AP_NavEKF3: flow use parameter improvements

libraries/AP_NavEKF3/AP_NavEKF3.cpp

@@ -34,7 +34,7 @@
 #define FLOW_M_NSE_DEFAULT      0.25f
 #define FLOW_I_GATE_DEFAULT     300
 #define CHECK_SCALER_DEFAULT    100
-#define FLOW_USE_MASK_DEFAULT   1
+#define FLOW_USE_DEFAULT        1
 
 #elif APM_BUILD_TYPE(APM_BUILD_APMrover2)
 // rover defaults
@@ -59,7 +59,7 @@
 #define FLOW_M_NSE_DEFAULT      0.25f
 #define FLOW_I_GATE_DEFAULT     300
 #define CHECK_SCALER_DEFAULT    100
-#define FLOW_USE_MASK_DEFAULT   1
+#define FLOW_USE_DEFAULT        1
 
 #elif APM_BUILD_TYPE(APM_BUILD_ArduPlane)
 // plane defaults
@@ -84,7 +84,7 @@
 #define FLOW_M_NSE_DEFAULT      0.15f
 #define FLOW_I_GATE_DEFAULT     500
 #define CHECK_SCALER_DEFAULT    100
-#define FLOW_USE_MASK_DEFAULT   2
+#define FLOW_USE_DEFAULT        2
 
 #else
 // build type not specified, use copter defaults
@@ -109,7 +109,7 @@
 #define FLOW_M_NSE_DEFAULT      0.25f
 #define FLOW_I_GATE_DEFAULT     300
 #define CHECK_SCALER_DEFAULT    100
-#define FLOW_USE_MASK_DEFAULT   1
+#define FLOW_USE_DEFAULT        1
 
 #endif // APM_BUILD_DIRECTORY
 
@@ -579,15 +579,13 @@ const AP_Param::GroupInfo NavEKF3::var_info[] = {
     // @Units: m/s
     AP_GROUPINFO("WENC_VERR", 53, NavEKF3, _wencOdmVelErr, 0.1f),
 
-    // @Param: FLOW_MASK
+    // @Param: FLOW_USE
     // @DisplayName: Optical flow use bitmask
-    // @Description: Bitmask controlling if the optical flow data is fused into the 24-state navigation estimator OR the 1-state terrain height estimator.
+    // @Description: Controls if the optical flow data is fused into the 24-state navigation estimator OR the 1-state terrain height estimator.
     // @User: Advanced
     // @Values: 0:None,1:Navigation,2:Terrain
-    // @Bitmask: 0:Navigation,1:Terrain
-    // @Range: 0 2
     // @RebootRequired: True
-    AP_GROUPINFO("FLOW_MASK", 54, NavEKF3, _flowUseMask, FLOW_USE_MASK_DEFAULT),
+    AP_GROUPINFO("FLOW_USE", 54, NavEKF3, _flowUse, FLOW_USE_DEFAULT),
 
     AP_GROUPEND
 };

libraries/AP_NavEKF3/AP_NavEKF3.h

@@ -419,7 +419,12 @@ private:
     AP_Float _visOdmVelErrMax;      // Observation 1-STD velocity error assumed for visual odometry sensor at lowest reported quality (m/s)
     AP_Float _visOdmVelErrMin;      // Observation 1-STD velocity error assumed for visual odometry sensor at highest reported quality (m/s)
     AP_Float _wencOdmVelErr;        // Observation 1-STD velocity error assumed for wheel odometry sensor (m/s)
-    AP_Int8  _flowUseMask;          // Bitmask controlling if the optical flow data is fused into the main navigation estimator and/or the terrain estimator.
+    AP_Int8  _flowUse;              // Controls if the optical flow data is fused into the main navigation estimator and/or the terrain estimator.
+
+// Possible values for _flowUse
+#define FLOW_USE_NONE    0
+#define FLOW_USE_NAV     1
+#define FLOW_USE_TERRAIN 2
 
     // Tuning parameters
     const float gpsNEVelVarAccScale = 0.05f;       // Scale factor applied to NE velocity measurement variance due to manoeuvre acceleration

libraries/AP_NavEKF3/AP_NavEKF3_Control.cpp

@@ -209,7 +209,7 @@ void NavEKF3_core::setAidingMode()
             // GPS aiding is the preferred option unless excluded by the user
             if(readyToUseGPS() || readyToUseRangeBeacon()) {
                 PV_AidingMode = AID_ABSOLUTE;
-            } else if ((readyToUseOptFlow()  && (frontend->_flowUseMask & (1<<0))) || readyToUseBodyOdm()) {
+            } else if ((readyToUseOptFlow()  && (frontend->_flowUse == FLOW_USE_NAV)) || readyToUseBodyOdm()) {
                 PV_AidingMode = AID_RELATIVE;
             }
             break;

libraries/AP_NavEKF3/AP_NavEKF3_OptFlowFusion.cpp

@@ -52,14 +52,14 @@ void NavEKF3_core::SelectFlowFusion()
     }
 
     // if have valid flow or range measurements, fuse data into a 1-state EKF to estimate terrain height
-    if (((flowDataToFuse && (frontend->_flowUseMask & (1<<1))) || rangeDataToFuse) && tiltOK) {
+    if (((flowDataToFuse && (frontend->_flowUse == FLOW_USE_TERRAIN)) || rangeDataToFuse) && tiltOK) {
         // Estimate the terrain offset (runs a one state EKF)
         EstimateTerrainOffset();
     }
 
     // Fuse optical flow data into the main filter
     if (flowDataToFuse && tiltOK) {
-        if (frontend->_flowUseMask & (1<<0)) {
+        if (frontend->_flowUse == FLOW_USE_NAV) {
             // Set the flow noise used by the fusion processes
             R_LOS = sq(MAX(frontend->_flowNoise, 0.05f));
             // Fuse the optical flow X and Y axis data into the main filter sequentially
@@ -89,7 +89,7 @@ void NavEKF3_core::EstimateTerrainOffset()
     // don't fuse flow data if LOS rate is misaligned, without GPS, or insufficient velocity, as it is poorly observable
     // don't fuse flow data if it exceeds validity limits
     // don't update terrain offset if grpund is being used as the zero height datum in the main filter
-    bool cantFuseFlowData = (!(frontend->_flowUseMask & (1<<1))
+    bool cantFuseFlowData = ((frontend->_flowUse != FLOW_USE_TERRAIN)
     || gpsNotAvailable 
     || PV_AidingMode == AID_RELATIVE 
     || velHorizSq < 25.0f