Dr. Gerald Cook Profile

Dr. Gerald Cook

Professor of E & CE at George Mason Univ

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Publications (6)

Proceedings Article | 2 May 2007 Paper

Optimal steering of a mobile robot

Gerald Cook

Proceedings Volume 6561, 656127 (2007) https://doi.org/10.1117/12.729308

KEYWORDS: Mobile robots, Mathematical modeling, Kinematics, Motion models, Switches, Computer engineering, Environmental sensing, Remote sensing, Unmanned systems, Lead

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Proceedings Article | 10 January 2005 Paper

Exploitation of complementary sensors for precise ground-registration of sensed objects

Gerald Cook, Smriti Kansal

Proceedings Volume 5657, (2005) https://doi.org/10.1117/12.606737

KEYWORDS: Sensors, Radar, Infrared sensors, Radar sensor technology, Remote sensing, Error analysis, Cameras, Cadmium sulfide, Electrochemical etching, Sensor performance

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Proceedings Article | 22 December 2004 Paper

Remote sensing using vehicular mounted sensors and GPS instrumentation

Smriti Kansal, Gerald Cook

Proceedings Volume 5661, (2004) https://doi.org/10.1117/12.581864

KEYWORDS: Sensors, Global Positioning System, Infrared sensors, Cameras, Remote sensing, Infrared cameras, Target detection, Filtering (signal processing), Error analysis, Electrochemical etching

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When performing remote sensing, one often uses vehicular mounted sensors. This provides the flexibility of moving around and searching over a large area and can be done via airborne vehicles, ground vehicles or marine vehicles. For this type of sensing, one needs to know the position and orientation of the sensor platform in order to ground register the location of detected objects. The research reported herein is concerned with the use of a ground vehicle as a sensor platform. Digital camera-type sensors such as infra-red are considered. The focus is on requirements for accurate ground registration of detected objects of interest. A four-antenna GPS array has been chosen for vehicle attitude measurement. Relationships between positions of the array elements and vehicle attitude are derived. It is seen that the attitude computations depend on differences in the various measurements. Thus common-mode errors in the measured position of the array elements cancel, enabling quite accurate attitude measurement even when utilizing somewhat imprecise units in the GPS array. A more precise single differential GPS (DGPS) has been chosen for vehicle position measurements. Relationships between pixel coordinates in the image frame and the angle of the corresponding ray from the camera to the object of interest are derived. A series of transformations are used to convert this ray to ground coordinates. Finally the intersection of the ray with the ground is computed based on the assumption that the ground in the field-of-view is flat and at a known elevation. In this manner an object of interest in the image frame may be ground registered. Sensitivity of the ground registration with respect to vehicle attitude measurement errors is developed. It is seen that small errors in pitch, roll or yaw can cause quite large errors in the computed ground coordinates. In the case of multiple looks at the same object of interest, the geo-registration process involves target tracking and data association. This process is facilitated by combining the single-look measurements in an optimal fashion via a Kalman Filter. In fact the accuracy obtained via multiple looks can be significantly greater than for a single look. The results obtained indicate that accurate geo-registration of remotely sensed objects is possible when using vehicular mounted sensors in conjunction with DGPS and that such a scheme is feasible with commercially available GPS and IR cameras. Geo-registration accuracy within a fraction of a meter is attainable for near objects.

Proceedings Article | 13 August 2002 Paper

Impact of uneven terrain on geo-location errors for mines detected via vehicular mounted sensors

Gerald Cook, Shwetha Jakkidi, Smriti Kansal, Kelly Sherbondy, Charles Amazeen

Proceedings Volume 4742, (2002) https://doi.org/10.1117/12.479131

KEYWORDS: Sensors, Radar, Cameras, Land mines, Antennas, Error analysis, Ranging, Mining, Roads, Computer engineering

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When searching for land mines using vehicular mounted sensors, it is important that the ground locations of the detected mines be accurately determined. This is useful for data association when one has multiple looks at a mine by a single sensor or if one uses multiple sensors. It is of ultimate importance for the primary mission, which is to neutralize the detected mines or at least to mark them for avoidance. Factors that contribute to errors in geo-location include inaccurate knowledge of the vehicle position and/or attitude, and also incomplete knowledge about the terrain being searched. This paper addresses the problem of incomplete terrain knowledge and presents relationships between terrain unevenness and the resulting geo-location errors. The results of this analysis indicate that there may be significant geo-location errors for situations where the terrain is not so smooth, e.g., off road searches. The problem can be alleviated via better knowledge of the terrain. Such knowledge could be acquired via scanning the field of view with a ranging device, recording range as a function of azimuth and elevation. A variety of uneven surfaces have been simulated. Two types of sensors are considered, Linear-Array Radar and Camera Type Sensors. Geo-location is then computed based on: a) no range measurements, b) four range measurements (to the four vertices of the sensor field of view), and c) nine range measurements (to the four vertices and intermediate points at the top and bottom row, as well as three measurements across the center row). The geo-location errors are much worse for the Camera Type Sensor, but they can be significant for the Linear-Array Radar also. If the field of view is planar or almost planar, even coarse range scanning can improve geo-location accuracy. For more complex surfaces fine scanning may be required. The computed geo-location errors, and the conclusions drawn as to the effectiveness of the different models are presented in the paper.

Proceedings Article | 18 October 2001 Paper

Geolocation of mines detected via vehicular-mounted forward-looking sensors

Gerald Cook, Kelly Sherbondy, Shwetha Jakkidi

Proceedings Volume 4394, (2001) https://doi.org/10.1117/12.445420

KEYWORDS: Sensors, Mining, Land mines, Target detection, Filtering (signal processing), Antennas, Image sensors, Motion models, Lithium, Data modeling

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Proceedings Article | 29 September 1999 Paper

Principal components analysis: extension to scaling for application to images acquired at various ranges

Gerald Cook, Gary O'Brien

Proceedings Volume 3810, (1999) https://doi.org/10.1117/12.364066

KEYWORDS: Principal component analysis, Sensors, Image analysis, Image restoration, Atmospheric sensing, Phase modulation, Electronics, Night vision, Infrared imaging, Infrared radiation

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