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JasonDorie
Code Poet
      
Date Joined Sep 2008
Total Posts : 146
|  Posted 10/13/2008 12:08 AM (GMT -8) |   | | I've been working on a quad-rotor project for a while, but the Propeller chip made my life a lot easier. Remote control in and servo output each on their own cogs is a LOT easier and more accurate than using interrupts. It's not finished yet, but I've now had my first few successful flights in my garage.
Video:
Jason
Update: Oct 13, 2008 - Code and schematic are attached. Note that the 'H48C' in the schematic is now an MCP3208 connected to a dual-axis gyro and an accelerometer. The interface is identical. Post Edited (JasonDorie) : 10/16/2008 6:34:51 AM GMT Image Attachment :
SpyderSchematic.png 51KB (image/x-png)This image has been viewed 1410 time(s). | | | |
File Attachment : WolfSpyder.zip 35KB (application/x-zip-compressed) This file has been downloaded 455 time(s). | | Back to Top | | |
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Joss
Registered Member
Date Joined Feb 2007
Total Posts : 32
| Posted 10/13/2008 3:25 AM (GMT -8) | | | Wow. That knocked my socks off! Amazing work. | | Back to Top | | |
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Tom C
Registered Member
Date Joined Mar 2007
Total Posts : 299
| Posted 10/13/2008 9:17 AM (GMT -8) | | |
Hi Jason,
A couple of questions:
Are the motors outrunner brushless or what?
The receiver appears to possibly be a Spektrum unit, possibly an AR6000 or AR6200?
Are you running a lipo battery and if so what size?
How long can it stay in the air?
Have you determined what kind of payload it can handle?
Regards,
TCIII
If you are going to send a Robot to save the world, you better make sure it likes it the way it is! | | Back to Top | | |
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JasonDorie
Code Poet
Date Joined Sep 2008
Total Posts : 146
| Posted 10/13/2008 9:21 AM (GMT -8) | | Chris,
It's finished in the sense that it now flies and is reasonably stable. Prior to posting I hadn't read the rules on finished/unfinished, so I apologize. I will comment the full code enough that others should be able to read it, and will post the schematic and code for what you see in the video.
It's unfinished in that I want to add self-levelling to the flight control loop, and the plan is for this to ultimately have moveable rotors (like an Osprey) and real wings, so it'll fly normally, or do VTOL. I figured the VTOL part would be the hardest, so I did that first.
Jason | | Back to Top | | |
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JasonDorie
Code Poet
Date Joined Sep 2008
Total Posts : 146
| Posted 10/13/2008 11:19 AM (GMT -8) | | Tom,
The receiver is a Spektrum AR6200, but anything should work. Motors are indeed brushless. Motors are 1050Kv, 20A max, and I'm using TowerPro 20A brushless speed controls. A pair of 3 cell, ThunderPower 2070 batteries in parallel gives it about 4.1Ah of power, and I have yet to figure out my power draw exactly. At 2 Lbs, 13 oz, it's pretty heavy with the packs loaded, but it hovers at approximately 1/2 throttle.
I haven't figured out the flight duration, but I suspect it's around 6 minutes or so. To be fair, I'm not using the most efficient prop for this kind of flight. I think my props are 8.5x6, but if I were to go to a lower pitch with larger diameter it would be more efficient. Ultimately I want the thing to do 'plane like' flight as well as hover, so I wanted the props to balance between fast forward flight and decent hover performance. If I was going for JUST hover performance, lower KV motors and 10x4 props would probably be much better for payload capacity and flight time.
Also, the platform is still somewhat unstable, though that's in my garage in a lot of propwash, so it might not be as bad as I think. I fly R/C helicopters, so I'm pretty good at controlling the thing. This would not be something I'd recommend for someone with no flight experience. If and when the self-levelling works it'll be easier to handle.
Jason Post Edited (JasonDorie) : 10/14/2008 4:28:28 AM GMT | | Back to Top | | |
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JasonDorie
Code Poet
Date Joined Sep 2008
Total Posts : 146
| Posted 10/13/2008 10:16 PM (GMT -8) | | No problem. I've update the original post to include the full code and schematic. I flew it outside for a few minutes today, and even with a small breeze it was more stable than it was indoors. Still a little twitchy, but I'm working on it.
Jason | | Back to Top | | |
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sailman58
Registered Member
Date Joined Feb 2006
Total Posts : 103
| Posted 10/14/2008 6:17 AM (GMT -8) | | Jason,
I am not able to view the schematic using gEDA schematic editor in Linux. Can you post it as a jpg?
