TU Delft PhD student Rienk van der Slikke has developed a method to measure the response in terms of speed of a sports wheelchair when changes are made to the wheelchair. His aim is to be able to give athletes personalised advice.
To optimise a sports wheelchair, you first need to know what happens during a match. How quickly do the athletes accelerate from rest? How often do they turn, and how fast? According to Rienk van der Slikke, very little research has until now been carried out in this area, and certainly not in matches. He therefore first wants to properly analyse this.
Van der Slikke has developed a measurement method using sensors for his research project, which is part of a collaboration between the Hague University of Applied Sciences and human movement scientists at VU Amsterdam and the University of Groningen. He placed ‘shimmers’ on both wheels and on the frame beneath the seat: sensors that measure the rotational speed and acceleration. On a computer screen, he can then see how the wheels turn and the distance they travel.
Van der Slikke’s particular area of interest is wheelchair basketball. “In basketball you know that it is important that one player moves more quickly than the other,” he explains, “for example if you want to get the ball or block someone.” But do you simply want the fastest wheelchair? According to the part-time lecturer in human movement technology at the Hague University of Applied Sciences, coaches want their players to sit as high as possible so that they are ‘taller’ than their opponents and can score more easily. However, the higher a player sits, the more slowly he reportedly moves. Van der Slikke wants to explore this relationship. “Imagine you let someone sit five centimetres lower – how much faster will he be then? Or, how much better will he be able to accelerate? If you sit a bit lower and you can reach a larger area of the hand grip on your wheels, you can accelerate more quickly and maybe get there just
before your opponent.”
Another variable is the camber, which is the angle of the wheels in relation to the frame. On a normal wheelchair, the wheels are vertical, but most sports wheelchairs have slightly angled wheels. “This makes them easier to manoeuvre,” explains van der Slikke.
It is also possible to vary the position of the wheels. All sports wheelchairs have an anti-tip wheel at the back to prevent players from tipping backwards if they set off too quickly. This wheel makes it possible to set the large wheels quite a way forwards, so that the weight is placed more over the back wheels. “The advantage of this is less rolling resistance, and it is easier to manoeuvre.” Van der Slikke has carried out measurements on dozens of wheelchair basketballers, rugby players, tennis players and track sprinters, both during matches and on a test circuit. He wants to conduct further tests using various wheelchair settings with wheelchair basketballers on a test circuit to investigate the effect of the various settings: with and without extra weight, at various seat heights and with gloves for more grip.
As a spin-off, van der Slikke wants to market his measuring system in the form of a box mounted on the wheelchair frame. This will allow athletes to evaluate their own training and matches and, possibly, enable the early detection of injuries.