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Ardupilot Mega vs MultiWii vs (?)

jaygreco

Junior Member
#1
What's up FT forum! I've had an account on the regular website for a while, and while I lurk the forums often, I'm posting my first question today!

Right now, I have a David Windestål style Tricopter, running on a KK2.0 board with the 1.4 software, and while I can fly it confidently, the board just isn't really living up to my expectations. I've built my tri with aerial videography in mind. It gets smooth fotoage (I've built a few different vibration dampening systems), but it's tough to keep in the area I want to get certain shots. While the multirotor is stable, it's very "drifty", and once it gets moving it's hard to bring back to center, hold still, etc. I've played with the I gain, so I don't think that's going to change much. What I'm wondering is:

Which control board, (I'm between Ardupilot and MultiWii) would be better for this type of steady video I'm trying to do? Ideally, a board which brings the aircraft back to center when the sticks are released would be the best, though I don't know if there are any like that. I really like the DJI control board, but it's way out of my price range, and I'm using a tricopter. I know that Ardupilot supports tricopters, does the Multiwii? I know there are questions about which control board is the "favorite", but I'm mostly trying to decide between these two...unless there is a better board that does what I'm looking for.
 

IBeHoey

The Warranty Voider
#2
Hey jay, I don't have a kk2 board, so I really can't advise in the tuning department but how well is your tricopter balanced? If you find that it likes to drift forward, try shifting the battery back some. If it leans to the right, shift it some to the left.

I've been flying Multwii for awhile now and really like it. It does support tricopters, and when setup correctly, it'll make a great AP platform regardless of which control board you go with. As you might already know, setup is not going to be as easy compared to the kk2, there's just a lot more to it (same goes for Ardupilot.) Tuning will be done via a PC, and you'll have to tweak some code in the Arduino IDE. If you do opt to go with Multiwii, and you have a smartphone, I HIGHLY recommend picking up a Bluetooth adapter. With this, you'll be able to tune your PID settings with your phone without the need to use a PC, very handy. You can also add on GPS, which with Multiwii will give you return-to-launch and position hold (waypoint navigation is on it's way, it just hasn't been released yet). Even without GPS position hold, and when setup correctly, you can have a drift free tri, but for AP, position hold is really nice to have.

As for Ardupilot, I'm just now starting to play with it, so I don't have too much experience myself. It's a bit more complex to setup, but man, the GPS features are awesome. You've got loiter, position hold, circle, RTL, follow, and waypoint navigation. I'd say, if you're wanting to build an autonomous aircraft, go with Ardupilot but for the features you're looking for, I think you'd be happy with Multiwii.

If you want the "best of both worlds", I'd recommend checking out the Crius AIOP v2. By itself, it stands as a great Multiwii board. ATMega 2560 MCU, which gives you 4 serial ports (handy if you want to add GPS, telemetry, or OSD later). The cool thing about this board is that you can also run MegaPirateNG firmware on it which is a port of the Arduplane/Arducopter firmware. It's a win-win!

Well, that's my 2cents. :D
 

xuzme720

Dedicated foam bender
Mentor
#3
What about the multiwii pro? That's what I'm running now on the hex with megapirate FW. Still need to get it dialed in more. I may have to give the bluetooth a try...it would make tuning alot faster...
 

IBeHoey

The Warranty Voider
#4
Very cool, I was not aware of other MW boards being able to run megapirate, but seeing as the Pro uses the same MCU, I guess it's fair to say any MW board with a ATMega2560 is capable of running it. Learnt something new today. :D

Unfortunately, I've had no luck getting the bluetooth (combined with the copter-gcs android app) to work with megapirate, a real bummer too. I believe it's because of the Mavlink protocol. I've seen some workarounds where people have made a Xbee-to-bluetooth bridge, and got it to work but meh, I'd rather lug my laptop around than sacrifice an Xbee module for that. You can however, use the USB OTG interface of your phone and connect that way, but I've never tried it. Been meaning to though.
 

xuzme720

Dedicated foam bender
Mentor
#5
Yeah, I see your point. I just loaded the planner on the lappy since i'd been dragging the copter inside so far. Bit of a hassle doing it that way, so I finally just did it to the laptop...and haven't been able to test any since! ahh, me...
 

Tritium

Amateur Extra Class K5TWM
#6
If a KK2 drifts in a direction on auto level it is usually because when the ACC calibration was performed the craft was not level, for this example let's say it drifts forward and right, then set it down on a flat level surface and shim up the side a bit that it is drifting towards (front right in this case) and do the ACC calibration again. Test and repeat as necessary.

