Hi Guys and Girls. Until now I have been doing an IMU calibration before leaving home to guarantee a good level surface and then doing a compass calibration in the field. I made this from a spare piece of kitchen worktop and 4 kitchen unit adjustable feet. Now I can have a perfectly level surface to carry out "in the field" IMU calibration prior to flight. Not exactly complicated but it works.   

What if your substrate isn't level?

scooter do you mean the ground itself?

Nice! Do you use it often? Most of the time my inspire has accurate readings so I don't do IMU cal in the field. This does come in handy should you need it. You can find a bubble level at homedepot or lowes and attach it to the board. That way you don't have to carry one with you.

Good idea xzces. I intend to use it everytime I arrive at a flying site, just to be sure.  

Dave E Posted at 2015-2-25 03:23
Good idea xzces. I intend to use it everytime I arrive at a flying site, just to be sure.

That'll get old fast, luggin' that around.

I do mine at home and that's good enough.  Looks like just more stuff to carry around but that's your choice.

Hi all...I bought four tapered plastic door stops that I use as shims to level  my case in the field if the IMU readings show I need calibration.
I put the bird on the top of the case and slide the door stops in at each corner until the case surface is level.  I have a small 9 inch bubble level in my case.  Works well and weighs nothing.

That's not for the inspire!...It's crowd control.
One decent whack with that ought to keep them on the level!! :@
Alternatively you could use it for making your lunch on

scooterlam Posted at 2015-2-25 03:03
What if your substrate isn't level?

Isn't that what the level will compensate for?   

jimhare Posted at 2015-2-26 11:00
Isn't that what the level will compensate for?

The legs aren't adjustable from what I can tell on that platform he built so therefore if the substrate wasn't level, the platform wouldn't be level ;)

scooterlam Posted at 2015-2-26 11:06
The legs aren't adjustable from what I can tell on that platform he built so therefore if the subs ...

The legs are adjustable, says it in the first post.  Otherwise yeah, you'd be at the mercy of everything under it!

"spare piece of kitchen worktop and 4 kitchen unit adjustable feet."

jimhare Posted at 2015-2-26 12:29
The legs are adjustable, says it in the first post.  Otherwise yeah, you'd be at the mercy of every ...

I'm a typical guy, go straight for the pictures and skip the text reading ;) My bad. Those legs don't look very adjustable but kudos to the OP for making a DIY fix for IMU calibration!

Speak your mind guys if you don't like it!!! lol
The whole idea was to make a rock solid stable platform that can be adjusted to compensate for uneven ground.This is to provide a level surface that wont be affected by wind for the 10 minutes it can take to do an IMU calibration. Yes its heavy but I manage it. (but then again I can eat 3 shredded wheat)The legs are removable for transport and they are adjustable by unscrewing the foot part. See pics.
I'm working on a balsa and polystyrene version to keep the weight down. I'll put wings and an engine on it and use it for flight practice when my inspire battery goes flat. Yes I've only got 1 battery because you lot keep buying them up!! lol.      Safe flying Guys and Girls.

I am using an iPad mini 2 with the inspire, also a spirit level app. less to carry around should I need to do IMU on site. Normally do this at home before I leave. no problems so far, fingers crossed.

Does it really need to be that level ??

Surely all you need do is place the aircraft on the case lid and make sure it is more or less level

Very nice man!! I'm also working on some take-off/landing platform for the inspire. I'm thinking of OSB material, but so far I haven't found good legs for leveling - yours are good, but could take loads of time to unload+level it. I want to make it also foldable, with the size of 1.2x1.2 meter. I Found that the inspire can take of from any leveled surface, but the landing is a problem. If you take off from a unleveled surface you might get IMU calibration error. And if you calibrate it on unleveled surface, you better not take off, cause the bird will drift hardcore. Will keep you updated, if I find the right legs for it

I was thinking of a similar solution when I first got the inspire.. How do you think a tripod would work for legs? I was thinking it is pretty quick to level a tripod then attach a quick release to the bottom of the platform for easy set up... Do you think wind would be an issue on a tripod?

For me it does need to be that level!...... I have a small quad that drifts if not calibrated correctly. The thickness of 1 piece of paper under 1 of its legs makes a big difference. So in my book the more level the surface the better the calibration.

My understanding is that If the aircraft has been calibrated with a very slightly nose down attitude ie. not perfectly level, then it will constantly tend to drift forward thinking that nose down is level. Its gps system will always be trying to correct for this. If it loses gps, as mine often does, it will therefore start to drift forward. With the problems that the inspire's current firmware has, I am trying to reduce the risks as much as possible.  

