Ken/Cluso99/ W9GFO/JasonD's QuadCopter Build Log (updated info ELEV-8 + availability)

[Ken Gracey]

Ken,

Do you have display goggles for the FPV stuff? What kind?

Also, what's with the lack of snow?

-Phil

Hey Phil! Yesterday was my first FPV flight off of my office. It was a tenuous situation with alligator-clip wiring, zip ties, and a lot of excitement. The setup worked like this - a patch antenna was outside and a 32" TV was showing the video inside. I was standing inside the office, then outside, then inside, switching back and forth between visual control and FPV. The whole setup was so crazy I couldn't quite get my head around it, mostly because of my chaotic test conditions (couldn't wait till today). I would much rather fly from a TV than goggles, but the TV must be in shade - and who carries a TV around anyway? If I'm inside and watching the TV then I'm going to cripple the R/C transmitter.

I'll get some goggles. Where's erco?

[Cluso99]

Really neat Ken! All this without accelerometer... seems to me they are completely unnecessary from the stability you and Jason have achieved.

I am still going for the whole hog, at least for later (gyro, accel, compass & pressure) plus GPS later. But for a cheap solution, gyro looks fine.

[JasonDorie]

The gyro is the only thing you need if you want to "pilot" it. Mine is very stable now, and I'm still tweaking it, so I suspect it's going to get better still.

The accelerometer is necessary for holding level flight, magnetometer is necessary for holding a fixed heading, altimeter is for holding a fixed altitude, and the GPS is to hold a fixed position. Each of these additions complicate the programming of the thing - everything new sensor means more readings, more control loops, and more tuning.

The code for the gyro only solution is actually quite elegant, but it doesn't need a "real world" reference frame. As soon as you require that, now you need to start working with real units of measurement, like radians or degrees. Then you encounter problems like gimbal lock, so you have to hack, or use solutions like quaternions which are hard for most people to visualize and require more complicated math.

I'm not arguing for one or the other - they both have their place, and I'm looking forward to tackling the above problems, but if you want something cheap that's fun to fly, a 3-axis gyro is plenty.

I think I'm going to add a bunch of "make users happy" features to mine, allowing for easy configuration with an external piece of software. Keep an eye out - I'm hoping to have something in the next little while.

[JasonDorie]

Ken - You mentioned adding an accelerometer for leveling - You need that for the camera, not the quad.

I've been thinking of adding code to mine to allow for that as well - I could pretty easily alter my DCM code to handle leveling a camera gimbal even without making it deal with the flight controls. I could have that done a lot sooner than a full flight stabilization model. Since I've started doing the on-board filming I realize how important it will be for aerial video work, so I'll likely add that soon.

The video was awesome - Does your heart rate go up with altitude? I think for every foot beyond about 15 feet my heart rate goes up about a bpm. I've had my quad up to about 50 feet I think, and I'm just terrified that I'll screw up and it'll fall out of the sky and shatter. I'm slowly getting over that as I fly it more and get used to the orientations again. I was out today doing figure eights in the park and I'm getting a lot more comfortable with it.

Jason

[W9GFO]

About leveling... what would be really, really cool is to control the roll and yaw of the camera based upon it's motion through 3d space. So many of the videos, even professional ones, don't have the camera pointing in the direction of travel or banking in sync with the turns. I think you would need accelerometers to accomplish this, I am sure it is possible.

Even some code to keep the quad facing it's direction of travel would be a huge help in aerial video.

[ratronic]

Ken can you let us know the make and model of the battery you are using? So far I've seen in this thread the requirements seem to be 11.1 volt LiPo, 4000mah, 35C, EC-3 connector. I need to get the correct battery ordered and would like to find one that has the most current capabilty with the lowest weight. Could you please let us know what your using?

[Ken Gracey]

Ken can you let us know the make and model of the battery you are using? So far I've seen in this thread the requirements seem to be 11.1 volt LiPo, 4000mah, 35C, EC-3 connector. I need to get the correct battery ordered and would like to find one that has the most current capabilty with the lowest weight. Could you please let us know what your using?

Yes, and I apologize for not responding earlier to this request. You can choose any manufacturer you wish. This is what I'm using:

PowerWing Lithium Polymer Battery 4000 mAh YT9042125PH 3S 30C
PowerWing Lithium Polymer Battery 3300 mAh YT7042125PH 3S 30C

I suggest a discharge rate of 25C or higher, which seems to be typical for this battery rating anyway. As far as capacity is concerned, we're using up to 4400 mAh - storage larger than that seems to jump up significantly in size and weight. We've also purchased LiPo batteries from HobbyKing at very low prices and they seem to perform just as well as the domestically-sourced brands (which are also from China). I'd order them from HobbyKing and get about 2-3 batteries for the same price as the PowerWings listed above. Get your order in now because they take time to ship.

