26. Barometer Errors and Calibration
Nd787 C4 L2 A21 Barometer Errors And Calibration V1
Barometer Summary
The barometer is really just an air pressure sensor.
As you increase your altitude, air pressure decreases in a predictable way. By comparing the current air pressure to the air pressure at some known altitude, the barometer can infer the height of the vehicle.
Measurement model
A barometer infers its height h_b from a measurement of pressure, p_b , according to the following equation:
h_b - h_s = \frac{T_s}{k_T}\left[ \left( \frac{p_b}{p_s} \right )^{-\frac{Rk_T}{g_0}}-1 \right ]
| Variable | Significance |
|---|---|
| h_b | Current height of barometer |
| h_s | Reference (surface) height |
| p_b | Current pressure measurement |
| p_s | Reference pressure |
| T_s | Reference Temperature |
| R | Gas constant (287.1\text{ J kg}^{-1}\text{ K}^{-1}) |
| k_T | Atmospheric temperature gradient (6.5 \times 10^{-3} \text{K m}^{-1}) |
| g_0 | Surface acceleration due to gravity (9.81 \text{m s}^{-2}) |