   

Dave E. check that level you bought,  I made a similar table and found that 3 different levels I bought at a major home supply store were not actually level.  To check... take your level on any surface and note very carefully where the bubble is,  now spin your level on that same exact spot 180 degrees and your bubble should be the same distance from the marks, if not ... your level is not level or square whatever you want to call it.  I found most of them are off, in fact I have not found one that passes this test yet.

Agreed 100% pkoepnick. The level shown is the best I have and it is accurate using the 180 degree method. There is also the innacuracy of reading the bubble itself to be taken into account. I also tried two different ipads with a "digital" level app. They both gave slightly different readings. We can only do the best we can.

Here's a thought, what if there is a slight discrepancy with the landing gear down position.
Really need a perpendicular datum line on the craft to know it's bolt upright.

I like the DIY, but who gave you my spirit level?

Very true ambam. Nothing we ever do will make it perfectly perfect but every little helps.

I'll give you your level back if you give me my spare battery back!!!!!!  

If you've ever been to a place named Electric Brae in Scotland you will know that what appears to be level or even downhill, often isn't!! Google "Electric Brae" and have a look.

Dave E Posted at 2015-2-27 00:36
Very true ambam. Nothing we ever do will make it perfectly perfect but every little helps.

I'll giv ...

Sincerely wish I had your spare battery to give you back.
Spare batteries are like the proverbial "Hens teeth".

Keep up the good work DIY.

Marktho1 I wouldn't like to put my kitchen worktop thingy on a tripod, well not unless its made of scaffy bar but a lighter rigid surface may work.  

Captain obvious, my mrs was working herself earlier and I can confirm the "calibration aid" works a treat!!!!! I may not post for a while until they let me out.

An Idea for a featherweight emergency IMU calibration rig, when all around is at crazy angles.
4 pieces of non-kink, non-stretch string.
All fastened together at one end all exactly the same length.
With the means to quickly attach the 4 free ends to the 4 motor mounts in exactly the same way.
When suspended cleanly from the point where the strings meet the whole rig will be like a Plumb-bob.
And if kept still the machine should be within a hair of being level thanks to Gravity.
Also if the machine is in landing gear up mode it could make the rig more stable.

Great idea ambam. If we got together we could also play Inspire conkers with that method   

not a bad idea too

nice one dundee

Since we're talking about imu ' s can someone walk me threw where I find the imu values  On the is app?

Hi ruddy, Android here but its probably the same or very similar in ios ..........click on the mode section of the app which is top left just to the right of the home key. Scroll down and click on "Advanced Settings". Choose "Sensors" and there you go.

Hello

I do not yet have a Inspire (But a Phantom ) - I am very confused after following this forum for a while.

Do you realy calibrate your compas and imu before every flight ???
It must be a misunderstanding here ??

Hi nilsblix. Some people just do an IMU calibration when prompted to by the app but I think most people do a compass calibration at least athe start of a flying session.
I have a phantom and I check it now and again but the inspire is a little bit buggy at present and its best to be sure.

That's correct, IMU calibrations are rare, but some owners add it to their preflight checklist.

The common compass calibration takes 5 seconds and that should be done at the start of each session or if you move to another location.

You can check the IMU at any time and it's easy to see if it's off and needs redoing.

absolutely no need for that extent of level accuracy, buy quite inventive all the same.

jimhare Posted at 2015-2-28 04:53
That's correct, IMU calibrations are rare, but some owners add it to their preflight checklist.

Th ...

Hello

I can not discuss how its done with an Inspire - but personally I would never calibrate my compas before every flight session - only when prompt to do it or moving over very large distances or changing of the quad. To fix what is working is adding a chance to get it wrong. I am flying a Phantom and I am flying about 50 flights a month - I have no experience with an Inspire so take it for what it is.
Are now reading everything I can come over before bying an Inspire therefore I jumped into this forum.

The phone for a level is a good idea just keep in mind that the tolerance for most phone companies in parts is 2%. I think I'd stick with dual axis bubble levels (at least 6-8" long) and let gravity and mother nature handle the accuracy on something that has proven to be as sensitive as it is.  

Is it better to level across bottom (such as board above would do), or to place level across the top of prop screws as I do?  I went with above figuring that is the blade location so that should be level.  I use playing cards under feet to level front/back & side/side.  

I have minimal if any drift but always open to a better way of doing things.