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author | Andrew Tridgell <tridge@samba.org> | 2014-02-12 12:18:20 +1100 |
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committer | Lorenz Meier <lm@inf.ethz.ch> | 2014-04-05 13:10:35 +0200 |
commit | 00c82f0836388ffa1e1c4a5827eefe28c0521df8 (patch) | |
tree | 76b86553dd99a09bcac65b95a16d98da556e2601 | |
parent | 06d5c6ad285a46cfb59ce07bc3cd49507305a997 (diff) | |
download | px4-firmware-00c82f0836388ffa1e1c4a5827eefe28c0521df8.tar.gz px4-firmware-00c82f0836388ffa1e1c4a5827eefe28c0521df8.tar.bz2 px4-firmware-00c82f0836388ffa1e1c4a5827eefe28c0521df8.zip |
Merged airspeed changes
-rw-r--r-- | src/drivers/meas_airspeed/meas_airspeed.cpp | 62 |
1 files changed, 59 insertions, 3 deletions
diff --git a/src/drivers/meas_airspeed/meas_airspeed.cpp b/src/drivers/meas_airspeed/meas_airspeed.cpp index 2c3efdc35..2324475ce 100644 --- a/src/drivers/meas_airspeed/meas_airspeed.cpp +++ b/src/drivers/meas_airspeed/meas_airspeed.cpp @@ -87,6 +87,7 @@ #include <uORB/uORB.h> #include <uORB/topics/differential_pressure.h> #include <uORB/topics/subsystem_info.h> +#include <uORB/topics/system_power.h> #include <drivers/airspeed/airspeed.h> @@ -121,6 +122,14 @@ protected: virtual int collect(); math::LowPassFilter2p _filter; + + /** + * Correct for 5V rail voltage variations + */ + void voltage_correction(float &diff_pres_pa); + + int _t_system_power; + struct system_power_s system_power; }; /* @@ -129,10 +138,11 @@ protected: extern "C" __EXPORT int meas_airspeed_main(int argc, char *argv[]); MEASAirspeed::MEASAirspeed(int bus, int address, const char *path) : Airspeed(bus, address, - CONVERSION_INTERVAL, path), - _filter(MEAS_RATE, MEAS_DRIVER_FILTER_FREQ) + CONVERSION_INTERVAL, path), + _filter(MEAS_RATE, MEAS_DRIVER_FILTER_FREQ), + _t_system_power(-1) { - + memset(&system_power, 0, sizeof(system_power)); } int @@ -207,6 +217,9 @@ MEASAirspeed::collect() diff_press_pa = 0.0f; } + // correct for 5V rail voltage if possible + voltage_correction(diff_press_pa); + struct differential_pressure_s report; /* track maximum differential pressure measured (so we can work out top speed). */ @@ -288,6 +301,49 @@ MEASAirspeed::cycle() } /** + correct for 5V rail voltage if the system_power ORB topic is + available + + See http://uav.tridgell.net/MS4525/MS4525-offset.png for a graph of + offset versus voltage for 3 sensors + */ +void +MEASAirspeed::voltage_correction(float &diff_press_pa) +{ +#ifdef CONFIG_ARCH_BOARD_PX4FMU_V2 + if (_t_system_power == -1) { + _t_system_power = orb_subscribe(ORB_ID(system_power)); + } + if (_t_system_power == -1) { + // not available + return; + } + bool updated = false; + orb_check(_t_system_power, &updated); + if (updated) { + orb_copy(ORB_ID(system_power), _t_system_power, &system_power); + } + if (system_power.voltage5V_v < 3.0f || system_power.voltage5V_v > 6.0f) { + // not valid, skip correction + return; + } + + const float slope = 70.0f; + /* + apply a piecewise linear correction, flattening at 0.5V from 5V + */ + float voltage_diff = system_power.voltage5V_v - 5.0f; + if (voltage_diff > 0.5f) { + voltage_diff = 0.5f; + } + if (voltage_diff < -0.5f) { + voltage_diff = -0.5f; + } + diff_press_pa -= voltage_diff * slope; +#endif // CONFIG_ARCH_BOARD_PX4FMU_V2 +} + +/** * Local functions in support of the shell command. */ namespace meas_airspeed |