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.
The more I think about it, the more I think the issue has something to do with the the fact that tail servo is running off the battery direct, and the rest of the system is running through the UBEC power supply (switching type). It's a 5 amp unit which I assumed was enough, but I wasn't paying enough attention and never saw anything discussing it. Possibly it's approaching the 5 amp limit so the voltage is dropping, not enough to cause a true brownout, but enough to cause the signal to the tail servo to drop, such that the signal recognition is coming in and out. The fact that it's switching unit may also cause electrical noise.
I've ordered an 8 amp SBEC (linear) power supply and I'll see if that makes a difference. This will be a bit tricky, because the SBEC is only rated at 7.4V, and the servo needs 11.1V. Apparently the SBEC can run on 11.1V at least long enough for me to run the test before overheating.
Tonight I'll try recharging the battery and testing again, maybe there's a chance that had an effect, though it was at 90% I believe. But it's worth a shot. I'm still trying to figure out "what changed" mid-flight.
After all the testing I did yesterday, it looks like I'm going to have to abandon the 3S servo. I can't figure out why it's doing what it's doing. Bummer. I don't even think I can use it for a camera gimbal, because it appers like any channel it is connected to causes the problem.
I wonder if maybe attaching a voltage regulator and/or a capacitor between the battery and the servo might help to get rid of some of that noise. Now..I've only ever found/played with regulators of 3.3v, 5v or 12v..none of which would really serve your purpose..but I'm pretty 9v regulators can be found..
I guess I could give that a shot, but I'm assuming the problem is more on the signal side.
I have a problem with the current code from the GIT. The collective, pitch and roll of our heli is limited but when in CLI the movement is okay. Any ideas?
Is the code from GIT same as the code outputted by the ardupilot mission planner? I used the APMP and the collective, pitch and roll is in full.
That's almost certainly the throttle scaling. Check the COL_MIN and COL_MAX values, you should also check that COL_MID is reasonable (i.e. between COL_MIN and COL_MAX).
By the way, it's possible that trunk is a little unstable at the moment. I had a light crash today where my APM just lost conciousness after about a minute of flight. It's the first crash in quite a while and I haven't determined whether it was some small changes I made to the code, hardware or something in trunk. I'll post again when I have an update.
BTW, the version coming out of APMP is a good stable version but doesn't include the throttle scaling which is why you're seeing a difference in behaviour.
We tested the code coming from the APMP. The stabilize was okay, but when we switched to ALT_Hold the helicopter skyrocketed and spinned (fast). And had a crash, nose first. We have this PID:
Do you think its the PID? Because this is what we were using before with a good ALT_Hold but bad Guided.
Also the COL_MIN, COL_MAX and COL_MID of our last set up was okay. with almost 200+ difference from each other.
I might guess it's the PID. Those numbers look really high for Throttle_Rate. I think I have a P term of 0.020 or something like that.
Still, it shouldn't have skyrocketed. When mine was set too high, it just made the heli bounce a lot.
Michael Oborne has released 1.0.95 of the mission planner including an improved heli set-up screen.
1st thing, this new screen only works with the latest version of the code that I've just checked into GIT. if you try to use an older version of the code, you'll see an error message.
I also removed a couple of bugs from the swash set-up code and throttle scaling. Please give it a try and tell me if you see any issues.
As a reminder of how the above screen works - to set the travel of the collective:
1. push the center "manual" button to allow the swash to move freely
2. use the collective pitch to move the swash to it's min and max.
3. move the collective so the main blade pitch is 0, then push the "zero" button
4. finally push the "save" button again ("manual" will have become "save") and check the swash travel is as you'd like
5. if you don't like the results you can push manual again and manually type in min, max and zero values referring to the value printed below just "Collective".
Setting the rudder travel works in a very similar way.
One thing I have noticed is the roll and pitch reaction to your input becomes less as you shrink the collective's travel. Please tell me if this is good or bad. One solution is to increase your roll and pitch PID values to counter-act this..