Organizational Unit:

Unmanned Aerial Vehicle Research Facility

Permanent Link

https://hdl.handle.net/1853/70748

Parent Organization

Organizational Unit

Daniel Guggenheim School of Aerospace Engineering

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https://finding-aids.library.gatech.edu/agents/corporate_entities/1139

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Publication Search Results

Now showing 1 - 10 of 52

Multi-resolution Path Planning: Theoretical Analysis, Efficient Implementation, and Extensions to Dynamic Environments

(Georgia Institute of Technology, 2010-12) Cowlagi, Raghvendra V. ; Tsiotras, Panagiotis

A multi-resolution path planning algorithm based on the wavelet transform of the environment has been reported previously in the literature. In this paper, we provide a proof of completeness of this algorithm. In addition, we present an implementation of this algorithm that reuses information obtained in previous iterations to perform subsequent iterations more efficiently. Finally, we extend this path planning algorithm to dynamic environments by presenting a simple scheme for updating the wavelet transform coefficients to reflect changes in the environment.
Beamlet-like Data Processing for Accelerated Path-Planning Using Multiscale Information of the Environment

(Georgia Institute of Technology, 2010-12) Lu, Yibiao ; Huo, Xiaoming ; Tsiotras, Panagiotis

We consider the deterministic path-planning problem dealing with the single-pair shortest path on a given graph. We propose a multiscale version of the well known A* algorithm (m-A*), which utilizes information of the environment at distinct scales. This information is collected via a bottom-up fusion method. Comparing with existing algorithms such as Dijkstra’s or A*, the use of multiscale information leads to an improvement in terms of computational complexity.
A Note on the Consensus Protocol with Some Applications to Agent Orbit Pattern Generation

(Georgia Institute of Technology, 2010-11) Tsiotras, Panagiotis ; Reyes Castro, Luis I.

We propose an extension to the standard feedback control for consensus problems for multi-agent systems in the plane. The proposed extension allows for a richer class of trajectories including periodic and quasi-periodic solutions, as well as agreement to consensus states outside the convex hull of the initial positions of the agents. We investigate in great detail the special case of three agents, which results in non-trivial geometric patterns described by ellipsoidal, epitrochoidal and hypotrochoidal curves.
Methodology to support dynamic function allocation polices between humans and flight deck automation

(Georgia Institute of Technology, 2010-09-30) Johnson, Eric N.
Modeling Urban Environments for Communication-Aware UAV Swarm Path Planning

(Georgia Institute of Technology, 2010-08) Christmann, Hans Claus ; Johnson, Eric N.

The presented work introduces a graph based approach to model urban (or otherwise cluttered) environments for UAS utilization beyond line-of-sight as well as out of direct R/F range of the operator's control station. Making the assumption that some a priori data of the environment is available, the proposed method uses a classification of obstacles with respect to their impact on UAV motion and R/F communication and generates continuously updateable graphs usable to compute traverseable paths for UAVs while maintaining R/F communication. Using a simulated urban scenario this work shows that the proposed modeling method allows to find reachable loiter or hover areas for UAVs in order to establish a multi-hop R/F communication link between a primary UAV and its remote operator by utilizing an overlay of motion (Voronoi based) and R/F (visibility based) specific mapping methods.
Design, Development, and Testing of a Low Cost, Fully Autonomous Indoor Unmanned Aerial System

(Georgia Institute of Technology, 2010-08) Chowdhary, Girish ; Sobers, D. Michael Jr. ; Salaün, Erwan ; Ottander, John ; Johnson, Eric N.

