AP_NavEKF2: Fix typos

libraries/AP_NavEKF2/AP_NavEKF2.cpp

@@ -585,7 +585,7 @@ void NavEKF2::UpdateFilter(void)
 
     for (uint8_t i=0; i<num_cores; i++) {
         // if the previous core has only recently finished a new state prediction cycle, then
-        // dont start a new cycle to allow time for fusion operations to complete if the update
+        // don't start a new cycle to allow time for fusion operations to complete if the update
         // rate is higher than 200Hz
         bool statePredictEnabled;
         if ((i > 0) && (core[i-1].getFramesSincePredict() < 2) && (ins.get_sample_rate() > 200)) {

libraries/AP_NavEKF2/AP_NavEKF2_Buffer.h

@@ -113,7 +113,7 @@ private:
 };
 
 
-// Folowing buffer model is for IMU data,
+// Following buffer model is for IMU data,
 // it achieves a distance of sample size
 // between youngest and oldest
 template <typename element_type>

libraries/AP_NavEKF2/AP_NavEKF2_Control.cpp

@@ -94,7 +94,7 @@ void NavEKF2_core::setAidingMode()
     prevIsAiding = isAiding;
     // Don't allow filter to start position or velocity aiding until the tilt and yaw alignment is complete
     bool filterIsStable = tiltAlignComplete && yawAlignComplete;
-    // If GPS useage has been prohiited then we use flow aiding provided optical flow data is present
+    // If GPS usage has been prohiited then we use flow aiding provided optical flow data is present
     bool useFlowAiding = (frontend->_fusionModeGPS == 3) && optFlowDataPresent();
     // Start aiding if we have a source of aiding data and the filter attitude algnment is complete
     // Latch to on
@@ -105,7 +105,7 @@ void NavEKF2_core::setAidingMode()
         // We have transitioned either into or out of aiding
         // zero stored velocities used to do dead-reckoning
         heldVelNE.zero();
-        // set various  useage modes based on the condition when we start aiding. These are then held until aiding is stopped.
+        // set various  usage modes based on the condition when we start aiding. These are then held until aiding is stopped.
         if (!isAiding) {
             // We have ceased aiding
             // When not aiding, estimate orientation & height fusing synthetic constant position and zero velocity measurement to constrain tilt errors
@@ -121,7 +121,7 @@ void NavEKF2_core::setAidingMode()
             // reset the vertical position state to faster recover from baro errors experienced during touchdown
             stateStruct.position.z = -meaHgtAtTakeOff;
         } else if (frontend->_fusionModeGPS == 3) {
-            // We have commenced aiding, but GPS useage has been prohibited so use optical flow only
+            // We have commenced aiding, but GPS usage has been prohibited so use optical flow only
             hal.console->printf("EKF2 IMU%u is using optical flow\n",(unsigned)imu_index);
             PV_AidingMode = AID_RELATIVE; // we have optical flow data and can estimate all vehicle states
             posTimeout = true;
@@ -131,13 +131,13 @@ void NavEKF2_core::setAidingMode()
             // Reset the last valid flow fusion time
             prevFlowFuseTime_ms = imuSampleTime_ms;
         } else {
-            // We have commenced aiding and GPS useage is allowed
+            // We have commenced aiding and GPS usage is allowed
             hal.console->printf("EKF2 IMU%u is using GPS\n",(unsigned)imu_index);
             PV_AidingMode = AID_ABSOLUTE; // we have GPS data and can estimate all vehicle states
             posTimeout = false;
             velTimeout = false;
             // we need to reset the GPS timers to prevent GPS timeout logic being invoked on entry into GPS aiding
-            // this is becasue the EKF can be interrupted for an arbitrary amount of time during vehicle arming checks
+            // this is because the EKF can be interrupted for an arbitrary amount of time during vehicle arming checks
             lastTimeGpsReceived_ms = imuSampleTime_ms;
             secondLastGpsTime_ms = imuSampleTime_ms;
             // reset the last valid position fix time to prevent unwanted activation of GPS glitch logic

libraries/AP_NavEKF2/AP_NavEKF2_MagFusion.cpp

@@ -102,8 +102,8 @@ void NavEKF2_core::alignYawGPS()
             // calculate new filter quaternion states from Euler angles
             stateStruct.quat.from_euler(eulerAngles.x, eulerAngles.y, gpsYaw);
 
