The iPad Cooling Case Reboot

Posted on October 1, 2018 by Julian Chua

How It All Started

The iPad overheating was first brought to my attention back in 2013 when a sports scientist approached me and needed a solution to cool down his iPad when he used it in the sun. I designed a proof of concept and a prototype and showed that an iPad case with fans and cooling channels was likely the simplest and most effective solution.

Read more about that design and testing here: Designing An iPad Cooling Case.

The original case with cooling channels

[If you are just interested in finding out how to get an iPad cooling case for beta testing or want to be notified when it is available, feel free to skip to the last part: here]

Putting it aside

At that time, I thought that an iPad cooling case was probably a product only a handful of people in the world would want. Few people (in my opinion) would use their iPad to the extent of overheating and even if it did they might give it a rest or move it to the shade assuming it was in the sun in the first place. Never the less, I created a survey to seek out what other possible applications it might have and tried to share it around. Unfortunately, I did not get any response for the next 5-6 months. Convinced then that the solution wasn’t needed, I decided to just let it rest.

Reboot 0.5

Fast forward to 2016, I received a couple of emails/comments from people who read the above blog post. Someone commented that they need it too for sports. The other 2 were from pilots who used iPads when flying. I had an email exchange with one of the pilots and found that the iPad overheating (and shutting down) was a big enough problem for him as it kept him from using it for navigation. I spent some time looking at redesigning the cooling case and possibly making a small batch of it. But with other life demands on my end, I had to put it on hold.

Reboot 2

Roll forward again to 2018, Survey Monkey, where I created the survey, sent me a notification reminding me that I should log in again to their website or else they will delete my account. As I logged in, lo and behold, the iPad cooling case survey had continued to live (even with my neglect) and it had collected a good number of responses since March 2014. Over 70% of those responses would like to have a cooling solution for their iPads! (I am a bit curious why I didn’t get a notification from Survey Monkey about all those responses.)

The Survey Monkey Notification

Another check on WordPress stats tells me that the story/blog post I wrote about designing the iPad cooling case is the top four (most viewed) posts in the last 3-4 years. That’s quite surprising. I was a bit bummed that I let all that slip past me but on a positive note I take those as signs telling me enough people wanted a cooling solution.

The Top 4 posts excluding the home pages.

So here we are, back at the drawing board – ironing out the designs (mechanical and electronics), figuring out the bill of materials (how much it will cost), planning out the path to production, organising testing and sorting out any other issues.

What has been done so far in the last couple of months:

rebuilt the temperature sensor circuit and cooling mechanism
redesigned the case so that it is slimmer
relooked at the cooling case design and how it could be more universal

What else needs to be done:

build the electronics on custom PCBs and test them
build a small quantity for beta testing with users
finalising designs
get electrical testing done to make sure it’s all safe.

Testing

Currently, I am organising testing with people who use their iPads during flying. For logistical reasons, my preference is to get people who are local in Australia to do the beta testing and get their feedback. Also, for a start, I am working on cases that fit the iPad mini 4 and the newer 9.7″ models (iPad Pro 9.7″ and iPad Air 2).

If you are keen to be involved in testing an iPad cooling case, please contact me here (link), select “iPad cooling case” and let me know:

which iPad model you need a case for (preferably it would be one of those mentioned above but if not I will do my best to accommodate)
how regularly you need to use it.
any additional information you feel is required

Also, if you would like to pre-order or be notified when the iPad cooling case is available on the market, please fill up the same contact form.

With that thanks for reading and stay cool. 🙂

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

Posted on March 2, 2018 by Julian Chua

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:

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.
The feet are also commonly scanned to produce custom orthotics or high-performance athletic footwear.
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)
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.

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:

https://www.youtube.com/watch?v=kyGKWUzb-tU.

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.

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.

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!

