First flight, 3DR Y6 to bear my aerial photography in the Amazon?

Rai February 25, 2014 at 1:38am

Hi Yanjun,

I myself haven't tried DIY h-copter (and flying wing) intended to support my research on the rainforest of Borneo (will be there very soon, in a week time) with similar objectives like what you want to do (making images and audiovisual, well I will try to perform mapping of customary forest managed by the indigenous community (only if they ask and allow) as well using Canon camera and CHDK). However, I have three considerations (sharing those of Thomas and Gary as well especially regarding GPS). I have worked in rainforest for year and use handheld GPS and not flying but walking (literally under the 20m to 60 m trees canopy). I tested several GPS and for some GPS it worked well enough to receive satellite signals. But as you also pointed out, relying on GPS only in such situation is not "enough". I think our instinct and spatial orientation is still needed (as well as our "old" map).

Thus, related to your Y-copter, I agree with Thomas, unless you want to do mapping / you want to work on "2D" area then I think GPS is not very much needed for the flight. It might be needed to have your Y copter back to you (RTL). But maybe I am totally wrong interpreting what you want to do with it. Just a suggestion.

Second consideration is, as mentioned by the other fellows above, about the size of your Y, means also the weight, etc. It looks great and ready to fly, and bulk. You might want to think about flight time and your area of coverage. I have no idea at all how long a copter can fly nowadays. I tested my H-quad with different lipo batteries (2200 3S, 3600 3S, 5000 3S and 4S) to find an "optimal" combination for my purpose in the forest. In general, I have never reached more than 20 minutes flying time. Not sure exactly is it caused by weight (my H-quad is 1350 grams of weight with camera etc) or what. I have seen one guy in youtube (I think he is from Rumania, search for FAD ...) who can fly his quad for around 30 minutes (at least 17 minutes for sure). From the video, you can see the quad is "empty".

Third consideration is related to the Mission Planner. You might want to fetch the map of the area in Amazon that you are working at. As I can imagine there will be no internet there :). With my speed of internet in Europe now, It took me hours (around 2 hours) to fetch the map of a rather "not large" area of Borneo that I will work in (I will work in 6 remote areas there, so 10 more hours to go to download / fetch the map). It is not a "big" deal, but you might want to think about it. Otherwise... your Mission Planner will be with "white blank" background and yeah believe me, it's pretty difficult to navigate (although with the "green trees" background is also not that easy).

Just my two cents, and I hope it's useful.

Best wishes,

R

mP1 February 23, 2014 at 1:11am

@Thomas

First off you have given two bad bits of advice.

Companies like DJI and others have a solid engineering experience behind placing their GPS above the multicopter, to avoid EMI and other interference which affects performance of your positioning readings. I cant say for sure but ships and awacs probably have their sonars and other sensitive equipment away from other sources of EMI.

Secondly when your flying FPV you want a wide range lens not a narrow. With a narrow lens its very difficult to judge distance compared to a wide lens. I have flown fpv with a narrow lens and i found i was often thinking i was much closer to some target than i actually was. I then corrected myself but i was uncomfortable as i wasnt really sure just how close or far i was from said object. With a wide lens this is not a problem.

Mustafa TULU February 22, 2014 at 6:35pm

Thing the beauty... The bottom side prop conf. looks odd to me, i think you wrongly attached them( they should be upside down) We need flying video of this urgent:)

Gary McCray February 22, 2014 at 4:21pm

Hi Yanjun,

The APM/Pixhawk firmware we are using absolutely does not at this time support PX4Flow or Object avoidance sonar in copter.

And the PX4 Flow does definitely not plug into the ADC 6.6volt port as it is a bidirectional serial bus that needs a UArt Port.

At least one person is currently working on the PX4Flow, but it is not operational at this time.

And there has been some work done on object avoidance, but it was for a specific use and is not usable for general object avoidance and is not in the current firmware in any case.

These situations will change in the future but for the time being unless you are writing the firmware yourself, both the PX4Flow and the object avoidance Sonar are useless dead weight on your copter.

Best Regards,

Gary

Gary McCray February 22, 2014 at 4:18pm

Regarding GPS in rainforest (RC signal, Telemetry and FPV signals too for that matter.

Trees both block and reflect all of the high frequency wavelengths used by these services.

With GPS you get both multipath and blocking which can rapidly displace your perceived position - a lot.

With your RC and FPV links, the dense cover can block or greatly degrade your signal.

Basically you need to fly with a clear line of sight to your copter at all times and if you are down in the trees - DO NOT - rely on your GPS.

Do not fly with large trees or tree canopy between you and your copter - ever.

These are just a few thoughts, but if you do not follow them, your copter is very likely to make an unscheduled departure :-)

mP1 February 22, 2014 at 4:04pm

Are those sonars actually working ? I thought the APM could only handle one sonar to measure height. I understand the idea but without the software reading the sonar what are they doing ?

mP1 February 22, 2014 at 4:02pm

@Yanjun

I think the 3S is your carrying to power everything but the motors is way to much. I use a 1000 3S for my gimbal, and video transmitter and it always has plenty left over. What im saying is the remainder of the 2600-1000 is just extra weight.

Yanjun Zhang February 22, 2014 at 11:23am

I fear the GPS. I have a painful experience, GPS guided me into no man's land of the Amazon, and where he spent three years.
Although my idea is wrong, but, my is difficult to accept dependence GPS, again.

Use 12V photography head for FPV is a good idea, I will adopt.
I have been confused on how to choose the right .
Thank You Thomas Butler

Yanjun Zhang February 22, 2014 at 5:19am

I have two batteries. 4S 6000 mAh powered (ESC) and Pixhawk, 3S 2600 mAh supply FPV. Provided separately to avoid mutual interference.
I also use the ESC link Pixhawk, in order to achieve a redundant power and as a supplement to the power loss.
I2C link to the 3-wire servo cable, power supply for multiple devices.

Yanjun Zhang February 21, 2014 at 10:40pm

John Githens, thank you very much!

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First flight, 3DR Y6 to bear my aerial photography in the Amazon?

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