Copter tilts to side before starting to fly

Post Reply
projectDemon
Posts: 8
Joined: Tue Aug 28, 2012 3:55 pm

Copter tilts to side before starting to fly

Post by projectDemon »

Hello,

we have a problem with our multwii quadrocopter. It tilts directly at the start to a side.

Our copter has an aluminium-carbon-frame, wich is three times screwed and 35cm long. As mainboard we have an Arduino Mini Pro with a Drotek 10DOF as IMU.
Our motors are improved emax gf2210 with Turnigy Plush 12A as ESCs.

We have set the right sensor directions already after the manual on the multiwii.com site. Also we have calibrated the gyroscope manually with a sender on hopefully main level and there we have calibrated the ACC with MultiWiiConf, too.
The ESC are calibrated to the right throttle range via the new option in MultiWii 2.1 and all four have the same settings (with high timing and nimh).
As we checked the propeller should be balanced and the frame shouldn't have much vibrations due very strong screws.
The pitch, roll and yaw from the sender in normal position is at 1500 +- 3.
We checked also that the motors are connected in the right order (opposite site in the same direction and neighboring in different direction), we also put the propeller every time correct on the motors.
Our copter is a + copter.

But every time, when we start it and give more and more throttle it tilts to one side (wether front-left, like in the video, or front-right).

We captured it on video, so you can see it here:

http://chisaw.de/projectDemon.avi

We also toked pictures of the copter:

http://chisaw.de/IMG_1486.png
http://chisaw.de/IMG_1487.png
http://chisaw.de/IMG_1488.png
http://chisaw.de/IMG_1490.png

Could it be, that the PID-values have to be changed? (currently standard value). Because it seems that it tilts so the lower side an when its on a floor its normally that it goes higher on the higher side, but normally multiwii should correct it at the stard, when it goes flying, or? Maybe it correct it to slow.
Or have your some other ideas, what it could be.

Sorry for my english, but i hope you understood it.

Greets,
projectDemon

tovrin
Posts: 705
Joined: Tue Sep 20, 2011 4:08 pm

Re: Copter tilts to side before starting to fly

Post by tovrin »

assuming that you've calibrated your ESC's min and max already, and you've connected everything right, and your ACC ('level mode' or 'hover mode') is turned off

you will need to give it some thrust and get it in the air first.

your copter isnt going to just launch perfectly level, you will need to be prepared to correct it.
and your not going to get anything useful out of it until your above 3 feet high, high enough to get away from the ground wash.

projectDemon
Posts: 8
Joined: Tue Aug 28, 2012 3:55 pm

Re: Copter tilts to side before starting to fly

Post by projectDemon »

I made a little test in the garden, but with a nearly emtpy accu. But also wenn ACC is off and i give more throttle it flips and landed on his head, but this time to the rear-right (maybe because the ground is uneven).

Here is a picture of the current MultiWiiConf setting:
http://chisaw.de/28_8_2012_20_31_59.png

Is there something wrong?

I will make a new test tomorrow, because here in Germany it is night.

Greets :) ,
projectDemon

tovrin
Posts: 705
Joined: Tue Sep 20, 2011 4:08 pm

Re: Copter tilts to side before starting to fly

Post by tovrin »

but with a nearly emtpy accu


what is accu?

if you mean battery, you can cause a copter to react very poorly on a low battery, but it has to be really low.

have you armed it while watching gui at minimum throttle and watch for vibrations? carefully give it a little throttle and make sure there's not a huge vibration problem. adjust your LPF if you cant remove vibration.

also, you should do a handheld test to make sure your sensors are all configured right.

start with motors off, unplug battery but plug in usb/ftdi and connect to GUI.

hold it in your hand and make sure that when you lean or turn it in any direction the GUI shows the same thing happening. pay attention to your horizon and pitch and roll arrows also.

if that seems to check out, try connecting the battery and doing a handheld motor test. take a very firm hold on your bird, arm the motors, give it about 25% throttle, and see if it tries to lean or flip, then gently lean it one way or another and make sure the motors are responding properly. you can get a good grasp of your PID controls this way, the copter should resist your movements.