Ken Gracey

[schill]

Ken:

How are things looking for ordering the ELEV-8s?

Is there anything else we would need other than the batteries and radio?

[ratronic]

Thanks Ken.

[Ken Gracey]

Ken:

How are things looking for ordering the ELEV-8s?

Is there anything else we would need other than the batteries and radio?

Yes, see post #2 here http://forums.parallax.com/showthrea...bly-and-flight!.

These are being kitted up today and tomorrow. Our crew is working to get the ordering page up really quickly for you.

[schill]

Thanks, Ken.

Somehow I missed the bottom section of that thread. I was probably just skimming it since it's unusual for me to encounter tools I don't already have for a project like this.

[ratronic]

Ken trying not be a pest, but.... now that I have the specs for your battery I can not find it on the net to find it's weight. Can you tell us what your 4000mah battery weighs?

[Ken Gracey]

Ken trying not be a pest, but.... now that I have the specs for your battery I can not find it on the net to find it's weight. Can you tell us what your 4000mah battery weighs?

Sure - weight is here http://www.hobby-lobby.com/3_cell_11...34051_prd1.htm and it appears to be 12.16 oz.

We will need to post some specifications on the ELEV-8 too.

Ken Gracey

[JasonDorie]

I run pairs of 2200mAh batteries in parallel, as a lot of my planes take the ~2000mAh size. I can fly for 14:50 on a 4400 pack, so a single 2200 pack will get better than half that because there's less weight, and it'll be more nimble - good for aerobatic flights.

[Ken Gracey]

I run pairs of 2200mAh batteries in parallel, as a lot of my planes take the ~2000mAh size. I can fly for 14:50 on a 4400 pack, so a single 2200 pack will get better than half that because there's less weight, and it'll be more nimble - good for aerobatic flights.

That's a valuable point for all of us to consider. Quadcopters behave quite differently without extra weight - flying sideways and fast vertical flight is so much easier without a full load.

[Roy Eltham]

I had no problems running my "release candidate" ELEV-8 (is that the right thing to call it Ken? It was pretty close to final I think) with a Zippy 3S(11.1v) 3000mA 20C LiPo. I believe I got about 10-12 minutes of operation.

Of course that was broken up in few minute increments as my current flying technique is to take off and fly around a bit then unintentionally land (not exactly crash, just come down to the ground on the landing gear slightly before planned and sometimes slightly faster than intended ). Although, towards the end of the day, I did manage a few flights where I took off, flew around and landed intentionally and safely.

[Ken Gracey]

I had no problems running my "release candidate" ELEV-8 (is that the right thing to call it Ken? It was pretty close to final I think) with a Zippy 3S(11.1v) 3000mA 20C LiPo. I believe I got about 10-12 minutes of operation.

Of course that was broken up in few minute increments as my current flying technique is to take off and fly around a bit then unintentionally land (not exactly crash, just come down to the ground on the landing gear slightly before planned and sometimes slightly faster than intended ). Although, towards the end of the day, I did manage a few flights where I took off, flew around and landed intentionally and safely.

This is a skill, for certain, and it will take time to become a good R/C quadcopter pilot. From what I saw at Parallax I think you should be able to fly just fine - but stay on the grass. It's much more forgiving.

[schill]

Now we just need the kit to be available while the sensor sale is still running so I can put them on the same order.

[Ken Gracey]

Now we just need the kit to be available while the sensor sale is still running so I can put them on the same order.

Agreed. The first run of kits is being carefully assembled by our Tech Support team this week. We're doing this as an intermediate step before we move it to the Kitting department, mostly because they are busy and we want to make some final checks ourselves. I haven't heard from Kevin and Nick today probably because they're busy with this project. I've been working from home just to let others be productive, so it seems to be working.

I need to get with them about making a crash pack, too. Just to be honest, you guys are going to have an insatiable appetite for replacement propellers, landing gear, and the motor mounts. The frame and booms seem to be immune to sustaining real damage so far.

[Roy Eltham]

Ken is right, I already want to order more props, landing gear, and stuff just so I have it. Right now I am being really cautious with mine, but if I had a few spares of everything he mentioned, I would be less worried and have more fun.