ardupilot/libraries/AP_HAL_SITL/sitl_rangefinder.cpp

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/*
SITL handling
This simulates a rangefinder
*/
#include <AP_HAL/AP_HAL.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_SITL && !defined(HAL_BUILD_AP_PERIPH)
#include "AP_HAL_SITL.h"
#include "AP_HAL_SITL_Namespace.h"
#include "HAL_SITL_Class.h"
#include "SITL_State.h"
#include <SITL/SITL.h>
#include <AP_Math/AP_Math.h>
extern const AP_HAL::HAL& hal;
using namespace HALSITL;
/*
setup the rangefinder with new input
*/
void SITL_State::_update_rangefinder(float range_value)
{
float altitude = range_value;
if (is_equal(range_value, -1.0f)) { // Use SITL altitude as reading by default
altitude = _sitl->height_agl;
}
// sensor position offset in body frame
const Vector3f relPosSensorBF = _sitl->rngfnd_pos_offset;
// adjust altitude for position of the sensor on the vehicle if position offset is non-zero
if (!relPosSensorBF.is_zero()) {
// get a rotation matrix following DCM conventions (body to earth)
Matrix3f rotmat;
_sitl->state.quaternion.rotation_matrix(rotmat);
// rotate the offset into earth frame
const Vector3f relPosSensorEF = rotmat * relPosSensorBF;
// correct the altitude at the sensor
altitude -= relPosSensorEF.z;
}
float voltage = 5.0f; // Start the reading at max value = 5V
// If the attidude is non reversed for SITL OR we are using rangefinder from external simulator,
// We adjust the reading with noise, glitch and scaler as the reading is on analog port.
if ((fabs(_sitl->state.rollDeg) < 90.0 && fabs(_sitl->state.pitchDeg) < 90.0) || !is_equal(range_value, -1.0f)) {
if (is_equal(range_value, -1.0f)) { // disable for external reading that already handle this
// adjust for apparent altitude with roll
altitude /= cosf(radians(_sitl->state.rollDeg)) * cosf(radians(_sitl->state.pitchDeg));
}
// Add some noise on reading
altitude += _sitl->sonar_noise * rand_float();
// Altitude in in m, scaler in meters/volt
voltage = altitude / _sitl->sonar_scale;
// constrain to 0-5V
voltage = constrain_float(voltage, 0.0f, 5.0f);
// Use glitch defines as the probablility between 0-1 that any given sonar sample will read as max distance
if (!is_zero(_sitl->sonar_glitch) && _sitl->sonar_glitch >= (rand_float() + 1.0f) / 2.0f) {
voltage = 5.0f;
}
}
// if not populated also fill out the STIL rangefinder array
if (is_equal(_sitl->state.rangefinder_m[0],-1.0f)) {
_sitl->state.rangefinder_m[0] = altitude;
}
sonar_pin_value = 1023 * (voltage / 5.0f);
}
#endif