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Old Jun 15, 2012, 02:59 PM
Begin with end in mind...
power's Avatar
Eagle Lake, Minnesota
Joined Apr 2003
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Quote:
Originally Posted by Xnaron View Post
Could we seem some pics of peoples multirotors and a post of the working x,y,z coordinates. Would be good to see a baseline for these. The x an y are pretty straightforward but the z might be a bit trickier to set.
Good idea...

IMO, the "Z" value is being way over thought. Here is how I look at it...The Z axis needs to be set from the prop hub base to the center of the module. The prop hub base is actually where a multirotor wants to rotate in Z. With this I set mine to -9 cm and it is as solid as a rock. Honestly, I feel this number can vary a bit if you have payload as I do. If you have payload under the copter and it's centered ignore it. The copter wants to rotate around the thrust. This is what I did, it's simple and it is working amazingly well.

Mike
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Old Jun 15, 2012, 03:06 PM
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gww528's Avatar
United States, FL, Jacksonville
Joined Mar 2008
846 Posts
Just installed the GPS and it works great. Before the GPS was installed while testing Failsafe, it would land gently and turn off.

Now with the GPS installed, I switch on Failsafe (landing mode) it hovers 6 seconds, then it comes down gentley (height of 10 feet) touches down but then it proceeds to rise about 10 inches and comes down harder. It does this four times after the first touch down and then finally lands and turns off. I am afraid it going to brake the frame.

FailSafe pre-set setting:
Throttle = 25%
GPS mode

How do I get it to land gently the first time like it did without the GPS?
Thx
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Old Jun 15, 2012, 03:24 PM
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Joined Feb 2003
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Quote:
Originally Posted by power View Post
Good idea...

IMO, the "Z" value is being way over thought. Here is how I look at it...The Z axis needs to be set from the prop hub base to the center of the module. The prop hub base is actually where a multirotor wants to rotate in Z. With this I set mine to -9 cm and it is as solid as a rock. Honestly, I feel this number can vary a bit if you have payload as I do. If you have payload under the copter and it's centered ignore it. The copter wants to rotate around the thrust. This is what I did, it's simple and it is working amazingly well.

Mike
I think I agree with what you are saying. Where is the prop hub base in your picture? ie: where is 9cm from the gps?
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Old Jun 15, 2012, 03:30 PM
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Quote:
Originally Posted by power View Post
Good idea...

IMO, the "Z" value is being way over thought. Here is how I look at it...The Z axis needs to be set from the prop hub base to the center of the module. The prop hub base is actually where a multirotor wants to rotate in Z. With this I set mine to -9 cm and it is as solid as a rock. Honestly, I feel this number can vary a bit if you have payload as I do. If you have payload under the copter and it's centered ignore it. The copter wants to rotate around the thrust. This is what I did, it's simple and it is working amazingly well.

Mike
Is this what you mean? I edited your picture with some lines and arrows.
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Old Jun 15, 2012, 03:37 PM
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United Kingdom, Bures
Joined May 2012
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Originally Posted by Xnaron View Post
Is this what you mean? I edited your picture with some lines and arrows.
Not sure I think your Z line would be somewhere near your batt as its heavier below the frame therefore you need to measure from the cog (CENTER point where gimble/batt tilts the frame......I think that will be from top of lipo.....IMO.
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Old Jun 15, 2012, 03:44 PM
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Originally Posted by Mustflynow View Post
Not sure I think your Z line would be somewhere near your batt as its heavier below the frame therefore you need to measure from the cog (CENTER point where gimble/batt tilts the frame......I think that will be from top of lipo.....IMO.
The picture was more a question for power. I think we need to keep in mind the rotational axis for x/y/z, which ideally should be the c of g but may not always be the case. This is especially true for Z.
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Old Jun 15, 2012, 03:59 PM
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United Kingdom, Bures
Joined May 2012
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Quote:
Originally Posted by Xnaron View Post
The picture was more a question for power. I think we need to keep in mind the rotational axis for x/y/z, which ideally should be the c of g but may not always be the case. This is especially true for Z.
Believe me I'm no expert and the Z value was the hardest to get my head around, especially after a couple of beers!

For me the best way I can describe "Z" is .....if you hold a stick vertically at what point will the top part of it will tip and that point is your COG therefore if the gps was mounted on top of the said stick the Z value is the measure of the tipping point to the top.

