Sensitive throttle - No low throttle - Discussions

Hi,

So my quad had been sitting around for a few months and I decided to upgrade the software and try to fly it. It's a stock 3DRobotics kit. I downloaded the latest version of Mission Planner 1.2.29 and uploaded the quadrotor firmware it came with.

I went through the wiki and followed all the instructions including the ESC calibration. After that I decided to do a throttle ramp up to see how sensitive the throttle is (test was done without blades). I barely touched the throttle (~2%) and the motors spun up and started to ramp up to 100% very quickly. I could hear it start slow for a quarter of a second then it just starts ramping up getting faster and faster. I assume this is the altitude hold control (integration term?) trying harder to get to the goal altitude.

I then put on the blades and held it down to see if I could get it to low idle. Instead, at 2% throttle the blades just quickly ramp up to high speed. I'm certain if I let it go it would just fly off and crash.. which I want to avoid. I recall the previous firmware, I could ease the motors on and do small hops..

Anyone have any ideas why this is happening? Is it the altitude hold? Anyway to turn this off?

My controller is a DX8, and the APM2

Thanks

Replies

Arko January 15, 2013 at 10:51pm

Ok, so an update in case someone in the future has this same problem. I ended up adding an ultrasonic sensor to help the altitude state estimation. I just trusted the code, slowly brought up the throttle and it took off and hovered! I did two or three flights until the battery holder band broke mid-air... while flying the battery just dropped, disconnected mid-air, and the whole quad dropped from the sky.. I wasn't even moving around that fast...

I had a good laugh though, watching the whole thing just lose power in mid-air was pretty hilarious. Now I have the joy of repairing it again.

Is this normal? Defective?

http://i.imgur.com/FLQEm.jpg
T3

Richard Boyhan January 11, 2013 at 4:22am

Stabilize just allows for much more stable flight. You still have control over throttle. Even in ALT HOLD and LOITER modes allow you control throttle and change altitude. Just remember when in these flight modes you will need to move the throttle quite a bit to change altitude either up or down. Most importantly you need to remember where your throttle was before changing it up and down and place it back there before exiting ALT HOLD or LOITER. Fail to do this will result in either your copter falling like a rock or shooting up like rocket. Very scary to see. LOL.
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Richard Boyhan January 9, 2013 at 5:38pm

I checked out your video, boy does that bring back memory's. and to think its only been 6 months and $1000 with of parts. LOL. Your copter looks fine, give it a bit more throttle and get it up about 6 to 10 feet and try to hold altitude. Be easy with the throttle, you copter can shoot up like a rocket. Also if you get up to high, don't drop the throttle to much. Reduce it just under 50% and let it come down slowly. I also recommend you set the flight mode for ALT HOLD. If you try to manually hold altitude you will be adjusting throttle constantly. With flight mode ALT HOLD the copter will do all the work for you. Just remember to get a altitude stable before you turn on ALT HOLD. Otherwise you'll get a copter bouncing up and down trying to hold altitude.
Happy Flying,
Richard
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Richard Boyhan January 9, 2013 at 5:27pm

Grass is your friend. You got to find a grasses field to test from. Especially if you are not 100% sure of the flight. I'm always on the look out for grass fields to fly from, plus always checking the weather and wind. I sometimes think its some kind of disease me watching wind socks or tree leafs in the breeze. LOL
The real problem with a parking lots is if you have kill the throttle and drop the Quad, the asphalt is not very figuring.
Good luck,
Richard
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Richard Boyhan January 9, 2013 at 3:02pm

Do you know anyone that might have a receiver you could borrow and test with? I realized that when I fly, my copter the motors spin pretty fast and it takes at least 50% throttle to lift off. I can't tell the differnce in speed by looking at the motors spinning. Have you looked at the logs on the motors? Does it show a little throttle input and then a steadying increase of motors?
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Richard Boyhan January 9, 2013 at 1:39pm

Do you have another receiver you can use to test with? I had a bad receiver that gave me problems with my throttle twitching.
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Richard Boyhan January 9, 2013 at 12:44pm

Some things come to mind. Have you calibrate all your ESC? Do you have flight modes setup on your transmitter? Do you have fail safe setup in Mission Planner? Did you calibrate your transmitter in Mission Planner? Also, your transmitter can be programmed, make sure it does not have any kind of programming set on the throttle.

Richard

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