Switzerland’s infrastructure includes 3,500 motorway bridges and cantonal roads which help peope travel safely across valleys, streams and rivers. The amazing number of bridges are made of reinforced concrete. During snow de-icing salts are used to avoid slippery winter roads. The chlorides present in these salts damage the reinforced concrete leading to corrosion. The damage becomes severe over time and is often visible only at the final stage. Repairing these structures is very expensive: the greater the damage caused by corrosion, the more expensive the restoration work.
Professor Elsener and a team of researchers from the Institute for Building Materials and the Autonomous Systems Lab at ETH Zurich patented in 2012, and have developed a robot that can inspect the undersides of bridges, identifying corrosion at an early stage. This little bot dubbed C2D2 can reach places humans can’t and detect hidden corrosion at an early stage.
Roland Siegwart, professor at the Institute of Robotics and Intelligent Systems and Vice President Research and Corporate Relations at ETH Zurich, explained in a press statement –
The students in one of our focus projects developed a robot four years ago that can move not only on the ground, but also along walls and ceilings. This made it ideal for our project.
The C2D2 was originally called Paraswift and was designed with a view to being used by Disney. When a camera is fixed on to the robot, it can easily shoot a room from all angles. For their new project the team renamed Paraswift as C2D2 (Climbing Corrosion Detecting Device) and modified it for use as a corrosion detector.
We made the casing and wheels more robust and incorporated the corrosion-identification technology.
explains Elsener, who is spearheading the project. The tiny robot has the potential to stick to the walls and ceilings. Thanks to the movable, active-suction cup system wherein a propeller mounted to the bottom of the vehicle generates the sucking force, while its four wheels propel the robot forward and back. The robot gets a new camera exclusively designed for navigation and obstacle avoidance. The C2D2 is also fitted with a large pink ball so that it gets easily noticed by the cameras and crews on the ground.
The robot uses an electrode wheel to measure the potential difference of the reinforced concrete as the robot moves along the structure. The bigger the potential difference, the worse the hidden corrosion is.
“We analyze the half-cell potential map, checking for local minima and gradients,” said Elsener in replying answers to questions posed by Civil Engineeringonline.
Statistical evaluation of the data helps in the interpretation, determining the potentials values for passive and corroding reinforcement in concrete. A camera system on the ground follows precisely the pink ball on the robot and the position of the robot. This allows [us] to determine the position and [then] the x-y coordinates in the plane of measurement can be exactly calculated.
The robot currently is operated via remote control or terminal uplink. The researchers plan to incorporate a self-steering measure in the robot’s next iteration and are working on software for autonomous data analysis.