-            // The correlations between attitude errors and positon and velocity errors in the covariance matrix
-            // are invalid becasue og the changed yaw angle, so reset the corresponding row and columns
+            // The correlations between attitude errors and position and velocity errors in the covariance matrix
+            // are invalid because og the changed yaw angle, so reset the corresponding row and columns
             zeroCols(P,0,2);
             zeroRows(P,0,2);
 
@@ -111,7 +111,7 @@ void NavEKF2_core::alignYawGPS()
             P[1][1] = P[0][0] = sq(radians(5.0f));
             P[2][2] = sq(radians(45.0f));
 
-            // reset tposition fusion timer to casue the states to be reset to the GPS on the next GPS fusion cycle
+            // reset tposition fusion timer to cause the states to be reset to the GPS on the next GPS fusion cycle
             lastPosPassTime_ms = 0;
         }
     }

libraries/AP_NavEKF2/AP_NavEKF2_Outputs.cpp

@@ -280,7 +280,7 @@ bool NavEKF2_core::getLLH(struct Location &loc) const
             location_offset(loc, outputDataNew.position.x, outputDataNew.position.y);
             return true;
         } else {
-            // we could be in constant position mode  becasue the vehicle has taken off without GPS, or has lost GPS
+            // we could be in constant position mode  because the vehicle has taken off without GPS, or has lost GPS
             // in this mode we cannot use the EKF states to estimate position so will return the best available data
             if ((_ahrs->get_gps().status() >= AP_GPS::GPS_OK_FIX_2D)) {
                 // we have a GPS position fix to return
@@ -461,7 +461,7 @@ void  NavEKF2_core::getFilterStatus(nav_filter_status &status) const
     bool optFlowNavPossible = flowDataValid && (frontend->_fusionModeGPS == 3);
     bool gpsNavPossible = !gpsNotAvailable && (PV_AidingMode == AID_ABSOLUTE) && gpsGoodToAlign;
     bool filterHealthy = healthy() && tiltAlignComplete && yawAlignComplete;
-    // If GPS height useage is specified, height is considered to be inaccurate until the GPS passes all checks
+    // If GPS height usage is specified, height is considered to be inaccurate until the GPS passes all checks
     bool hgtNotAccurate = (frontend->_altSource == 2) && !validOrigin;
 
     // set individual flags

libraries/AP_NavEKF2/AP_NavEKF2_PosVelFusion.cpp

@@ -274,7 +274,7 @@ void NavEKF2_core::FuseVelPosNED()
         R_OBS[5] = posDownObsNoise;
         for (uint8_t i=3; i<=5; i++) R_OBS_DATA_CHECKS[i] = R_OBS[i];
 
-        // if vertical GPS velocity data and an independant height source is being used, check to see if the GPS vertical velocity and altimeter
+        // if vertical GPS velocity data and an independent height source is being used, check to see if the GPS vertical velocity and altimeter
         // innovations have the same sign and are outside limits. If so, then it is likely aliasing is affecting
         // the accelerometers and we should disable the GPS and barometer innovation consistency checks.
         if (useGpsVertVel && fuseVelData && (frontend->_altSource != 2)) {
@@ -589,7 +589,7 @@ void NavEKF2_core::selectHeightForFusion()
         hgtMea = gpsDataDelayed.hgt;
         // enable fusion
         fuseHgtData = true;
-        // set the observation noise to the horizontal GPS noise plus a scaler becasue GPS vertical position is usually less accurate
+        // set the observation noise to the horizontal GPS noise plus a scaler because GPS vertical position is usually less accurate
         // TODO use VDOP/HDOP, reported accuracy or a separate parameter
         posDownObsNoise = sq(constrain_float(frontend->_gpsHorizPosNoise * 1.5f, 0.1f, 10.0f));
     } else if (baroDataToFuse && !usingRangeForHgt && !usingGpsForHgt) {