Thurmond
 
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#7
I own both the multiwii PRO and the Arduflyer 2.5 w/CN06 gps and 3dr radio. For 150 bucks from uav objects or pay 300 for the real ardupilot with the LEA-6h gps. Either way the ardu is way better. the altimeter is much more accurate and the firmware is much more stable. AND MAN IS IT FEATURE LOADED. With mission planner you can load automated missions, click and fly (like wookong), set altitude limits, circle your home location, return to launch for failsafe, set up a virtual fence (3D box) so that if the craft leaves the box it automatically recovers itself and returns to a determined point, and the list goes on and on! Arducopter is way better than multiwii. Unless you dont want the precision and features
 
#8
There is a stable feature of the newer firmware of the KK2 board which should return to center when the controls are released. The only thing then that would make it drift is the wind. Only GPS enabled boards would be able to counter the wind to a certain degree of error.
 

jaygreco

Junior Member
#9
Thanks for the replies, guys! All really great information. I might give the newer firmware on the KK a shot and see if I can really tune my auto-level, and then probably give the Multiwii a shot! For real though, the input was super helpful.
 

xuzme720

Dedicated foam bender
Mentor
#10
I own both the multiwii PRO and the Arduflyer 2.5 w/CN06 gps and 3dr radio. For 150 bucks from uav objects or pay 300 for the real ardupilot with the LEA-6h gps. Either way the ardu is way better. the altimeter is much more accurate and the firmware is much more stable. AND MAN IS IT FEATURE LOADED. With mission planner you can load automated missions, click and fly (like wookong), set altitude limits, circle your home location, return to launch for failsafe, set up a virtual fence (3D box) so that if the craft leaves the box it automatically recovers itself and returns to a determined point, and the list goes on and on! Arducopter is way better than multiwii. Unless you dont want the precision and features
Have you tried the multiwii with megapirate NG firmware? I'm still in the tuning phase so I can't say how stable it is yet but I use mission planner and have all those options available on the multiwii. And the board I got has GPS as well, not the LEA-6h but the MTK3329.
 
#11
Yes MegapirateNG is the way to go, so you can use both "worlds". Arducopter and mwii. Personally i would stay away from MTK GPS at all costs. Buy a 20$ Ublox from HK and you are done.
 

xuzme720

Dedicated foam bender
Mentor
#12
Yes MegapirateNG is the way to go, so you can use both "worlds". Arducopter and mwii. Personally i would stay away from MTK GPS at all costs. Buy a 20$ Ublox from HK and you are done.
I've heard that from someone else too. But why? Is the Ublox that much better? The MTK seems to pick up quite a few sats(8-9)and be fairly accurate. I had my multi hooked to the laptop this afternoon and was walking around the yard with no tracking issues until I got up under the metal roof over the patio. Even then it only wandered around a 20' circle.
 
#13
Yes, uBlox is better. I was using the stock gps on my jDrones ArduCopter and am now using the HK 50$ ublox and its really accurate. It autolands with an error of around 1-1.5 metres.

I've been using the APM2 for a little over a year now, no problems as such till now, the recent firmwares have advanced quite a bit,they're very precise. I've never used MultiWii, so can't say what that's like. Even I'm gonna start out on fpv, so I feel the loiter(gps hold) is really nice. For instance, if I lose my way, I'll put it on loiter and then do an RTL(return to launch). Once it's back near me I can either land it manually or program an auto land into the RTL itself. I also have an APM2.5 sitting around. They're actually all my dad's. He's a doctor and has been flying and bulding since I was two, and I'm studying electronics right now, so I help him setup all these. The apm has a really nice community over on diydrones.

I also recently built David's tricopter and am using the kk2.0 with 48cm arms. On the stock firmware it was really drifty and wobbly. After upgrading to v1.6, it flew pretty well on the stock gains only. Some minor rought adjustments were necessary. Even mine drifts in Self level, but haven't really bithered to tune that; maybe I'll do it sometime as Tritium suggested. I'm using HK's SS series 25A escs on it, and saw noticable improvement after I flashed them. I still haven't fine tuned it, too much fun flying it :D I have plans of building another an putting the APM2.5 on it.

Here's a flight with the Tri :

I put on the HK wingcam on it, I was flying LOS, no vTx:

Now, for the apm: The stock firmware that you get from the Mission Planner is pre tuned for the jDrones and 3DR arducopter frames. So if your frame varies a lot you'll still need to fine tune it; but even then you still get a solid starting point. One thing to keep in mind, after Arducopter f/w v2.9.1.b almost all stabilization has been put on to the IMU, so you'll need to ensure minimal vibration to your board. Another new feature they've added in v3.0 is compass motor compensation. It basically compensates for the magnetic interference caused by all the wiring on your multicopter, which may lead to magnetometer/compass errors. I'm still running 2.9.1b as my quad isn't the tidiest :) Overall, the APM platform is really solid, I really like it. It also has this really great wiki that's maintained by 3DR and Diydrones, which'll help you out with all the basic setup necesssary to get your copter up. When I started out with my APM, I wasn't a member of any forums, and didn't have access to anyone who'd used the apm on a quad here, so. I only used the wiki to get started; it's fantastic.

Hoping that wasn't too much info, and that it may be of some help, cheers :D
 
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#14
@ xuzme720: Well there are a few reasons why to stay away from Arducopter MTK (3329 with custom 1.9 arducopter FW)
- more lag between motiondetection
- worse multipathing
- not as accurate esp. not tunable moving model for GPS pos calculation
These are the first reasons that come to my mind. There will be several more why DJI/Arm O Copter etc don't use MTK.
 
#15
Have you tried the multiwii with megapirate NG firmware? I'm still in the tuning phase so I can't say how stable it is yet but I use mission planner and have all those options available on the multiwii. And the board I got has GPS as well, not the LEA-6h but the MTK3329.
I also own the multiwii pro, just bought it, Xuzme can you send some "tips" as I am very new to this.