ardupilot/libraries/AP_OpticalFlow/AP_OpticalFlow_SITL.cpp

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/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* AP_OpticalFlow_SITL.cpp - SITL emulation of optical flow sensor.
*/
#include <AP_HAL/AP_HAL.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
#include "AP_OpticalFlow_SITL.h"
extern const AP_HAL::HAL& hal;
AP_OpticalFlow_SITL::AP_OpticalFlow_SITL(OpticalFlow &_frontend) :
OpticalFlow_backend(_frontend)
{
_sitl = (SITL::SITL *)AP_Param::find_object("SIM_");
}
void AP_OpticalFlow_SITL::init(void)
{
}
void AP_OpticalFlow_SITL::update(void)
{
if (!_sitl->flow_enable) {
return;
}
// update at the requested rate
uint32_t now = AP_HAL::millis();
if (now - last_flow_ms < 1000*(1.0f/_sitl->flow_rate)) {
return;
}
last_flow_ms = now;
Vector3f gyro(radians(_sitl->state.rollRate),
radians(_sitl->state.pitchRate),
radians(_sitl->state.yawRate));
OpticalFlow::OpticalFlow_state state;
// NED velocity vector in m/s
Vector3f velocity(_sitl->state.speedN,
_sitl->state.speedE,
_sitl->state.speedD);
// a rotation matrix following DCM conventions
Matrix3f rotmat;
rotmat.from_euler(radians(_sitl->state.rollDeg),
radians(_sitl->state.pitchDeg),
radians(_sitl->state.yawDeg));
state.device_id = 1;
state.surface_quality = 51;
// sensor position offset in body frame
Vector3f posRelSensorBF = _sitl->optflow_pos_offset;
// estimate range to centre of image
float range;
if (rotmat.c.z > 0.05f && _sitl->height_agl > 0) {
Vector3f relPosSensorEF = rotmat * posRelSensorBF;
range = (_sitl->height_agl - relPosSensorEF.z) / rotmat.c.z;
} else {
range = 1e38f;
}
// Calculate relative velocity in sensor frame assuming no misalignment between sensor and vehicle body axes
Vector3f relVelSensor = rotmat.mul_transpose(velocity);
// correct relative velocity for rotation rates and sensor offset
relVelSensor += gyro % posRelSensorBF;
// Divide velocity by range and add body rates to get predicted sensed angular
// optical rates relative to X and Y sensor axes assuming no misalignment or scale
// factor error. Note - these are instantaneous values. The sensor sums these values across the interval from the last
// poll to provide a delta angle across the interface
state.flowRate.x = -relVelSensor.y/range + gyro.x;
state.flowRate.y = relVelSensor.x/range + gyro.y;
// The flow sensors body rates are assumed to be the same as the vehicle body rates (ie no misalignment)
// Note - these are instantaneous values. The sensor sums these values across the interval from the last
// poll to provide a delta angle across the interface.
state.bodyRate = Vector2f(gyro.x, gyro.y);
optflow_data[next_optflow_index++] = state;
if (next_optflow_index >= optflow_delay+1) {
next_optflow_index = 0;
}
state = optflow_data[next_optflow_index];
if (_sitl->flow_delay != optflow_delay) {
// cope with updates to the delay control
if (_sitl->flow_delay > 0 &&
(uint8_t)(_sitl->flow_delay) > ARRAY_SIZE(optflow_data)) {
_sitl->flow_delay = ARRAY_SIZE(optflow_data);
}
optflow_delay = _sitl->flow_delay;
for (uint8_t i=0; i<optflow_delay; i++) {
optflow_data[i] = state;
}
}
_applyYaw(state.flowRate);
// copy results to front end
_update_frontend(state);
}
#endif // CONFIG_HAL_BOARD