AP_NavEKF2: Get IMU accelerometer body position offset data

libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp

@@ -276,8 +276,10 @@ void NavEKF2_core::readIMUData()
     // use the nominated imu or primary if not available
     if (ins.use_accel(imu_index)) {
         readDeltaVelocity(imu_index, imuDataNew.delVel, imuDataNew.delVelDT);
+        accelPosOffset = ins.get_imu_pos_offset(imu_index);
     } else {
         readDeltaVelocity(ins.get_primary_accel(), imuDataNew.delVel, imuDataNew.delVelDT);
+        accelPosOffset = ins.get_imu_pos_offset(ins.get_primary_accel());
     }
 
     // Get delta angle data from primary gyro or primary if not available

libraries/AP_NavEKF2/AP_NavEKF2_core.h

@@ -908,6 +908,8 @@ private:
     bool gndOffsetValid;            // true when the ground offset state can still be considered valid
     Vector3f delAngBodyOF;          // bias corrected delta angle of the vehicle IMU measured summed across the time since the last OF measurement
     float delTimeOF;                // time that delAngBodyOF is summed across
+    Vector3f accelPosOffset;        // position of IMU accelerometer unit in body frame (m)
+
 
     // Range finder
     float baroHgtOffset;                    // offset applied when when switching to use of Baro height