A flexible robot designed to do repairs in confined spaces on submarines could one day prove useful in other areas from aerospace to Formula One racing.
The developers of the machining robot – Professor Dragos Axinte and Dr John Allen at the Rolls-Royce University Technology Centre in Manufacturing Technology at Nottingham University and Ralph Anderson of Rolls-Royce – have been awarded an Excellence through Innovation Award by Rolls-Royce Submarines.
The award recognises the trio's research work on the special-purpose miniature machine tool they call a Free-leg Hexapod, or FreeHex. They have now created a portable version of this flexible machining system which promises to reduce costs and time spent fixing problems.
The idea for the FreeHex came from a request made by Rolls-Royce’s submarines business. It required in-situ repairs to be done in a very confined workspace. Its own machine was heavy and hard to move, so the company asked for something smaller and more flexible with the same functions.
Axinte said: “Rolls-Royce presented us with a challenge that tested our abilities and gave us a chance to rethink traditional machine tools. Many of these are still ‘serial manipulators’ like robot arms – a chain of rigid links in a series. These serial kinematic machines stack independent stages to provide multi-axis movement. But this can lead to compound errors.
“Alternative parallel kinematic mechanisms driven by actuators, often telescopic jacks and ball-screw drives linked in pairs, are flexible but also more complex. Our development of a Free-leg Hexapod – a unique parallel kinematic configuration without base platform so that the lower joints (feet) can be attached to the surfaces of various geometries – makes this kind of robotised in-situ processing machine a reality.”
The development work will be continued as an EU-funded project, MiRoR. Project partner Tekniker will support the manufacture of the Walking FreeHex.
Anderson said: “The FreeHex design is mechanically very simple. It is a versatile, lightweight machine tool. The prototype has served extremely well to demonstrate the practical potential for carrying out complex machining operations, such as profile milling and thread milling, in situ on in-service engineering plant.
“The technology offers us a genuine alternative to our traditional bespoke machine designs.”
Axinte believes that the portable CNC machine could create a new machine-tool market segment for in-situ repairs. “Previous attempts to produce machines for in-situ maintenance resulted in bespoke machines designed for just one purpose. Our machine has enough flexibility to tackle many tasks,” he said.
“The technology has great potential – it’s a new type of CNC machine, and we’ve had strong interest from many businesses, including Formula One teams.”
Rolls-Royce is looking at using the machine in other parts of its business, such as aerospace.