Professor Mike Caine, Director, Sports Technology Institute, Loughborough University [MC]
Wheelchair basketball is a very dynamic sport and the players will manoeuvre incredibly quickly with versatility around the court to the point where they’ll tilt backwards, they’ll roll over, they’ll bump into the floor and each other.
As Professor Mike Caine explains, wheelchair basketball is not for the fainthearted. It’s fast, rigorous and tough. Mike is Director of the world-leading Sports Technology Institute at Loughborough University. Researchers here have been improving seat design for the sport. Thanks to their work, for the first time, some British athletes competing at London 2012 will have custom-made seats to suit their individual requirements.
If you were to look at the chairs that will be used in London they would all look different. The key being that they have not been designed to be generic, but that we’ve approached each of the individual athletes with a blank canvas and come up with a seat construction that’s tailored specifically to them. If you have an athlete that has a trauma to the spinal cord that’s very high then often they will have lost the ability to stabilise their trunk, so I’m thinking here about their torso, the abdominal area, their lower back, and so they need a seat configuration that’s much more supportive around the lumbar area, the lower spine. If on the flip side you look at an athlete and they’ve got very strong abdominal muscles, their lower back is well conditioned, they’re very flexible, they don’t need that support and it actually gets in their way. They want to be more manoeuvrable and they have the ability to almost have a stripped-down seat where they have the minimal amount of support that promotes the biggest range of movement. There are many nuances within that continuum, but that’s perhaps an example of the two most extreme versions.
The research labs at the Institute are wonderfully surreal. You can see anything from running shoes being put through their paces on a huge test bed to headless mannequins wearing newly designed clothing. To produce the wheelchair seats 3D scans of the athletes are taken. Moulding bags, similar to bean bag style seats containing polystyrene balls, are also used to capture the shape of the player when seated. The seat is then made up by hand. Computer-aided design or CAD as it’s known is then used to refine the shape. Using this prototype, copies of the seat can be quickly produced for testing using an additive manufacturing technique called selective laser sintering, otherwise known as 3D printing. In this the seat is physically built up layer by layer. Dr Gavin Williams explains more.
[Dr Gavin Williams, Research Associate, Sports Technology Institute, Loughborough University - GW]
Initially what we have used 3D scanning for is capturing the position of the player in their current chair and then capturing the player whilst they have been moulded for their new seat, so that it ensures that we’ve positioned the player, once they have been moulded for their new seat, in the same position that they are in their current seat. It’s very difficult to capture how they’re positioned in terms of seat height and bucket angle, backrest height, position relative to the wheels, those kinds of aspects. The players that we are dealing with, the elite players, have formed that set up over many years, in some cases, so they know that position works and we need to recreate that exactly. So we use 3D scanning to digitise their position and then once it’s in a 3D computer package we can then take measurements accurately. We can then add or take away certain elements, modify very easily features or certain aspects of the seat which help interface with the frame more effectively. Selected laser sintering or 3D printing basically uses a laser to sinter a powder material, and it builds up in very fine layers to recreate the outside shell of the seat. So the finished article, once it’s been taken out of the machine, is effectively an exact replication of what was on the computer screen 24 hours earlier. There are different powders or polymers that can recreate certain plastics. We use one that replicates the flexibility of polypropylene which gives good flexibility without the brittleness, so it’s strong, but yet allows flex in certain areas.
The significant aspect of the research, according to Gavin, is that it is combining these different processes to produce the tailor-made seats.
It’s bringing together all these technologies into one sports chair. The technologies themselves are relatively established. The additive manufacturing techniques we’re using aren’t new, they’ve been well established and used extensively in areas like the automotive industry. The advantage of additive manufacturing mainly is that there’s no mould required, so you don’t have to make a mould to make the product. You make the product directly from the CAD model so each seat, because it is so customised, is completely different. What we’ve been able to do is to introduce complete customisation into the wheelchairs, which are already made to measure, but we’ve introduced a new level of customisation which the players are benefiting from.
And so far the seats seem to be working well for the athletes.
We’ve developed these seats for the GB men and women’s teams, selected players in both teams and to the best of our knowledge no other nation competing in London 2012 will be using this technology. In the straight line sprint tests and agility tests that we’ve been doing we are managing to shave vital, albeit tenths of a second, off times compared to the current chairs. But in a game like wheelchair basketball, those kind of short sharp sprints, twisting and turning, tenths of a second can matter greatly.
The research has been developed with UK Sport funding and the work of the Institute is supported by the Engineering and Physical Sciences Research Council (EPSRC). Other partners are the Great Britain Wheelchair Basketball Association, RGK Wheelchairs, Contour 886, BAE Systems , BMW and of course the Standard Life GB Wheelchair Basketball Team. In the long-term the research could also be used to customise seat design for wheelchair users in general, improving comfort and mobility and reducing injuries from pressure sores.