In search of underwater locomotion methods as alternatives to propellers, systems relying on the propagation of waves along a fin have already been designed and evaluated by several scientists. Considerable effort has been undertaken to optimise their efficiency both by fluid dynamic analysis and experiments on physical prototypes. One drawback of the systems hitherto has been their electro-mechanical complexity in that they required many actuators and refined control strategies to generate the desired fin undulation. Our approach has been to translate the result of these optimisations into a simpler, purely mechanical model relying on the principle of camshafts to achieve a similar undulatory fin motion. The goal was to evaluate whether this type of propulsion system is feasible and whether it was a viable alternative to propellers in Autonomous Underwater Vehicles. The prototype built during the project, CUTTLEFIN, reached comparable speeds to other undulating robot solutions. Force measurements also showed that the thrust produced is in qualitative accordance to a simplified fluid dynamics model. This makes the camshaft approach a promising option for generating an undulating wave in a membrane-based fin propulsion system, if one is willing to pay the price of lower flexibility compared to current dexterously actuated solutions.

In this paper, we present the mechanical design of a compact magnetic wheeled robot - with the goal to do inspection and vibration measurements in the housings of large generators and similar environments in power plants. After a detailed analysis of the specifications in this application, we present a new vehicle structure that allows for passing sharp concave corners - even with low friction coefficient between wheels and surface - and without using an additional active DOF. The advantages of this structure and the core parameters for its optimization are described in a quasi-static 2D calculation model. A prototype was implemented and successfully tested both in laboratory and real environments. The paper concludes pointing out the future improvements for a final industrial version.

In this paper describes a pair of wall climbing robots that use magnetic wheels for adhesion. They are designed for inspecting the interior surfaces of gas-tanks in oversea ships. Environments like this were impossible to access by previous climbing robots, as they are made out of very thin sheet metal that cannot support a high robot mass and contain several types of difficult obstacles. In order to master these challenges, the system described in this work uses two robots in a "mother-child"-structure: the smaller robot is built very lightweight and simple, without the ability to steer or climb vertically. It just moves horizontally and uses ridges in the gas tank surface as guidance rails. In order to pass from one ridge to the next one, the smaller robot docks to the bigger "mother"-robot. This robot always stays in an area where the sheet metal is thicker and never enters the extremely fragile surfaces. Thus, its mass is not critical for the structural stability of the environment and the robot can hence be built big enough to be able to climb in all directions of gravity and to pass difficult obstacles along its path. In the present paper, the basic concept, the mechanical design of all important components and the proposed control strategy are described briefly, followed by test results of the most critical components. An outlook to similar applications to which the basic idea of this work can be successfully transferred concludes this article.

This paper describes a compact robot with two magnetic wheels in a bicycle arrangement, which is intended for inspecting the inner casing of pipes with complex shaped structures. The locomotion concept is based on an adapted magnetic wheel unit integrating two lateral lever arms. These arms allow for slightly lifting off the wheel in order to locally decrease the magnetic force, as well as laterally stabilizing the wheel unit. The robot has the main advantage to be compact and mechanically simple. It features 5 active degrees of freedom: 2 driven wheels each equipped with an active lifter-stabilizer and 1 steering unit. This paper also presents the design and implementation of a prototype robot and its high mobility is shown. It is able to pass 90deg convex and concave obstacles with any inclination regarding the gravity. Finally, it only requires limited space to maneuver, since turning on spot around the rear wheel is possible.