapidly exploring random trees (BI-RRT) as the local planner. With small modifications to the standard algorithms, we obtain a multiple query planner, which is significantly faster and more reliable than its component parts. Our method provides a smooth spectrum between the PRM and BI-RRT techniques and obtains the advantages of both. We observed that the performance differences are most notable in planning instances with several rigid nonconvex robots in a scene with narrow passages. Our work is in the spirit of non-uniform sampling and refinement techniques used in earlier work on PRM.

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ICRA Conference 2002 Conference Paper

Generalizing the Analysis of PRM

Andrew M. Ladd
Lydia E. Kavraki

This paper presents it novel analysis of the probabilistic roadmap method (PRM) for path planning. We formulate the problem in terms of computing the transitive closure of a relation over a probability space and give a bound in terms of the number of intermediate points for some path and the probability of choosing a point from a certain set. Explicit geometric assumptions are not necessary to complete this analysis and consequently it provides some unification of the previous work as well as generalizing new path planning problems, two of which, 2k-DOF kinodynamic point robots and deformable robots with force field control, are presented in this paper.

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ICRA Conference 2002 Conference Paper

Simulated Knot Tying

Jeff M. Phillips
Andrew M. Ladd
Lydia E. Kavraki

Applications such as suturing in medical simulations require the modeling of knot tying in physically realistic rope. The paper describes the design and implementation of such a system. Our model uses a spline of linear springs, adaptive subdivision and a dynamics simulation. Collisions are discrete event simulated and follow the impulse model. Although some care must be taken to maintain stable knots, we demonstrate our simple model is sufficient for this task. In particular, we do not use friction or explicit constraints to maintain the knot. As examples, we tie an overhand knot and a reef knot.

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IROS Conference 2002 Conference Paper

Using wireless Ethernet for localization

Andrew M. Ladd
Kostas E. Bekris
Guillaume Marceau
Algis Rudys
Dan S. Wallach
Lydia E. Kavraki

IEEE 802. 11b wireless Ethernet is rapidly becoming the standard for in-building and short-range wireless communication. Many mobile devices such as mobile robots, laptops and PDAs already use this protocol for wireless communication. Many wireless Ethernet cards measure the signal strength of incoming packets. This paper investigates the feasibility of implementing a localization system using this sensor. Using a Bayesian localization framework, we show experiments demonstrating that off-the-shelf wireless hardware can accurately be used for location sensing and tracking with about one meter precision in a wireless-enabled office building.

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