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AP_OpticalFlow: added _applyYaw method to backend 

for common handling of yaw correction
This commit is contained in:
Andrew Tridgell 2016-11-20 08:22:02 +11:00
parent abc42c737c
commit ea462d80e6
4 changed files with 31 additions and 8 deletions
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18
libraries/AP_OpticalFlow/AP_OpticalFlow_PX4.cpp
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@ -79,18 +79,20 @@ void AP_OpticalFlow_PX4::update(void)
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
// rad/sec measured optically about the X body axis
state.flowRate.x = flowScaleFactorX * integralToRate * report.pixel_flow_x_integral;
state.flowRate.y = flowScaleFactorY * integralToRate * report.pixel_flow_y_integral;
_applyYaw(state.flowRate);
// rad/sec measured inertially about the X body axis
state.bodyRate.x = integralToRate * report.gyro_x_rate_integral;
state.bodyRate.y = integralToRate * report.gyro_y_rate_integral;
_applyYaw(state.bodyRate);
} else {
state.flowRate.zero();
state.bodyRate.zero();

3
libraries/AP_OpticalFlow/AP_OpticalFlow_Pixart.cpp
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@ -313,6 +313,9 @@ void AP_OpticalFlow_Pixart::update(void)
integral.sum.y * flowScaleFactorY);
state.flowRate *= flow_pixel_scaling / dt;
// we only apply yaw to flowRate as body rate comes from AHRS
_applyYaw(state.flowRate);
state.bodyRate = integral.gyro / dt;
integral.sum.zero();

15
libraries/AP_OpticalFlow/OpticalFlow_backend.cpp
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@ -36,3 +36,18 @@ void OpticalFlow_backend::_update_frontend(const struct OpticalFlow::OpticalFlow
frontend._state = state;
frontend._last_update_ms = AP_HAL::millis();
}
// 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;
}

3
libraries/AP_OpticalFlow/OpticalFlow_backend.h
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@ -48,6 +48,9 @@ protected:
// get the yaw angle in radians
float _yawAngleRad(void) const { return radians(float(frontend._yawAngle_cd) * 0.01f); }
// apply yaw angle to a vector
void _applyYaw(Vector2f &v);
// get access to AHRS object
AP_AHRS_NavEKF &get_ahrs(void) { return frontend._ahrs; }