ardupilot/libraries/AP_HAL_SITL/sitl_optical_flow.cpp

133 lines
3.8 KiB
C++

/*
SITL handling
This simulates a optical flow sensor
Andrew Tridgell November 2011
*/
#include <AP_HAL/AP_HAL.h>
#include <AP_Math/AP_Math.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
#include "AP_HAL_SITL.h"
using namespace HALSITL;
extern const AP_HAL::HAL& hal;
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <cmath>
#define MAX_OPTFLOW_DELAY 20
static uint8_t next_optflow_index;
static uint8_t optflow_delay;
static OpticalFlow::OpticalFlow_state optflow_data[MAX_OPTFLOW_DELAY];
/*
update the optical flow with new data
*/
void SITL_State::_update_flow(void)
{
Vector3f gyro;
static uint32_t last_flow_ms;
if (!_optical_flow ||
!_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;
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;
// for effiency only do offset correction if offset is non-zero
bool correctForOffset = !posRelSensorBF.is_zero();
// estimate range to centre of image
float range;
if (rotmat.c.z > 0.05f && height_agl() > 0) {
if (!correctForOffset) {
range = height_agl() / rotmat.c.z;
} else {
Vector3f relPosSensorEF = rotmat * posRelSensorBF;
range = (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
if (correctForOffset) {
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 > MAX_OPTFLOW_DELAY) {
_sitl->flow_delay = MAX_OPTFLOW_DELAY;
}
optflow_delay = _sitl->flow_delay;
for (uint8_t i=0; i<optflow_delay; i++) {
optflow_data[i] = state;
}
}
_optical_flow->setHIL(state);
}
#endif