Author name cluster

James Keller 0002

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.

6 papers

1 author row

IROS Conference 2016 Conference Paper

Towards fully autonomous visual inspection of dark featureless dam penstocks using MAVs

Tolga Özaslan
Kartik Mohta
James Keller 0002
Yash Mulgaonkar
Camillo J. Taylor
Vijay Kumar 0001
Jennifer M. Wozencraft
Thomas Hood

In the last decade, multi-rotor Micro Aerial Vehicles (MAVs) have attracted great attention from robotics researchers. Offering affordable agility and maneuverability, multi-rotor aircrafts have become the most commonly used platforms for robotics applications. Amongst the most promising applications are inspection of power-lines, cell-towers, large and constrained infrastructures and precision agriculture. While GPS offers an easy solution for outdoor autonomy, using on-board sensors is the only solution for autonomy in constrained indoor environments. In this paper, we present our results on autonomous inspection of completely dark, featureless, symmetric dam penstocks using cameras and range sensors. We use a hex-rotor platform equipped with an IMU, four cameras and two lidars. One of the cameras tracks features on the walls using the on-board illumination to estimate the position along the tunnel axis unobservable to range sensors while all of the cameras are used for panoramic image construction. The two lidars estimate the remaining degrees of freedom (DOF). Outputs of the two estimators are fused using an Unscented Kalman Filter (UKF). A moderately trained operator defines waypoints using the Remote Control (RC). We demonstrate our results from Carters Dam, GA and Glen Canyon Dam, AZ which include panoramic images for cracks and rusty spot detection and 6-DOF estimation results with ground truth comparisons. To our knowledge ours is the only study that can autonomously inspect environments with no geometric cues and poor to no external illumination using MAVs.

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IROS Conference 2013 Conference Paper

Planning for opportunistic surveillance with multiple robots

Dinesh Thakur
Maxim Likhachev
James Keller 0002
Vijay Kumar 0001
Vladimir N. Dobrokhodov
Kevin D. Jones
Jeff Wurz
Isaac Kaminer

We are interested in the multiple robot surveillance problem where robots must allocate waypoints to be visited among themselves and plan paths through different waypoints while avoiding obstacles. Furthermore, the robots are allocated specific times to reach their respective goal locations and as a result they have to decide which robots have to visit which waypoints. Such a problem has the challenge of computing the allocation of waypoints across robots, ordering for these waypoints and dynamical feasibility of the paths between waypoints. We present an algorithm that runs a series of graph searches to solve the problem and provide theoretical analysis that our approach yields an optimal solution. We present simulated results as well as experiments on two UAVs that validate the capability of our algorithm. For a single robot, we can solve instances having 10–15 waypoints and for multiple robots, instances having five robots and 10 waypoints can be solved.

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IROS Conference 2008 Conference Paper

Time-optimal UAV trajectory planning for 3D urban structure coverage

Peng Cheng 0009
James Keller 0002
Vijay Kumar 0001

In this paper, we study the time-optimal trajectory planning of a sensor attached to an unmanned aerial vehicle (UAV) to provide complete 3-dimensional coverage with applications to urban environments with 2. 5-dimensional features. The basic approach is to approximate the features of interest with a set of non planar coverage surfaces and to design a motion plan that guarantees the coverage surface is swept completely with a conical-field-of-view sensor. We establish a lower bound on time for a UAV to achieve complete coverage and derive the analytical coverage plan whose duration is a constant times this lower bound. Our hardware-in-the-loop simulation results verify the effectiveness of the proposed algorithm.

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ICRA Conference 2005 Conference Paper

Information Driven Coordinated Air-Ground Proactive Sensing

Ben Grocholsky
Rahul Swaminathan
James Keller 0002
Vijay Kumar 0001
George J. Pappas

This paper concerns the problem of actively searching for and localizing ground features by a coordinated team of air and ground robotic sensor platforms. The approach taken builds on well known Decentralized Data Fusion (DDF) methodology. In particular, it brings together established representations developed for identification and linearized estimation problems to jointly address feature detection and localization. This provides transparent and scalable integration of sensor information from air and ground platforms. As in previous studies, an Information-theoretic utility measure and local control strategy drive the robots to uncertainty reducing team configurations. Complementary characteristics in terms of coverage and accuracy are revealed through analysis of the observation uncertainty for air and ground on-board cameras. Implementation results for a detection and localization example indicate the ability of this approach to scalably and efficiently realize such collaborative potential.

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ICRA Conference 2004 Conference Paper

Experiments in Multirobot Air-Ground Coordination

Luiz Chaimowicz
Ben Grocholsky
James Keller 0002
Vijay Kumar 0001
Camillo J. Taylor

This paper addresses the problem of coordinating aerial and ground vehicles in tasks that involve exploration, identification of targets and maintaining a connected communication network. We focus on the problem of localizing vehicles in urban environments where GPS signals are often unreliable or unavailable. We first describe our multi-robot testbed and the control software used to coordinate ground and aerial vehicles. We present the results of experiments in air-ground localization analyzing three complementary approaches to determining the positions of vehicles on the ground. We show that the coordination of aerial vehicles with ground vehicles is necessary to get accurate estimates of the state of the system.

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IROS Conference 2003 Conference Paper

Design and verification of controllers for airships

Jongwoo Kim
James Keller 0002
Vijay Kumar 0001

Robotic airships have several beneficial properties such as low operation cost, low noise, and low speed flight capability. We present in this paper the design and verification of a feedback control algorithm for waypoint to waypoint navigation of an outdoor blimp. A rapidly exploring random tree (RRT) is used for the validation of the blimp system control law. We describe an implementation of an algorithm that systematically searches the set of all disturbances to validate viability of the control law in the presence of winds. Experimental results with a simulator show that the RRT method can be effective in verifying controller design under unpredictable but bounded disturbances.

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