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Old Aug 25, 2011, 02:51 PM
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Current from Lipo to drone at low battery conditions and fast landing

UFO Doctor did some additional measurements:

After activated LVBA and landing the current consumption is still about 300mA.

But if the voltage of the Lipo (in my laboratory measured with an external power supply) drops below 8.8 V, the connection from Lipo to drone will be almost interrupted and the current from the lipo to drone is about 0.08 mA only!

Congratulations to the designer of the Parrot drone!

However, this 8.8V threshold is not good in general. A limit of 3V/cell (9V for Drone Lipo with 3 cells) would be the minimum for a long life of the lipo.

Without proof I would say that the Parrot limit of 8.8 V might be good for a new lipo, but not for a lipo used 20 times (voltage/cell cannot be assumed as equal)

Thus, my advice again: disconnect the lipo from drone after landing as soon as possible.

Or: Miru offers an other genius idea

Kind regards
UFO Doctor
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Old Aug 25, 2011, 04:16 PM
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Quote:
Originally Posted by miru View Post
I would just turn off the VLBA output with the high current LEDs to preserve the lipo longer. If the drone is not flying, it can run for quite some time on the remaining charge. I don't know yet if the hardware can be turned off like in a regular Linux system on a PC (ACPI).
My 2 high intensity LEDs draws 33mA, also insignificant as indicated by Dr UFO when compared to what the ardrone is drawing.

Quote:
At present, I see only a n-typ 10 A MOSFET in series between Lipo and Drone, controlled by the Ardunio with new Miru software
If this is option is available I personally probably would not implement it. I'm not too comfortable putting in a device (an extra point of failure) that could shut off main power to the complete system.

Also, having the LED flashing is a visual reminder to remove the battery. It was strictly a "pilot error" when I left the battery connected to take extra photo/videos.

Now, it would be a different story if the ardrone is forced to land in the bushes a couple hundreds of meters away...

Did a quick flight in my backyard an hour ago - from 30 feet away with the ardrone up 20 feet, the 2 white LED is actually very visible against the sky. Sorry, with the ardrone flying in confined space 20 feet up, my hands were full, no photos or videos this time.

Edit - It is more likely you would forget to turn off your RC transmitter - it happened to me after completed some testing and left the "lab". I didn't hear the RC tx's low battery beeping from the family room... The RC tx's Lipo is now ballooned!
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Old Aug 25, 2011, 05:37 PM
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Originally Posted by MathiewH View Post
Hello Candu1,
the GoPro Hero Cam has a ultra wide angle lens like a fisheye, its normal that the horizion changes the curviature, if the horizion is not in the middle.
It happens the same, if you use a Key Chain Spy Cam with extra fisheye lens,
My cam was not fixed total flat to the horizion, looking more to the ground, perhaps therefore your "wonderings"...
Greetings Matthias
With the GoPro Hd, using 1080 X 1920 yields a smaller field of view (and a 16:9 image ratio) than using the 960 default resolution. With 1080 you would get less edge distortion.
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Old Aug 25, 2011, 06:35 PM
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Originally Posted by Doc_Avid View Post
With the GoPro Hd, using 1080 X 1920 yields a smaller field of view (and a 16:9 image ratio) than using the 960 default resolution. With 1080 you would get less edge distortion.
Oh thank you, will try it next flight.

One question to the VLB:
After the LEDs were blinking and landing, if I measure the lipo with a lipo tester, the tester shows always 7-8%, but in the sketch is a 15% limit.
Is it better to change the limit in the sketch to 25%, or is the lipo tester bad?

Kind regards Matthias
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Old Aug 25, 2011, 07:05 PM
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Originally Posted by MathiewH View Post
Oh thank you, will try it next flight.

One question to the VLB:
After the LEDs were blinking and landing, if I measure the lipo with a lipo tester, the tester shows always 7-8%, but in the sketch is a 15% limit.
Is it better to change the limit in the sketch to 25%, or is the lipo tester bad?

Kind regards Matthias
It's not a direct comparison. When you made the measurement, the lipo is off loaded (motors are not running). mirumod's reading is done when the motors are running (which draws 4000+mA as measured and reported by Dr UFO).

