Author name cluster

Saul Simhon

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5 papers

2 author rows

IROS Conference 2005 Conference Paper

A visually guided swimming robot

Gregory Dudek
Michael Jenkin
Chris Prahacs
Andrew Hogue
Junaed Sattar
Philippe Giguère
Andrew German
Hui Liu

We describe recent results obtained with AQUA, a mobile robot capable of swimming, walking and amphibious operation. Designed to rely primarily on visual sensors, the AQUA robot uses vision to navigate underwater using servo-based guidance, and also to obtain high-resolution range scans of its local environment. This paper describes some of the pragmatic and logistic obstacles encountered, and provides an overview of some of the basic capabilities of the vehicle and its associated sensors. Moreover, this paper presents the first ever amphibious transition from walking to swimming.

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AAAI Conference 2004 Conference Paper

Analogical Path Planning

Saul Simhon
Gregory Dudek

We present a probabilistic method for path planning that considers trajectories constrained by both the environment and an ensemble of restrictions or preferences on preferred motions for a moving robot. Our system learns constraints and preference biases on a robot’s motion from examples, and then synthesizes behaviors that satisfy these constraints. This behavior can encompass motions that satisfy diverse requirements such as a sweep pattern for floor coverage, or, in particular in our experiments, satisfy restrictions on the robot’s physical capabilities such as restrictions on its turning radius. Given an approximate path that may not satisfy the required conditions, our system computes a refined path that satisfies the constraints and also avoids obstacles. Our approach is based on a Bayesian framework for combining a prior probability distribution on the trajectory with environmental constraints. The prior distribution is generated by decoding a Hidden Markov Model, which is itself is trained over a particular set of preferred motions. Environmental constraints are modeled using a potential field over the configuration space. This paper poses the requisite theoretical framework and demonstrates its effectiveness with several examples.

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ICRA Conference 2003 Conference Paper

Path planning using learned constraints and preferences

Gregory Dudek
Saul Simhon

In this paper we present a novel method for robot path planning based on learning motion patterns. A motion pattern is defined as the path that results from applying a set of probabilistic constraints to a "raw" input path. For example, a user can sketch an approximate path for a robot without considered issues such as bounded radius of curvature and our system would then elaborate it to include such a constraint. In our approach, the constraints that generate a path are learned by capturing the statistical properties of a set of training examples using supervised learning. Each training example consists of a pair of paths: an unconstrained (raw) path and an associated preferred path. Using a Hidden Markov Model in combination with multi-scale methods, we compute a probability distribution for successive path segments as a function of their context within the path and the raw path that guides them. This learned distribution is then used to synthesize a preferred path from an arbitrary input path by choosing some mixture of the training set biases that produce the maximum likelihood estimate. We present our method and applications for robot control and non-holonomic path planning.

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IROS Conference 1998 Conference Paper

A global topological map formed by local metric maps

Saul Simhon
Gregory Dudek

We describe a method of mapping large scale static environments using a hybrid topological-metric model. A global map is formed from a set of local maps organized in a topological structure. Each local map contains quantitative environment information using a local reference frame. They are denoted as islands of reliability because they provide accurate metric information of the environment. The mapping problem then becomes where to place the islands of reliability and to what extent should they cover the environment. This is accomplished by defining the placement criteria in terms of the task the islands of reliability portray.

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ICRA Conference 1998 Conference Paper

Selecting Targets for Local Reference Frames

Saul Simhon
Gregory Dudek

Addresses the problem of seeking out parts of the environment that provide adequate features in order to perform robot localization. The objective is to choose good regions in which local metric maps can be established. A distinctiveness measure is defined as a measure of how well the environment allows the robot to accomplish a task, in our case the task being localization. The distinctiveness measure is evaluated as a function of both the localization strategy and the environment. Areas in the environment are considered to have high distinctiveness measures if they exhibit both sufficient spatial structure and good sensor feedback. The problem is treated as defining an evaluation criterion based on the usefulness of gathered information.

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