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Ground effect Vehicle: which one to use between Arduplane or Arduboat Firmware?

Hello gentlemen, I would like to build a ground Effect Vehicle complete with Pixhawk, gps, etc. This GEV will do way point mission on the sea. I am a bit doubt about autopilot config. May somebody will help me how to configure the Pixhawk Autopilot. Which one to use between Aurduplane or Arduboat? Any advise is appreciated. Thank you.

May be this question is outdated, but i think you need to be more specific about the type of vehicle you want(ed) to build. Is it a WIG? If so, your best bet would be to use the plane firmware in case you want to ensure pitch and height stability. If the vehicle is guaranteed to cruise above water like a hovercraft then boat firmware may be sufficient.

Hello Albcem, thank you for your comment. Yes it is basically a plane but will fly (cruise) less than 5 meter above the water (sea) to take advantage of Ground effect . Yes it is same as WIG. I also think it is a plane, so will use arduplane. However my question is, is it possible to do way point mission by cruising on the water like a boat without take off?? Or way point mission with combination altitudes zero (on the water) and non zero (flying above the water)??
Thank you…

5m above the water is for what size aircraft? To benefit from the ground effect, the wing needs to be at height about half the mean wing chord length. So if your aircraft will cruise at 5m, then we are talking about an aircraft that is quite large or it flying out of the ground effect.

If your cruise height is a couple of multiples of your wing span, then I would definitely use the plane firmware with altitude specifications on the waypoints. Perhaps you could use a lidar sensor to measure height relative to ground and cruise at that altitude.

I am actually not familiar with the boat firmware, but I suspect it will not support a lot of the 3D stability control features that the plane firmware supports. I think pitch and height stability will be the most critical items to take care of… If you designed the aircraft correctly, the stability will be inherent with the design but it is quite tricky to get all done right and quite impossible to find weather and sea conditions so ideal (small waves or no gusts)… I think one needs electronic stabilizers one way or another. Perhaps, you could do those independently of Ardupilot. Then you could use the boat firmware…

As I know little about your project, I am unable to provide a solid recommendation.

Cem

You would need to use Plane. There is no control over altitude in Rover/Boat and I would expect you would need good control over this to remain in ground effect.

I use two fliggtcontrollers in my amphibious rover. One for “rover mode”, one for “boat mode”. The problem I see for your vehicle, is to divide the controls/motors between the two “modes”. Perhaps you could use a water rudder and multiple motors to have two vehicles in one.
Changing between the two modes in a auto mission might also be interesting. It works with my rover, but both modes are equally slow and it does not fall out of the sky if something goes wrong.

Yes, I have been thinking about using two Pixhawk since begining. Maybe this is the best solution. @Sebastian, are the they working independently that each autopilot has their own gps, telemetry and Rc.and motor? Do you make connection/communication between this two autopilot?

The two Pixhawks share a GPS, telemetry and the SBUS RC receiver.
The GPS TX line is connected to both Pixhawks, RX only to one. One Pixhawk has a telemetry radio and they are connected together via “telem2”. I only use one power module at the moment, so only the boat Pixhawk knows when the battery runs dry. I guess, I could split the signal lines from the power module to both Pixhawks, too.

Thank you Sebastian, but I have some questions here:
1). One Gps is shared but Rx (from Gps) is connected only to one Pixhawk (which one?) meaning the second Pixhawk does not get Rx connection. What is the impact of this connection to the second Pixhawk (because of no Rx connection)??
2). About one Rc connected to 2 Pixhawk, do you mean just a simple parrarel connection of the 3 wires to the Sbus port?
3). One Telemetry connected to both Pixhawk. Is this just a simple parrarel connection like the Rc wire connection?? That means you just connect the 4 wires together, and then connect to the Telemetry port of the Radio Telemetry )???
Why do you use Telemetry 2 instead of just Telemetry one?? Thank you…

Hi Tony, I will try to answer your questions.

  1. Both Pixhawks need the GPS data, but only one needs to send the configuration settings to the GPS. So the GPS TX line is split to both Pixhawks and only one has the GPS RX line connected.

  2. Yes, I used a simple servo y-cable. I read somewhere, that it might not work, but with a FrSky X6R receiver and two Pixhawk 1, I had no problem.

  3. There is an ESP8266 wifi module connected to one Pixhawk on telem1 and the two Pixhawks are connected together with a “crossover” cable (Tx to Rx, Rx to Tx) via telem2. Missionplanner shows both Pixhawks/vehicles in its dropdown list under the connect button. You have to set different SysIDs for the Pixhawks, of course.

Thank you Sebastian, I will make a try using 2 Pixhawk on my next drone…

Hi Tony, I am working on a similar project. Did you perform a flight test yet? How do you measure precision height above water? Did you use height control with range finder or terrain following as in copter?

@ferdicakmak, no not yet. The project is postponed…

I also got my hands dirty with a ground effect vehicle for use above water. The project never advanced to the level of using ArduPilot, but based on what I learnt, I don’t think terrain follow feature will serve you any good. it is based on ground topography at relatively low resolution and isinadequate for the minute height adjustments that the vehicle needs to do at extreme proximity to the ground (heights less than 50 percent of mean wing chord to benefit from ground effect). So you need to use a height sensor that will not fail due to texture of the surface - ie water reflectivity or vegetation irregularities if you plan on flying above ground.

History shows that ground effect vehicles are a bit of a lost cause because of the height control challenges. You can design a “height stable” vehicle (look up Irodov) for ideal conditions, ie the ground surface is absolutely flat . In reality, you have waves and sharp variations of height on the ground. This forces the designer to scale up the design to gigantic sizes (look up the Soviet Caspian Sea monster) so that ground irregularities are relatively small. Japanese implemented a ground effect railway system in which they guaranteed the ground flatness with precise prelaid tracks. Clearly this is far from the common purposes we pursue with ArduPilot (flexible autonomous navigation at the least in 2 axes)…

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