|
|
| Author |
Message |
sturgessb
Joined: 25 Apr 2008
Posts: 246
Location: Norwich, UK
|
|
Posted: 11 October 2008, 18:57 PM Post subject: ZX Quad |
 |
|
Hey Guys
Though some of you might be interested in my latest progress.
http://www.vimeo.com/1923952
Cheers
Ben |
|
| Back to top |
|
 |
mikep
Joined: 24 Sep 2005
Posts: 765
Location: Austin, TX
|
|
Posted: 11 October 2008, 19:38 PM Post subject: Re: ZX Quad |
|
|
| sturgessb wrote: | | Though some of you might be interested in my latest progress. |
You have made a lot of progress since the early test flight I saw. Excellent !! Excellent !! |
|
| Back to top |
|
|
twesthoff
Joined: 17 Mar 2006
Posts: 191
Location: Fredericksburg, VA
|
|
Posted: 11 October 2008, 20:00 PM Post subject: ZX Quad |
|
|
vERY IMPRESSIVE! looks like you have it working very well!
Great job... |
|
| Back to top |
|
|
sturgessb
Joined: 25 Apr 2008
Posts: 246
Location: Norwich, UK
|
|
Posted: 11 October 2008, 23:38 PM Post subject: |
|
|
Thanks guys, really appreciate your kind words!
It's coming on, still lots and lots to do, including:
Barometric Sensor
GPS for holding position and waypoint navigation
Long range Data Link (maybe GSM)
But the main flight model is 90% there. Just a bit more tweaking for extra stability.
Im using Mikes ZX-128ne for flight stabilization, and a zx-24n for secondary functions like Radio Data and GPS, these are linked via SPI.
The zx-128ne crunches all this data with a whopping loop speed of 600hz, hopefully by the time ive added all the extra code it will still be 500hz+ as this is the sweet spot.
Cheers
Ben
PS: A huge thank you to all those that have helped me with my mostly moronic questions! |
|
| Back to top |
|
|
spamiam
Joined: 13 Nov 2005
Posts: 666
|
|
Posted: 13 October 2008, 1:45 AM Post subject: |
|
|
This is really wonderful! I live the sound of it. It is like an angry hive of bees. It is so good that I am full of questions!
I am inerested in how you made it maintain its tilt orientation. Does it take your radio signal and then interpret this as an amount to tilt off level, so that if you center the stick it returns to level? Or do you have to feed it corrections to maintain the tilt?
When you perform an acceleration to the side (i.e. not "up" or "down"), and the copter starts to sideslip, does it automatically compensate for the loss of lift and increase the motor speed (by Tan(tilt angle)???) so that you do not lose altitude?
Does it override your input if it will result in excessive tilt (i.e. so much tilt that you can not speed up the motors enough to maintain altitude)?
Does it monitor battery capacity (or voltage) so that it knows that with partly run down batteries that it will not be able to drive the motors quite as fast, and therefore not be able to tilt as much?
What flight time do you get? What type and size of batteries do you use? If the batteries run too low in flight what happens? Can it soft-land automatically? I.E. run the motors at just enough speed to lose altitude at a specified slow speed?
I am sure I will have lots of follow-up questions!
-Tony |
|
| Back to top |
|
|
sturgessb
Joined: 25 Apr 2008
Posts: 246
Location: Norwich, UK
|
|
Posted: 13 October 2008, 16:39 PM Post subject: |
|
|
Thanks spamiam
here are your answers....
| Quote: | | I am inerested in how you made it maintain its tilt orientation. Does it take your radio signal and then interpret this as an amount to tilt off level, so that if you center the stick it returns to level? Or do you have to feed it corrections to maintain the tilt? |
Yes. the cyclic stick position defines the X and Y tilt and the copter tries to maintain it. -30 to +30 degrees. If the stick are released it returns to level.
It is VERY easy to fly, I'm going to post up a video of my partner flying it for the first time. She has never flown anything in her life.
| Quote: | | When you perform an acceleration to the side (i.e. not "up" or "down"), and the copter starts to sideslip, does it automatically compensate for the loss of lift and increase the motor speed (by Tan(tilt angle)???) so that you do not lose altitude? |
The loss in altitude is not much, as the airspeed makes up for this with extra lift (just like a helicopter is needs less power the faster it is going). However it mixes in appropriate extra throttle to reduce this further.
| Quote: | | Does it override your input if it will result in excessive tilt (i.e. so much tilt that you can not speed up the motors enough to maintain altitude)? |
Max tilt is 30degrees, this could be extended to any value up to 90degrees depending on how aggressive you want to fly!
| Quote: | | Does it monitor battery capacity (or voltage) so that it knows that with partly run down batteries that it will not be able to drive the motors quite as fast, and therefore not be able to tilt as much? |
Yes, the zx-24 monitors battery voltage and notifies the 128 if things are getting risky, in which case a buzzer sounds and if it drops below critical then an autoland is initiated (tilt set to 0 and motors reduced to slow descent)
| Quote: | | What flight time do you get? What type and size of batteries do you use? If the batteries run too low in flight what happens? Can it soft-land automatically? I.E. run the motors at just enough speed to lose altitude at a specified slow speed? |
Flight time on 2500mah lipo is around 15 mins.
Cheers
Ben |
|
| Back to top |
|
|
spamiam
Joined: 13 Nov 2005
Posts: 666
|
|
Posted: 13 October 2008, 18:23 PM Post subject: |
|
|
| sturgessb wrote: | The loss in altitude is not much, as the airspeed makes up for this with extra lift (just like a helicopter is needs less power the faster it is going). However it mixes in appropriate extra throttle to reduce this further.
Ben |
I always understood that on a helicopter the airspeed did influence the lift of the blades, but I thought that what was gained on one side (upwind side), was equally lost on the other side. The net effect being neutral as far as overall lift is concerned, but there was a rolling force developed.
In the quad copter, is there any use/benefit to counter-rotating blades?
As I said, it is really impressive what you have done. Will you be publishing your designs & software?
-Tony |
|
| Back to top |
|
|
sturgessb
Joined: 25 Apr 2008
Posts: 246
Location: Norwich, UK
|
|
Posted: 13 October 2008, 23:20 PM Post subject: |
|
|
Effective Translational Lift causes an overall increase, but like i say the effect is small, mixing in extra power does the trick.
Counter rotating blades are needed to cancel the torque, and also to allow the creation of deliberate toque to have yaw control.
Not sure about releasing hw spec and code, I'm thinking about it.
Cheers
Ben |
|
| Back to top |
|
|
stevech
Joined: 23 Feb 2006
Posts: 657
|
|
Posted: 14 October 2008, 5:01 AM Post subject: |
|
|
| is the wireless link a common proportional RC product transmitter with PCM detection aboard the 'copter since there aren't servos? |
|
| Back to top |
|
|
sturgessb
Joined: 25 Apr 2008
Posts: 246
Location: Norwich, UK
|
|
Posted: 14 October 2008, 13:48 PM Post subject: |
|
|
Yup, common Futaba RC transmitter, the zx-24n is doing the PPM capture and demuxing.
this is then requested over SPI from the zx-128 when it needs it (about 40hz)
Motor controllers are hacked commercial units and use I2C for comm rather than PWM
Ben |
|
| Back to top |
|
|
|
ZBasic Home
Forum Rules
Memberlist
Usergroups
RSS Feed
Site Search
Links
Download
Digests and Subscriptions
Profile
Log in to check your private messages
Log in
Register