This may seem like a silly question, but reading the docs, I read about individual components, but not how they fit together (or maybe I am not getting it).
I have this
[Base Station] [Rover]
uBlox GNSS Antenna uBlox GNSS Antenna
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ArduSimple ArduSimple
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RTK radio RTK radio
Apart from power management (not shown here), I think I need a remote control, to move the rover manually, to a charge point, etc… I was going to use a RadioMaster TX16S for that, but which component receives the remote control signals.
I figure the recciever connects to the Pixhawk 4.
I also have ordered a Pixhawk 4 board and a Sabertooth 2x32A to control the two drive motors for the rear wheels.
I envisage to use QGoundControl (being on Linux).
The questions are:
a) how does QGC talk to the rover? What is needed?
b) how does the RadioMaster talk to the rover? What is needed?
Somehow I need more radios for that communication.
I read this ArduPilot RC page, but do not understand what to use on the Rover side to receive the commands. also can the same receiver be used for the QGC software control.
The Radiomaster is a goid choice. It is a multiprotocol radio. This means it can be used with almost any receiver make and model out there.
You can also plug a seperate transmitter module into the back of the radio, to use long range (433, 868, 915MHz) systems with it. The Radiomaster transmitter is also sold as a “Masterfire” combo. The combo contains a crossfire MicroTX longrange module. There are receivers which send back telemetry to the transmitter, to get information about the vehicle status.
To get the telemetry to your GCS (GroundControlStation) device and setup/control in your vehicle in the field, you usually have to use some kind of seperate telemetry radio. Like the longrange systems they come in different frequencies, depending on the regulations of your country/region.
RC receivers usually are connected to the RC In port of the flightcontroller, while the telemetry radio is connected to a UART port (labeled Telem1, Telem2 i.e.). RC receivers with telemetry support might require a second connection to a UART port, too.
It is also possible to use Wifi as a telemetry link, but the range is usually limited and weather dependend.
Thanks; and to structure this:
a) there is a RC path, requiring a sender (e.g. RadioMaster) and a receiver
b) there is a telemetry path; requiring a transmitter and a receiver.
So I end up with three radio paths:
for the GPS RTK
for the remote control
for the telemetry data
OK…
Would I not require transceivers or a transmitter and a receiver for the QGC machine?
Can RC and telemetry run on the same transmitter/receiver?
I am not asking for special or exotic configurations; I am interested in common solutions and approach taken by most.
Also, I am in Australia, and [edit1] deleted 433[/edit] 915MHz seems to be the go.
I have picked brand products, simply to avoid any headaches with compatibility issues which can takes hours and days to solve.
And what if I want to run a camera on the rover? Would the video information form part of the telemetry data? Wouldn’t video add bandwidth requirements, which might be difficult to address.
The key thing I want to achieve is building an autonomous mower, two drive motors, a three blade mowing deck, and control it by either uploading ‘missions’ and tinker with tuning values in real-time. It is the comms that does my head in; too many choices…
It is not easy to get all possible options together in a simple way, but I try:
RC
In some countries it is a requirement to have a dedicated RC link to the vehicle. Either by law or for insurance reasons.
You can control the vehicle through a telemetry link, too. A joystick/gamepad connected to the GCS will provide the input.
Telemetry
The telemetry radios are usually sold as pairs. They have USB and UART connectors to use them on both ends.
Some RC TX/RX combos also provide bidirectional telemetry.
RTK GPS
I never used RTK GPS, so someone with more knowledge should step in, but it might be possible to use the telemetry link for that. MissionPlanner has some RTK features for example.
Video
No RC or telemetry radio has enough bandwidth to transmit video. You could use analogue FPV equipment. This also comes in a variety of frequencies. You can also transmit video over wifi or mobile data connections.
Wifi for all of the above
While Wifi has its limitations, it also can be a single link for all of the above tasks. It has enough bandwidth for control, telemetry, RTK and video at the same time. You will have to check your local regulations.
I use Alfa adapters on my rovers (omni antenna) and on my antenna tracker (directional antenna). I get 200m range with 2.4GHz at 100mW and some obstacles. Using 5GHz Wifi is complicated/forbidden in Germany, but might be possible in Australia.
