I have just bought the ArduPilot Mega 2560 Full Kit... plus the Triple Axis Magnetometer HMC5883L. I should have it built over the weekend.. then i'm off to a my mates machine shop, and i'll make the splitter plate for the lower frame onto which i am going to fit the Ardupilot. the magnetometer i'll put on the tail as suggested. I am going to use my X-cell Razor 600E. For those that dont know its around the 50 size nitro heli.

Do i need to buy any other sensors i.e. the Sonar... i can fly a helicopter all day long but this is my first time flying one with stabilisation so any tips would be gratefully appreciated.

If this works well then i am going to try and use it on my x-cell gasser. i can get up to 20 minute flights with this. But i think for the time being a battery 600 is the way to go.

i'll post some pictures when i have it all together.



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  • Well guys tomorrow I will join the test group. The APM 2.5 will finally arrive. I'm excited to play with this thing and hope I don't have build a quad to use it. Its going on a Raptor 50 that is tuned perfectly with no servo trims and will hover in one place with no input for about 20 seconds. So off to the races. From what I'm reading, i should not use 2.7.1, correct?

  • I will try using the sonar as-is with a plate to angle it and the sonar the same angle as the APM to at least not have a default ~10 degree tilt in the mix by mounting it parallel to the bottom of the heli.

    Gotta spend less time reading and more time playing, haven't even taken the 2.5 out of its antistatic bag yet :-)

  • Did a bunch of reading last night looking at the eagle files and available ArduIMU stabilization stuff out there. I found that of the 6 available PWM channels on the Atmega328p only 2 of them are available off the board (labled PWM0 and PWM1), 2 of them are running the red and blue LED's, 1 is used for data ready at the 5883 and 1 is used for the SPI communication.

    So it looks like what guys are doing for camera gimbals ect, is either inputting/outputting PPM on the PWM0 & 1 lines, or using A0-A7 pins as PWM inputs, using PWM0 and PWM1 as outputs and converting other pins (D8, ect) to do PWM as a non phase correct PWM on a generic I/O's.

    Haven't decided the best approach yet for what I want to do, but I am considering either removing the red/blue LED's and reconfiguring the pins (red/blue PWM and PWM0 & PWM1 output phase correct PWM to 4 channels, using PPM input on D8), or just running a Sparkfun Pro Micro or other small processor board as a PWM to PPM converter as an oil pan, but I haven't looked into that option much yet. I'd like to make this work with just the ArduIMU and not have to mod the board.

    Any good reason NOT to use generic I/O's as PWM? How significant is it to not be phase corrected?

  • I have just loaded the latest code 2.7.1, setup the heli, the apm is mounted a lot more solidly than it was before. Everything works well on the bench, I have removed the sonar and will be concentrating on getting the barometer to hold the altitude. I have removed all the I term from the stab settings. Will report more tomorrow. 

  • Sorry, I've touched on this subject in two other threads now, but they are all related though I think most relevant here.

    Using an ArduIMU V3 as a "camera gimbal" to stabilize the Optical Flow and sonar sensors.

    The goal really is for me to get into some of the software that contains the DCM and AHRS code. I am also working on modding the code for the ArduIMU V3 to make it a simple flybarless module for my 250 traditional heli (not to save money over a legit AP solution as I could strap one to it right now, but space requirements of 28mm in width). I also have been feeling that using the OF for countering drift during hover would significantly improve the feel of my flying....

    I won't get long and drawn out about *why* the gimbal, I just think an OF that does not change angle relative to the ground when the heli pitches and rolls will make for an easier tunable setup.

    Your thoughts?

    P.s. Robert, I hope I didn't come out snooty in the Announcing APM thread answering your question about how I'm going to mount the APM. Felt like it could have been mis-taken after reading my own post this morning.