check back, let us know what happens, take video when you can.

projectDemon
Posts: 8
Joined: Tue Aug 28, 2012 3:55 pm

Re: Copter tilts to side before starting to fly

Post by projectDemon »

Today we tested alot of things. First we recalibrated the gyroscope and acc on a flat, even surface (measured with a water spirit level). Then we held the copter with our hands tried to "feel" if it reacts to our tilting movements.
We felt that the copter always keept moving to a specific side, regardless of the position we held it in.
Afterwards we went to the garden and tried to make it fly (at least) by applying more throttle that we used to.
We captured it on video (in Acro-mode):
http://www.youtube.com/watch?v=45VSUoCl6Hs&feature=plcp
http://www.youtube.com/watch?v=26_8mPcIFgA&feature=plcp

We tried to correct the copter's position but the tilt was so strong that we couldn't.

By now we have already tested and corrected so many things and to be honest, we've kinda run out of ideas what the problem might be, because the gyroscope is calibrated on main levvel and should correct all tilts, or?
Any ideas?
Last edited by projectDemon on Wed Aug 29, 2012 4:38 pm, edited 1 time in total.

tovrin
Posts: 705
Joined: Tue Sep 20, 2011 4:08 pm

Re: Copter tilts to side before starting to fly

Post by tovrin »

from your new video it looks like
1. your ESCs arent calibrated to the same min/max, at least one of them is not. (i know you said you did this)
2. or youve got something backwards in your motor wiring. (i know you said you checked this too)

anyone else see something better?

projectDemon
Posts: 8
Joined: Tue Aug 28, 2012 3:55 pm

Re: Copter tilts to side before starting to fly

Post by projectDemon »

Maybe its something with the orientation?

Because this is a video before my changes:

http://www.youtube.com/watch?v=rgVspb_tRhA&feature=plcp

Then i changed the orientation to standard.

Now the animated Copter does nearly the same i do with the real copter, but when i tilt rear up the animated copter rotates a little bit, but i think thats maybe because the mag isn't calibrated.

My sonsor orientation (now standard of Drotek 10DOF again):
#define ACC_ORIENTATION(X, Y, Z) {accADC[ROLL] = -X; accADC[PITCH] = -Y; accADC[YAW] = Z;}
#define GYRO_ORIENTATION(X, Y, Z) {gyroADC[ROLL] = Y; gyroADC[PITCH] = -X; gyroADC[YAW] = -Z;}
#define MAG_ORIENTATION(X, Y, Z) {magADC[ROLL] = X; magADC[PITCH] = Y; magADC[YAW] = -Z;}

And here is a picture of how the motors are connected:
http://chisaw.de/motor_connections.png

Here is a video of it, where you can see, that tiliting to the right and left is correct, but tilting forwards or backwards the copter rotates a little bit. In the video the motor in front is front (pin 3), right is pin 11, left pin 10 and in the back is pin 9: (the animated copter is 90° ccw rotated)
http://www.youtube.com/watch?v=cn8blsofzxo&feature=plcp

LuFa
Posts: 160
Joined: Fri Jan 27, 2012 7:56 pm

Re: Copter tilts to side before starting to fly

Post by LuFa »

Das sie so aus als ob die orientation falsch ist .
Nach Rechts Kippen : Gyro Roll Positiv , ACC Roll Positiv
Nach Links Kippen : Gyro Roll Nagativ , ACC Roll Negativ
Nach Vorn Kippen : Gyro Nick Positiv , ACC Nick Positiv
Nach Hinten Kippen : Gyro Nick Negativ , ACC Nick Negativ
Nach Rechts drehen : Gyro Gier Positiv
Nach Links drehen : Gyro Gier Negativ

Ansonsten mal darauf achten , ob ihr QuadX oder Quad im Config defined habt .

projectDemon
Posts: 8
Joined: Tue Aug 28, 2012 3:55 pm

Re: Copter tilts to side before starting to fly

Post by projectDemon »

Also wir haben nochmal getestet und nun hat der nicht mehr so gegiert:
We have tested again and now it doesn't yaws on pitch: ( the real copter is now 180° rotated from the animated (i don't know how to change ). But when i tilt the front of the real up, the front of the animated (with the arrow) also tilt up.)
http://www.youtube.com/watch?v=cvCIH_8iVrY&feature=plcp

Wir haben das gerade getestet mit den Werten die du angegeben hast, passt alles.
We tested, if our data is, like you said and its right.

