forked from Archive/PX4-Autopilot
79 lines
3.1 KiB
C
79 lines
3.1 KiB
C
/****************************************************************************
|
|
*
|
|
* Copyright (C) 2012-2013 PX4 Development Team. All rights reserved.
|
|
* Author: Lorenz Meier <lm@inf.ethz.ch>
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in
|
|
* the documentation and/or other materials provided with the
|
|
* distribution.
|
|
* 3. Neither the name PX4 nor the names of its contributors may be
|
|
* used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
|
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
|
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
|
|
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
|
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
|
|
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/**
|
|
* @file airspeed.c
|
|
* Airspeed estimation
|
|
*
|
|
* @author Lorenz Meier <lm@inf.ethz.ch>
|
|
*
|
|
*/
|
|
|
|
#include "math.h"
|
|
|
|
|
|
float calc_indicated_airspeed(float pressure_front, float pressure_ambient, float temperature)
|
|
{
|
|
return sqrtf((2.0f*(pressure_front - pressure_ambient)) / air_density_sea_level);
|
|
}
|
|
|
|
/**
|
|
* Calculate true airspeed from indicated airspeed.
|
|
*
|
|
* Note that the true airspeed is NOT the groundspeed, because of the effects of wind
|
|
*
|
|
* @param speed current indicated airspeed
|
|
* @param pressure_ambient pressure at the side of the tube/airplane
|
|
* @param temperature air temperature in degrees celcius
|
|
* @return true airspeed in m/s
|
|
*/
|
|
float calc_true_airspeed_from_indicated(float speed, float pressure_ambient, float temperature)
|
|
{
|
|
return speed * sqrtf(air_density_sea_level / get_air_density(pressure_ambient, temperature));
|
|
}
|
|
|
|
/**
|
|
* Directly calculate true airspeed
|
|
*
|
|
* Note that the true airspeed is NOT the groundspeed, because of the effects of wind
|
|
*
|
|
* @param pressure_front pressure inside the pitot/prandl tube
|
|
* @param pressure_ambient pressure at the side of the tube/airplane
|
|
* @param temperature air temperature in degrees celcius
|
|
* @return true airspeed in m/s
|
|
*/
|
|
float calc_true_airspeed(float pressure_front, float pressure_ambient, float temperature)
|
|
{
|
|
return sqrtf((2.0f*(pressure_front - pressure_ambient)) / get_air_density(pressure_ambient, temperature));
|
|
} |