[heisenbit]

> the inertial measurement unit (IMU) and the navigational camera. The IMU measures acceleration in three dimensions, using data from several sensors to estimate altitude, velocity, and position. Even though this system samples at 500 Hz, the error would accumulate over time, causing the helicopter to become lost quickly.

I understand the IMU is not an ideal input and integration over time leads to positional errors. But gyros are much better and the orientation of the drone in flight is paramount. What I wonder is what ‚advanced‘ control law allowed the drone to become unstable wrt. orientation when there was noisy positional input.

[jamiedamien]

I suspect what happened is that the position and velocity estimates from the VIO system (cameras) were wrong (and perhaps wildly jumping) and since position and velocity errors are inputs to the attitude controller, the tilt oscillated as well. It's not that the IMU did a poor job estimating attitude (tilt), but rather that the attitude controller was asked to tilt in erratic directions to compensate for the erratic and incorrect position and velocity readings.

It's quite hard to detect when position and velocities are "obviously incorrect", especially when they come from VIO, where the optimization result can jump around in non ideal conditions, so I'm not surprised there was not a more graceful anomaly detection.