Foldable magnetic wheeled climbing robot for the inspection of gas turbines and similar environments with very narrow access holes

Purpose - The purpose of this paper is to describe the design and prototype implementation of a miniature climbing robot with magnetic adhesion, developed for the inspection of gas turbines and other environments that require vertical mobility along curved steel surfaces, but only offer very narrow access holes - in the case of turbines only Ø15 mm.Design methodology approach - After a detailed description and analysis of the industrial environment where the robot is supposed to be used (inspection of gas turbines, housing not opened), the paper describes the basic mechanical concept which is based on two traction units on magnetic wheels and a folding mechanism which allows the robot for changing between two configurations - one for passing through the narrow access holes and one for climbing with 2D mobility on curved surfaces. A special focus is put on how the most difficult design challenges were solved - torque transmission at this very small size and the design of the folding mechanism.Findings - The feasibility of the concept is proven with a prototype implementation and successful test results.Research limitations implications - Discussions with field service engineers at ALSTOM showed that gas turbines are relatively easy to open thus do not require access through the narrow bore-scope-holes.Practical implications - However, in the field of boiler drum inspection, there is a need for such robots. The final industrial version of this robot, which is currently under development at ALSTOM Inspection Robotics, is optimized for this type of environments (more space but higher requirements regarding the robustness against shocks).Originality value - The robot concept presented here allows for accessing environments with very narrow access holes and afterwards climb with 2D mobility - an ability which opens several new applications for compact mobile climbing robots, especially in the field of power plant inspection.