R. H. Chesney’s research while affiliated with Defence Research and Development Canada and other places

The Improved Landmine Detection System (ILDS) is intended to meet Canadian military mine clearance requirements in rear area combat situations and peacekeeping on roads and tracks. The system consists of two teleoperated vehicles and a command vehicle. The teleoperated protection vehicle precedes, clearing antipersonnel mines and magnetic and tilt rod-fuzed antitank mines. It consists of an armoured personnel carrier with a forward looking infrared imager, a finger plow or roller and a magnetic signature duplicator. The teleoperated detection vehicle follows to detect antitank mines. The purpose-built vehicle carries forward looking infrared and visible imagers, a 3 m wide, down-looking sensitive electromagnetic induction detector array and a 3 m wide down-looking ground probing radar, which scan the ground in front of the vehicle. Sensor information is combined using navigation sensors and custom navigation, registration, spatial correspondence and data fusion algorithms. Suspicious targets are then confirmed by a thermal neutron activation detector. The prototype, designed and built by Defence R&D Canada, was completed in October 1997. General Dynamics Canada delivered four production units, based on the prototype concept and technologies, to the Canadian Forces (CF) in 2002. ILDS was deployed in Afghanistan in 2003, making the system the first militarily fielded, teleoperated, multi-sensor vehicle-mounted mine detector and the first with a fielded confirmation sensor. Performance of the prototype in Canadian and independent US trials is summarized and recent results from the production version of the confirmation sensor are discussed. CF operations with ILDS in Afghanistan are described.

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.

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.

An experimental facility which measures and stores magnetostatic signatures of ferrous objects as a function of position and allows online analysis of the data is described. The facility consists of a remotely situated nonmetallic laboratory which contains two caesium vapour magnetometers. One magnetometer is stationary and is used to correct for geomagnetic fluctuations. The other magnetometer moves on a track and its position is measured by an optoelectronics sensor system. The magnetometers and position measuring system are controlled by a microcomputer through a special purpose interface and communicate with a distant mainframe computer. Data are presented to demonstrate some of the capabilities of the facility.

A vehicle-width array of metal detectors is one of the sensor systems used in most present day vehicle-mounted mine detectors. Data furnished by such a metal detector array consist of an output from each sensor channel as a function of time which is usually converted to a function of position. In multisensor systems where target-level data fusion is used, there is a need for techniques to process such data in order to detect and locate targets in realtime as the array scans the ground surface. One conventional way of processing such data is to apply a thresholding algorithm to data from each sensor channel separately and infer the presence of a target under a given coil or a number of coils. Such as approach could be very limited and cumbersome particularly when one has to consider large arrays with complex interaction between sensor and targets that produce a response in a number of sensor channels simultaneously. In this paper we model the data from the detector array as a scrolling image and develop a target detection and location scheme based on image processing concepts. Modifications of multiresolution and template-matching algorithms of 'peak' detection are developed using domain -specific knowledge of metal detector arrays. The resulting technique, which also uses dynamic thresholding to allow realtime operation, is illustrated using measured data from a 24-element, 3-meter wide metal detector array.

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.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

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.

A method of determining the depth of a shallowly buried metallic object by using its electromagnetic response is investigated. The method consists in relating the distance of the object from the sensor to the ratio of voltages induced in two coils by the object when it is subjected to a pulsed magnetic field. While the theory is developed for a spherical object, experimental data for both spheres and spheroids are used to evaluate the technique. It is shown that over the range of depths for which the signal-to-noise ratio is large enough, the error in determining a sphere's depth should not exceed approximately 10 cm.

An investigation into the feasibility of applying pattern recognition concepts to the classification of metallic objects by their electromagnetic induction responses was performed. The effect on the response of a limited set of steel spheroids due to various factors such as object shape, size, and orientation was examined and a pattern recognition scheme based on these results was proposed. Implementation of the scheme involved the development of a novel extension to the nearest mean vector type of classifier in which the concept of the class mean as a point in feature space was generalized to be a curve. The resultant pattern recognition scheme was tested on a representative test set which included 815 responses, corresponding to 104 variations in object and orientation. A success rate of greater than 96 percent was achieved. It is noted that the classifier extension developed provides a viable approach to classification of responses that very continuously with respect to a single parameter.

The time-harmonic solution for the anomalous vector potential due to a conducting permeable sphere in the field of a current-carrying loop is used to derive the corresponding step response. The step response is then used to obtain analytical expressions for the voltage induced in a second loop due to a chosen exciting current pulse train. The voltage induced in an actual system of coils is obtained by superposition. The effect of the measurement system is included in the analysis in order to experimentally verify the model. Measured responses of a number of aluminum and steel spheres at various distances from the coils are compared with theoretical predictions. The agreement between the two is generally good.