ardupilot/libraries/AP_AHRS/AP_AHRS.cpp

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/*
APM_AHRS.cpp
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License
as published by the Free Software Foundation; either version 2.1
of the License, or (at your option) any later version.
*/
#include <FastSerial.h>
#include <AP_AHRS.h>
// table of user settable parameters
const AP_Param::GroupInfo AP_AHRS::var_info[] PROGMEM = {
// index 0 and 1 are for old parameters that are no longer used
// @Param: GPS_GAIN
// @DisplayName: AHRS GPS gain
// @Description: This controls how how much to use the GPS to correct the attitude
// @Range: 0.0 1.0
// @Increment: .01
AP_GROUPINFO("GPS_GAIN", 2, AP_AHRS, gps_gain, 1.0),
// @Param: GPS_USE
// @DisplayName: AHRS use GPS
// @Description: This controls how how much to use the GPS to correct the attitude. This is for testing the dead-reckoning code
// @User: Advanced
AP_GROUPINFO("GPS_USE", 3, AP_AHRS, _gps_use, 1),
// @Param: YAW_P
// @DisplayName: Yaw P
// @Description: This controls the weight the compass has on the overall heading
// @Range: 0 .4
// @Increment: .01
AP_GROUPINFO("YAW_P", 4, AP_AHRS, _kp_yaw, 0.4),
// @Param: RP_P
// @DisplayName: AHRS RP_P
// @Description: This controls how fast the accelerometers correct the attitude
// @Range: 0 .4
// @Increment: .01
AP_GROUPINFO("RP_P", 5, AP_AHRS, _kp, 0.4),
// @Param: WIND_MAX
// @DisplayName: Maximum wind
// @Description: This sets the maximum allowable difference between ground speed and airspeed. This allows the plane to cope with a failing airspeed sensor. A value of zero means to use the airspeed as is.
// @Range: 0 127
// QUnits: m/s
// @Increment: 1
AP_GROUPINFO("WIND_MAX", 6, AP_AHRS, _wind_max, 0.0),
// @Param: BARO_USE
// @DisplayName: AHRS Use Barometer
// @Description: This controls the use of the barometer for vertical acceleration compensation in AHRS
// @Values: 0:Disabled,1:Enabled
// @User: Advanced
AP_GROUPINFO("BARO_USE", 7, AP_AHRS, _baro_use, 1),
AP_GROUPEND
};
// get pitch rate in earth frame, in radians/s
float AP_AHRS::get_pitch_rate_earth(void)
{
Vector3f omega = get_gyro();
return cos(roll) * omega.y - sin(roll) * omega.z;
}
// get roll rate in earth frame, in radians/s
float AP_AHRS::get_roll_rate_earth(void) {
Vector3f omega = get_gyro();
return omega.x + tan(pitch)*(omega.y*sin(roll) + omega.z*cos(roll));
}
// return airspeed estimate if available
bool AP_AHRS::airspeed_estimate(float *airspeed_ret)
{
if (_airspeed && _airspeed->use()) {
*airspeed_ret = _airspeed->get_airspeed();
if (_wind_max > 0 && _gps && _gps->status() == GPS::GPS_OK) {
// constrain the airspeed by the ground speed
// and AHRS_WIND_MAX
*airspeed_ret = constrain(*airspeed_ret,
_gps->ground_speed*0.01 - _wind_max,
_gps->ground_speed*0.01 + _wind_max);
}
return true;
}
return false;
}