Craig Lobsey

Seeing through dust and water vapor: Millimeter wave radar sensors for mining applications

This paper defines the issues required for the development of successful visualization sensors for use in open cut and underground mines. It examines the mine environment and considers both the reflectivity of the rock and attenuation effects of dust and water droplets. Millimeter wave technology, as an alternative to the more commonly used laser and sonar implementations, is selected due to its superior penetration through adverse atmospheric conditions. Of the available radar techniques, frequency modulated continuous wave (FMCW) is selected as being the most robust. The theoretical performance of a number of 77 and 94 GHz FMCW millimeter wave radar systems is determined and these confirm the capability of these sensors in the mining environment. Implementations of FMCW radar sensors for simple ranging and three-dimensional surface profiling are discussed before data obtained during field trials in mines is presented to justify the selection of this technology. (c) 2007 Wiley Periodicals, Inc.

High‐resolution millimeter‐wave radar systems for visualization of unstructured outdoor environments

This paper examines the use of millimeter-wave radar systems for visualization and navigation in unstructured outdoor environments. Three types of radar systems are described. The first is a long range, 94 GHz, frequency modulated interrupted continuous wave radar which is capable of producing two-dimensional (2D) reflectivity images to a range of more than 3 km. This is intended for use in long-range path planning. The second is a class of medium range 77 GHz frequency modulated continuous wave (FMCW) radar with two axis mirror scanners which is capable of producing high resolution threedimensional (3D) imagery out to 500 m at a reasonably slow frame rate. The final class also operates using the FMCW principle, but at 94 GHz, to produce high resolution 2D and 3D images out to about 50 m at a much higher update rate. These shorter range sensors may be used to determine the traversability of the local terrain. The outputs produced by the different classes of radar are examined and the paper considers their advantages when compared to other sensors such as vision and scanning laser. Using radar images, the final section compiles rules for interpreting radar reflectivity images from a path-planning perspective.

Application of Millimetre Wave Radar Sensor to Environment Mapping in Surface Mining

This paper presents the application of a millimetre wave radar technology to environment mapping in surface mining. Sensor requirements for ranging and surface profiling in shovel and dragline operations were determined based on machines performance requirements. Frequency modulated continuous wave (FMCW) technique was selected to achieve the correct range resolution while fast Fourier techniques (FFT) was used to extract the range data from the radar output. Radar data processing was undertaken using stochastic environment representation technique in real-time. The results of field trials show successful radar performance in terms of the systems accurate measurement of excavation terrain, real-time imaging, robustness, reliability and penetration through dust and water

Millimetre Wave 3D Imaging for Industrial Applications

Within the next few years, improvements in graphic rendering and the application of millimetre wave radar technology will, together, allow operators of industrial processes in poor visibility environments to control their machines remotely. At the ACFR, we have been developing the 3D radar systems and displays to make this a reality in the mining industry. This paper discusses the principles involved in generating such images, and gives a number of examples of systems that have been implemented in the field.

Radar cross sections of small boats at 94 GHz

This paper briefly discusses a procedure to measure the radar cross section (RCS) of small boats at 94 GHz. It describes an extremely simple and moderately low cost set of hardware that was used to perform these measurements. An analysis of the calibration method including measurements of reference corner reflector returns and those from the sea were made throughout the trials. Results include polar patterns made from the peak RCS at each angle. In the case of the largest boat, a 41 ft fly-bridge cruiser, it was possible to process the high resolution range profile data to identify the positions of the larger scatterers. Analysis of the measured data for all of the craft shows a linear relationship between the median RCS of the non-metallic boats and their physical cross-section when viewed side on.

Low Cost Measurement of Small Boat RCS at 94GHz

This paper discusses a procedure to measure the radar cross section (RCS) of small boats at 94 GHz. It describes a simple and moderately low cost set of hardware that was used to perform these measurements. Results include polar patterns made from the peak RCS at each angle and probability density functions to characterise the distribution of RCS. In the case of the largest boat, a 41 ft fly-bridge cruiser, it was possible to process the high resolution range profile data to identify the positions of the larger scatterers. Analysis of the measured data for all of the craft shows a linear relationship between the median RCS of the non-metallic boats and their physical cross-section when viewed side on

Real aperture imaging of a small boat at 94GHz

This paper investigates the feasibility of real-aperture imaging a small boat by exploiting the good range resolution of a millimetre wave radar, and the known trajectory of the target. Two different image types are generated, one that includes the uncertainty in the angle of arrival introduced by the antenna beamwidth and uses the largest return only, and the other which exploits the complete range-amplitude return to obtain more information about the size of each target and its position on the boat. This second method produces images which are easier to interpret and could possibly be used to identify a target.

Combined Infrared and Acoustic Beacon Tracker and its Application on an Autonomous Following Vehicle

This paper outlines the design and implementation of a combined IR and acoustic beacon tracker and its evaluation as the guidance sensor on a radio controlled car. The implementation is unique insofar as it combines the broad acquisition angle of IR sensors (nearly 180ˆ) with the precision angle measurement capability of an acoustic monopulse tracker. Additionally it uses the time difference of arrival of the IR and acoustic signals to measure the range to the beacon. A control loop was designed using the sensor to allow the car to follow the beacon at a fixed distance. Tracker and control performance on the car were good with the vehicle capable of following a fast moving person with a turn radius of less than 3 m.

Millimetre Wave Radar Visualisation System: Practical Approach to Transforming Mining Operations

Over the last three decades, mining operations have undergone massive transformation to mechanized, semi- and automated mining systems; manual labor has been gradually replaced by machine operations and processes have become more integrated. This change was possible due to technological advances in sensing techniques, improved excavation methods, bigger and more reliable mining machines and better understanding of geological conditions. Yet, with all the technological advances, majority of mining operations still rely on human “operator” to achieve production goal, whose performance, in turn, is influenced by the accuracy of information provided by various data gathering systems and by the variable, sometimes unmanageable or unpredictable environmental conditions. In order to achieve and maintained high level of performance of man-machine systems, the information acquired using various technologies must be accurate and must be provided in time for uninterrupted operation.

Millimetre Wave Radar Vision for the Mining Industry

This paper examines the background and application of millimetre wave radar technology to control and direct the material mix introduced to refill large underground voids. In addition it documents the use of radars for surface mine visualisation to produce images of the bucket fill on large rope shovels and on draglines to help reconcile dig volumes and to specify dig and fill surface profiles.