  This paper presents a novel design of a multi-directional bicycle robot,
which targets inspecting general ferromagnetic structures including
complex-shaped structures. The locomotion concept is based on arranging two
magnetic wheels in a bicycle-like configuration with two independent steering
actuators. This configuration allows the robot to possess multi-directional
mobility. An additional free joint helps the robot naturally adapt to non-flat
and complex surfaces of steel structures. The robot has the biggest advantage
to be mechanically simple with high mobility. Besides, the robot is equipped
with sensing tools for structure health monitoring. We demonstrate the
deployment of our robot to perform steel rust detection on steel bridges. The
final inspection results are visualized as 3D models of the bridges together
with marked locations of detected rusty areas.
