Need help understanding RC with ArduCopter
My Arducopter is built and flying, but I'm crashing on most my flights. Here are the issues:
1. When I slowly increase the throttle to take off, the front and back props spin, but the side props usually don't. If I move the stick left/right, I can sort of trick the sides props into spinning, and then once they're spinning, I keep moving the throttle up with increased power to get them all spinning. Sometimes while trying to do this, I'll get the sides spinning, but front and back will stop spinning. Eventually, after playing around with it enough, and giving it quite a bit of throttle, I can get them all spinning. I then have the confidence to increase throttle and take off. Is this normal? (It could be that I just need to push the throttle hard with confidence and take off, but I don't like seeing propellers that aren't spinning).
2. Once I'm airborne, the unit is stable, flat, and responsive, but actually far too responsive. The slightest movement of the throttle stick makes it go up or down very fast, which makes hovering and flying very difficult. When trying to hover or land, I usually crash.
3. In a previous forum topic, "jasonshort" said, "You can tell it's in Acro mode because the motors only spin at low throttle while the model is moving. In stable, they spin continuously." I'm not sure If I understand the full context of what he was talking about. I'm also not sure if he's talking about the "Acro" (airplaine) mode on the Futaba Transmitter or "Acrobatic" mode in the ArduCopter software. I assume I'm in "Stable" mode. When I arm the motors, the green light blinks slowly, not fast, so I assume it's in "Stable" mode. However, if it's not, that would certainly explain it's hypersensitivity. Is it possible I'm in Acrobatic mode even though my green light is blinking slowly?
4. When trying to land, or if I make a half-hearted attempt at launching (because I'm worried about the fact that not all the propellers are spinning), the Arducopter usually flips very fast and crashes.
5. In my last outing, I was hovering around pretty nicely about 10' off the ground, but then the Arducopter suddenly shot straight up into the air really fast to about 200'. I brought the throttle down to reverse its upward climb, and I was trying to be careful not to over-react and slam the throttle down. I was able to reverse the climb, it started coming down, then it rocketed toward the ground very fast, did an instantaneous perfect flip about four feet off the ground, and slammed top down into the ground. (Replacement arms and propellers are now on order).
So, my theories are...
1. I'm new to flying RC aircraft. Maybe I just need more practice on using the transmitter, and in particular the throttle. I'm trying to be very, very careful, but it's not working.
2. Perhaps the Futaba transmitter isn't setup properly and is sending the wrong instructions to the Arudcoputer.
3. Perhaps the ArduCopter software has a problem (This seems very unlikely, since others are flying without these problems).
Although I'm sure #1 is part of it, I'm thinking it's probably more #2. In a previous forum topic "jasonshort" mentioned that he uses H1 Heli mode with his Futaba rather than using Airplane mode, and that he adjusted the throttle curve so that it's not so sensitive, so perhaps that's an option.
I would really appreciate any advice people could give me on what I can do to resolve my problem(s). Although I'm having fun, my poor Arducopter is taking a serious beating while I try to figure this out.
In case any of these details matter, here is my configuration:
RC: Futaba T10CHG Tx (in airplane mode) & 8-channel Rx.
Software: Arducopter_alpha_1.0
ESCs: Turnigy Basic 18A
Motors: KDA20-22L
Front/Back Props: APC 10x4.7 Pushers, lettering facing up
Side Props: APC 10x4.7-P Pullers, lettering facing up
Frame Arms: aluminum arms from beta kit
Frame center: several thin sheets of perforated aluminum, same size as beta kit
Battery: zippy 2200 3 cell lipo
Total Weight: 967 grams
I've used the Configurator as indicated in the Arducopter manual, and I've also done the pre-flight test, all of which checks out fine as far as I can tell. Please note that I can fly the arducopter, and it flies quite nicely and flat, it's just very hard to control the altitude (and then there's the sudden flipping issue).
Tags: Arducopter, Futaba, crash, flip, hovering
Replies to This Discussion
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Permalink Reply by Robert Beatty on -
Thanks for the tip, John. I'll give that a try. The last line of your last post made me laugh. :)
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Permalink Reply by Ed Kirk on -
I was getting good flights and now I am seeing some issues in configuration that might be related, the Z axis acceleration bar hovers around the top of the scale at 430 instead of going to center or 0. It drops toward 0 when I rapidly lower the arducopter and returns to the top of the scale when at rest. When I arm the throttle the motor indicators all jump from 1040 to 1100 and the motors start turning when they are armed. Lowering the trim doesn't affect it. Recalibration doesn't help either.
Thanks, Ed
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Permalink Reply by Sebastian Gralla on -
that is the correct behavior =)
you can lower the MIN_THROTTLE parameter in your code
Z-axis is the earth gravity, it should be around 408
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Permalink Reply by Ed Kirk on
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I lowered the MIN_THROTTLE from +40 to +10, it gave me enough throttle trim to stop the motors. Thanks. When I turn the copter upside down the Z-axis goes to the negative side of zero, gravity answered that question but I had to ask, thanks again. Everytime I go through the instructions, threads and stuff I discover something new, I am still looking for the purpose of the slider switch, the 4 dip switches and the two small buttons. I am assuming they are for future digital inputs yet to be programed, I am amazed at the computing power of the boards. Thanks, Ed
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Permalink Reply by John on
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There is small printing next to one button.
It says reset.
After I connect the battery and wait until the solid green comes on, I then push the reset and wait for the solid green to come on again.
This was recommended to me as a kind of fail safe for the powering on of the receiver and the ESC's and brains.
* -Dual 3.3V Regulator!!! (One dedicated for analog sensors!)
* -Relay switch for cameras, lights or payloads (WOW!)
* -12-bit ADC for better Gyro/Accel/AirSpeed resolution. (YEAH!)
* -Built-in 16MB Data Logger (The Black Box).
* -Piano DIP switch for servo reverse or user customizable.
* -Built-in FTDI, making the board native USB.
* -Dedicated Modem/OSD port.
* -I2C Port with incoming "Daisy Chain board" allowing you to build sensor arrays.
* -Two user-programmable buttons (one momentary, the other slide).
* -10-Bit analog expansion ports.
* -Reset button.
* -Optional "Through Hole" voltage dividers (Easy to solder).
* -Tons of Status LEDs.
* -New vibration resistance Invensense Gyros (Triple Axis).
* -Analog Devices ADX330 Accelerometer.
* -AirSpeed sensor port (optional, sold separately).
* -Absolute Bosch pressure sensor and temp for accurate altitude
* (Yes you can use your shield as a Weather Logger too!).
So far so good.
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Permalink Reply by Sebastian Gralla on
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the push button which says SW1 is for the data logger
if you hold it down while you power your apm it will go into log read mode -> it sends all the flight data via usb / xbee to your computer
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