Mobile data connection for all of the above
If you use a mobile data connection, the range is virtually unlimited/limited only by the coverage in your area. I never used it, because mobile data is still expensive in Germany.
Thanks for the detailed response… I meant to say that suggestions should be run-off-the mill, standard solutions… generically speaking… not implying your reply was ‘esoteric’
The problem for me is, the more I read, the more I am confused… it never ends… too many possibilities… and I am asking myself “why” (all these variations)… my GPS RTK solution was the easiest pick
I reckon this applies to systems run in public… the joystick idea is interesting.
I am starting out, buying hardware ATM, that hopefully works together.
Aha, both transceivers and TX/RX combos exist for that
At least one technology I had no problems choosing.
Yes, what I thought too… it is not important initially, but can see some better (range) WiFi gear to cater for that; e.g. RaspberryPi and Pi cam or IP cam (endless possibilities, but an area I understand).
For this prototype I (think ATM) I would use dedicated radios for telemetry; will have a look at the CrossFire thingies you’ve mentioned.
Yes, Germany… as a long-ago ex-German I have an idea about everything being regulated in particular with frequencies.
yes, I get that part too… but no plans to use it.
Certainly a good summary…
I reckon there is no way around for me to buy something and see how it works… worst case, chuck it out and start over.
So the questions remain:
What do I plug into the laptop with QGC? Do I even plug something in? I reckon yes, otherwise how do I upload the mission to the rover.
Assuming I get a RadioMaster, it will cover the RC side.
I need a receiver in the rover. and need to watch out, how many on/off or servo channels it has… depending on what I want to switch or regulate.
The Radiomaster is the transmitting side of the RC link.
Ardupilot requires a RC receiver which outputs all RC channels over one wire. There are many different protocols around. Analogue PPM, Futaba (and FrSky) SBUS, Graupner SUMD, Multiplex SRXL, FlySky IBus and so on. I would avoid PPM, it is jittery and only supports 8 channels.
If you control two motors with the Pixhawk4, you can use all other outputs as you like. You can control them manually through the GCS or the RC transmitter or program them in auto missions. There are also special functions available like gripper, spraying, camera gimbal. So there is no need to have a receiver with many servo outputs. FrSky would be my first choice for 2.4GHz receivers. Unfortunatly FrSky has started to push their own closed RC protocol recently (ACCESS, as in “no” access for others) and those receivers are not usable with the Radiomaster. Be aware!
Yes, this will be ok, except for video transmission. The Radiomaster is the best radio you can get for that money at the moment. I weep, remembering what I spent for my Graupner gear…(also made in china)
You are right, but now we have alternatives like Jumper and Radiomaster (and FrSky before them), instead of having to pay a premium for less capable radio gear that more or less comes from the same manufacturing lines. I just saw Spektrum charges 540€ for its new 10 Channel radio with a puny little screen…
If a radio doesn’t run OpenTx I’m not interested. I thought the Frsky Taranis was the best piece of hardware I bought for the hobby until I sold it and bought a Radiomaster. And before that I happily kicked the Spectrum radio to the curb. What an overpriced piece of kit it was.
FYI, one point about RTK. You can get correction data from 2 sources. A Base RTK unit or from an Ntrip server. In the later case your Ground Station would be connected to the internet with access to an Ntrip service provider. What’s available world wide varies greatly. Here I can get it for free, with 1 station <10km away and the other ~20km but almost the entire state of Michigan is covered. Then you only need the Rover unit. But, if you are going to mow the same lawn in the same location all the time then perhaps a base unit is good choice.
@dkemxr, so with RTK am I right in thinking that no matter weather one chooses base station or internet based correction data, the corrections are passed to the rover from mission planner to ardupilot via the mavlink in place for the system?
Do so. Ntrip service providers have fixed stations that supply it’s location data via internet. Consider it the same as a fixed RTK GPS Module which is supplying the same fixed location data.
You’re going to spend a lot of money on a autonomous mower, the cost of a Base Station RTK GPS module and antenna is trivial. Take that route.
Tell me about it…
Bought the simpleRTK2B - Starter Kit LR yesterday, based on what I understand so far (which is very little)… and your post just confirmed taking this route was a good idea. Thanks.
Tell me about it…