DJI Naza sub trim

[RCNut]

My Naza is a stable as I could ever want it. When I lift off it seems to tilt slightly towards the left but stabilises straight away. It then hovers dead steady as if its on GPS position hold. When I first built it, it used to wander a little bit and I found it was susceptible to changes in balance. Over the 6 months that Ive had it, Ive changed its configuration several times and noticed that it handles and balances differently each time. My current configuration has it bottom heavy i.e. all the weight is below the COG although it's balance pretty well horizontally. What tended to make it drift most was adding weight to the top which seems to want to make it roll off its COG. My GoPro is mounted underneath the front tab and the battery (3000mAh) is strapped sideways underneath the rear tab for horizontal balance. I also have a set of IrisAerial's carbon fiber legs bolted to each arm. All my trims and sub trims are set to zero. The stiff Graupner props also help with stability especially when its windy.

 

[cones]

This morning I decided to move everything around so I could make changed to the Naza position without having to undo lot of mounting plate screws each time.

This is now the Naza was mounted.

This is the new setup

 

[cones]

The inside of the Naza looks like this.

 

[cones]

The Naza unit has red and greed LED on the top of the PCB.

I would like to know what they signify?

Looks like the red one is power on. But the green one comes on then goes out while the unit goes through the self check, then it comes back on again.

 

[cones]

The whole set of pictures is here http://s699.photobucket.com/albums/vv357/cones_stuff/DJI Naza F450 Flame Wheel Redesign/ for those that want more detail.

The first flight with the new layout was a success with no big drift to the right at the start of the flight.

Still a little windy to try a full hands off hover, but first impressions are that it will be O.K. when I do.

I think the far lower C of G with the battery on the base is a better idea anyway. I just cannot use my JVC Picsio with the Naza now sitting on the top plate.

As you can see the Naza sensor only sits between the foam pads. I wonder if my crash impact has moved it in some way, hence the crazy angle of the case to get it to stop drifting.

 

[cones]

I did think of putting a shim inside the Naza case to press on one side of the base of the foam pad. So that I could then mount the case level on the plate. But I think compressing the foam may alter the damping it is designed to provide for the sensor.

Mark

 

[cones]

Hi,

Even with the 2.8 Degree tilt applied to the Naza unit it still drifts to the right. I tried again last night in dead calm conditions. It is taking about 5-10% aileron trim to stop it happening, but by the end of the flight it is drifting to the left and needs the trim moving back to the middle.

Something in the Naza electronics must be causing the movement. Other issues like the C of G (Which i have checked and is perfect) would remain constant and not shift right then left during the flight.

I have the GPS unit on order and it will be interesting to see what happens with this installed? But I think the platform should be stable and not drifting before adding yet another control input device.

Thanks

Mark

 

[cones]

A quick update.

I installed the Naza GPS unit this evening.

Because of the constant drift to the right the GPS is useless in position hold mode.


I am now convinced that my Naza unit is broken and that I need to order a replacement for it.

I'll report back when I have got a new unit.

Thanks

Mark

 

[little nellie]

Thanks for sharing the pictures of the inside of the NAZA. I noticed in your original position picture, the NAZA doesn't appears to sit flat on the plate. The picture that shows the board on the side (last picture), the boards seem like not very even. Is that off center or just the picture? What is inbetween the board?

Silas

 

[cones]

Hi Silas,

Yes, I had to shim it up to try and stop it drifting to the right. It does work by shimming it more as seen with the cocktail stick on the later picture. But the unit gradually moves from drifting to the right to drifting to the left during the flight. I suspect my crash has damaged the Naza unit in some way.

I need a larger space to see what happens if I climb a little more and let the GPS position hold have control longer than it takes to collide with the fence in the garden. :nevreness:

Thanks

Mark

 

[little nellie]

Hard to say what to do next other than replace the NAZA.. Do you have someone near by and borrow one to try? BTW, is that metal looking item in the center the sensor?

In this case, if it is drifting back, shimming is not going to work.

Silas

 

[cones]

This morning I tried again with the Naza GPS and F450 frame.

I think I am making some progress,

First of all I calibrated the GPS compass. Perhaps I should have done this to start with?

Then I waited until I had a full satellite lock. No red flashes.

I noticed that after 2 minutes or so waiting for the GPS lock that I get a lot of green led flashes together for a few seconds.

I then had a successful flight in both Atti and GPS modes with no major move to the right.

It seems after all of these green flashes in a row the both the Naza and the GPS recalibrate and zero their positions. I can now fly without ANY sub trim applied.

So I tried again without waiting for the green flashes and the drifting to the right re-occurs.

It seems something is happening to the Naza level position when I wait for the GPS lock.

But if this is now repeatable, it seems it is after a further 4 flights. Then I just have to wait for the green flashes and then start my flight.

I can now see the GPS working. The wind is 20mph and gusting in my garden today and the GPS is now holding the frame very well indeed. I am now happy that I am getting the results that everyone else seems to be getting.

Thanks

Mark

 

[cones]

Today's Flight.

Thanks

Mark