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.
I improved the sonar scaling over the weekend so you will see it better in the next release. In fact it's already out in the 2.1 quad code. This will likely fix the 85cm vs 65cm but you'll find the sonar never reads less than 20 or 30cm..this is a limitation of the sonar..it can't send the noise and then be ready to hear the reply in less time than it takes the sound to travel 20cm. This is a built in limitation of the sonars which use the same 'speaker' like thing for both sending and receiving the signal.
the noise i was talking about was little spikes that appear in the sonar measurements, often caused by interference from other sensors, escs, etc near by.
Yeah, I've actually thought about producing something that DIYD store would sell. Maybe I'll look into it a bit more.
28ga would be fine, it's nice and small and flexible, but it's hard for human hands to terminate. 22ga is typical for servo wire, and it's just nice. One of the issues trying to do something here is that I think we just don't do anything with that fine of a strand, and we don't have jacket material that is flexible enough.
I wonder if a braid would be better than foil shield in any case. That would actually be easier for me to do in a small batch.
Ultimately, somebody probably already makes exactly what we need, and it would be just easier to buy it.
basically it depends on the source..it could come from the power supplied to the sonar in which case you need some caps added. or it could be from nearby sensors (which you've likely resolved) or it could be caused by interference on the cables (in which case you need a shielded cable)...so many possibilities!
Well, to start with, you need to add the RC filter to the sonar, as explained at the bottom of the page:
It also needs to be sheltered from physical noise and vibration. This is a bit trickier. I am not totally happy with my setup yet. I'll see how it goes. But I think Trad.Helis have an advantage here because our main vibration source is so far out of range of the sensor's frequency.
Then you could consider using shielded wire. Of all the sensors, it's the sonar that needs it most because the signal is analog. We always use shielded wire for analog signals on industrial equipment.
I used shielded wire for the mag and gps... just because. With the mag, I'm hoping it makes it a bit less likely to lose the signal and cause an APM freeze.
My Engine has been paid for, or more correctly, the shipping costs for my engine have now been paid for so as soo as it arrives I can get down to tuning. I am using the Arducopter V1 hardware meaning the AC2 with OILPAN and sonar, mag sensor and GPS so wil report my finding once I get airborne. I have talked to Malc about starting PID values but will most probably talk with randy about where to start with those too seeing as this is a gas powered 90 size helicopter. Good news at any rate. Although the engine I am getting is not the one I desired - I am getting the G260puh and I really wanted the G231puh instead as they have lower vibration - but whatev.
Just received my latest Hobby King order which included the 783,333uF capacitor bank. And I did some power testing with the Power Analyzer. First, I had to disconnect the servo power supply BEC from the APM in order to break a ground-loop that was confusing the power analyzer. Once I did that, I was able to measure the full-boat APM power requirement with the mag, GPS, sonar and Xbee (not active) at only 0.2A. That proves (I think) that the L7805 is more than capable of powering the entire system. Anecdotal is that these things are reliable. I also tested the inrush current to charge the cap bank. It shows a spike up to 1.4A when first plugged in, which quickly decays to about 0.5A. After disconnecting the power supply, the cap bank can power the APM for something like 2 seconds. It then does something... sort of like a brownout, but it's weird. The servos seem to go to some undefined location, even though the APM LED's are still on. After reconnecting the power (even though the LED's never went off) it appears like the APM has to reboot. So, I'd say you have about 2 seconds power protection from a complete blackout, after which, the heli will enter some undefined flight mode which will probably result in a crash. In any case, you've got 2 seconds you didn't have before.
The cap bank is about the size of a D-cell battery, but is very light. Maybe 1 oz or something. Actually, HK shows 26g. I think it's well worth the weight on any heli if you can fit it.
I've had the L7805 powering the system for about 15 minutes now with no airflow, and it's... it's warm. I can touch my bottom lip to it (much more sensitive than a finger) and it's almost painful. Finger temp, barely feel anything. I dunno, maybe 60C.
I should note, these brownout protection times (actually, they're blackout protection) are NOT powering the servos. If you were powering the servos, much less. But still better than nothing. Long enough to get you through an transient servo load spikes, but not a stalled servo.
One thing I'm slightly concerned about is the effect of the cap-bank on powering down the board. Will this prolonged period of being at 1-4V cause any problems for the APM?
Hi! Any news with the arducopter? Left our heli at school for the display so we cant do some testing yet.
With it getting colder each day in Japan, I'm now fighting with my own sonar issues. It seems they simply stop working under about 10deg celsius. There's a solution to the problem here which involves surrounding it with 10ohm resistors to keep it warm.
So, what's the latest on coding from the trad. heli guys? I hope to be able to spend the next 3 days getting my heli flying, and I'm not sure what code I should be using?
I saw on the dev list that the I2C problem has been largely solved with a new library. Is that in the APMP hex yet?
Hi Robert, Marianne,
I updated the code that's dispensed by the AP Mission Planner about a week ago and I think that's the most stable code. I can't guarantee that what's in GIT works although if you want the security of the I2C fix, then the git code is the place to get it.
I get the feeling that there's an alt hold problem in the code although I don't see any issues and so the evidence is just anecdotal at this point.
I'd like to coordinate the next release of the heli code with the next release of the quad code so I need to talk to jason about when he's going to push it out. This is important because trunk moves so quickly it's hard to find a time when there are absolutely no bugs in it.
At the moment, my main focus is getting the optical flow code out and working in both APM1 and APM2 (i.e. the new board).
I'm also thinking about making a little board to attach to the sonar to resolve all the spikes that people see and also include a little heater for those of us who are trying to fly where the temp is <10C.
Randy, I'm not sure I'll be able to use the code out of GIT, so what is coming out of the download section? I'd like to use the I2C fix code.
What is the detail on the Alt_Hold problem?
I'd like to start working on a the code to implement something for myself, but would be useful for the community. Basically using one of the open outputs to send power to my ESC. The ESC is opto isolated. So receiver side of the board is powered by the receiver bus already. The power side is opto-isolated and powered by the battery. What I'd like to do is, instead of simply powering the ESC from the receiver, I'd like to power it through the APM via an output which will be switched using "ARMED" exactly like the quads do. Where is the "arming" section of code located? Which library?