Comparing Precision of Autopilots for Survey Missions

SPH Engineering has a fleet of various small UAV for diverse research and development projects. This enables UgCS Support Team to consult UgCS users to choose most suitable hardware combination for their aerial imaging projects.

When it comes to using drones for land surveying, mapping or 3D reconstructions, flight precision plays an important role. Each drone has its level of accuracy of flying predefined routes.

We decided to test most of UgCS supported drones, to illustrate the diverse precision of autopilots. To do that, all drones will fly a short photogrammetry mission planned with UgCS (Figure 1). It is a simple yet typical photogrammetry route with added overshoot, to compare different turn types and to see more accurately how precise the drone is flying according to survey lines.

Figure 1: Photogrammetry test route with added overshoot

The flight path will be recorded and demonstrated in Google Earth. The flight conditions are similar to all drones: wind speed around 2-3m/s.
 

Part I
DJI Phantom 4

One of most modern ready-to-fly drones, which has become quite popular also for photogrammetry even amongst professionals. The DJI Phantom 4 flew the mission twice comparing flight precision with different turn types: first flight with Stop and Turn, second - Adaptive Bank. See the flight comparison in the video:

Download KML files to see the test route and flight path in Google Earth:

• Test route KML file
• KML file for DJI Phantom 4 flight (Turn type: Stop and Turn)

Part II
DJI Naza-M V2

The Naza-M V2 is a popular autopilot from DJI used by hobbyists and professionals alike. In our case it was mounted on a DJI F450 frame. It flew the exact same photgrammetry route as DJI Phantom 4 with three different turn types: Stop and Turn, Bank turn and Adaptive Bank turn.

As expected, with DJI Naza-M V2 being an older autopilot, it did not fly as precisely as the Phantom 4. Out of the three turn types the Adaptive Bank gave the best results as far as keeping to survey lines.

Download KML files to see the test route and flight path in Google Earth:

• Test route KML file
• KML file for DJI Naza-M V2 flights (.ZIP file for all 3 flights)

Part III
MikroKopter Quad XL

MikroKopter is a well-established German company making drone systems for quite some time. MikroKopter drones are quite popular in Germany, many other European countries as well as internationally.

Here is the video of MikroKopter Quad XL flying the same photogrammetry route created in UgCS which we used for other drones:

Download KML files to see the test route and flight path in Google Earth:

• Test route KML file
• KML file for MikroKopter Quad XL flights (.ZIP file)
   

Part IV
DJI A2

A2 is mounted on a DJI S900 platform. Each of three flights was performed with different turn type – stop and turn, bank turn and adaptive bank turn. Here are the results:

Download KML files to see the test route and flight path in Google Earth:

• Test route KML file (.ZIP file)
• KML file for DJI A2 flights (.ZIP file)
   

Part V
3DR Iris with PX4 firmware

The flight trajectory is very smooth and consistent with no unexpected deviations from survey lines. The drone went off the planned route only when turning - but, because there is overshoot added to the survey lines, it wouldn’t affect the overall photogrammetry mission.

Download KML files to see the test route and flight path in Google Earth:

• Test route KML file (.ZIP file)
• KML file for PX4 flight (.ZIP file)
• KML files for all tests flights Part I-V (.ZIP file)
  
   

Part VI
DJI Phantom 3

The DJI Phantom 3 flew the mission twice comparing flight precision with different turn types: first flight with Stop and Turn, second - Adaptive Bank. The flight path of Phantom 3 corresponds with test-route almost exactly, slightly diverging only when cornering. See the flight comparison in the video:

Download KML files to see the test route and flight path in Google Earth:

• Test route KML file (.ZIP file)
• KML file for DJI Phantom 3 and Phantom 4 flights (.ZIP file)
   

Part VII
DJI Inspire 1

Like all DJI drones, also Inspire 1 flew the test route with 2 different turn types: first flight with Stop and Turn, second - Adaptive Bank.  See the flight comparison in the video:

Download KML files to see the test route and flight path in Google Earth:

• Test route KML file (.ZIP file)
• KML file for DJI Inspire 1 flights (.ZIP file)
   

Part VIII
Lockheed Martin Indago

The flight trajectory of Lockheed Martin Indago is very smooth and precise - perfect result. For our test flight automatic settings of Indago were not changed, therefore Indago reached routes planned height gradually - this has to be taken in account when planning photogrammetry missions with Indago: before starting the flight in automatic mode, manually desired height should be reached. See the flight details in the video:

Download KML files to see the test route and flight path in Google Earth:

• Test route KML file (.ZIP file)
• KML file for Lockheed Martin Indago (.ZIP file)
   

Part IX
Microdrone MD4-200

Microdrone MD4-200 starts flying the route higher than the set altitude - this is due to the fact that the Auto-mode was enabled after the drone was already in the air causing the gap in altitude. See the flight details in the video:

Download KML files to see the test route and flight path in Google Earth:

• Test route KML file (.ZIP file)
• KML file for Microdrone MD4-200 (.ZIP file)
   

Part X
3DR Iris Pixhawk with ArduCopter

Pixhawk with ArduCopter 3.4.6 firmware is tested in the tenth episode in our series of videos comparing precision of various autopilots. The flight is very smooth and precise! See the flight details in the video:

Download KML files to see the test route and flight path in Google Earth:

• Test route KML file (.ZIP file)
• KML file for 3DR Iris Pixhawk with ArduCopter (.ZIP file)