Augmented reality improves ply lay-up

A visual control system helps operators position plies more accurately onto a tool – including their fibre orientation. Lou Reade reports.

Despite the wide success of hand lay-up, there is still a distinct lack of repeatability in the process. Most other industrial processes – such as injection moulding or stamping – are fully automated, and almost free of human intervention.

However, laying up wet or dry plies by hand is a very manual process. It requires an operator to interpret a design, then lay up a ply in the manner specified. Any deviation can lead to a sub-standard part.

One common way of ensuring accuracy has been to use a laser projection system. Here, a number of lasers shine a ‘line’ onto a tool to indicate where the edge of the ply should be positioned.

However, some of the limitations of the technique – such as needing a direct line of sight, and the expense of multi-laser systems – led UK-based software company Anaglyph to develop a screen-based system to improve the way in which plies are laid.

The system, called PlyMatch, uses cameras to capture an image of the tool. In addition, an augmented reality image – such as the position required by each ply – is overlaid onto it. The camera and mould are movable, while the system tracks their relative positions after an initial calibration.

“Instead of looking at the mould, the operator looks at the screen – and aligns the actual ply with the image as drawn by the software,” says George Kretsis, CEO of Anaglyph.

Different shades

At its simplest, the software indicates an outline for the next ply. However, using different colours of shading, the system can indicate other important factors such as fibre orientation.

“This is particularly useful for highly curved parts, as operators need to know where the fibres are meant to go,” he adds.

There is still a large degree of skill in matching the orientation to the computer image, but it helps to make the process more repeatable – overcoming factors such as different operators making the same part.

“The extra fibre orientation lines help you lay it in a way that matches what the designer created,” he says. “The ultimate aim is to make something as it was designed. Accuracy is important for good quality parts.”

It is not always possible to get an exact match with fibre orientation. PlyMatch can calculate how far the final part deviates from the design, in terms of degrees.

“In theory, you could feed this back into an analysis package to see what effect this would have,” he states. “In practice, it’s only used to see if a ply is in tolerance.”

Although working on a screen – rather than looking directly at the mould – can be fiddly at first, Kretsis says people quickly adapt. He likens it to using a computer mouse – which nobody looks at while they use it.

Once users are over this initial hurdle, the system offers many advantages, according to Kretsis. Firstly, it is suitable for very curved parts. (This can be done with laser systems, but requires multiple lasers – which is expensive.) The tool can also be moved multiple times, without the need for recalibration. It can also be used when laying ‘internal’ moulds – where there is no line of sight. Because of its ability to ‘track’ parts accurately, it can even be used to position elements such as metal inserts onto a mould.

Caught on camera

Because the work is captured on camera, it means that recordings of each operation can be made. This is a useful feature for quality control purposes. Often, lay-up is carried out by a sub-contractor. A recording of the process – in which the creation of each part is carefully documented – acts as ‘proof’ that a job has been done properly. It records not just the operator laying the plies, but the augmented reality overlays – to ensure that the correct instructions were followed.

The data for the augmented images can come from a CAD file, or from Anaglyph’s own Laminate Tools program – which is used to create plies. The standard software, supplied with the system, works with CAD files. However, those that have created plies using Laminate Tools can connect it directly to the system.

“Instead of exporting files to use with the system, you can use the native data that was created by the designer,” Kretsis says. “This means there is less error.”

The system can be used to create parts “the size of a small car”, according to Kretsis. While it is particularly useful in motorsport – where many changes are needed very quickly – he adds the main user is the aerospace industry, although not for very large objects like wings.

Although the company built its user base in the UK, overseas customers – from countries including the USA, Italy, Sweden and China – now account for more of its business. For example, US company Systima Technologies recently began using the system to make an aerospace nose cone. Anaglyph also signed up a new UK customer recently, but Kretsis was unable to reveal any details.

Product variants

The system was originally developed in collaboration with the National Physical Laboratory as a way of more accurately converting a design into manufacturing reality. There are now several variants of PlyMatch available, but many are not advertised – as Kretsis says “we offer custom solutions”. He is also looking for ways to develop the system further. One angle, which he is actively investigating, is to lower the cost of the system and get rid of cables – making it wireless. This is close to completion, he says.

Another avenue of investigation is to get rid of the screen completely and use modern devices such as goggles and glasses to display the images. Research on this has already begun, he says.

“It doesn’t yet have the accuracy of the current commercial version – and I’m also concerned about health and safety,” he concludes. “I can’t imagine somebody wearing that kind of device for eight hours every day.”

Whether future versions of the system are handled on wireless equipment or augmented reality goggles, operators will continue to welcome the ability to bring more accuracy to the process of hand lay-up.

www.anaglyph.co.uk