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Old 08-29-2015, 04:42 PM   #1 (permalink)
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Default s800evo drift

Hey guys, have a s800 evo, running a wookong.
I'm pretty new with this bird. I bought used from a gentleman, so he did all the setup on it. So far everything has been going pretty well. I haven't engaged any of the satellite features much yet, mostly because I don't know what all the LED blinking statuses mean, other then when during orientation preflight.

The problem Ive run into so far is that every so often, say maybe every 3rd or 4th flight, after doing the orientation, I put the bird in the air, and it immediately gets a drift to it, sometimes a small one and sometimes really bad. Last night it was so bad that I had to the stick almost all the way pulled back in the "reverse" direction to keep it one spot. As you might imagine, landing went a little rough back but got it down safely.

So I unplugged it, plugged it in, did my orientation, put it in the air and everything is fine. Question being, anyone know why this happens?
The direction of the drift doesn't always seem the same, but is usually either forward, or strafing to the left.
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Old 08-31-2015, 07:39 PM   #2 (permalink)
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Suggest you read up on the manual, learn what all the blinky light things mean, they are important...

What do you mean by doing the orientation? Do you mean calibrating the compass? If so, it's not necessary to do it every flight. Only when you change locations, and even then only really large changes, like over 20 miles or so..

Since you are unfamiliar with the lights, it may be that you are failing the compass calibration and don't know it... That's why it drifts...
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Old 08-31-2015, 09:24 PM   #3 (permalink)
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According to the manual the compass calibration is to be done before each flight. that's why I do it each flight. I am aware when the calibration works correctly, I've learned those lights. It happens after successful calibrations, and it might be useful to know it happens in manual flying mode.
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Old 09-01-2015, 04:52 PM   #4 (permalink)
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"According to the manual the compass calibration is to be done before each flight."

From the WKM manual...

"3. When to do re-calibration.
 The flight field is changed.
 The multi-rotor mechanical setup has changed, including the following situations:
a) If the GPS & Compass module is re-positioned.
b) Electronic devices added, removed or re-positioned (Main Controller, servos, batteries, etc).
c) When the mechanical structure of the multi-rotor is changed.
 If the flight direction appears shifting (meaning the multi-rotor doesn’t “fly straight”).
 The LED indicator often indicates abnormality blinking when the multi-rotor spins. But it is normal
for this to happen only occasionally.
 LED blinks yellow and green ( ) continually, indicating that the compass data is abnormal."

From the A2 manual...

"Situations that require recalibration
Situations Descriptions
Compass Data abnormal LED blinks yellow and green alternatively( (∝)).
Flying field altered Flying field has changed over a long distance.
Mechanical alteration
The mounting position of GPS-COMPASS PRO PLUS module changes.
Electronic units such as Controller Unit, CAN-HUB, battery etc. have been added,
removed, remounted or other alterations.
Mechanical structures of the aircraft has changed
Drifting during flying Evident drifts occurred in flight such as the aircraft doesn’t fly straight
Attitude errors LED often blinks error indicator when the aircraft turns around"

I could not find any mention of Compass calibration in the S800 manual.

NONE suggest that it be done before every flight.

Concerning Manual mode, this mode, while not completely turning off the gyros (Another user here corrected me on this ) they are very much limited and the GPS is turned completely off, so any drift you see in manual mode is absolutely normal. You can equate it to flying a standard form helicopter with NO autopilot installed. While sometimes it may appear to stay in one place with no control from you, eventually it WILL move in some direction.

BTW, the manual for the WKM is here, http://www.dji.com/product/wookong-m/download

The A2 Manual is here, http://www.dji.com/product/a2/download
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Old 09-01-2015, 06:22 PM   #5 (permalink)
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My mistake on the calibration on every flight. I mistook the step under preflight checklist for assuring configuration to mean calibration.
As far as the drift, I can assure you what I'm referring is more than just the normal random movement. It would be as if the joystick was being moved. And I've checked the tx as well and all is normal
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Old 09-02-2015, 02:34 PM   #6 (permalink)
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OK, But in Atti mode or GPS mode it stays stable right?

There is a reason that people don't typically fly multi's in man mode, why these autopilots have made multi's the new great thing. A multirotor in man mode can be unpredictable, requiring 110% concentration to fly it. Any difference in one or more of the 4,6, or 8 motors or esc's will throw it it any direction without the autopilot making any corrective action. THAT'S manual mode.