libraries/AP_NavEKF2/AP_NavEKF2_core.cpp

@@ -508,7 +508,7 @@ void NavEKF2_core::UpdateStrapdownEquationsNED()
     accNavMag = velDotNEDfilt.length();
     accNavMagHoriz = norm(velDotNEDfilt.x , velDotNEDfilt.y);
 
-    // save velocity for use in trapezoidal intergration for position calcuation
+    // save velocity for use in trapezoidal integration for position calcuation
     Vector3f lastVelocity = stateStruct.velocity;
 
     // sum delta velocities to get velocity
@@ -563,7 +563,7 @@ void  NavEKF2_core::calcOutputStatesFast() {
     Vector3f delVelNav  = Tbn_temp*imuDataNew.delVel + delVelCorrection;
     delVelNav.z += GRAVITY_MSS*imuDataNew.delVelDT;
 
-    // save velocity for use in trapezoidal intergration for position calcuation
+    // save velocity for use in trapezoidal integration for position calcuation
     Vector3f lastVelocity = outputDataNew.velocity;
 
     // sum delta velocities to get velocity
@@ -619,7 +619,7 @@ void  NavEKF2_core::calcOutputStatesFast() {
 
 /*
  * Calculate the predicted state covariance matrix using algebraic equations generated with Matlab symbolic toolbox.
- * The script file used to generate these and otehr equations in this filter can be found here:
+ * The script file used to generate these and other equations in this filter can be found here:
  * https://github.com/priseborough/InertialNav/blob/master/derivations/RotationVectorAttitudeParameterisation/GenerateNavFilterEquations.m
 */
 void NavEKF2_core::CovariancePrediction()

libraries/AP_NavEKF2/AP_NavEKF2_core.h

@@ -680,8 +680,8 @@ private:
     uint32_t lastPosPassTime_ms;    // time stamp when GPS position measurement last passed innovation consistency check (msec)
     uint32_t lastHgtPassTime_ms;    // time stamp when height measurement last passed innovation consistency check (msec)
     uint32_t lastTasPassTime_ms;    // time stamp when airspeed measurement last passed innovation consistency check (msec)
-    uint32_t lastTimeGpsReceived_ms;// last time we recieved GPS data
-    uint32_t timeAtLastAuxEKF_ms;   // last time the auxilliary filter was run to fuse range or optical flow measurements
+    uint32_t lastTimeGpsReceived_ms;// last time we received GPS data
+    uint32_t timeAtLastAuxEKF_ms;   // last time the auxiliary filter was run to fuse range or optical flow measurements
     uint32_t secondLastGpsTime_ms;  // time of second last GPS fix used to determine how long since last update
     uint32_t lastHealthyMagTime_ms; // time the magnetometer was last declared healthy
     bool allMagSensorsFailed;       // true if all magnetometer sensors have timed out on this flight and we are no longer using magnetometer data
@@ -776,7 +776,7 @@ private:
     uint8_t localFilterTimeStep_ms; // average number of msec between filter updates
     float posDownObsNoise;          // observationn noise on the vertical position used by the state and covariance update step (m)
 
-    // variables used to calulate a vertical velocity that is kinematically consistent with the verical position
+    // variables used to calculate a vertical velocity that is kinematically consistent with the verical position
     float posDownDerivative;        // Rate of chage of vertical position (dPosD/dt) in m/s. This is the first time derivative of PosD.
     float posDown;                  // Down position state used in calculation of posDownRate