  Motivated by a high demand for automated inspection of civil infrastructure,
this work presents a new design and development of a tank-like robot for
structural health monitoring. Unlike most existing magnetic wheeled mobile
robot designs, which may be suitable for climbing on flat steel surface, our
proposed tank-like robot design uses reciprocating mechanism and roller-chains
to make it capable of climbing on different structural shapes (e.g., cylinder,
cube) with coated or non-coated steel surfaces. The proposed robot is able to
transition from one surface to the other (e.g., from flat surface to curving
surface).
  Taking into account of several strict considerations (including tight
dimension, efficient adhesion and climbing flexibility) to adapt with various
shapes of steel structures, a prototype tank-like robot incorporating multiple
sensors (hall-effects, sonars, inertial measurement unit and camera), has been
developed. Rigorous analysis of robot kinematics, adhesion force, sliding
failure and turn-over failure has been conducted to demonstrate the stability
of the proposed design. Mechanical and magnetic force analysis together with
sliding/turn-over failure investigation can serve as an useful framework for
designing various steel climbing robots in the future. Experimental results and
field deployments confirm the adhesion and climbing capability of the developed
robot.
