ardupilot/libraries/AP_OpticalFlow/AP_OpticalFlow_MAV.cpp

107 lines
3.3 KiB
C++

/*
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/>.
*/
#include <AP_HAL/AP_HAL.h>
#include <AP_AHRS/AP_AHRS.h>
#include "AP_OpticalFlow_MAV.h"
#define OPTFLOW_MAV_TIMEOUT_SEC 0.5f
// detect the device
AP_OpticalFlow_MAV *AP_OpticalFlow_MAV::detect(OpticalFlow &_frontend)
{
// we assume mavlink messages will be sent into this driver
AP_OpticalFlow_MAV *sensor = new AP_OpticalFlow_MAV(_frontend);
return sensor;
}
// read latest values from sensor and fill in x,y and totals.
void AP_OpticalFlow_MAV::update(void)
{
// record gyro values as long as they are being used
// the sanity check of dt below ensures old gyro values are not used
if (gyro_sum_count < 1000) {
const Vector3f& gyro = AP::ahrs().get_gyro();
gyro_sum.x += gyro.x;
gyro_sum.y += gyro.y;
gyro_sum_count++;
}
// return without updating state if no readings
if (count == 0) {
return;
}
struct OpticalFlow::OpticalFlow_state state {};
state.surface_quality = quality_sum / count;
// calculate dt
const float dt = (latest_frame_us - prev_frame_us) * 1.0e-6;
prev_frame_us = latest_frame_us;
// sanity check dt
if (is_positive(dt) && (dt < OPTFLOW_MAV_TIMEOUT_SEC)) {
// calculate flow values
const float flow_scale_factor_x = 1.0f + 0.001f * _flowScaler().x;
const float flow_scale_factor_y = 1.0f + 0.001f * _flowScaler().y;
// copy flow rates to state structure
state.flowRate = { ((float)flow_sum.x / count) * flow_scale_factor_x * dt,
((float)flow_sum.y / count) * flow_scale_factor_y * dt };
// copy average body rate to state structure
state.bodyRate = { gyro_sum.x / gyro_sum_count, gyro_sum.y / gyro_sum_count };
_applyYaw(state.flowRate);
_applyYaw(state.bodyRate);
} else {
// first frame received in some time so cannot calculate flow values
state.flowRate.zero();
state.bodyRate.zero();
}
_update_frontend(state);
// reset local buffers
flow_sum.zero();
quality_sum = 0;
count = 0;
// reset gyro sum
gyro_sum.zero();
gyro_sum_count = 0;
}
// handle OPTICAL_FLOW mavlink messages
void AP_OpticalFlow_MAV::handle_msg(const mavlink_message_t *msg)
{
mavlink_optical_flow_t packet;
mavlink_msg_optical_flow_decode(msg, &packet);
// record time message was received
// ToDo: add jitter correction
latest_frame_us = AP_HAL::micros64();
// add sensor values to sum
flow_sum.x += packet.flow_x;
flow_sum.y += packet.flow_y;
quality_sum += packet.quality;
count++;
// take sensor id from message
sensor_id = packet.sensor_id;
}