A Low-Cost Robotic System for the Efficient Visual Inspection of Tunnels

Abstract

We introduce a low-cost robotic system designed to enable the safe, objective and efficient visual inspection of tunnels. The system captures high resolution images and processes them to produce maps of tunnel linings that are suitable for detailed inspection. It is unique in that the total cost of hardware is an order of magnitude less than most existing systems while producing an equivalent or higher quality of output. The device makes use of consumer-grade digital cameras and high-power LEDs in a rotating rig, carried by a lightweight aluminium frame which is designed to reduce vibrations during data capture. It is portable and installable by hand and has a modular design, making it possible to adapt to different types of carriage units, tunnels and sensors. Within the paper, we share insight into features of the device’s design, including lessons learned from trials of earlier prototypes and comparisons with alternative systems. Using field data gathered from a 2km utility tunnel, we demonstrate the use of our system as a means of visualising tunnel conditions through image mosaicing, cataloguing tunnel segments using barcode detection and improving the objectivity of visual condition surveys over time by the detection of sub-mm crack growth. We believe that our device is the first to provide comprehensive survey-quality data at such a low cost, making it very attractive as a tool for the improved visual monitoring of tunnels.