ardupilot/libraries/AP_HAL_SITL/sitl_ins.cpp

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/*
SITL handling
This emulates the ADS7844 ADC
Andrew Tridgell November 2011
*/
#include <AP_HAL/AP_HAL.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
#include "AP_HAL_SITL.h"
#include "AP_HAL_SITL_Namespace.h"
#include "HAL_SITL_Class.h"
#include <AP_Math/AP_Math.h>
#include <AP_Compass/AP_Compass.h>
#include <AP_Declination/AP_Declination.h>
#include <AP_RangeFinder/AP_RangeFinder.h>
#include <SITL/SITL.h>
#include "Scheduler.h"
#include <AP_Math/AP_Math.h>
#include <AP_ADC/AP_ADC.h>
#include "SITL_State.h"
#include <fenv.h>
extern const AP_HAL::HAL& hal;
using namespace HALSITL;
/*
convert airspeed in m/s to an airspeed sensor value
*/
uint16_t SITL_State::_airspeed_sensor(float airspeed)
{
const float airspeed_ratio = 1.9936f;
const float airspeed_offset = 2013;
float airspeed_pressure, airspeed_raw;
airspeed_pressure = (airspeed*airspeed) / airspeed_ratio;
airspeed_raw = airspeed_pressure + airspeed_offset;
if (airspeed_raw/4 > 0xFFFF) {
return 0xFFFF;
}
// add delay
uint32_t now = hal.scheduler->millis();
uint32_t best_time_delta_wind = 200; // initialise large time representing buffer entry closest to current time - delay.
uint8_t best_index_wind = 0; // initialise number representing the index of the entry in buffer closest to delay.
// storing data from sensor to buffer
if (now - last_store_time_wind >= 10) { // store data every 10 ms.
last_store_time_wind = now;
if (store_index_wind > wind_buffer_length-1) { // reset buffer index if index greater than size of buffer
store_index_wind = 0;
}
buffer_wind[store_index_wind].data = airspeed_raw; // add data to current index
buffer_wind[store_index_wind].time = last_store_time_wind; // add time to current index
store_index_wind = store_index_wind + 1; // increment index
}
// return delayed measurement
delayed_time_wind = now - _sitl->wind_delay; // get time corresponding to delay
// find data corresponding to delayed time in buffer
for (uint8_t i=0; i<=wind_buffer_length-1; i++) {
time_delta_wind = abs(delayed_time_wind - buffer_wind[i].time); // find difference between delayed time and time stamp in buffer
// if this difference is smaller than last delta, store this time
if (time_delta_wind < best_time_delta_wind) {
best_index_wind = i;
best_time_delta_wind = time_delta_wind;
}
}
if (best_time_delta_wind < 200) { // only output stored state if < 200 msec retrieval error
airspeed_raw = buffer_wind[best_index_wind].data;
}
return airspeed_raw/4;
}
float SITL_State::_gyro_drift(void)
{
if (_sitl->drift_speed == 0.0f ||
_sitl->drift_time == 0.0f) {
return 0;
}
double period = _sitl->drift_time * 2;
double minutes = fmod(_scheduler->_micros64() / 60.0e6, period);
if (minutes < period/2) {
return minutes * ToRad(_sitl->drift_speed);
}
return (period - minutes) * ToRad(_sitl->drift_speed);
}
/*
emulate an analog rangefinder
*/
uint16_t SITL_State::_ground_sonar(void)
{
float altitude = height_agl();
float voltage = 5.0f;
if (fabsf(_sitl->state.rollDeg) < 90 &&
fabsf(_sitl->state.pitchDeg) < 90) {
// adjust for apparent altitude with roll
altitude /= cosf(radians(_sitl->state.rollDeg)) * cosf(radians(_sitl->state.pitchDeg));
altitude += _sitl->sonar_noise * _rand_float();
// Altitude in in m, scaler in meters/volt
voltage = altitude / _sitl->sonar_scale;
voltage = constrain_float(voltage, 0, 5.0f);
if (_sitl->sonar_glitch >= (_rand_float() + 1.0f)/2.0f) {
voltage = 5.0f;
}
}
return 1023*(voltage / 5.0f);
}
/*
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, float altitude)
{
if (_ins == NULL) {
// no inertial sensor in this sketch
return;
}
// minimum noise levels are 2 bits, but averaged over many
// samples, giving around 0.01 m/s/s
float accel_noise = 0.01f;
float accel2_noise = 0.01f;
// minimum gyro noise is also less than 1 bit
float gyro_noise = ToRad(0.04f);
if (_motors_on) {
// add extra noise when the motors are on
accel_noise += _sitl->accel_noise;
accel2_noise += _sitl->accel2_noise;
gyro_noise += ToRad(_sitl->gyro_noise);
}
// get accel bias (add only to first accelerometer)
Vector3f accel_bias = _sitl->accel_bias.get();
float xAccel1 = xAccel + accel_noise * _rand_float() + accel_bias.x;
float yAccel1 = yAccel + accel_noise * _rand_float() + accel_bias.y;
float zAccel1 = zAccel + accel_noise * _rand_float() + accel_bias.z;
float xAccel2 = xAccel + accel2_noise * _rand_float();
float yAccel2 = yAccel + accel2_noise * _rand_float();
float zAccel2 = zAccel + accel2_noise * _rand_float();
if (fabsf(_sitl->accel_fail) > 1.0e-6f) {
xAccel1 = _sitl->accel_fail;
yAccel1 = _sitl->accel_fail;
zAccel1 = _sitl->accel_fail;
}
Vector3f accel0 = Vector3f(xAccel1, yAccel1, zAccel1) + _ins->get_accel_offsets(0);
Vector3f accel1 = Vector3f(xAccel2, yAccel2, zAccel2) + _ins->get_accel_offsets(1);
_ins->set_accel(0, accel0);
_ins->set_accel(1, accel1);
// check noise
_ins->calc_vibration_and_clipping(0, accel0, 0.0025f);
_ins->calc_vibration_and_clipping(1, accel1, 0.0025f);
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float p = radians(rollRate) + _gyro_drift();
float q = radians(pitchRate) + _gyro_drift();
float r = radians(yawRate) + _gyro_drift();
float p1 = p + gyro_noise * _rand_float();
float q1 = q + gyro_noise * _rand_float();
float r1 = r + gyro_noise * _rand_float();
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float p2 = p + gyro_noise * _rand_float();
float q2 = q + gyro_noise * _rand_float();
float r2 = r + gyro_noise * _rand_float();
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_ins->set_gyro(0, Vector3f(p1, q1, r1) + _ins->get_gyro_offsets(0));
_ins->set_gyro(1, Vector3f(p2, q2, r2) + _ins->get_gyro_offsets(1));
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sonar_pin_value = _ground_sonar();
float airspeed_simulated = (fabsf(_sitl->aspd_fail) > 1.0e-6f) ? _sitl->aspd_fail : airspeed;
airspeed_pin_value = _airspeed_sensor(airspeed_simulated + (_sitl->aspd_noise * _rand_float()));
}
#endif