Do you have a multicopter running APM, and do you use it for waypoint missions? What do you have WP_SPEED set at? The default is 5 m/s... Anybody had luck flying up to 10 m/s or higher? How about in winds? How about with a payload? It would help if you could list your copter specs too.
I personally am flying a Tarot 650 frame, with 4 x MN3508-29's, 15x5 CF props, 4x20a Quattro ESC with BLHeli 10.2, powered by a 4s x 10.6 Ah pack. And obviously APM:copter, version 3.1.3 on a Pixhawk. Things feel really stable around 2 m/s, wobbly at 5 m/s, and uncomfortably wobbly / occasionally unstable at 10 m/s. I've had a couple times at 5 and 10 m/s where I was halfway between waypoints, and a wind gust led to the copter losing control and rocking back and forth until it "landed." =/
Just curious to see what others have experienced... If you have any tips, bring 'em on!
Thanks
Replies
There's an issue in AC3.1.3 (and earlier versions) in that it doesn't properly prioritise altitude over position during missions (it does in Loiter). This means that if you set the WPNAV_SPEED faster than the vehicle can manage it will begin to lose altitude. It'll be fixed in AC3.2. My slightly old stock 3DR quad can certainly manage 13m/s with 3S battery. I'm slightly unsure what it's absolute top speed is but it's under 18m/s I'm sure.
There's no easy answer to this question, as it depends a lot on the copter design and setup. At 60% hover throttle, you're not over-powered, and speed will be limited. Still, I should think you should be able to do 10-15 m/s, and I'd guess that your problem is currently just the PID tuning.
Quads can easily be set up to be capable of 20 m/s. And I've seen them to 30, but that's a very powerful machine, purpose built. You can see it here, Dave's final run is at 30 m/s.
41 m/s is smokin... That is THE fastest I've ever heard of. Was that with a tailwind maybe?
I thought my copter was stable until I watched Dave's backyard tuning video, very impressive.
http://youtu.be/U_KNgjwHizY (starting @2:20)
Spent more than a few hours tuning, set it up to be very agile at lower speeds(<10m/s), but any faster would cause a wobble/fall while turning. Tuned for agility, not speed. All fast runs were flown with stock PIDs, back when I was afraid to look at them.
Rob, thank you for your work on ACRO mode. It's awesome. Feels like I'm in control again. Reminds me of my flybarless 450 heli.(Blade 450x-No APM, yet) In ACRO I feel responsible for keeping it in the air. Instead of just telling it where to go while APM does the heavy lifting.
Mike
Ok, this might be the problem. You should hover at about 35-50% (55% should still be ok). I have a comparable setup but a hexa. You might try some higher kv (470) motors. This will for sure reduce flight time but your copter will be more stable. Or try a lighter frame.
What is your AUW and at what throttle does it hover?
my brother (our acro crash tester) flies at about 30ish m/s. you have to get the pids set for these higher throttle levels. it's all about how you like to fly and then tune to that level. so speed really isn't the issue. figure out your mission parameters, set the speed to that level, tune to that level, and all should be good. this takes a lot of tuning of many PIDs.
p.s. if you find your copter difficult to control from a momentum point of view, then you have a different issue--ship design (ship weight, motor power, battery S are the key factors).
67 mph, impressive!
The OP is asking about speed in AUTO.
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