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Code Issues Releases Activity

Added power-up barometric altitude calibration. Height accuracy is not sufficient, for better results we may want some filtering and/or another sensor/ADC. But at least now the BaroAltitude.Altitude object provides meaningful data comparing to uncalibrated zero height.

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git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@2251 ebee16cc-31ac-478f-84a7-5cbb03baadba
This commit is contained in:
osnwt 2010-12-18 23:40:17 +00:00 committed by osnwt
parent 7f00e88321
commit 7d084aca49
1 changed files with 10 additions and 1 deletions
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11
flight/OpenPilot/Modules/Altitude/altitude.c
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@ -69,6 +69,10 @@ int32_t AltitudeInitialize()
*/ */
static void altitudeTask(void *parameters) static void altitudeTask(void *parameters)
{ {
// For power-up zero height pressure calibration
static float p0 = BMP085_P0 / 1000.0;
static uint32_t i = 15;
BaroAltitudeData data; BaroAltitudeData data;
portTickType lastSysTime; portTickType lastSysTime;
@ -93,8 +97,13 @@ static void altitudeTask(void *parameters)
// Convert from Pa to kPa // Convert from Pa to kPa
data.Pressure = PIOS_BMP085_GetPressure() / 1000.0; data.Pressure = PIOS_BMP085_GetPressure() / 1000.0;
// Save zero height pressure as p0
if (i && (--i == 0)) {
p0 = data.Pressure;
}
// Compute the current altitude (all pressures in kPa) // Compute the current altitude (all pressures in kPa)
data.Altitude = 44330.0 * (1.0 - powf((data.Pressure / (BMP085_P0 / 1000.0)), (1.0 / 5.255))); data.Altitude = 44330.0 * (1.0 - powf((data.Pressure / p0), (1.0 / 5.255)));
// Update the AltitudeActual UAVObject // Update the AltitudeActual UAVObject
BaroAltitudeSet(&data); BaroAltitudeSet(&data);