P2V+ retractable landing gear mod my mod

[sdtag]

I know there is no good reason for a retractable landing gear on my Phantom 2 Vision Plus, other than I think it looks cool with the gear up. I ordered a kit on Ebay and it's coming on the slow boat from China. The kit I ordered uses the original stock landing gear and adds some hinges and servos and an interface. It utilizes the thumb wheel for the camera. There are videos on you tube demonstrating it. It's like a fast flick of the wheel or maybe two flicks, but it seems to work and not interfere with the camera tilting.
Since it's coming from China I have a few weeks to plan on how to mod my mod. I want to add an ultrasonic sensor and an Arduino to automate the landing gear. When it is less than 6-8 feet (2 meters) AGL the gear will come down. Anything over 6-8 and the gear will be up.
I don't have any experience with Arduino's but I started digging in a little and I ordered some stuff on Ebay. They have a whole bunch of examples so I don't think I need to learn a new language, I think I can copy and paste. And maybe tweak that a little.
Anyone here have any experience with Arduinos?
Think I'm nuts?
Has anyone done this?
All comments, criticisms, flames, suggestions are more than welcome. Let me have it! TIA.

 

[sdtag]

I got my Arduino stuff today. Man this is great. there's a whole other world out there. 2 to 3 hours of play time and I have bread boarded and downloaded schematics and "sketches" (their programs) from the internet and I have this ultrasonic sensor working. I can't get it to 10 feet, I think it's too small and cheap. But so far it works reliably at about 5 feet. this might just work. I have it sitting on my desk looking out horizontally and I push my desk chair up to it and it reliably triggers at about 5 feet. Simulating a landing I pushed my chair up to about 2" away from the sensors and the LED never flickered. I think this will work. Pulling away it resets at about 5 feet. perfect.
Then I still have to figure out how to interface this with that.
Nobody here has played with Arduinos before? I find that hard to believe.
...still going

 

[sdtag]

I received my landing gear fast - 2 weeks on the speed boat from China!
Needless to say I have been consumed these last few days, learning this Arduino stuff.
It turns out these Arduino's can drive a servo directly. I downloaded sketches (programs) for the ultrasonic sensor and for the servos. I learned and tweaked and copied and pasted and guess what! I have a working system on my desk. I have the distance set to 2 feet for testing and it works. It works reliably. If the sensor sees something at less than 2 feet the servos are in the gear down position. When it sees nothing the servos go to the gear up position. When I install it I want to set it to 5 feet.
So far the only drawback I see is I will need two 5 volt sources, one for the servos and one for the Arduino. I haven't even begun to look at the quad yet, I was focused on getting the electrical and programming done first. And I haven't checked the power draw yet either. I'm getting there. Videos soon.

 

[HDtallrider]

I can't imagine the total draw will exceed 5 or 6 amps. here are 2 choices for ubec's that can handle big draws from multiple sources;

http://www.castlecreations.com/products/ccbec.html
You would need to increase awg if you exceed 5 amps

http://www.kdedirect.com/collections/xf-multi-rotor-electronics/products/kdexf-ubec22
This one can handle ANYTHING you could possibly put on your quad and it generates zero RFI. I have one mounted beside of, and touching, my Rx and there have been no problems. Hope this helps. Cool project, by the way.

 

[sdtag]

still working on it but I had my maiden flight today. I am getting some false triggers.

 

[HDtallrider]

still working on it but I had my maiden flight today. I am getting some false triggers.

Ya know. Once you work the bugs out that's gonna be seriously cool! Any idea what the glitch is? Emf? Sensors not matched? One higher than the other? Gotta admit when you came down the first time and the gear went back up a foot off the ground I thought that was all she wrote. Good piloting!

 

[sdtag]

I found out that the cheap little ultrasonic sensors are "seeing" rotor wash sometimes. That's why they false trigger when flying, and never false trigger when I carry it around and test it. I need to add some code to look, wait a second and look again, and if the two answer match, then act. I'm not a programmer so this might take me a while. I have been copying and pasting up to now, with very minor tweaking.
Yeah I am being very careful. Don't want to waste my camera and gimbal. It was a little breezy and I had kind of a rough landing. And again, I know there is no good reason for this, other than I think it looks cool with the gear up.

