Two-Week Check-in #3: 16g

Not "grand"... but 16 times the acceleration of gravity, ~160 m/s². This is the ceiling of our accelerometer and your foot is faster than that when running!

As y'all know from the last update, our gait detection algo couldn't accurately detect running. Running steps, distance, ground contact time, cadence... anything. Those metrics for walking worked fine, but running fell apart.

We tuned the algorithm → test it → nop. Changed thresholds → test it → nop. Reordered logic → test it → nop. A lot of nops. 🫠

So we went back to fundamentals and measured raw acceleration, hoping it can shine some light. Tbh, I didn't think measuring raw acceleration was this hard.

This was Friday at midnight when we finally got raw acceleration working on our tags:

Now that we had raw acceleration... how fast do you think your foot accelerates during a run? Pretty mfing fast. When we selected our accelerometer we picked a 16g one (i.e. it can't measure acceleration greater than 16g) and figured there's no way a foot goes faster than that.

That assumption was wrong 💀.

We looked at the raw data and were like "oh shit." A massive chunk of the running data was missing after 16g.

So how do we figure out what the actual max acceleration is? How do we even pick a new accelerometer? Well, our phones can measure it. So let's tape one to a foot.

The funny part? We hit the hard cap on those too 😅. Phone accelerometers cap out at 20g, and we were clipping it. Based on our tests, full-sprint acceleration is probably sitting around 21 or 22g.

So now, back to redesigning the board. We're moving the accelerometer up to the 32g tier. New chip, new firmware, and everything else downstream. Needless to say, everything is delayed. We will get a functioning alpha soon! Trust the process!

Anyways, I know there's been many races in the last couple of weeks. Proud of ya'll for finishing strong!!

More soon ✌️ Brian