A Look at Smart Balls

Posted on July 26, 2014 by Julian Chua

Tracking how fast a ball was kicked or thrown used to be done with an external device – it could be a speed radar or a high speed camera or maybe even a very trained (and experienced) eye. However, in the last 5-6 years, more and more engineers and scientists have tried to put some form of sensors inside the balls to measure linear velocity, spin velocity, spin axis. This has mostly been made possible with advanced developments in microelectromechanical sensors (MEMS), where accuracy and measurement range has increased significantly (while still keeping the small form factor). Another 2 tech contributions that helped keep the sensors (more permanently) in the balls are wireless connectivity (Bluetooth or Wifi) with the micro-controllers and wireless charging.

Smart Ball Construction

Although the electronics is key to measuring movement signals and processing, there is still the very important task of holding those components (sensors + micro-controller + wireless modules + battery) inside the ball. Let’s call all those components the core. So while designing a method to secure the core within the ball, one has to consider the weight and position of the core and how it affects the centre of mass of the ball. The method has to be robust enough since the ball will take lots of impacts as it’s kicked or thrown or bounced. The method of securing the core will also affect or determine how the ball is constructed. Here’s a look at some of the different type of “smart” balls and their construction:

Smart Basketball: 94Fifty

Image from their patent file

The way that the 9DOF sensor is built into the 94Fifty ball is rather unique (thus the patent). According to their patent application, there is an inner cavity on the surface of the inside of the ball, which is purposed for a casing to house the electronic components (core). The casing is built with a flexible material such that the walls can flex with the pressure difference between the inside of the bladder and the inside of the housing. The patent application also mentions providing access for battery charging but that was probably the early version. The new version is built with Bluetooth connectivity and wireless charging.

The ball is constructed according to the official size and weight which is 29.5 inches (749.3mm) and 22 ounces (623.7g). So with the extra weight added from the core, the designers made adjustments to the enclosure material so that the overall weight is close to the standard weight, and more importantly, the weight distribution is compensated so it spins like a standard ball. For example, if the core is positioned at the top of the ball (see image above), and the valve is placed 180 degrees from the core, the extra weight would be added around the valve until the balance is achieved.

Smart Soccer ball: adidas micoach

adidas miCoach Smartball

adidas’ smart ball is designed with its core positioned within the ball and held there by what looks like 12 sets of supports. The core is positioned or suspended right in the centre of the ball, and the supports are meant to be rigid so that the core is always in the dead centre. There doesn’t seem to be any patent related to the method of supporting the core but there was a patent with regards to the electrical wiring within the ball. The patent basically describes how the wiring is arranged along the bladder wall to interconnect two electronic devices. It also mentions that the electronic components are arranged in such as way that the ball is balanced and doesn’t affect playing properties of the ball. According to the adidas page, the core consists of only a tri-axial accelerometer. There is also wireless charging with their custom induction-charging stand. The induction coils would likely be placed along the bladder wall instead of in the core.

Smart Cricket ball

The Sportzedge group at RMIT developed an instrumented cricket ball for measuring the spin rate and calculating the position and movement of the spin axis (link to the conference paper). Due to the high spin rates of wrist spinners (up to 42 rps or 15,120 deg/s), typical off the shelf gyroscope sensors can’t manage that measurement range. What this smart cricket ball has are three high-speed gyros that can measure +/- 20,000 deg/s, one for each axis. This ball is not built in the typical manufacturing process. In order to house the electronics, meet weight requirements, and keep it balanced, 2 solid halves of the ball were designed and CNC machined from the material Ureol or RenShape® BM 5460 which had the right density and hardness. Eight holes within the ball allowed for additional masses to be inserted to balance the ball. According to the paper, this design is an initial prototype and it is still not robust enough to be hit by a cricket bat. But it is fully capable of measuring spin rates during fast bowling. Subsequent versions will be more sturdy and also include wireless charging.

