Kevin L. Russell

Multisensor vehicle-mounted teleoperated mine detector with data fusion

The Improved Landmine Detector Project (ILDP) was initiated in Autumn 1994 to develop a prototype teleoperated vehicle mounted mine detector for low metal content and nonmetallic mines to meet the Canadian requirements for rear area mine clearance in combat situations and peacekeeping on roads and tracks. The relatively relaxed requirements, such as low speed and reduced detectability of completely nonmetallic mines, greatly increase the likelihood of success. The ILDP system consists of a unique teleoperated vehicle carrying a forward looking infrared imager, a 3 m wide down-looking highly sensitive electromagnetic induction detector and a 3 m wide down-looking ground probing radar, which all scan the ground in front of the vehicle. Scanning sensor information is combined using a suite of navigation sensors and custom designed navigation, spatial correspondence and data fusion algorithms. Suspect targets are then confirmed by a thermal neutron analysis detector. A key element to the success of the system is the combination of sensor information. This requires coordinated communication between the sensors and navigation system and well designed sensor co-registration, spatial correspondence and data fusion methodologies. These complex tasks are discussed in detail. The advanced development model was completed in October 1997 and testing and improvements are ongoing. Results of system performance during extensive field trials are presented. A follow-on project has been initiated to build four to six production units for the Canadian Forces by the year 2000.

Articulated robotic scanner for mine detection: a novel approach to vehicle-mounted systems

Conventional vehicle-mounted mine detector system employ an array of sensor elements to achieve a detection swath. Some systems employ more than one type of sensor technology. These systems, while being very useful, are often expensive, complex and inflexible. A human operator, on the other hand, sweeps a mine detector from side to side while moving forward to cover ground. The operator can follow the ground profile with the detector head close to the ground without hitting the ground or any objects on it. She can also vary the width of sweep to suit a particular situation, and is usually not limited by terrain. In this paper we present the concept and early prototype of a system that incorporates the advantages of the two methods described above while minimizing the disadvantages of both. For example, it will have the flexibility of a manual system with the rapid and safer mechanized scanning of the vehicle-mounted system but at a reduced cost, size and overall system complexity, when compared to existing approaches. Our approach uses an articulated robotic device capable of automatically moving mine detection sensor over natural ground surfaces including roads and tracks in a manner similar to a human operator. The system can also easily be used to place a confirmatory point sensor at a specific location if needed. The early prototype, which incorporates only a metal detector for a mine sensor, implements ground following by using a laser range finder and four ultrasonic sensors.

Remote performance prediction for infrared imaging of buried mines

IR imagers are being investigated by several groups for use in landmine detection. The ability to predict detection performance is necessary to establish confidence for single sensor systems or to allow appropriate weighting of detector output for data fusion algorithms in multiple sensor systems. Preliminary studies had shown that the in-ground vertical temperature gradient was a good indicator of mine/background contrast in IR images if temperature measurements and imager wee collocated and limited data suggested that remote performance monitoring might be possible. To establish practicality of remote monitoring, temperature probes were buried at 5 sites separated by various distance between 30 m and 5.8 km, in asphalt, sand and gravel, both on and off road. Vertical temperature profiles were automatically recorded at all sites simultaneously with IR images of buried thermal IR surrogate mines located at a gravel road site. The in-ground vertical temperature gradient was confirmed to be a practical indicator of the performance of an IR imager, for probes buried in all materials at distances up to almost 6 km from the imager. A five element probe with thermocouples uniformly placed at depths from -3 to -11 cm would be sufficient to predict detection performance.

Canadian teleoperated landmine detection systems. Part I: The improved landmine detection project

The system developed under the Improved Landmine Detector Project is a teleoperated, multi-sensor, vehicle-mounted mine detector for low metal content and non-metallic mines to meet the Canadian requirements for rear area mine clearance in combat situations and peace-keeping on roads and tracks. The system consists of a purpose-built teleoperated vehicle carrying a forward looking infrared imager, a 3 m wide, down-looking highly sensitive electro-magnetic induction detector and a 3 m wide down-looking ground probing radar, which all scan the ground in front of the vehicle. Scanning sensor information is combined using a suite of navigation sensors and custom designed navigation, spatial correspondence and data fusion algorithms. Suspicious targets are then confirmed by a thermal neutron analysis detector. Key to the success of the system is the combination of sensor information, which requires coordinated communication between the sensors and navigation system and well designed sensor co-registration, spatial correspondence and data fusion methodologies. The advanced development model was completed in October 1997. Results are presented from Canadian and independent US trials in summer 1998. Four production units, based on the prototype technology, were delivered to the Canadian Forces in 2002, making the system the first militarily fielded, teleoperated, multi-sensor vehicle-mounted mine detector.

Soil information requirements for humanitarian demining: the case for a soil properties database

Landmines are buried typically in the top 30 cm of soil. A number of physical, chemical and electromagnetic properties of this near-surface layer of ground will potentially affect the wide range of technologies under development worldwide for landmine detection and neutralization. Although standard soil survey information, as related to conventional soil classification, is directed toward agricultural and environmental applications, little or no information seems to exist in a form that is directly useful to humanitarian demining and the related R&D community. Thus, there is a general need for an information database devoted specifically to relevant soil properties, their geographic distribution and climate-driven variability. A brief description of the various detection technologies is used to introduce the full range of related soil properties. Following a general description of the need to establish a comprehensive soil property database, the discussion is then narrowed to soil properties affecting electromagnetic induction metal detectors - a problem of much restricted scope but of immediate and direct relevance to humanitarian demining. In particular, the complex magnetic susceptibility and, to a lesser degree, electrical conductivity of the host soil influence the performance of these widely used tools, and in the extreme instance, can render detectors unusable. A database comprising these properties for soils of landmine-affected countries would assist in predicting local detector performance, planning demining operations, designing and developing improved detectors and establishing realistic and representative test-evaluation facilities. The status of efforts made towards developing a database involving soil electromagnetic properties is reported.