 

[HDtallrider]

I found out that the cheap little ultrasonic sensors are "seeing" rotor wash sometimes. That's why they false trigger when flying, and never false trigger when I carry it around and test it. I need to add some code to look, wait a second and look again, and if the two answer match, then act. I'm not a programmer so this might take me a while. I have been copying and pasting up to now, with very minor tweaking.
Yeah I am being very careful. Don't want to waste my camera and gimbal. It was a little breezy and I had kind of a rough landing. And again, I know there is no good reason for this, other than I think it looks cool with the gear up.

Glad you were able to identify the problem. It does indeed look cool . A lot of the custom work on my bike is just because it looks cool. Sounds like a great reason to me.

 

[sdtag]

I got it all working pretty well.
The answer was to have it looking for 2 feet 8 times in 2 seconds. If all the answers match, lower the gear.
It worked, but there were 2 issues that developed.
1. this stuff reduced my flight time by 25%. I think it was because the servos have to keep the gear up, fighting the rotor wash. I think if they latched up and stayed up with no power it would be a lot better.
2. I dropped video at about 100 feet. something I added is interfering with the video feed.
2.5 It just doesn't feel right. It seems to be a little "twitchy" something might be interfering with the control frequency also.

I flew around a while testing it through 3 batteries. Very reliable, very stable, but the battery and video issue is a deal breaker.
I took it all back off and returned to my stock landing gear. I instantly got my flight time and distance back.
I'm glad I did this, it was fun learning. And now I know a little bit about Arduino's too. They are amazing little boards.
Live and learn in the name of experimenting

 

[HDtallrider]

Thanks for the update. I have been fooling around with manual, not automatic, retracts. I have been a little disappointed in flight times as well. I think my issue is I've installed them on too small a quad. The retracts are 116g heavier than the fixed gear. That's like another camera and gimbal. I'll try again on a more powerful quad.

 

[GJH105775]

Vibrations could be causing the "false triggers" have you tried increasing the range or better balancing the motor hubs and props?

 

[sdtag]

HD WOW! 116g thats too heavy! try it on a hex haha

GJH yes to both. I balance my props and I played with all kinds of values for distance. everywhere from 1 foot to 10 feet. 2 feet gave me the most reliable operation. But looking at 2 feet, then counting 8 times in 2 seconds... a lot can happen in 2 seconds. I had to fly it down below 2 feet and hover there for 2 seconds so the gear would come down, then land. not bullet proof by any means.

...just re read what you said - I don't know how to balance motor hubs - I never heard of that. enlighten me/us please

 

[GJH105775]

You have a few types of imbalance in your motor hubs, most common and easily fix is when one side is just a little heavier; just add tape in the right spot (divisions of 8 are usually accurate enough). The next has to do with the prop holder/adapter, as they can be bent, to fix this you usually just get a new one. The hardest is probably the bearing, if your bearings are causing the shake/vibration then you can change the bearings, but it is a bit of a job to get it out, once out you can use a bearing press or for motors this small a little vice or even tack hammer. Take props of to test if it is the motors, try without the motor adapter and then with the adapter.

http://www.itsqv.com/QVW/index.php?title=How_To_-_Motor_Balancing

This is a more complete guide, but as you have a KK2.1.x I can give you an easier way (no unmounting the motors and you can do it in place), if you have a KK and a flash tool get Stevie's 1.8, if not then get the iphone app he mentions and mound your motor to something like he did in the guide. You will hook the motor DIRECTLY to the receiver's throttle channel (usually 3) with NO PROPS and spin it up, you then try adding tape to the different sections, it should take you about 8 minutes or less per motor AFTER you have it setup, once you balance one try the tape in the same section on the other motors, as manufacturing defects are often consistent.