Magnetic Wall Climbing Robot for Thin Surfaces with Specific Obstacles

Abstract

S u m m a r y . This paper describes a novel solution to a mobile climbing robot on magnetic wheels, designed for inspecting the interior surfaces in gas tanks made out of thin metal sheets. These surfaces were inaccessible by previous climbing robots due to the following restrictions: 1. Ridges, where the magnetic force decreases to almost zero 2. Angular transitions between the surfaces (135°) 3. Thin metal sheets that cannot provide high magnetic forces The main optimization criterion for this robot was to design it as light as possible, as the surface was also considered to be very fragile. As the here described type of application is very special and was not examined much in previous publications, this work also stresses on the early analysis phase. This phase mainly consists of tests to optimize magnetic wheels for thin surfaces and mechanical calculations for robots on magnetic wheels. The chosen concept is described in detail, explaining how the robot moves around and passes the obstacles. The analysis of the most critical cases is presented, as well as some details about magnetic wheels and actuators.

Lightweight Magnetic Foot With Variable Force, for Docking/Landing With Micro-Helicopters on Rust-Covered Walls in Boiler Furnaces

“…After a few cm, this robot already failed, as the ferromagnetic rust was sticking to all parts of the magnetic wheelnot only destroying the rubber but also penetrating into the gears. For this reason, the idea to use magnetic wheeled robots with additional mechanisms for passing specific obstacles [1][2][3][4] had to be rejected very soon. The alternative of using magnets in the structure instead of magnetic wheels [5], which is slightly more dirt-resistant than magnetic wheels, had to be rejected as well, as these robots usually do not achieve the required mobility for the difficult topology that is formed by the uneven surface of several tubes and the specific geometry of the coal nozzles.…”

“…In order to find the most appropriate principle for the magnetic foot, the mechanisms used in classical climbing robots with magnetic adhesion and in manipulators for industrial robots were analyzed and compared against each other. Basically, three groups can be distinguished -electromagnets [6,7], assemblies with moving magnets [12,13] and lift mechanisms [1][2][3][4]14]. The lift mechanisms can be further divided according to the way of motion (either rotary [1], linear with spindles [2,3,14], linear with pulley/wire-transmissions [4] or linear with pneumatics/hydraulics).…”

“…In order to protect the device from ferromagnetic rust particles, a dirt-protection out of a thin rubber foil (thickness: 0.5mm) is placed at the contact area towards the environment. For guiding the motion of the magnet, linear slide guiding elements are used -similar as in our previous robot for gas tank inspection [3]. For electrically controlling the motion, a circuit with two end-switches and two diodes has been chosen (see Fig.…”

Force and Traction Controlled Propulsion of the Omnidirectional Wheeled Climbing Robot Cromsci

“…The most common technology is to use passive suction cups [1]. Other methods use magnetic [2], van-der-Waals molecular adhesion [3] or kind of claws [4]. These systems are not suitable to concrete walls because of the rough surface, missing ferromagnetic material or low payload.…”

Cromsci - A Climbing Robot With Multiple Sucking Chambers for Inspection Tasks

“…In literature multiple kinds of climbing robots can be found using different propulsion and a mass of adhesion techniques like passive suction cups, magnetic adhesion [1] [2], van-der-Waals molecular adhesion or kind of claws [3] [4]. The most confident technology for our application is the negative pressure adhesion [5] [6] [7] [8] [9].…”