Der Copter ist als QuadP definiert.
The Copter is defined as QuadP in MultiWIi.

chris ables
Posts: 317
Joined: Wed Feb 08, 2012 8:42 pm
Location: United states

Re: Copter tilts to side before starting to fly

Post by chris ables »

I looked at yhe pic of your quad you posted and was wondering how you have the props mounted ? The pic looks like they are just pressed on ! Props cannot spin on shaft or you will never get it to fly right ! :D

chris ables
Posts: 317
Joined: Wed Feb 08, 2012 8:42 pm
Location: United states

Re: Copter tilts to side before starting to fly

Post by chris ables »

chris ables wrote:I looked at yhe pic of your quad you posted and was wondering how you have the props mounted ? The pic looks like they are just pressed on ! Props cannot spin on shaft or you will never get it to fly right ! :D

Ok i see the prop savers installed ! That might be your problem though ! :D be sure the letters on prop are facing upwards on all props !

projectDemon
Posts: 8
Joined: Tue Aug 28, 2012 3:55 pm

Re: Copter tilts to side before starting to fly

Post by projectDemon »

Yes, we are watching very closely with mounting the props that all is in the right position and on its right place :D

tovrin
Posts: 705
Joined: Tue Sep 20, 2011 4:08 pm

Re: Copter tilts to side before starting to fly

Post by tovrin »

Chris, he has prop savers on. the rubber bands are not good for quadcopters. your props need to be rigid because of how quickly and how often they need to change speeds.
get something like this.
Image

projectDemon
Posts: 8
Joined: Tue Aug 28, 2012 3:55 pm

Re: Copter tilts to side before starting to fly

Post by projectDemon »

Hi,

it flies now. It was a wrong interpretation of left and right. Here is a video:
http://www.youtube.com/watch?v=w02w42oKKc0

Now we have to learn to fly with the copter and trim the acc.

Greets,
projectDemon

tovrin
Posts: 705
Joined: Tue Sep 20, 2011 4:08 pm

Re: Copter tilts to side before starting to fly

Post by tovrin »

sweet action! i would still get rid of the prop savers!

projectDemon
Posts: 8
Joined: Tue Aug 28, 2012 3:55 pm

Re: Copter tilts to side before starting to fly

Post by projectDemon »

Yes, thanks for the tip. We are looking for some (i don't know the name for them) and will buy them soon.

tovrin
Posts: 705
Joined: Tue Sep 20, 2011 4:08 pm

Re: Copter tilts to side before starting to fly

Post by tovrin »

they are called Prop Collets in english

LenzGr
Posts: 166
Joined: Wed Nov 23, 2011 10:50 am
Location: Hamburg, Germany
Contact:

Re: Copter tilts to side before starting to fly

Post by LenzGr »

chris ables wrote:I looked at yhe pic of your quad you posted and was wondering how you have the props mounted ? The pic looks like they are just pressed on ! Props cannot spin on shaft or you will never get it to fly right ! :D

If you look closely, you will notice the prop savers - black on black is hard to distinguish :)

chris ables
Posts: 317
Joined: Wed Feb 08, 2012 8:42 pm
Location: United states

Re: Copter tilts to side before starting to fly

Post by chris ables »

Lenz i put a post up right after that post that i seen them ! I would never run those prop savers on my multi's , they can vibrate , stretch in flight and hard throttle ! Just not good for this purpose ! :D i never had one save a prop anyway !

Post Reply