Hello,
I’m currently designing an art project involving 6-10 autonomous ground vehicles. I have some experience with drones, but not really much. It would be great if I got some tips, advice and constructive criticism here.
The planned setup:
6-10 vehicles that need to be able to navigate pretty precisely (outdoor). The goal is to perform a choreography or a kind of dance. The position tracking must therefore be 10-20cm accurate.
The planned hardware:
Pixhawk cubes
Here + RTK GPS
433Mhz telemetry
Groundstation Laptop (s)
With just one vehicle, everything would be manageable for me, I think. But because of the several vehicles there are some questions.
Is it a good idea or possible to safely control all vehicles with only one ground station? With only one ground station and several vehicles, how do I best solve the telemetry? Only one radio module on the laptop or several for each vehicle? Is it even possible to operate several modules on one laptop at the same time?
For the Here + RTK GPS, it would be best to have just one ground station. (one GPS rover module on each vehicle, one base module on ground station) Otherwise I would have to find a solution that several ground stations somehow share the one base RTK module. Or I had to use 6-10 complete kits, what sounds a bit overdosed.
So far for now. Maybe someone is working on a similar project. Thanks a lot for some feedback.
Best to have 1 RTK base station for all the vehicles, as the relative error between the vehicles would be reduced.
The Qgroundcontrol software should let you monitor and control multiple vehicles from a single GCS. You’ll need a method to communicate with all the vehicles though. For a quick solution you could use a powered USB hub to plug the GCS end of all the telemetry radios into the GCS.
Otherwise maybe some kind of WiFi network would work. You could put a Raspberry Pi on each vehicle and use that to connect the vehicles and GCS to the WiFi.
I’ve done up to 3 vehicles with the MP. I used separate SiK radios for each. The MP has a hidden feature to allow connecting to multiple vehicles by right-mouse-button clicking around the Connect button.
Telemetry is the really tricky part. The RFD900 can be loaded with a (closed source) firmware that allows a network of connections (i.e. multiple vehicles connected to a single radio on the GCS computer). I haven’t used it personally but I suspect it works well.
I hope that we will eventually enhance the ESP8266 firmware to support small networks which would work very well in this situation but I can’t promise when we will get to that.
ArduPilot Copter (but not rover) supports a NAV_DELAY command which can be used to syncronise missions across vehicles by adding time delays (using the GPS’s clock which will be the same across vehicles) but I’m afraid we haven’t added support for this command to Rover yet but it’s on the to-do list.