Pushing through

How Apple cracked the wheelchair mode in watchOS 3

Most modern businesses are chasing volumes. Anything niche commands a premium. It is rare for any company to do things just because it had to. But, then, Apple is not any company.

At the Apple Worldwide Developers Conference (WWDC), the Cupertinobased tech giant announced that watchOS 3 will be available for Apple Watch users this Fall. There were many improvements on offer, also a whole new wheelchair mode. In that footnote of an announcement, Apple kick-started a whole new segment, for motion or calorie trackers aimed at wheelchair users, which has never been done before.

“Apple has always led on accessibility features. Even when we were finishing watchOS 1.0, we knew we wanted to do something for wheelchair users. We get a lot of feedback how they love getting messages and notifications on their wrist and we wanted to ensure they also got a first class experience when it came to health and fitness,” says Ron Huang, Director of Software Engineering for Location and Motion Technologies.

But it was not an easy jour ney. “When we started looking at this, we tried to see if there were some studies out there or literature on the topic. There were a few studies, but most had really small number of subjects and done inside labs on wheelchairs provided by those conducting the study,” Huang adds.

In real life, wheelchairs are very different when it comes to wheel width, seat height, etc. Apple’s challenge was ensuring the chairs were like the ones used by consumers, and the environment for data collection had to be closer to real life and not treadmills where movements don’t correspond to actual pushes. “We found that some of the basic principles used to calculate calories don’t convert well for wheelchair users. We had to pretty much start from scratch.”

This is when Apple reached out to the Challenged Athletes Foundation (CAF)—established in San Diego in 1997—to run studies with the help of their members. The partnership gave them the opportunity to correct all the issues with the earlier studies. So, the volunteers got survey grade GPS on the chairs, rotational sensor on the wheels and accelerometers on their wrists. Plus, they wore masks to measure oxygen intake and calorie burn. No data point could be ignored. While they were already using a variety of wheelchairs, the study was conducted on different surfaces—from asphalt to carpet, flat grounds and ramps. Also, the volunteers were pushing themselves and at times accompanied by walkers, a scenario that slows them down and thus resulting in a different set of data points. The attempt was to capture a complete day in the life of someone who was on a wheelchair.

By the end of the study, Apple had 3,500 hours of data across over 300 subjects and 720 sessions. This was the kind of exhaustive data needed to create a dependable algorithm for the Apple Watch to track wheelchair users well. However, this was just the beginning when it came to creating the Wheelchair Mode for watchOS 3.

How the Apple Watch measures steps and thus calories bur nt was not going to work in this scenario. They had to figure out how to measure pushes, which, like steps, is the fundamental element to track energy for wheelchair users. This was tough, as users had different styles and encountered different obstacles as well as generated more false positives.

The team mapped three different styles of pushes—the efficient semi-circular push, the quicker arc-push for uphill or downhill, and single loop over which is used for racing—to calculate energy usage. Then there was the issue of hand gestures that seemed like pushes. So they banked on real life data which showed that while pushing the wrist it would be going towards the ground, when talking or gesturing it is parallel to the ground or is going upwards. This helped filter out the false positives.

As the watch uses new algorithm to count calories, it also tells users to move around a bit or spin their chair back and forth from time to time to achieve their activity goals. Instead of the regular Apple Watch “Time to Stand” alerts, there would be a “Time to Roll” alert if users haven’t been moving for a while.

At this point, Apple roped in Alabama-based Lakeshore Foundation to understand how their large community of diverse wheelchair users went about their daily lives. In fact, much before this year’s WWDC in June, members of the foundation were secretly testing the new software and its new features. In three weeks, this community also gave insight into fitness levels of users and their injury types, making a crucial difference to the final product.

When the new watchOS version becomes available for users this Fall, they will be able to get the software upgrade on existing Apple Watches. Users will be able to switch to Wheelchair Mode at the end of the initial set-up itself, after which everything else will set up automatically. Also, the new data from the mode will be added to Apple HealthKit.

Apple believes this had to be done right because there is no other tracker for people on wheelchairs, who are often prone to diseases brought in by a lack of movement. nandagopal.rajan@expressindia.com