Customising What Athletes Wear And Use – 3D Scanning And Other Tech

The term bespoke or tailor-made brings to mind an image of a tailor measuring up a customer with a measuring tape so that he can make a suit that fits the customer. Four things typically happen in the whole suit-making process: 1) measuring the customer, 2) picking the preferred materials, 3) making the first fitting and 4) making adjustments based on the first fitting and customer’s feedback. The fourth step might repeat if the subsequent fittings are still not satisfactory. It is a tedious process but the outcome is getting the perfect fit for the customer.

In sports, athletes can have custom made helmets, shoes, protective gear, mouth guards, seats, suits, prosthetics and other adaptive equipment. We are not talking about just having custom aesthetic designs that are unique and represents the athlete. Custom made apparel or equipment that fits a specific athlete’s shape and style can not only improve comfort, protection, their range of movement, aerodynamics and overall performance. Let’s have a look at what technologies or methods are involved in customising them.

3D scanning

3D scanning is able to capture a lot more detailed measurements including curves (down to the millimetres) which standard ‘straight-line’ measurement tools like the measuring tape or vernier callipers are not quite capable of doing. Here are some parts of the body that are 3D scanned in order to be fitted:

  1. The athlete’s head; it can be scanned to create a 3D model, which is then used to design and make a custom fit helmet liner for football players.
  2. The feet are also commonly scanned to produce custom orthotics or high-performance athletic footwear.
  3. The lower body where athletes need to be seated or positioned in a certain way during competition; and it helps with designing custom-fit equipment, enhancing comfort and aerodynamics.  (e.g. slalom kayak seat or racing wheelchair seats or a luge)
  4. Stumps (amputations or limb difference) are scanned to help design better fitting prosthesis.

The more common 3D scanners are hand-held scanners like the Artec3D Eva or Creaform3D. They are typically portable and great for scanning around an object or body part. One of the downsides I find is the person doing the scan needs to have steady hands to maintain continuation/tracking and it takes some practice to get a scan right. There are measuring arm scanners that are basically a robotic arm that moves in multiple axes and has a laser scanner or touch probe at the end.  The user moves the scanner/probe at the end of the arm around the object and translates the coordinates to a 3D model. It helps with the problem of shaky hands but it might take longer for the probe to travel around the object. Terrestrial laser scanners are capable of scanning an entire stadium but might be an overkill to scan a wrist or a hand. There are also laser scanners built specifically for the foot where the foot is placed into the scanner and the scanning is done in just 15 seconds or less. Another increasingly popular 3D scanning method is photogrammetry. It is a good and cheap option that allows ‘scanning’ to be done with just a smartphone camera and the key factor is really the software.

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Kayak Athlete (Jess Fox) being scanned with a Creaform scanner (source: 3D systems)

Moulds

Before 3D scanning, moulds were probably the next best thing to getting the shape of a foot or stump or mouth. In some cases, moulds are still used due to a lack of access to 3D scanning and it is an effective low-cost solution in developing countries. In the case of the mouth guard, getting the mould or impression of the athlete’s teeth and gums is still the best if not the only way to make a custom mouth guard. Athletes can get the impressions themselves using a DIY kit or go to a dental clinic and have the dentist or dental prosthetist ensure that everything is aligned properly. There is also this custom ski boot liner that is designed to be fitted while the user is wearing it and the ski boot liner is injected with polyurethane foam that moulds around the wearer’s feet and solidifies after a short time. If you find it hard to imagine how that works, check out this video about the custom ski boot fitting process that also includes foot scanning and assessment:

3D Motion Capture

Motion capture or MoCap for short is typically used for biomechanical analysis. The typical ‘gold-standard’ MoCap systems are the optical systems. Athletes are (sometimes) made to put on compression garments and have markers placed on the joints that need to be analysed. Then multiple cameras set up around the athletes capture their movement. An example of customisation using Mocap is bike fitting systems. MoCap based bike fitting systems by STT Systems or Retul analyse the athlete’s posture and various biomechanical parameters and recommend an ideal configuration and position. It results in a combination of improved ergonomics as well as performance. Another application that utilises MoCap is golf fitting. The athlete’s golf swing is analysed during the MoCap session and the software breaks down the data and looks at key swing characteristics of the athlete. Then with reference to a huge database of golf swing profiles, a recommendation is generated for the clubs best suited to the athlete’s swings.

Note: There are many other optical (MoCap) systems out there for bike or golf fitting and some of their technology vary and some of them incorporate high-speed cameras. There are also inertial sensing systems and different products will have different levels of accuracy but they all track 3D motion.

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An example of a bike fitting mocap system from Bioracer Motion.

Other Complementary Tech

Sometimes, applying any of the above technologies alone is not enough to complete the customisation process and they are complemented with other measurements or sensing technologies.

Pressure sensing technologies are often used for gait analysis and customising footwear. It gives the podiatrist a better idea of how the athlete walks/runs, where the pressure points are and which parts of the sole require more support. They are also used in golf fitting clinics together with Mocap to provide data on the golfer’s balance and pressure distribution during each swing.

3D printing almost goes hand in hand with 3D scanning and we will find in many links or examples above where 3D printing has been utilised to prototype the equipment and sometimes even used as the final product in competition as seen in this paracyclist’s prosthetic leg.

