All accelerometers are "broken"

Often users see their accelerometer gauges and ask "Why is my accelerometer wrong? It shows 1G when I'm not moving". Well, that just means you are standing on Earth, not the Moon, not Mars and certainly not floating in space.

Most accelerometer sensors will record about 1G when standing on Earth, 0.4G on Mars and 2.8G on Jupiter (if you could stand there). They would only show zero G when floating (orbiting) in space, or when in free fall.

The technical explanation for this behaviour is too complex for this newsletter, but it suffices to say that visualising this value is useful in some sports and activities. For example, we can analyse how long a skydiver is free falling before they reach terminal velocity, how much air-time a rollercoaster generates, or how high a motorcycle rider is jumping in a ballistic trajectory.

The MX Guru flies for some seconds on his motorbike, resulting in near-zero accelerometer values.

On the other hand, sports where vertical movement is not that relevan benefit from acceleration data relative to the surface of Earth. That is, where the value is 0G if standing still.

This is sometimes achieved by ignoring the vertical axis of the accelerometer sensor, which is not always possible or easy, so another common solution is to compute acceleration data from highly accurate GPS coordinates over time, instead of a dedicated sensor.

Aaron Vogel shows his racing lateral and longitudinal accelerations, along with many more metrics recorded with RaceCapture.

So if your acceleration gauge shows 0G don't scream in horror either. You might not be floating in space.