  • Ok, I think I'm officially done with Hobby King helis. Or at least the 600 parts.  I finally got down to rebuilding this thing, and it's a constant struggle.  It just sucks.  None of the parts fit, even when new.  I feel like an 18th century gunsmith, filing things to fit.  Last night I struggled with the washout control arms, finally got them on so they don't bind.  Today, I am trying to get the seesaw hub on, and it keeps binding up when I tighten the screws.  Must have a small machining error.  I throw it in my mill just to open it up a smidge inside. Just enough to take off the anodizing... but the pattern left reveals the surface wasn't flat to start with!  Now I try to put it on, and find out that apparently I've squished it a bit in the vice, because it's tighter than before!  Now, I couldn't possibly have squished it unless the aluminum was stupid soft.  Which it is...

    So on goes the old one.  Looks OK.  I just wanted to rebuild a fresh head to be sure.  But looking through my old crashed parts, I see that I've had to file out that washout hub before.  I forgot, thought I'd be smart and mill it, but it just squishes in the vice.

    Anyway, enough of this.  I may check out the new 550GT parts, because the new 450 Pro kit the released the parts are not bad.  But otherwise, I'll build with good quality stuff.

    I've already got a 550 half built using all high quality aftermarket upgrades, should be nice.

    I just don't want to buy an Align kit because they make you take all their electronics which I don't want.

    On the other hand, I have to keep reminding myself I've had several crashes completely the fault of developing the code, and I couldn't afford genuine parts at the rate I was going through them.  But, hopefully things will have settled down now.

  • Finally got around to uploading a video, photobucket isn't working so I used YouTube.

    I like the last minute... nothing impressive to speak of though :-)

  • On the compass front, I'm really surprised that no one has come up with a good solution for a work around on the 2.0.

    I am just beginning to learn the programming side of things, but I would already think that there must be a way to do it via software as the compass module itself is inaccessible without removing the daughter board, and even then how many of us want to try to pull a component off the middle of a tiny board like the APM?

    I will be getting an ArduimuV3 and external compass with my order, and will be looking into what it would take to integrate the data "off board" from an external port on the 2.0... I have two of them and I can't envision a project where I would not want to place the compass separate from the control module. I don't see why the DEV team hasn't done this even with the 2.5 on the way, seems like a lot of people have this need?

    HDMI- I am not using a servo controller, just have 7 female servo connectors robbed from some Y cables that land the 7 servo signals I'm pulling from the APM. The servo's are powered directly at the Y connectors and the shield for the servo outputs is not landed at the Y connector (else it would be a ground loop). The ground goes BEC-> 8ch receiver-> APM inputs-> APM outputs, and stops just before the servo plugs. That shields ALL the wires going to and from the APM, keeps the servo power off the APM, and allows for an HV setup if I ever decide to go that route. If you want I can draw up a diagram for more clarity? I got the unassembled 2.5 to do the same thing without the fear of damaging the board to pull all the forest of unused pins that came with the assembled 2.0 ;-) I still think it's bad to have them surround the GPS.

    TBH though, my efforts for the APM's are only in an interest to preserve my hard earned $$. The 2.5 I bought is to facilitate a resolution to the compass issue AND stay involved in the development of the future ArduPilot(32bit?) platform even if I can't find a good solution for the 2.0 compass issue...

    I am far too aware that the 32bit FPU processors readily available and ALREADY FLYING contain the processing power to run very complex algorithms at high cycle rates to truly facilitate a stable platform. This is not the forum for that kind of talk though so I'll try keep it to the APM for now.

    Off topic;

    "IF" you are separately interested I am settled on trying to build my own micro-controller based on the FEZ Cerb40 (with some boot-loader changes can get 3xI2C bus, 2xSPI, 1xUSART, 1xHS USB, and it has a FPU on the STM32) $25 and 3/4" by 2" footprint (2"x1-1/2" for a pair side by side, one for AHRS one for nav). Link it (or them) up to external sensors (sparkfun, ArduIMU, AliEpress)... how about 4xMPU6050 running out of sync for 32kHz resolution?

    Back on topic.

    Long post, sorry. Good coffee :-)

  • Some more photo's of the mounting. Video is all on the wife's phone, will get that up later.


  • Only good pic I've got on my phone is the HDMI routing to the bottom of the APM, I think the wall-o-servo wires around the inboard GPS is partially to blame for the poor reception issues. After the mod the GPS works significantly better.
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