With customisations that are trying to improve aerodynamics, they usually need to perform wind tunnel tests (or aero tests) or simulations. The results of the wind tunnel tests will provide feedback for further design optimisations such as the cycling helmet. And the team at NTNU has even gone to the extent of 3D printing a model of Chris Froome to test and optimise his time trial suit.

 

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Luca Oggiano and the Chris Froome 3D replica in the NTNU wind tunnel (source: NTNU)

 

Final word

We are in a period where customisation of sportswear and equipment is slowly becoming a norm. Other than the improvement of technologies and processes involved in customisation, the mindsets of athletes have also shifted to see the benefits of wearing and using tailor-made equipment. With major shoe companies like Nike, adidas and New balance partnering with technology companies to further explore performance centred customisation, it will be interesting to see how the technologies will progress and what boundaries can be pushed with customisation.

What else do you think could be or should be customised for an athlete? Would you like to explore making something unique or bespoke? Do leave a comment or feel free to reach out. With that thanks for reading!

Of Racing Suits and Aerodynamics

Wind Tunnel tests with custom designed mannequins and different Under Armour speed skating suit prototypes.

In many sports that involve high speed movements, drag or air resistance is probably one of their biggest enemy in achieving their peak performance. One winter sport that faces this challenge is speed skating, and turns out altitude plays a big part as well – the higher the skating venue is, the less air resistance there is (more about that in this article). Also the effect of drag on the skater’s speed and performance is pretty significant and the suit that the skaters wear could have an impact on the colour of the medal they get.

So just before the 2014 Sochi Winter Olympics, there was a bit of news about the revolutionary speed skating suit designed and made by Under Armour and Lockheed Martin. The “Mach 39” was supposed to be the fastest speed skating suit ever made. Unfortunately, instead of delivering medals (gold ones for that matter), the result was the US athletes performed below expectations. Now, this could be due to the suit OR if we break it down, could be due to a thousand other reasons (on top of the suit)..

There was a bit of history to the design of the suit, and the basic idea was: just as dimples on golf balls reduced aerodynamic drag, adding dimples on the suit would have the same effect. Of course, other than the dimple design, there were other considerations like textile selection and compression fitting design. Just have a look at the video below that describes what the designers and researchers looked at to reduce friction and improve aerodynamics of the suit. What’s really interesting is how they customised the mannequins to typical skating positions for wind tunnel tests. (Drag to 4:00 of the video to just see the custom mannequins)

Although the rational behind the design and testing all seems to make sense, I can’t help but have a few questions:

a. With so much movements during speed skating, is it really possible to estimate the drag based on wind tunnel experiments? I mean, there are a number of sports that do drag tests in wind tunnels; like skiing and cycling. But these sports have moments of competing when the athlete maintains a certain position for a short period; and those are the moments where having an optimum position (aerodynamically) could really reduce drag significantly. But speed skaters hardly stay in one position during competition (maybe except at the starting line). Then if that’s the case, would the wind tunnel results be fully applicable on the track?

b. Friction plays 2 roles: it slows you down and it gives you more grip/control. If there is too much friction, it impedes movement; but if there is minimal or close to no friction, the athlete might lose control. How then, do we strike a balance between them?

c. Is it possible to measure drag dynamically on the track? Well, a company called Alphamantis seems to have done that, but with cycling, and in a velodrome fitted with gate sensors. Some additional input parameters they require include the bike’s wheel circumference and also inputs from standard power meters and speed/cadence sensors. With the power meters, there is a calibration process before the actual aerotesting where they apply a model to calculate drag. For more details of the testing, you can read ths interesting blogpost by DCrainmaker.

I reckon it is possible (in theory) to develop a model for speedskating (similar to what Alphamantis did for cycling) to estimate drag on the ice skating track. The model might be slightly similar to this one in wheelchair racing: when the speedskater is pushing off (and at equilibrium), there are 4 different forces applied on the speedskater: 1) Reaction force, 2) Inertia, 3) Friction between the ice and skates, and 4) Drag force.

  1. Reaction force (or applied force) can be measured by instrumenting the skates with a shoe sole pressure sensor similar to this or this.
  2. Inertia can be determined by measuring the forward acceleration of the skater (using an inertia sensor or a suit of sensors), then multiplying that by the overall mass of the skater.
  3. Friction can be calculate based on the coefficient of friction of ice which is different for straights and curves according to this paper.
  4. Finally, since the sum of all these forces equals to zero, we can determine the drag force!

Xsens Concept Tests in Speedskating

Of course this model is very much simplified and some assumptions are made, but if more thought is put into it, this might just work.

Anyway, going back to the lacklustre results of the Under Armour Mach 39 suit, there could be so many reasons why the athletes didn’t perform during those races. Since US speedskating has extended the contract with UA, they obviously know that the suit wasn’t the main culprit. It did sound like the athletes weren’t really used to the new suit, so maybe it’s just a matter of ‘breaking-in’ the suits.

Thanks for reading and if you have any thoughts or suggestions on aerodynamics or drag tests, do leave some comments!

(Also posted in SportsTechnologyBlog.com)