Game-changing technology - sports engineering

Materials World magazine
3 Apr 2011
Artistic rendering of a customised (additive manufactured) Taekwondo chest protector

The subtle machinations of sports engineering were discussed at a recent conference at Loughborough University, UK. Eoin Redahan kept score.

Speedo’s LZR swimsuit sent ripples through the Beijing Olympics in 2008. The NASA-engineered full bodysuit – which was said to reduce viscous drag by about 25% – was unveiled at the Games and scythed through the water at velocities that sparked intrigue and attention. It revealed how materials science and modelling can help innovate and provide catalysts for change.

Commercialising such technology successfully, however, involves managing a delicate relationship between a sport’s governing body and the designers, engineers and manufacturers involved. Delegates at the UK-Japan Sports Engineering Symposium in Loughborough, UK, on 24 February, revealed the complexities.

Compliance and analysis

Anthony Bull, of Imperial College in London, UK, discussed how the Marylebone Cricket Club (MCC) has outlawed certain materials for use in bat blades such as aluminium and composites. The MCC is at pains to ensure that the balance between the bat and ball is kept, without an obvious advantage being provided to either discipline. The importance of maintaining this parity, he said, could conceivably result in a bat being outlawed even if it complies with the material parameters. The laws do not allow for this at the moment.

The challenges of the compliance process were illustrated by sporting equipment manufacturer Shimano’s development of a rowing shoe. Hans Van Vliet, of Shimano Europe, explained the difficulty in tackling the age-old process where rowing shoes had to remain attached to the board inside the boat. ‘You have to change the regulations of rowing to change the shoes. This took two years. We [now] have permission for a clipless shoe. If we are talking about a different mechanism, this process starts all over again’.

One delegate noted that his company had developed golf clubs that surpassed the performance of existing clubs on the market, only for their inventions to have been outlawed by sport’s governing body, consigning considerable R&D investment to nothingness.

Indeed, substantial sums of money are invested to ensure equipment developed adheres to existing specifications and parameters. Katsumasa Tanaka, of the Tokyo Institute of Technology in Japan, has applied a finite analysis (FE) system to ‘create highperformance [golf] clubs that meet the rules’, He noted, ‘Golf club heads with high coefficients of restitution (CoR) have improved driving distance. There are now regulations for the upper limit of CoR as a result’.

He constructed FE models for golf impact using a club constructed from a simplified clubhead, a locking ring and a steel shaft. According to Tanaka, the model measures ‘impact simulations between the ball and rigid target for identifying material parameters’. Using FE, he measured the impact velocity, rebound velocity and CoR. He claims the FE model. ‘can precisely express impact behaviour’, between club and ball.

Respect the rules

Sports engineering advances have also been used to make sure that players adhere to the rules and to assess their performance.

Bull mentioned the material challenges inherent in sports as they evolve. He cited the advent of day-night cricket as one such example. The white balls in one-day games were difficult for players to see under floodlights, so a change of ball colour was proposed. He explained how the process proved problematic. Dye was applied, but impregnating the ball surface sufficiently was troublesome. Subsequently, when lacquer was applied, it had an adverse affect on the way the ball performed during match conditions. In the end, ‘they found better [proprietary] ways of making a coloured ball keep its colour for longer and behave more like a traditional red ball’.

Bull has used optical motion analysis to identify the elbow angle at the bowler’s point of release to assess a correct bowling action. However, ‘the exact time of release may change results by three or four degrees’. Similarly, when it came to identifying a legal bowling action, factors such as hyperextension and congenital medical conditions conspire against creating an objective monitoring system.

Train of thought

Another aspect of the event was to showcase some latest innovations. Dr Ruth Goodridge and her Loughborough University colleagues have applied additive manufacturing techniques to create customised shin pads, snowboard bindings and body armour.

End parts are produced directly from 3D-CAD models using laser sintering to create ‘geometries that were not possible using existing manufacturing [techniques]’. The system, she says, enables the creation of one-off parts with ‘the ability to create functionally graded structures within a part so that it can have different properties throughout the material’. That said, she underlined that the process is currently quite slow, and there is a need to improve the properties and variety of materials currently used for the process.

Improving the training performance level of elite athletes was also a central focus. Professor David Kerwin of the University of Wales Institute, Cardiff, UK, alongside colleagues from University College London, the University of Cambridge and the Royal Veterinary College, have developed trackside technology that gives sprinters immediate performance feedback using miniature infrastructural-based and wireless on-body sensors that are worn by athletes.

He emphasised the need to disturb the athlete’s environment as little as possible and of having technology that is quick and easy to use. The inertia profiling system to measure an athlete’s physical dimensions was improved from a 30-minute process with two per cent accuracy, to a 20-second process with four per cent accuracy.

Similarly, the integration of 13-gramme force sensitive resistors into the athlete’s running shoe improved upon previous systems, where athletes wore a lithium-ion battery in a pouch. These sensors then send data from the shoe to a remote device such as a smart phone.

With the technology’s multi lane light gate system, the performance of several athletes can be simultaneously monitored at each stage of a race, using reflective tapes placed at increments on the track, which are picked up by infrared beams on ceiling trusses. All of this is then integrated into a ‘turnkey system,’ where coaches activate the technology from a handheld device (such as iPod, iPhone) and obtain immediate feedback on the device or on an online portal.

Despite the considerable strides made by his team, Kerwin believes that, ‘the amount of technology and experience available is still below what is needed in a training session’. Nevertheless, the inexorable drive of athletes and engineers continues apace.  


All images courtesy of Loughborough University