AP_NavEKF2: stop relying on the presence of a RangeFinder

libraries/AP_NavEKF2/AP_NavEKF2.cpp

@@ -585,9 +585,8 @@ const AP_Param::GroupInfo NavEKF2::var_info[] = {
     AP_GROUPEND
 };
 
-NavEKF2::NavEKF2(const AP_AHRS *ahrs, const RangeFinder &rng) :
-    _ahrs(ahrs),
-    _rng(rng)
+NavEKF2::NavEKF2(const AP_AHRS *ahrs) :
+    _ahrs(ahrs)
 {
     AP_Param::setup_object_defaults(this, var_info);
 }

libraries/AP_NavEKF2/AP_NavEKF2.h

@@ -28,7 +28,6 @@
 #include <AP_NavEKF/AP_Nav_Common.h>
 #include <AP_Airspeed/AP_Airspeed.h>
 #include <AP_Compass/AP_Compass.h>
-#include <AP_RangeFinder/AP_RangeFinder.h>
 #include <AP_Logger/LogStructure.h>
 
 class NavEKF2_core;
@@ -38,7 +37,7 @@ class NavEKF2 {
     friend class NavEKF2_core;
 
 public:
-    NavEKF2(const AP_AHRS *ahrs, const RangeFinder &rng);
+    NavEKF2(const AP_AHRS *ahrs);
 
     /* Do not allow copies */
     NavEKF2(const NavEKF2 &other) = delete;
@@ -361,7 +360,6 @@ private:
     NavEKF2_core *core = nullptr;
     bool core_malloc_failed;
     const AP_AHRS *_ahrs;
-    const RangeFinder &_rng;
 
     uint32_t _frameTimeUsec;        // time per IMU frame
     uint8_t  _framesPerPrediction;  // expected number of IMU frames per prediction

libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp

@@ -5,6 +5,7 @@
 #include <AP_AHRS/AP_AHRS.h>
 #include <AP_Vehicle/AP_Vehicle.h>
 #include <GCS_MAVLink/GCS.h>
+#include <AP_RangeFinder/AP_RangeFinder.h>
 #include <AP_RangeFinder/AP_RangeFinder_Backend.h>
 #include <AP_GPS/AP_GPS.h>
 #include <AP_Baro/AP_Baro.h>
@@ -28,11 +29,16 @@ void NavEKF2_core::readRangeFinder(void)
 
     // get theoretical correct range when the vehicle is on the ground
     // don't allow range to go below 5cm because this can cause problems with optical flow processing
-    rngOnGnd = MAX(frontend->_rng.ground_clearance_cm_orient(ROTATION_PITCH_270) * 0.01f, 0.05f);
+    const RangeFinder *_rng = AP::rangefinder();
+    if (_rng == nullptr) {
+        return;
+    }
+
+    rngOnGnd = MAX(_rng->ground_clearance_cm_orient(ROTATION_PITCH_270) * 0.01f, 0.05f);
 
     // read range finder at 20Hz
     // TODO better way of knowing if it has new data
-    if ((imuSampleTime_ms - lastRngMeasTime_ms) > 50) {
+    if (_rng && (imuSampleTime_ms - lastRngMeasTime_ms) > 50) {
 
         // reset the timer used to control the measurement rate
         lastRngMeasTime_ms =  imuSampleTime_ms;
@@ -41,7 +47,7 @@ void NavEKF2_core::readRangeFinder(void)
         // use data from two range finders if available
 
         for (uint8_t sensorIndex = 0; sensorIndex <= 1; sensorIndex++) {
-            AP_RangeFinder_Backend *sensor = frontend->_rng.get_backend(sensorIndex);
+            AP_RangeFinder_Backend *sensor = _rng->get_backend(sensorIndex);
             if (sensor == nullptr) {
                 continue;
             }

libraries/AP_NavEKF2/AP_NavEKF2_Outputs.cpp

@@ -5,6 +5,7 @@
 #include <AP_AHRS/AP_AHRS.h>
 #include <AP_Vehicle/AP_Vehicle.h>
 #include <AP_GPS/AP_GPS.h>
+#include <AP_RangeFinder/AP_RangeFinder.h>
 