I set mine to 25% because I wanted to have more lead time to get the ardrone back for a controlled landing. With the default 15% I timed 30 seconds before it was forced to land which to me is not enough time in most situations.
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Old Aug 25, 2011, 07:23 PM
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Originally Posted by MathiewH View Post
Hello Candu1,
the GoPro Hero Cam has a ultra wide angle lens like a fisheye, its normal that the horizion changes the curviature, if the horizion is not in the middle.
It happens the same, if you use a Key Chain Spy Cam with extra fisheye lens,
My cam was not fixed total flat to the horizion, looking more to the ground, perhaps therefore your "wonderings"...
Greetings Matthias
I see. I really did see it: :-) You see, I took off my glasses (concave lens, I think or may be its convex) put it in front of me at arms length, pointing and looking through it at the horizon. I can then really see the horizon curvature bending and straighting out as I move my glasses up and down... So now I can stop wondering. My new wondering is whether the extra weight affects the handling and flight time at all?

Seriously, from what I've seen so far, I am very impressed with the GoPro video. But because of the price, I think I'll stick to my less expensive 808#11 for now.
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Old Aug 26, 2011, 03:27 AM
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Originally Posted by Candu1 View Post
I see. I really did see it: :-) You see, I took off my glasses (concave lens, I think or may be its convex) put it in front of me at arms length, pointing and looking through it at the horizon. I can then really see the horizon curvature bending and straighting out as I move my glasses up and down... So now I can stop wondering. My new wondering is whether the extra weight affects the handling and flight time at all?

Seriously, from what I've seen so far, I am very impressed with the GoPro video. But because of the price, I think I'll stick to my less expensive 808#11 for now.
With the GoPro on the drone I fly with the original lipo or with the 1250mA lipo which have the same weight. You are feeling the extra load of the cam, but its no problem to fly, the flight is more smooth than normal, if you are high and wants to go down you have to do this much more slowly than normal, because if you push full throttle up, the Drone will turn to the right or fallls down in the gras, the lift is not much enough.
Without cam I fly with a 1800mA lipo, no problem, 2200 mA is the limit, it makes no fun.

Best regards Matthias
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Old Aug 26, 2011, 07:09 PM
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Originally Posted by MathiewH View Post
With the GoPro on the drone I fly with the original lipo or with the 1250mA lipo which have the same weight. You are feeling the extra load of the cam, but its no problem to fly, the flight is more smooth than normal, if you are high and wants to go down you have to do this much more slowly than normal, because if you push full throttle up, the Drone will turn to the right or fallls down in the gras, the lift is not much enough.
Without cam I fly with a 1800mA lipo, no problem, 2200 mA is the limit, it makes no fun.

Best regards Matthias
One more Wonder, MathiewH. After reading the GoPro spec, I think I now understand why all the video I've seen so far on the GoPro were super smooth. The GoPro is capable of recording video at 60 frames a second which is typically more than double the normal video frame rate. When the recorded 60 f/s video is played back at the normal fame rate of 24 to 30 f/s, the net effect is like playing the video in slow motion. So all the quick jerky control action would be smoothed out during playback.

So, my vey last wondering... Wondering, when you have a chance, if you can just record a short video clip using 30 frames a second and see what it looks like when compared to a similar video taken a 60f/s. You can post your result here if it is more appropriate http://www.ardrone-flyers.com/forum/...php?f=8&t=1954

Sorry miru, didn't mean to hi-jacking your thread on unrelated topic but my curiosity is killing me and my little 808#11 camera...
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Old Aug 27, 2011, 04:11 AM
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Originally Posted by Candu1 View Post
One more Wonder, MathiewH. After reading the GoPro spec, I think I now understand why all the video I've seen so far on the GoPro were super smooth. The GoPro is capable of recording video at 60 frames a second which is typically more than double the normal video frame rate. When the recorded 60 f/s video is played back at the normal fame rate of 24 to 30 f/s, the net effect is like playing the video in slow motion. So all the quick jerky control action would be smoothed out during playback.

