10. Full 3D Attitude Update
Nd787 C4 L2 A08 Full 3D Attitude Update V1
Gyroscope Summary
Gyroscopes measure rotational rate (in radians per second) by measuring the Coriolis Force. They are highly accurate and operate with a high update rate (a few kHz).
Measurement Model
A simple measurement model for a gyroscope looks like this:
\tilde{\omega} = \omega + b +\eta
| Variable | Significance |
|---|---|
| \tilde{\omega} | Measured rotation rate |
| \omega | True rotation rate about some axis |
| b | Bias (constant or slowly changing over time) |
| \tilde{\eta} | Measurement Noise. Generally assumed to be a zero mean Gaussian. \eta \sim \mathcal{N}(0, \sigma_{\text{gyro}}^2) |
Gyro Integration (Dead Reckoning)
Even if the bias is known, a gyroscope is susceptible to drift when its used to estimate attitude. That's because attitude measurements are calculated by integration of the measured rates and this integration tends to accumulate error.
We need to use other sensor measurements to correct for this drift.