Jump to content

My little NAV/OSD project - under construction


Recommended Posts

  • Replies 735
  • Created
  • Last Reply

Top Posters In This Topic

Lol, you guys are funny! Actually I've finished revising the board to use a supercap instead so no more batteries to worry about. Right now I'm stalled for only one reason, need to buy a standard version of EaglePCB because the free one doesn't do more than 2 signal layers and I'm trying get a fully ground plane as a third layer. So basically the bill of materials have been updated, the board has been laid out, only need to buy the Eagle to convert the ground plane correctly. I will then forward everything to Mark and get the new boards done.

Daniel

p.s. Once that happens I'll get working on the IMU board for the Dragon - which will provide pitch, roll, barometric altitude, and G-forces information, and will enable better stabilization and autopilot, artificial horizon (if you've seen my night flight, you'll know why I want one), and more accurate altitude. This will plug into the UART2 port.

Link to post
Share on other sites

Daniel,

I hope you used the BOB-4-H rather than the BOB-4-S? I'm drafting my board as well at the moment, based on the 4012 rather than the 4011 and the BOB-4-H (with the header removed so the boards can be mounted real close) is a great fit. I have ample room to add a switched PSU for a the TX and camera. Actually, I could fit two 4012s if needed on a double sided board. Total size is 2.650"x1.50"x0.75".

Cheers,

Sander.

Link to post
Share on other sites

Daniel,

Quick question about the current sensor. I'm getting 65 amps WOT. However, there's no way that's accurate. It's only a 50 amp sensor and the motor I'm running is showing 30 amps on my wattmeter. Any ideas?

Thanks!

Edited by docphi
Link to post
Share on other sites

I'm not sure on the 5v power supply thing, have to ask daniel. Sounds like a good idea though except for one thing - the 5v linear power supply which gives the bob-4 power needs to be powered by more than 5v. The IF power supplies tend to give 4.95 to 4.99 volts.

Link to post
Share on other sites

Hi docphi,

Could be a couple of things in my mind about this problem:-

1. Could be the resistor on the current sensor board. I can't remember what value I used with that version, one way you could is to try lowering it.

2. Make sure that AMPSZERO is set that current is just zero when ESC is not connected. It should have a slight jitter between 0.0 and 0.1A.

3. Could be the software coefficient. This is actually very easy to change and I could do it for you. Just do some tests, and let me know some info:-

a) actual current and displayed current

B) from a fully charged battery, fly the plane normally then see how much it puts back in to the battery - actual mAh used, and the displayed mAh

I can compile a calibrated version for you. I should make these coefficients user adjustable (in fact I probably will).

Hope that helps.

Daniel

Link to post
Share on other sites

Definitely helps. I'll take some measurements tomorrow.

I noticed in the DragonOSD manual that it states the current sensor is directly connected to the OSD. However, I've been using the schematic you posted which has several components in the circuit diagram (the resistor is 22K, btw). The other thing I noticed is that in your circuit diagram, the pins are labeled 1-vcc/2-gnd/3-vout. But, Allegro's data-sheet has them running the opposite way (1-vout/2-gnd/3-vcc).

Should we use your diagram or just run the current sensor directly (with a 0.1uf cap as recommended)?

Thanks!

Link to post
Share on other sites

No, the current sensor for the original design is different from the revised board. Those extra components have been moved onto the main board. As such the instructions in the manual are for the new setup which s a bit simpler in that the sensor board involves very few components.

Daniel

Link to post
Share on other sites

Daniel,

I tried several lower value resistors which didn't change the reading. The Ampszero is set properly. I think we're left with the software coefficient. Here's the data I have from a static test today:

displayed current - 65

actual current - 30

displayed mah - 1000

actual mah used - 1386

This was on a 3s 2200 mah pack.

Edited by docphi
Link to post
Share on other sites
Hi docphi,

I've made some changes to the code to allow you to calibrate your own current sensor. But I don't have a system to test it right now (I lent some of my gear to a friend). Would you care to test it?

Daniel

Yes! I would love to test it! :D

Link to post
Share on other sites

Okay, I've actually added the features but need to clean up the code a bit. Meanwhile, to keep you guys amused, try this:-

City View (46MB, WMV)

And, a bit off topic but, yesterday me and my friend did a distance test and got 10km distance out of a 200mW Lawmate transmitter. This was with a 3dBi whip on the transmitter (EZStar) and 8dBi whip on the receiver. Nothing special in the setup. When the plane was high (200m and up) the picture was very good and usable. Below that it's a bit iffy. The lowest I got a usable image of was about 94m. This was with all kinds of tall buildings in between us.

Daniel

Edited by Daniel Wee
Link to post
Share on other sites

Daniel's videos? They all look great!

If I fly around here all you'll see is square mile upon square mile of grasslands and the occasional cow, maybe I should try paint bombs and a servo release mechanism and start dive-bombing the cows? That would make for an interesting video I'm sure :rolleyes:

Cheers,

Sander.

Link to post
Share on other sites
Daniel's videos? They all look great!

If I fly around here all you'll see is square mile upon square mile of grasslands and the occasional cow, maybe I should try paint bombs and a servo release mechanism and start dive-bombing the cows? That would make for an interesting video I'm sure :rolleyes:

Cheers,

Sander.

And please be sure you drop cluster bombs! Why peck a 1000 pound walking sirloin steak with a pea when you can Crayola her in techno colors!! :lol:

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...