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software [2018/07/21 14:45] seandepagnier created |
software [2018/07/30 20:16] (current) seandepagnier |
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=== Calibration === | === Calibration === | ||
- | For the autopilot to work correctly the inertial sensors must be calibrated. Typically this is just an offset or bias for each of the sensors. | + | For the autopilot to work correctly the [inertial sensors] must be calibrated. |
- | The gyroscopes continuously automatically update their bias, and many sensors have accurate accelerometer bias leaving the compass which can change widely depending on where it is mounted and what is around it. | + | First, the accelerometers may be calibrated. To calibrate, hold the sensors still for a few seconds in each side of the box until calibrated. video link |
- | mpu9250/mpu9255 -- With yellow capacitor the accelerometer is already biased, with orange capacitor accelerometer bias calibration needed. | + | Next, the IMU must be leveled to the boat. When it is mounted and secured to the vessel, level the sensors. |
+ | Last, the compass which can change widely depending on where it is mounted and what is around it must be calibrated. There are two possible results, 2D and 3D calibration. If the boat makes a flat circle, only 2D calibration is possible. | ||
+ | |||
+ | With 2D compass calibration, the heading is only accurate when level. | ||
+ | |||
+ | With 3D calibration is accurate when pitching and rolling. | ||
+ | |||
+ | To get a 3D calibration suggestions: | ||
+ | * Sail in a circle tacking through the wind with sufficient heeling angle until calibrated | ||
+ | * Get crude 3d compass calibration before fixing to boat. Then make circle, and 2d calibration updates 3d calibration. | ||
+ | |||
+ | - mpu9250/mpu9255 -- With yellow capacitor the accelerometer is already biased, with orange capacitor accelerometer bias calibration needed. | ||
+ | - LSM9DS0 (seems ok) | ||
+ | - L3GD20H, LSM303D (seems ok) | ||