So, my vey last wondering... Wondering, when you have a chance, if you can just record a short video clip using 30 frames a second and see what it looks like when compared to a similar video taken a 60f/s. You can post your result here if it is more appropriate http://www.ardrone-flyers.com/forum/...php?f=8&t=1954

Sorry miru, didn't mean to hi-jacking your thread on unrelated topic but my curiosity is killing me and my little 808#11 camera...
Hello " Mr. Wondering"
Yes I will make a shott Video clip with low video frame rate, but I have to find the user guide from the cam...
The video quality of the key chain cam looks very good, I have only the #3 version with wide angle and fisheye lens from Dealextreme.

@Miru
Hello Miru, I saw a link:

http://www.dronetuner.com/index.php?...t&product_id=9

where you can buy a complete set to modify the drone, I hope that they have not stolen your sophisticated Mirumod!

Greetings from Germany, Matthias
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Old Aug 27, 2011, 04:49 AM
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Acoustic low battery alert on iPhone

Hello everybody

The new FreeFlight 1.9 offers an acoustic low battery alert on iPhone.

The threshold can be set from 10% to 50 % of the remaining battery capacity. Below this level the bell of the iPhone rings 5 times within 5 seconds.

Combined with our Visual Low Battery Alert VLBA it tells you when it is time to land.

In contrast to the short acoustic alert (no need to be permanent) the continuous VLBA blinking LEDs are excellent if you have to bushwhack in order to localize the landed drone!

Kind regards
UFO Doctor
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Old Aug 27, 2011, 12:34 PM
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Originally Posted by UFO Doctor View Post
Hello everybody

The new FreeFlight 1.9 offers an acoustic low battery alert on iPhone.

The threshold can be set from 10% to 50 % of the remaining battery capacity. Below this level the bell of the iPhone rings 5 times within 5 seconds.

Combined with our Visual Low Battery Alert VLBA it tells you when it is time to land.

In contrast to the short acoustic alert (no need to be permanent) the continuous VLBA blinking LEDs are excellent if you have to bushwhack in order to localize the landed drone!

Kind regards
UFO Doctor
Good idea. I'd also have my earbud in place. Some times it could be too noisy to hear the alarm.

Completed my early morning thumb exercise. Shouldn't have flown since it was VERY foggy. From this the pictures, you can see condensations (actually water dropets) forming on the four legs.



You can also see my prototype 808 camera mount under the ardrone.



OK, here's the video clip showing the high intensity white LEDs triggered by mirumod's VLBA on arduino's pin9. The thing to look for is that ardrone's red LEDs are not visible at the same distance. I was trying to increase its altitude in an attempt to get a better video of the LEDs, but it executed a low battery land before I had a chance to do it. (I know, Dr UFO, a bad idea...) :-)

I was also the camera operator too since my spotter (a RC heli pilot) arrived late.



AR Drone mirumod test LED (0 min 31 sec)
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Old Aug 27, 2011, 01:40 PM
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would it be possible to use a long range modem like ( http://www.sparkfun.com/products/559) to control the ar drone ? and make a router connection on the ground to the second modem so tha computer can connect to it as if it was a normal router like the one on the ar drone , it says whatever signal you put in the other modem will see. so would an rc signal be able to be used to control the drone with the long range modem and have the drone transmit through the modem back to the second modem in 915 or 433 mhz instead of 2.4 and the modem on the ground serves to decode it on a mini laptop.
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Old Aug 27, 2011, 03:08 PM
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Very good video to demonstrate VLBA

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Originally Posted by Candu1 View Post
Hi Candu1
Very good video to show VLBA in reality!
Kind regards
UFO Doctor
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Old Aug 27, 2011, 03:31 PM
wmw
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Hi Candu1,
What kind of "feet" do you have on your drone?

Cheers
Max
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Old Aug 27, 2011, 03:41 PM
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Originally Posted by badboy14 View Post
would it be possible to use a long range modem like ( http://www.sparkfun.com/products/559) to control the ar drone ? and make a router connection on the ground to the second modem so tha computer can connect to it as if it was a normal router like the one on the ar drone , it says whatever signal you put in the other modem will see. so would an rc signal be able to be used to control the drone with the long range modem and have the drone transmit through the modem back to the second modem in 915 or 433 mhz instead of 2.4 and the modem on the ground serves to decode it on a mini laptop.
You might be able to make it work for the control channel up to the drone, but the downlink is definitely too slow (9600 baud) for any original navdata. You can forget video on that link as well.
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