This paper is concerned with the design, development, and autonomous flight testing of the GT Lama indoor Unmanned Aerial System (UAS). The GT Lama is a fully autonomous rotorcraft UAS capable of indoor area exploration. It weighs around 1.3 lbs (600 gms), has a width of about 27.6 inches (70 cm), and costs less than USD 900. The GT Lama employs only five off-the-shelf, extremely low-cost range sensors for navigation. The GT Lama does not rely on other expensive and sophisticated sensors, including inertial measurement units, Laser based range scanners, and GPS. The GT Lama achieves this by using simple wall following logic to ensure that maximum perimeter of an indoor environment is explored in a reasonable amount of time. The GT Lama hardware, and the Guidance, Navigation, and Control (GNC) algorithms used are discussed in detail. The details of a MATLAB based method that facilitates rapid in flight validation of GNC algorithms on real flight hardware is also discussed. Results from flight tests as the GT Lama autonomously explores indoor environments are presented.
Kinematic Feasibility Guarantees in Geometric Path Planning Using History-based Transition Costs over Cell Decompositions

(Georgia Institute of Technology, 2010-06) Cowlagi, Raghvendra V. ; Tsiotras, Panagiotis

The hierarchical decomposition of motion planning tasks into geometric path planning, followed by kinodynamic motion planning is useful for designing efficient algorithms, but it entails the possibility of inconsistency between the two layers of planning. In an earlier paper, we proposed a general framework, based on rectangular cell decompositions, for incorporating information about the kinodynamic behavior of the vehicle in the geometric planning layer itself. In this paper, we use this framework to design a geometric path planning scheme which simultaneously finds an obstacle-free channel of cells from the initial point to the goal, as well as a vehicle state trajectory lying within that channel.
Visual Marker Detection In The Presence Of Colored Noise for Unmanned Aerial Vehicles

(Georgia Institute of Technology, 2010-04) Shah, Syed Irtiza Ali ; Wu, Allen D. ; Johnson, Eric N.

This paper develops a vision-based algorithm to detect a visual marker in real time and in the presence of excessive colored noise for Unmanned Aerial Vehicles. After using various image analysis techniques, including color histograms, filtering techniques and color space analyses, typical pixel-based characteristics of the visual marker were established. It was found that not only various color space based characteristics were significant, but also relationships between various channels across different color spaces were of great consequence. A block based search algorithm was then used to search for those established characteristics in real-time image data stream from a colored camera. A low cost noise and interference filter was also devised to handle excessive noise that was encountered during flight tests. The specific implementation scenario is that of detection of a Blue LED for GeorgiaTech's participating aircraft into the International Aerial Robotics competition. The final algorithm that was implemented on GTAR lama aircraft, used both multiple thresholding and linear confidence level calculations and was successfully used in the competition in 2009.
On the Existence and Synthesis of Curvature-Bounded Paths Inside Nonuniform Rectangular Channels

(Georgia Institute of Technology, 2010) Cowlagi, Raghvendra V. ; Tsiotras, Panagiotis

Motion planners for autonomous mobile vehicles that are based on rectangular cell decompositions are often required to construct kinematically feasible path – typically curvature-bounded paths – traversing rectangular channels. In this paper, we present a numerical algorithm for determining the existence of a curvature-bounded path contained within a rectangular channel. The rectangular cells comprising the channel are assumed to be of arbitrary, non-uniform dimensions and the bounds on curvature are allowed to be different for different cells. The proposed algorithm is based on the explicit construction of the cone of feasible directions for a bounded-curvature path at the cell exit edge, given the entry point for each cell in the channel. Based on this analysis, we devise a path construction scheme that retains the convenience of cell-by-cell path synthesis but eliminates the guesswork involved in choosing terminal conditions within each cell.
Optimal Pursuit of Moving Targets using Dynamic Voronoi Diagrams

(Georgia Institute of Technology, 2010) Bakolas, Efstathios ; Tsiotras, Panagiotis

We consider Voronoi-like partitions for a team of moving targets distributed in the plane, such that each set in this partition is uniquely associated with a particular moving target in the following sense: a pursuer residing inside a given set of the partition can intercept this moving target faster than any other pursuer outside this set. It is assumed that each moving target employs its own "evading" strategy in response to the pursuer actions. In contrast to standard formulations of problems of this kind in the literature, the evading strategy does necessarily restrict the evader to be slower than its pursuer. In the special case when all moving targets employ a uniform evading strategy, the previous problem reduces to the characterization of the Zermelo-Voronoi diagram.