// apply yaw angle to a vector
void OpticalFlow_backend::_applyYaw(Vector2f &v)
{
float yawAngleRad = _yawAngleRad();
if (is_zero(yawAngleRad)) {
return;
}
float cosYaw = cosf(yawAngleRad);
float sinYaw = sinf(yawAngleRad);
float x = v.x;
float y = v.y;
v.x = cosYaw * x - sinYaw * y;
v.y = sinYaw * x + cosYaw * y;
}
// update - read latest values from sensor and fill in x,y and totals.
void AP_OpticalFlow_PX4::update(void)
{
// return immediately if not initialised
if (_fd == -1) {
return;
}
float sum = 0;
uint16_t count = 0;
struct optical_flow_s report;
while (::read(_fd, &report, sizeof(optical_flow_s)) == sizeof(optical_flow_s) &&
report.timestamp != _last_timestamp) {
struct OpticalFlow::OpticalFlow_state state;
state.device_id = report.sensor_id;
state.surface_quality = report.quality;
if (report.integration_timespan > 0) {
float yawAngleRad = _yawAngleRad();
float cosYaw = cosf(yawAngleRad);
float sinYaw = sinf(yawAngleRad);
const Vector2f flowScaler = _flowScaler();
float flowScaleFactorX = 1.0f + 0.001f * flowScaler.x;
float flowScaleFactorY = 1.0f + 0.001f * flowScaler.y;
float integralToRate = 1e6f / float(report.integration_timespan);
// rotate sensor measurements from sensor to body frame through sensor yaw angle
state.flowRate.x = flowScaleFactorX * integralToRate * (cosYaw * float(report.pixel_flow_x_integral) - sinYaw * float(report.pixel_flow_y_integral)); // rad/sec measured optically about the X body axis
state.flowRate.y = flowScaleFactorY * integralToRate * (sinYaw * float(report.pixel_flow_x_integral) + cosYaw * float(report.pixel_flow_y_integral)); // rad/sec measured optically about the Y body axis
state.bodyRate.x = integralToRate * (cosYaw * float(report.gyro_x_rate_integral) - sinYaw * float(report.gyro_y_rate_integral)); // rad/sec measured inertially about the X body axis
state.bodyRate.y = integralToRate * (sinYaw * float(report.gyro_x_rate_integral) + cosYaw * float(report.gyro_y_rate_integral)); // rad/sec measured inertially about the Y body axis
} else {
state.flowRate.zero();
state.bodyRate.zero();
}
sum += report.ground_distance_m;
count++;
_last_timestamp = report.timestamp;
_update_frontend(state);
}
if (count != 0){
float dist = sum / count * 100.0f;
setDistance( dist );
}
}
