ardupilot/libraries/AP_HAL_AVR_SITL/sitl_ins.cpp

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/*
SITL handling
This emulates the ADS7844 ADC
Andrew Tridgell November 2011
*/
#include <AP_HAL.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_AVR_SITL
#include <AP_HAL_AVR.h>
#include <AP_HAL_AVR_SITL.h>
#include "AP_HAL_AVR_SITL_Namespace.h"
#include "HAL_AVR_SITL_Class.h"
#include <AP_Math.h>
#include "../AP_Compass/AP_Compass.h"
#include "../AP_Declination/AP_Declination.h"
#include "../SITL/SITL.h"
#include "Scheduler.h"
#include <AP_Math.h>
#include "../AP_ADC/AP_ADC.h"
#include <SITL_State.h>
using namespace AVR_SITL;
/*
convert airspeed in m/s to an airspeed sensor value
*/
uint16_t SITL_State::_airspeed_sensor(float airspeed)
{
const float airspeed_ratio = 1.9936;
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const float airspeed_offset = 2013;
float airspeed_pressure, airspeed_raw;
airspeed_pressure = (airspeed*airspeed) / airspeed_ratio;
airspeed_raw = airspeed_pressure + airspeed_offset;
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return airspeed_raw/4;
}
float SITL_State::_gyro_drift(void)
{
if (_sitl->drift_speed == 0.0) {
return 0;
}
double period = _sitl->drift_time * 2;
double minutes = fmod(_scheduler->_micros() / 60.0e6, period);
if (minutes < period/2) {
return minutes * ToRad(_sitl->drift_speed);
}
return (period - minutes) * ToRad(_sitl->drift_speed);
}
/*
setup the INS input channels with new input
Note that this uses roll, pitch and yaw only as inputs. The
simulator rollrates are instantaneous, whereas we need to use
average rates to cope with slow update rates.
inputs are in degrees
phi - roll
theta - pitch
psi - true heading
alpha - angle of attack
beta - side slip
phidot - roll rate
thetadot - pitch rate
psidot - yaw rate
v_north - north velocity in local/body frame
v_east - east velocity in local/body frame
v_down - down velocity in local/body frame
A_X_pilot - X accel in body frame
A_Y_pilot - Y accel in body frame
A_Z_pilot - Z accel in body frame
Note: doubles on high prec. stuff are preserved until the last moment
*/
void SITL_State::_update_ins(float roll, float pitch, float yaw, // Relative to earth
double rollRate, double pitchRate,double yawRate, // Local to plane
double xAccel, double yAccel, double zAccel, // Local to plane
float airspeed)
{
double p, q, r;
if (_ins == NULL) {
// no inertial sensor in this sketch
return;
}
SITL::convert_body_frame(roll, pitch,
rollRate, pitchRate, yawRate,
&p, &q, &r);
// minimum noise levels are 2 bits
float accel_noise = 0.1;
float gyro_noise = ToRad(0.4);
if (_motors_on) {
// add extra noise when the motors are on
accel_noise += _sitl->accel_noise;
gyro_noise += ToRad(_sitl->gyro_noise);
}
xAccel += accel_noise * _rand_float();
yAccel += accel_noise * _rand_float();
zAccel += accel_noise * _rand_float();
p += gyro_noise * _rand_float();
q += gyro_noise * _rand_float();
r += gyro_noise * _rand_float();
p += _gyro_drift();
q += _gyro_drift();
r += _gyro_drift();
_ins->set_gyro(Vector3f(p, q, r) + _ins->get_gyro_offsets());
_ins->set_accel(Vector3f(xAccel, yAccel, zAccel) + _ins->get_accel_offsets());
airspeed_pin_value = _airspeed_sensor(airspeed);
}
#endif