Instrumented cricket ball (source: Fig 1 of the research paper)

Smart Oval Ball

Smart AFL ball

The same team that built the smart cricket ball also developed a smart AFL ball to assess angular flight dynamics and precision of kick execution. The same electronics (high-speed gyros) that were built into the smart cricket ball was also incorporated into this smart oval ball. The main difference is, this oval ball is made with two bladders that sandwich the core electronics, keeping them right in the middle of the ball. The bladders were inflated simultaneously to ensure a more even distribution of pressure. It was noted in their paper that the advantage of using an inflatable bladder (instead of replacing it with expanded polystyrene beads) is that it allows for realistic kicking whereas the foam beads will absorb too much energy thus dampening the performance. Other than the smart AFL ball, a recent patent search found another American style football that is built with an electronic circuit coupled to an inflatable bladder. Interestingly, the football in this patent is designed intentionally with the electronics causing imbalance, unlike the above designs where the creators made sure their balls are balanced. Even though Wilson Sporting Goods has been granted this patent, there has yet to be any news of them releasing an instrumented oval ball. This might be something to look out for?

Ball Movement Measurements

No smart ball is complete if there are no “smarts” involved. The acceleration and/or angular velocity that is measured do not mean much if they are not processed and analysed. So firstly, the inertia sensors would require calibration – to ensure that the measurements are linear and accurate or at least corrected based on a benchmark device. Then mathematical models would be derived to determine the parameters for analysis; parameters such as spin rate, spin axis, speed, timing, ball flight path, angles, point of kick, bounces etc.

Also, to ensure that relevant data is processed accurately, certain “markers” or references are put in place to indicate when ball movement needs to be analysed and how it should be analysed. For the smart cricket and AFL ball developed by RMIT, as they are still in the research stage, a lot of the sensor measurements, signal processing, calculations and analysis are done manually. However for the commercial products like 94Fifty and the micoach smart ball, they have developed algorithms as well as guided user interface and instructions to make sure that each throw or bounce or kick is analysed accurately. In both cases, the interfaces and algorithms come in the form of an iPhone or iPad app. Here’s a breakdown of how each ball does it:

Basically to analyse a kick with the adidas micoach ball, the micoach app needs to be turned on and connected to the ball via bluetooth. Then after the ball is positioned stationary on the ground, the user has to select his/her kicking foot and tap on the ‘Kick it’ screen before executing the kick. One condition for getting the parameters measured is to kick the ball at least a metre off the ground and for it to travel at least 10m. No bouncing or rolling kicks.

Similarly the 94Fifty ball requires its app to be turned on and connected via bluetooth for the shots to be measured. For measuring shots, the user’s height needs to be entered into the app as well as the distance where the user is shooting from. There are options in the app to utilise a shooting machine or a user can practice with a training partner who can pass the ball after each shot. The only condition is that the pass has to be a chest pass for the subsequent shot to be recognised by the app. There are also some workouts or skill trainings that allow users to practice on their own and ball handling tracking options.

The Coaching Element

All these sensor-laden balls and their accompanying apps with smart algorithms aims to help users become better players – whether it is improved technique in kicking or shooting or training of muscle memory to perform proper mechanics over and over.

The 94Fifty app provides real-time audio feedback for each shot that a user makes, whether the focus is on shot arc angle or shot speed or shot backspin. Based on ideal stats (e.g. arc angle of 52 deg and backspin of 180rpm), the user can fine-tune his/her technique to achieve the right angle/speed/backspin. This user shows how by utilising the app’s feedback and capturing his practice on video at the same time, he could analyse his shot mechanics and identify how he could correct his shooting technique.

Likewise, the adidas micoach smart ball app not only measures each kick with ball speed, spin, spin angle, ball strike location & flight path, it also provides “Coach Notes” with recommendations on how the user can boost each specific parameter. A video option within the app allows a second person to capture the user’s kick using the iPhone/iPad’s camera so that the user not only gets the kick statistics but also visual playback of the kick.

