I am planning a 15" 810mm hex build with an all up weight of 5500-6000g. The goal of this project is to fly short range autonomous missions. I currently have a Pixhawk 2.4.8 but due to the current draw of this build being in the range of 150A, powering the Pixhawk requires high amp power modules which are largely unavailable now. There is one option from Mauch Electronics, however it requires a separate BEC and voltage sensor to power the Pixhawk. This seems to be adding unnecessary complexity and weight to the build while eating away at my budget.
I see that some of the newer flight controllers that are geared at smaller quads can run Ardupilot. I recently saw a Matek F405-STD in a large hex build running Arducopter. A FC like this would reduce the clutter and weight, and they are cheaper than the Mauch components.
My concern is that I can find very few people that uses these flight controllers on a larger build and it seems like the support is almost non existent. For those that have experience, are these FC’s any more difficult to setup autonomous flights than with a Pixhawk? Should I even consider a FC like this for a larger build? Also I assume there must be some hardware features that are lacking in these tiny little boards compared to a large Pixhawk unit.
My main concern is that I would like whatever flight controller I decide to use to be able to interact with a Raspberry Pi3 (to process video for precise autonomous landing), and and Arduino Uno(controlling seperate motors and servos that are dependent on flight characterstics). From what I can find, both of these use the Mavlink interface to transfer information to/from a flight controller and I cannot find any concrete answers on the Matek or other non-Pixhawk flight controllers supporting Mavlink.
This if my first build ever and I have been doing non-stop research to try to figure out the best course of action but the amount of info is a little overwhelming. I know that I shouldn’t be building a drone like this for my first build, but it is for a school engineering design project and it requires a larger frame. Any help on this subject would be greatly appreciated.
I also began with a 3.5 Kg Hexa for my first build. It is as difficult as building a quad, but the build and the repair after my first crash were more expensive.
As you are not building a toy, I would use a Cube with no doubt. You will maybe want to upgrade the UAV, as I did, with new sensors and the controller won’t be a limit.
The power module is not critical. If you use a pack of two batteries, then Mauch would be my first option, but with a standard build, there are many power bricks that work properly with that current and are cheaper than Mauch. If your budget can afford it, Mauch is allways a good choice.
You can find some info of my first build here: Introducing my medium size 3D printed frame HEXACOPTER
Thank you for your reply. Do you know what other options there are besides Mauch that are still on the market? The standard “apm power modules” (like these: http://ardupilot.org/copter/docs/common-3dr-power-module.html) are rated for 90A max. Each of my motors is calculated(eCalc) to pull 28A at full throttle for a total of 168A. Thats why I was considering the Mauch.
That is a very cool build. Really liking the 3D printed frame.
One alternative is the The kore carrier board. It houses a proficnc Cube and integrates all power distribution.
Most people just pony up and get the real electronics like mauch. There are good reasons to have a separate bec like the mauch. For one, it’s cheaper to replace only the affected components after a crash. This assignment sounds like it has a budgeting component to it. A biggger copter means more cost. Build a smaller copter if that is out of the budget.
A 6 kg Hex at, i suppose, 6S doesn’t even come close to 150 amp. You are probably looking at around 35 Amp hovering current.
If it runs ArduCopter, it speaks Mavlink, period.
As Corrado said above, unless you go for a crazy motor/prop/pack combination, a 6 Kg hexacopter running 6S LiPo would drain it at 35 Amps in hover, 40-50 Amps flying a preprogrammed mission (depending on winds) and probably surpass 100 Amps only when doing aerobatics at 50 mph in Sport mode.
The ACS hall sensor inside a Mauch 100A module will happily pass thru a couple hundred Amps, but it will only report its max rated current. 95.5A iirc.
Your choice of Flight Controller is mostly one of usefulness. If you want to mainly run autonomous missions, you’d want a more precise barometer, with some wind-shielding, and redundant IMUs. You won’t get that from a racer-style FC. But your current Pixhawk will deliver. With 5 serial ports, to connect all your companion computers.
I have built five heavy lift multirotors, from 810 to 960mm - the Cube will easily handle the task.
I would use a 6S system - As @Corrado_Steri pointed out your hover current will likely be in the 30 to 35 amp range. I have only exceeded 100A when lifting a 10lb payload and then only on takeoff. I have a 810mm Hexa that draws <20 amps without payload at hover and 24 amps with payload a 5.5Kg AUW, but this is a highly optimized aircraft.
- FC - Cube Black for now. I cannot recommend the Cube Orange for anything but an experienced builder at the moment.
- Current Sensor - Mauch PL or HS Series 200A
- Tattu Batteries - expensive, but incredibly reliable. They will pay for themselves over time.
- KDE or T-Motor motors, although lately I have had better results from an efficiency perspective with the T-Motor engines
- Hobbywing 40A XRotor Pro ESCs have always worked well for me.