 #include <stdio.h>
 
@@ -103,7 +104,12 @@ bool NavEKF2_core::getHeightControlLimit(float &height) const
     // only ask for limiting if we are doing optical flow only navigation
     if (frontend->_fusionModeGPS == 3 && (PV_AidingMode == AID_RELATIVE) && flowDataValid) {
         // If are doing optical flow nav, ensure the height above ground is within range finder limits after accounting for vehicle tilt and control errors
-        height = MAX(float(frontend->_rng.max_distance_cm_orient(ROTATION_PITCH_270)) * 0.007f - 1.0f, 1.0f);
+        const RangeFinder *_rng = AP::rangefinder();
+        if (_rng == nullptr) {
+            // we really, really shouldn't be here.
+            return false;
+        }
+        height = MAX(float(_rng->max_distance_cm_orient(ROTATION_PITCH_270)) * 0.007f - 1.0f, 1.0f);
         // If we are are not using the range finder as the height reference, then compensate for the difference between terrain and EKF origin
         if (frontend->_altSource != 1) {
             height -= terrainState;

libraries/AP_NavEKF2/AP_NavEKF2_PosVelFusion.cpp

@@ -4,6 +4,7 @@
 #include "AP_NavEKF2_core.h"
 #include <AP_AHRS/AP_AHRS.h>
 #include <AP_Vehicle/AP_Vehicle.h>
+#include <AP_RangeFinder/AP_RangeFinder.h>
 #include <AP_RangeFinder/AP_RangeFinder_Backend.h>
 #include <AP_GPS/AP_GPS.h>
 #include <AP_Baro/AP_Baro.h>
@@ -813,8 +814,9 @@ void NavEKF2_core::selectHeightForFusion()
     // correct range data for the body frame position offset relative to the IMU
     // the corrected reading is the reading that would have been taken if the sensor was
     // co-located with the IMU
-    if (rangeDataToFuse) {
-        AP_RangeFinder_Backend *sensor = frontend->_rng.get_backend(rangeDataDelayed.sensor_idx);
+    const RangeFinder *_rng = AP::rangefinder();
+    if (_rng && rangeDataToFuse) {
+        const AP_RangeFinder_Backend *sensor = _rng->get_backend(rangeDataDelayed.sensor_idx);
         if (sensor != nullptr) {
             Vector3f posOffsetBody = sensor->get_pos_offset() - accelPosOffset;
             if (!posOffsetBody.is_zero()) {
@@ -832,13 +834,13 @@ void NavEKF2_core::selectHeightForFusion()
     if (extNavUsedForPos) {
         // always use external vision as the height source if using for position.
         activeHgtSource = HGT_SOURCE_EV;
-    } else if (((frontend->_useRngSwHgt > 0) && (frontend->_altSource == 1)) && (imuSampleTime_ms - rngValidMeaTime_ms < 500)) {
+    } else if (_rng && ((frontend->_useRngSwHgt > 0) && (frontend->_altSource == 1)) && (imuSampleTime_ms - rngValidMeaTime_ms < 500)) {
         if (frontend->_altSource == 1) {
             // always use range finder
             activeHgtSource = HGT_SOURCE_RNG;
         } else {
             // determine if we are above or below the height switch region
-            float rangeMaxUse = 1e-4f * (float)frontend->_rng.max_distance_cm_orient(ROTATION_PITCH_270) * (float)frontend->_useRngSwHgt;
+            float rangeMaxUse = 1e-4f * (float)_rng->max_distance_cm_orient(ROTATION_PITCH_270) * (float)frontend->_useRngSwHgt;
             bool aboveUpperSwHgt = (terrainState - stateStruct.position.z) > rangeMaxUse;
             bool belowLowerSwHgt = (terrainState - stateStruct.position.z) < 0.7f * rangeMaxUse;