Item 2 is the wire extending from the bottom of the aircraft. Is it for stabilization or is it an antenna extension?
Ron | | Back to Top | | |
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sailman58
Registered Member
Date Joined Feb 2006
Total Posts : 103
| Posted 10/14/2008 12:47 PM (GMT -8) | | Jason,
Actually I was hoping that you had a method of lengthening the 2.4 Ghz antenna. If that was the case, I was going to borrow the idea so I could use a 2.4 Ghz system on a submarine at periscope depth.
Ron | | Back to Top | | |
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sailman58
Registered Member
Date Joined Feb 2006
Total Posts : 103
| Posted 10/15/2008 6:00 AM (GMT -8) | | Thanks Tom C.I have been using a Spektrum DX-6 for a couple of years now in my surface boats, and just picked up a 6i. What I would like to do is to somehow lenghten the antenna so i could run it up a periscope and use it on the submarines too.
Ron | | Back to Top | | |
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JasonDorie
Code Poet
Date Joined Sep 2008
Total Posts : 146
| Posted 10/16/2008 11:23 PM (GMT -8) | | Adding the videos to YouTube would mean lower res, and that I'd actually have to learn to post videos on YouTube. :)
My goal is to produce this: http://www.knifeedge.com/forums/showpost.php?p=56116&postcount=4 (it only exists in that simulator)
I want to start working on the airframe now, but to me that's more daunting than the electronics. The motors rotate forward for normal flight, and up to hover. I've been working on getting the 'static motor' version as stable as possible before I move on. I'd like to be able to hover it hands off, though it's actually quite stable now. I'll take a new video in a few days if I have time. I reduced the weight of the propellers, so the motor response is quicker, and I added code to 'help' level it, using the accelerometer and Kalman filters. If I turn it up too high it starts to oscillate, but even with it set low it helps quite a bit.
I'll post more as it happens. Thanks for the encouragement, everyone. Thanks especially to Parallax for this very cool chip. This is my 3rd quadrotor, and the Propeller-based version was the simplest to code by far, and the most fun. I get to spend more time tweaking and less time figuring out how to drive servos, read RC inputs, and do math on one thread. :)
Jason | | Back to Top | | |
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JasonDorie
Code Poet
Date Joined Sep 2008
Total Posts : 146
| Posted 10/17/2008 3:04 PM (GMT -8) | |
In my design, the rotors are paired like this: (CW = ClockWise, CCW = CounterClockWise)
CW CCW
\ /
\ /
X
/ \
/ \
CCW CW
If all rotors rotate at the same speed, the sum of the motor torque is zero. To move left, the left pair slows down and the right pair speeds up, resulting again in a net torque of zero.
To change heading, one diagonal pair speeds up and the other diagonal pair slows down, resulting in a non-zero net torque, but identical net thrust. I believe this is the same as the DragonFlyer. Most quadrotors I've seen are arranged like a '+' instead of 'X', which seems odd since the '+' layout produces some yaw torque when doing pitch or roll moves.
Jason
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JasonDorie
Code Poet
Date Joined Sep 2008
Total Posts : 146
| Posted 10/19/2008 3:39 PM (GMT -8) | | | Jamie,
It all depends on how much you plan to lift. The one shown in the video pulled about 35A, and would probably lift 7 or 8 lbs, including itself (it weighs 3), but would only fly for 6 minutes on those packs, and produced more air speed than required. The current version (all I changed was the props) will lift less weight (5 or 6 lbs) but will fly for 12 minutes on the same packs. Going to lower RPM/Volt motors turning larger props would generate less thrust speed, but more overall lifting power.
I bought the motors from http://hobbycity.com, but there are lots of places that sell hobby motors with the kind of power you're looking for. There are also variable-pitch systems available, though they tend to be for small planes. I've considered using tail assemblies for a model helicopter to see if that would work, but I suspect the paddle-style props aren't as efficient as what I'm using now. The servo to drive the pitch would add weight, but would make the thing more responsive, and able to fly inverted.
For inexpensive stuff, I usually look at HobbyCity, NitroPlanes, or BPHobbies. For better quality, but higher prices, check out Hobby-lobby, HorizonHobby, Tower Hobbies, or plenty of other online places.
I'm planning to augment the anti-torque thing with movable motor pods. That will give me both forward flight, and far faster rudder response in a hover. The left/right motors will tilt fwd/back to spin in place, or all tilt forward for normal flight.
Jason
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