AP_OpticalFlow: Add separate scale factors for X and Y axis.

The resolution is also increased to take advantage of the planned introduction of automated calibration methods

libraries/AP_OpticalFlow/AP_OpticalFlow_PX4.cpp

@@ -64,10 +64,11 @@ void AP_OpticalFlow_PX4::update(void)
         _device_id = report.sensor_id;
         _surface_quality = report.quality;
         if (report.integration_timespan > 0) {
-            float flowScaleFactor = 0.01f * float(100 + _flowScaler);
+            float flowScaleFactorX = 1.0f + 0.001f * float(_flowScalerX);
+            float flowScaleFactorY = 1.0f + 0.001f * float(_flowScalerY);
             float integralToRate = 1e6f / float(report.integration_timespan);
-            _flowRate.x = flowScaleFactor * integralToRate * float(report.pixel_flow_x_integral); // rad/sec measured optically about the X sensor axis
-            _flowRate.y = flowScaleFactor * integralToRate * float(report.pixel_flow_y_integral); // rad/sec measured optically about the Y sensor axis
+            _flowRate.x = flowScaleFactorX * integralToRate * float(report.pixel_flow_x_integral); // rad/sec measured optically about the X sensor axis
+            _flowRate.y = flowScaleFactorY * integralToRate * float(report.pixel_flow_y_integral); // rad/sec measured optically about the Y sensor axis
             _bodyRate.x = integralToRate * float(report.gyro_x_rate_integral); // rad/sec measured inertially about the X sensor axis
             _bodyRate.y = integralToRate * float(report.gyro_y_rate_integral); // rad/sec measured inertially about the Y sensor axis
         } else {

libraries/AP_OpticalFlow/OpticalFlow.cpp

@@ -10,13 +10,21 @@ const AP_Param::GroupInfo OpticalFlow::var_info[] PROGMEM = {
     // @User: Standard
     AP_GROUPINFO("_ENABLE", 0,  OpticalFlow,    _enabled,   0),
 
-    // @Param: FSCALER
-    // @DisplayName: Optical flow scale factor correction
-    // @Description: This sets the percentage scale factor correction applied to the flow sensor optical rates. It can be used to correct for variations in effective focal length.
-    // @Range: -20 +20
+    // @Param: FXSCALER
+    // @DisplayName: X axis optical flow scale factor correction
+    // @Description: This sets the parts per thousand scale factor correction applied to the flow sensor X axis optical rate. It can be used to correct for variations in effective focal length. Each positive increment of 1 increases the scale factor applied to the X axis optical flow reading by 0.1%. Negative values reduce the scale factor.
+    // @Range: -200 +200
     // @Increment: 1
     // @User: Standard
-    AP_GROUPINFO("_FSCALER", 1,  OpticalFlow,    _flowScaler,   0),
+    AP_GROUPINFO("_FXSCALER", 1,  OpticalFlow,    _flowScalerX,   0),
+
+    // @Param: FYSCALER
+    // @DisplayName: Y axis optical flow scale factor correction
+    // @Description: This sets the parts per thousand scale factor correction applied to the flow sensor Y axis optical rate. It can be used to correct for variations in effective focal length. Each positive increment of 1 increases the scale factor applied to the Y axis optical flow reading by 0.1%. Negative values reduce the scale factor.
+    // @Range: -200 +200
+    // @Increment: 1
+    // @User: Standard
+    AP_GROUPINFO("_FYSCALER", 2,  OpticalFlow,    _flowScalerY,   0),
 
     AP_GROUPEND
 };

libraries/AP_OpticalFlow/OpticalFlow.h

@@ -79,7 +79,8 @@ protected:
 
     // parameters
     AP_Int8  _enabled;              // enabled/disabled flag
-    AP_Int8  _flowScaler;           // flow angular rate correction percentage
+    AP_Int16 _flowScalerX;          // X axis flow scale factor correction - parts per thousand
+    AP_Int16 _flowScalerY;          // Y axis flow scale factor correction - parts per thousand
 
     // internal variables
     uint8_t _device_id;             // device id