I maybe completely wrong here, as I said Z was hard for me on my Y6!
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Old Jun 15, 2012, 04:10 PM
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Originally Posted by gww528 View Post
Just installed the GPS and it works great. Before the GPS was installed while testing Failsafe, it would land gently and turn off.

Now with the GPS installed, I switch on Failsafe (landing mode) it hovers 6 seconds, then it comes down gentley (height of 10 feet) touches down but then it proceeds to rise about 10 inches and comes down harder. It does this four times after the first touch down and then finally lands and turns off. I am afraid it going to brake the frame.

FailSafe pre-set setting:
Throttle = 25%
GPS mode

How do I get it to land gently the first time like it did without the GPS?
Thx
I think it could be how you have the failsafe set on the throttle. When the Naza goes into failsafe it takes control of the copter including the throttle and if your failsafe is stopping the throttle from moving below 25% that would cause your problem. If you are changing the end points on your servo when you go into failsafe (Should be 100%) that will mess up the Naza's flame out. I fly with an Airtronics SD-10G and it has failsafe on all ten channels and I have my 4 primary flight channels all set to 50% and all of the servo travels stay at 100%. Mine lands like it is setting down on eggs and in just a second or two the Naza shuts the throttle off.

capman231
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Old Jun 15, 2012, 04:13 PM
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United States, CA, Fresno
Joined Mar 2011
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the naza does not use the throttle setting other than it being over 10% in failsafe... it has a preset determined throttle setting that is just under 50% no matter where you put the throttle stick on failsafe (as long as it is above 10%)


decent speed is determined by you thrust to weight ratio.... since we cannot change the failsafe auto land throttle settings the only course of action you have to change the speed that the rig descends is to increase thrust or decrease weight.
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Old Jun 15, 2012, 04:17 PM
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United States, FL, Jacksonville
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Originally Posted by Adidas4275 View Post
the naza does not use the throttle setting other than it being over 10% in failsafe... it has a preset determined throttle setting that is just under 50% no matter where you put the throttle stick on failsafe (as long as it is above 10%)


decent speed is determined by you thrust to weight ratio.... since we cannot change the failsafe auto land throttle settings the only course of action you have to change the speed that the rig descends is to increase thrust or decrease weight.
It comes down very gently and lands gently. The problem is, when it lands it takes off again to a height of about 10 inches and comes down hard from there, but it does it four times before it finally lands. ( did not do this before the GPS was installed.)
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Old Jun 15, 2012, 04:24 PM
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Originally Posted by gww528 View Post
It comes down very gently and lands gently. The problem is, when it lands it takes off again to a height of about 10 inches and comes down hard from there, but it does it four times before it finally lands. ( did not do this before the GPS was installed.)
If the throttle is set at 25% in the software, won't that stop the Naza from going below that?

capman231
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Old Jun 15, 2012, 04:35 PM
manual flying apologist
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United States, CA, Fresno
Joined Mar 2011
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Originally Posted by gww528 View Post
It comes down very gently and lands gently. The problem is, when it lands it takes off again to a height of about 10 inches and comes down hard from there, but it does it four times before it finally lands. ( did not do this before the GPS was installed.)
yeah perhaps your rig is too light for the present landing with the GPS

Quote:
Originally Posted by capman231 View Post
If the throttle is set at 25% in the software, won't that stop the Naza from going below that?

capman231
what do you mean
Quote:
If the throttle is set at 25% in the software
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Old Jun 15, 2012, 04:56 PM
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Originally Posted by Adidas4275 View Post
yeah perhaps your rig is too light for the present landing with the GPS



what do you mean
I was thinking he might have something in the software that was changing the end point on the throttle when he went into failsafe. Might also be that his throttle idle is set to high if his Multi is on the light side.
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Old Jun 15, 2012, 05:05 PM
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United States, CA, Fresno
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to my knowledge the naza does not look at the end point or anything else that is set in the radio once it is set to failsafe... it just needs 10% to kick it into failsafe...

throttle setting on failsafe does not change anything... as long at it is over 10%
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Old Jun 15, 2012, 05:10 PM
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Originally Posted by Adidas4275 View Post
to my knowledge the naza does not look at the end point or anything else that is set in the radio once it is set to failsafe... it just needs 10% to kick it into failsafe...

throttle setting on failsafe does not change anything... as long at it is over 10%
I was thinking about the end point in the naza, if somehow it was being changed.
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