Canadian teleoperated landmine detection systems. Part II: Antipersonnel landmine detection

Continuing with the description of the Canadian teleoperated mine detection systems, in this paper we will focus on systems developed primarily for antipersonnel (AP) landmine detection. The Articulated Robotic Scanner (ARS) is a system approach that uses a generic robotic device capable of automatically moving a landmine detection sensor over natural ground surfaces in a manner similar to an operator. Exploiting the cost efficiency of proven high sensitivity commercial-off-the-shelf sensors, such as the metal detectors widely employed by military and humanitarian deminers, the high-precision automation of the ARS can be utilized to provide a low cost and low weight scanning imaging sensor that can be carried on a small autonomous platform. Concurrent with the ARS project, Defence R&D Canada – Suffield has maintained an active programme in the development of portable AP landmine detection systems, a number of which will be described. Together, these projects inspired a more ambitious vision, the Canadian Sensor Integration Concept (CANSIC), which applies the successful multi-sensor landmine detection approach to a small autonomous vehicle, using complementary sensors designed for antipersonnel landmine detection. Using a high-mobility robotic platform, the envisioned system incorporates five separate technologies: two hyper-spectral cameras, thermal and visual/near infrared, along with a scanning sensor imaging system mounted on a purpose build articulated robotic scanner, working in conjunction with a nuclear imaging confirmation sensor. Designed to provide clearance options for areas off established roadways, the goal is not only to operate in all environments and conditions that a deminer is able to, but also to extend the demining capabilities of military commanders and humanitarian demining project managers to situations where there is a high probability of casualities.

Simulation of images by photometric stereo modeling

A cost-effective method of synthesizing images of arbitrary complexity is described that combines high-resolution depth maps of scale model scenes with reflectivity data. A small scale model is made of a scene of interest. Regions of the model are textured according to the type of surface they will represent. The model is digitized under different iilumination directions, and a depth map is calculated by photometric stereo. Tables of reflectivity and/or emissivity data for scene materials are cornbined with the surface gradient map and flight geometry information to yield an intensity image at any desired wavelength, after which various kinds of noise can be incorporated into the image. The method is discussed with respect to the simulation of airborne active thermal infrared images of surface-laid minefields. However, no specialized sensors are necessary, and the method can be used for active or passive sensors of any wavelength, provided reflectivity or emissivity values are published or can be measured. The method may be also applied to the generation of images that are more general than aerial views of terrain.

Improved cryogenic testing capability at Marshall Space Flight Center's X-ray Cryogenic Facility

Marshall Space Flight Centers X-ray Cryogenic Facility (XRCF) has been performing optical wavefront testing and thermal structural deformation testing at sub-liquid nitrogen cryogenic temperatures since 1999. Recent modifications have been made to the facility in support of the James Webb Space Telescope (JWST) program. The test article envelope and the chambers refrigeration capacity have both been increased. A new larger helium-cooled enclosure has been added to the existing enclosure increasing both the cross-sectional area and the length. This new enclosure is capable of supporting six JWST Primary Mirror Segment Assemblies. A second helium refrigeration system has been installed essentially doubling the cooling capacity available at the facility. Modifications have also been made to the optical instrumentation area. Improved access is now available for both the installation and operation of optical instrumentation outside the vacuum chamber. Chamber configuration, specifications, and performance data will be presented.

Pipelined algorithm and parallel architecture for real-time detection of sparse small objects in images

A pipe-lined algorithm and parallel architecture is under development for real time detection of sparse small objects in images. Monochromatic images from an airborne active infrared scanner, images from a low-altitude aircraft-mounted multispectral scanner, and passive infrared imagery obtained from cameras mounted on ground vehicle are the image types intended for the application of this system to the detection of minefields. The paper briefly describes the characteristics of these three different kinds of image sensors and the operating environments. The general image processing system architecture and the functions of each of the components are also presented. The feature selection and algorithm adaptations for each of the image classes are described. Preliminary results obtained from an experimental system consisting of a small transputer network and array processors are discussed.

Design and validation of inert homemade explosive simulants for Ground Penetrating Radar

The Canadian Armed Forces (CAF) identified a requirement for inert simulants to act as improvised, or homemade, explosives (IEs) when training on, or evaluating, ground penetrating radar (GPR) systems commonly used in the detection of buried landmines and improvised explosive devices (IEDs). In response, Defence R and D Canada (DRDC) initiated a project to develop IE simulant formulations using commonly available inert materials. These simulants are intended to approximate the expected GPR response of common ammonium nitrate-based IEs, in particular ammonium nitrate/fuel oil (ANFO) and ammonium nitrate/aluminum (ANAl). The complex permittivity over the range of electromagnetic frequencies relevant to standard GPR systems was measured for bulk quantities of these three IEs that had been fabricated at DRDC Suffield Research Centre. Following these measurements, published literature was examined to find benign materials with both a similar complex permittivity, as well as other physical properties deemed desirable - such as low-toxicity, thermal stability, and commercial availability - in order to select candidates for subsequent simulant formulation. Suitable simulant formulations were identified for ANFO, with resulting complex permittivities measured to be within acceptable limits of target values. These IE formulations will now undergo end-user trials with CAF operators in order to confirm their utility. Investigations into ANAl simulants continues. This progress report outlines the development program, simulant design, and current validation results.