Other than practicing for some type of autopilot failure, there's no reason to fly a professional AP type of machine manually. Turn on atti mode or GPS mode and go fly.
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Old 09-02-2015, 05:18 PM   #7 (permalink)
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A couple reasons right now. I've just been getting things up and running. Basically just flying it outside my house for testing purposes, and there are extremely tall trees here that I'm not comfortable putting it into gps mode due to allot of obstacles.
I do plan on bringing it down to a local open air area to test the gps modes.
As far as flying it in manual mode, I'm coming from sport/3D flying helis, so I'm not worried about it too much

The couple times I've switched into the gps modes, in alt lock mode it has shown a strong drift immediately upon switching into that mode. The one time I put it in gps lock, it immediately started to descend all the way to the ground.
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Old 09-04-2015, 08:11 PM   #8 (permalink)
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If you're getting solid GPS lock (iow, no red flashes) the obstacles should not be an issue. If it's moving around and not maintaining altitude when you switch to GPS, then you have other issues, such as bad compass calibrations.

And it's not altitude lock mode, it's attitude mode. Basically meaning that the GPS function is turned off, only using the gyros to stabilize the aircraft. Similar to rate mode on a helicopter tail gyro system. Ever hovered your heli in tail rate mode? The tail doesn't "lock" in...

Again suggest reading up on the manuals.... With the money you've spent and the danger to yourself and others, isn't that time well spent??
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Old 09-05-2015, 04:33 PM   #9 (permalink)
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Hey cbergen could some of that come from the declination of the compass puck not being set?
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Old 09-06-2015, 10:02 AM   #10 (permalink)
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Quote:
Originally Posted by cbergen View Post
If you're getting solid GPS lock (iow, no red flashes) the obstacles should not be an issue. If it's moving around and not maintaining altitude when you switch to GPS, then you have other issues, such as bad compass calibrations.

And it's not altitude lock mode, it's attitude mode. Basically meaning that the GPS function is turned off, only using the gyros to stabilize the aircraft. Similar to rate mode on a helicopter tail gyro system. Ever hovered your heli in tail rate mode? The tail doesn't "lock" in...

Again suggest reading up on the manuals.... With the money you've spent and the danger to yourself and others, isn't that time well spent??
I always flew in heading lock mode on the helis.
I have read over the manual you've linked to a few times already, before this conversation. I just don't always understand everything in it with its broken english. For instance, under advanced functions section, A1 control modes graph, there is an Altitude lock section, which functions in both attitude and gps mode. I thought it was automatic, but maybe needs to programmed to a switch and engaged? I haven't seen anything else in the manual for it.

But I just did notice that you are always supposed to take off in attitude mode and then switch to either GPS or Manual. So maybe that is where some of my drift problems have been occurring. I've always taken off in manual.
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Old 09-06-2015, 07:58 PM   #11 (permalink)
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Altitude lock IS automatic, but here's the exact wording from the manual...

"Maintain the altitude best above 1 meter from ground."

And this only functions in GPS mode and ATTITUDE mode. It is not available in MANUAL mode.

Something I have noticed, and you may be experiencing, Is the difference in the throttle stick position required for hover between manual mode and atti/GPS mode.

A given aircraft should hover at midstick when in atti/GPS mode. Advance the stick to climb, retard the stick to descend. Move back to center to stabilize the altitude and hover.

But in MANUAL mode, the stick position needed to stabilize altitude may NOT be mid stick!

So,let's say your aircraft hovers below mid stick in manual mode. When you switch to atti or GPS the aircraft will descend unless you move the stick to the halfway point.

A declination problem is typically noted by TBE, the toilet bowl effect. I don't think he's been in GPS mode long enough to determine if this is an issue or not...
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Old 09-06-2015, 08:56 PM   #12 (permalink)
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So. Just realized that I have been flying in gps mode the whole time. Had the switch order confused. So when I thought I was switching into g ps, I was actually going into manual. Hence the drop. So I played around in manual a bit. My god that is sloppy.
Before you give me a hard time :-/ I bought this rig used, basically ready to fly, tx programmed and all. He made me a video showing me all the switches, and apparently I had that confused. So, on to figuring out home lock
I appreciate the help, and apologize for basically wasting your time. But will be hoping for help down the line
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