Bottom Line

Designing a smart ball that analyses a player’s performance is definitely a complicated process. Not only must the instrumented ball behave like a normal standard ball with proper balance, but the electronics incorporated within the ball also have to be held robustly so that they don’t break under impact and the sensor data remains repeatable and reliable. Then there is the task of working out what parameters can be determined from the sensor data, if constraints/markers/references should be put in place to ensure accurate measurements, and how those parameters are helpful for improving an athlete’s skills and techniques.

Even with a properly designed ball that measures all the critical performance parameters accurately, it’s probably still not a complete coaching system. What the ball (and app) lacks is the ability to know (and break down) what exactly the athlete did in his kick or shot to achieve the numbers as calculated by the app. For example, in football, what affects a kick include foot speed, which part of the foot kicked the ball, and the amount of upper-body movement; and in basketball, a few things that influence a free throw include: the amount of trunk and knee flexion, shoulder flexion and elbow extension. These range of movements could be tracked with either video analysis (such as Kinovea which is markerless) or a 3D motion tracking system (such as Vicon which requires markers), or wearable sensors (such as SabelSense, XSens or this new sensor embedded compression suit).

In a nutshell, smart balls are definitely great coaching tools. But if combined with athlete movement tracking, it would give a lot more insight to improving the athlete’s shot performance.

Energy Returning Running Shoes

Posted on February 25, 2013 by Julian Chua

Adidas Energy Boost

adidas recently released a new pair of energy return running shoes called the Energy Boost. It promises to “change your run forever” by giving the runner high energy return and extremely soft cushioning. Based on this article, adidas is trying to grow their running market which is mainly dominated by ASICS, Brooks and New Balance; and a study done by RMIT not too long ago also revealed that Adidas shoes were not the top choices of most runners.

Adidas Bounce

But it’s not the first time that adidas has come up with a “energy return” shoe. There was the adidas bounce back in 2008/9 which has these ‘bounce’ tubes that goes horizontally across the sole. It would seem logical that those tubes can increase energy return and increase running performance but this study here showed that it would only work if the tubes were rotated by 18 degrees towards the rear thus transferring 34% of the vertical energy (from the foot landing) horizontally forward. Interestingly, the Adidas bounce shoes can no longer be found on the official Adidas website, and only on Ebay or Amazon.com.

Adidas Bounce Titan

Then adidas came up with a variation to their bounce design and called it the Bounce Titan and even had a Porsche Design version. However the same group that did the previous study also found in a subsequent study that this new design was still not optimum for running. Try and google adidas Bounce Titan and you will find that it suffered the same fate as the original bounce -> Ebay or Amazon.

Reebok Zigtech

Apart from adidas, Reebok developed the Zigtech while Mizuno has the Wave Prophecy. Both work on a slightly similar alternative to “bouncing”, that is “Waves”; and they basically promise to do the same thing – return energy or propel you forward and provide cushioning. Well, no tests (in the lab) has been done on them as far as I know, although if you google, you will find many wear reviews like this or this. Generally, they are positive.

Mizuno Wave Prophecy

Going back to the adidas Energy Boost shoes, their innovation is in the material of the sole that is developed by adidas partner, BASF. Based on this article and the video, the material likens to “thousands of small energy capsules“, that “stores and unleash energy” with every stride. Interesting. But I wonder how it really stacks up to other energy return shoes.

Maybe a showdown test should just be done with all these different “energy returning” shoes using a standard test like this one developed at RMIT, or the KMT test developed with Newton running, both addressing short falls of the existing ASTM test. So if anyone from adidas is reading this, feel free to drop me a note if you would like a test organised. 🙂

On Running

In fact I would add another shoe to the test list – on running – a swiss performance running shoe. Although they don’t promote energy return in their shoe, the “cushioned landing” and “barefoot takeoff” still makes an interesting concept that just can’t be left out!

Lastly, for those who would like to find out more about energetics of human movement and sports shoes or biomechanical concepts, do check out this article and this article.

Thanks for reading!