Person:
Dellaert, Frank

Permanent Link
https://hdl.handle.net/1853/71202
Associated Organization(s)
Organizational Unit
ORCID
ArchiveSpace Name Record

Filters

2004 - 2009 7
7
5 4 2
7
7
Reset filters

Settings
Author: Ranganathan, Ananth × End date: 2009 × Start date: 2000 × search.filters.applied.f.isOrgUnitOfPublicationTitle: College of Computing ×

Publication Search Results

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    Bayesian Surprise and Landmark Detection
    (Georgia Institute of Technology, 2009-05) Ranganathan, Ananth ; Dellaert, Frank
    Automatic detection of landmarks, usually special places in the environment such as gateways, for topological mapping has proven to be a difficult task. We present the use of Bayesian surprise, introduced in computer vision, for landmark detection. Further, we provide a novel hierarchical, graphical model for the appearance of a place and use this model to perform surprise-based landmark detection. Our scheme is agnostic to the sensor type, and we demonstrate this by implementing a simple laser model for computing surprise. We evaluate our landmark detector using appearance and laser measurements in the context of a topological mapping algorithm, thus demonstrating the practical applicability of the detector.
  • Thumbnail Image
    Item
    Place Recognition-Based Fixed-Lag Smoothing for Environments with Unreliable GPS
    (Georgia Institute of Technology, 2008-05) Mottaghi, Roozbeh ; Kaess, Michael ; Ranganathan, Ananth ; Roberts, Richard ; Dellaert, Frank
    Pose estimation of outdoor robots presents some distinct challenges due to the various uncertainties in the robot sensing and action. In particular, global positioning sensors of outdoor robots do not always work perfectly, causing large drift in the location estimate of the robot. To overcome this common problem, we propose a new approach for global localization using place recognition. First, we learn the location of some arbitrary key places using odometry measurements and GPS measurements only at the start and the end of the robot trajectory. In subsequent runs, when the robot perceives a key place, our fixed-lag smoother fuses odometry measurements with the relative location to the key place to improve its pose estimate. Outdoor mobile robot experiments show that place recognition measurements significantly improve the estimate of the smoother in the absence of GPS measurements.
  • Thumbnail Image
    Item
    Automatic Landmark Detection for Topological Mapping Using Bayesian Surprise
    (Georgia Institute of Technology, 2008) Ranganathan, Ananth ; Dellaert, Frank
    Topological maps are graphical representations of the environment consisting of nodes that denote landmarks, and edges that represent the connectivity between the landmarks. Automatic detection of landmarks, usually special places in the environment such as gateways, in a general, sensor-independent manner has proven to be a difficult task. We present a landmark detection scheme based on the notion of “surprise” that addresses these issues. The surprise associated with a measurement is defined as the change in the current model upon updating it using the measurement. We demonstrate that surprise is large when sudden changes in the environment occur, and hence, is a good indicator of landmarks. We evaluate our landmark detector using appearance and laser measurements both qualitatively and quantitatively. Part of this evaluation is performed in the context of a topological mapping algorithm, thus demonstrating the practical applicability of the detector.
  • Thumbnail Image
    Item
    A Rao-Blackwellized Particle Filter for Topological Mapping
    (Georgia Institute of Technology, 2006-05) Ranganathan, Ananth ; Dellaert, Frank
    We present a particle filtering algorithm to construct topological maps of an uninstrument environment. The algorithm presented here constructs the posterior on the space of all possible topologies given measurements, and is based on our previous work on a Bayesian inference framework for topological maps [21]. Constructing the posterior solves the perceptual aliasing problem in a general, robust manner. The use of a Rao-Blackwellized Particle Filter (RBPF) for this purpose makes the inference in the space of topologies incremental and run in real-time. The RBPF maintains the joint posterior on topological maps and locations of landmarks. We demonstrate that, using the landmark locations thus obtained, the global metric map can be obtained from the topological map generated by our algorithm through a simple post-processing step. A data-driven proposal is provided to overcome the degeneracy problem inherent in particle filters. The use of a Dirichlet process prior on landmark labels is also a novel aspect of this work. We use laser range scan and odometry measurements to present experimental results on a robot.
  • Thumbnail Image
    Item
    Data Driven MCMC for Appearance-Based Topological Mapping
    (Georgia Institute of Technology, 2005) Ranganathan, Ananth ; Dellaert, Frank
    Probabilistic techniques have become the mainstay of robotic mapping, particularly for generating metric maps. In previous work, we have presented a hitherto nonexistent general purpose probabilistic framework for dealing with topological mapping. This involves the creation of Probabilistic Topological Maps (PTMs), a sample-based representation that approximates the posterior distribution over topologies given available sensor measurements. The PTM is inferred using Markov Chain Monte Carlo (MCMC) that overcomes the combinatorial nature of the problem. In this paper, we address the problem of integrating appearance measurements into the PTM framework. Specifically, we consider appearance measurements in the form of panoramic images obtained from a camera rig mounted on a robot. We also propose improvements to the efficiency of the MCMC algorithm through the use of an intelligent data-driven proposal distribution. We present experiments that illustrate the robustness and wide applicability of our algorithm.
  • Thumbnail Image
    Item
    Inference In The Space Of Topological Maps: An MCMC-based Approach
    (Georgia Institute of Technology, 2004-09) Ranganathan, Ananth ; Dellaert, Frank
    While probabilistic techniques have been considered extensively in the context of metric maps, no general purpose probabilistic methods exist for topological maps. We present the concept of Probabilistic Topological Maps (PTMs), a sample-based representation that approximates the posterior distribution over topologies given the available sensor measurements. The PTM is obtained through the use of MCMC-based Bayesian inference over the space of all possible topologies. It is shown that the space of all topologies is equivalent to the space of set partitions of all available measurements. While the space of possible topologies is intractably large, our use of Markov chain Monte Carlo sampling to infer the approximate histograms overcomes the combinatorial nature of this space and provides a general solution to the correspondence problem in the context of topological mapping. We present experimental results that validate our technique and generate good maps even when using only odometry as the sensor measurements.
  • Thumbnail Image
    Item
    Dirichlet Process based Bayesian Partition Models for Robot Topological Mapping
    (Georgia Institute of Technology, 2004) Ranganathan, Ananth ; Dellaert, Frank
    Robotic mapping involves finding a solution to the correspondence problem. A general purpose solution to this problem is as yet unavailable due to the combinatorial nature of the state space. We present a framework for computing the posterior distribution over the space of topological maps that solves the correspondence problem in the context of topological mapping. Since exact inference in this space is intractable, we present two sampling algorithms that compute sample-based representations of the posterior. Both the algorithms are built on a Bayesian product partition model that is derived from the mixture of Dirichlet processes model. Robot experiments demonstrate the applicability of the algorithms.