Propeller with Propellers - My Turn :D

copacetic353

Hello all,

I was inspired by a project posted on here quite a long time ago and I now have the funds to go through with what I have been thinking about and hoping to do for a long time.

I plan to make an autonomous helicopter using the Propeller MCU. This will be different, however, than the quad rotor design already completed using Parallax microcontrollers - it will be a traditional helicopter design/layout/build/style whatever you want to call it.

The end goal is to have a helicopter that can take off, land, hover at any altitude, have GPS capabilities, route calculation, target aquiring/tracking capabilities along with datalogging. This is going to be a self sustaining machine.

I have a plan to reach my end goal which involves several stages in which there is an evolution required to reach the next stage. It is as follows:

1. Simple Cyclic control using the Hitachi H48C Tri-Axis Accelerometer Module.
2. Cyclic control + rudder/heading control (adding on Hitachi HM55B Compass Module)
3. Cyclic and Rudder + Altitude control using the third axis on the H48C
4. Full Attitude Control + GPS Hold capability using the PMB-248 GPS Receiver or Parallax GPS Receiver Module
5. Full Attitude Control + GPS Loc to Loc capability
6. F.A.C. + GPS Loc to Loc Capability with Obstacle avoidance
7. F.A.C. & Full GPS + Target Aquiring/Tracking
8. All of the above with Datalogging

Questions:

Which GPS chip to use?
What would be your suggestions for mid-air obstacle avoidance?
How would I go about aquiring and tracking any kind of target? Is this too complex for the Propeller?
I am unsure how to do any kind of datalogging, where should I start?

Is there anything I am missing?
Any suggestions?

Thank you very much for your time!

Any and all information is greatly appreciated, feel free to post on anything I may have missed or anything you would like to add.

-Scott

SRLM

1. I like this one: www.sparkfun.com/commerce/product_info.php?products_id=8975
2. Don't fly near obstacles. Really. There are two solutions to the kind of obstacle avoidance you're implying, and one involves a scanning laser while the other involves a pair of cameras.
3. Depends on the kind of target you're considering. More information is needed.
4. You should probably go with an SD card for your datalogging.

5. You need something to determine attitude (a 2-3 axis gyro or a xy thermophile.
6. Make sure that you're willing to spend thousands of dollars and hundreds of hours. Visit diydrones.com. Learn to fly the helicopter manually in extreme situations. Clearly define your goals and detail the steps you'll need to accomplish to reach them.

HollyMinkowski

WoW!

Great project, if you can build this thing then some defense contractor should snap you up
to design those autonomous flying vehicles

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- Some mornings I wake up cranky.....but usually I just let him sleep in -

Timmoore

A lot of the UAVs use a pressure sensor for altitude, something like the hp03 or the scp1000. You take atmospheric pressure and translate to altitude then look for the change. If I remember Earl also uses a pressure sensor on his autopilot.

HollyMinkowski

Can't you derive the altitude using the GPS data?

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- Some mornings I wake up cranky.....but usually I just let him sleep in -

Timmoore

Yes, but gps is much less accurate about altitude, pressure when used for altitude change can detect very small changes.

w8an

Scott,

You may want to check out autopilot.sourceforge.net/. I was following this project a few years ago but it has since become stale. Source code is available (in C) but there are useful algorithms for you to study.

I don't know if you have any experience with model helicopters. If not, you should educate yourself about them as well since they can be very dangerous if the proper safety precautions are not met. People have been killed by these models. There is a wealth of information here: runryder.com

Good luck with your project and keep us posted as I for one am very interested in this as well.

..Steve

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..Steve

Actual statement from an HP tech support chat session:
"do you have an email address to help you send you what i need you to send me to help you"

hover1

You can, but don't rely on it.

http://gpsinformation.net/main/altitude.htm

I like the last line in the report.

Jim

HollyMinkowski said...
Can't you derive the altitude using the GPS data?

P!-Ro

A good way to get datalogging is to use mictrivia's propmod, since it has a micro sd slot built right on to it. For obstacle detection you could try ir leds/detectors and it could also be used for safety, too if you had a small board strapped to you that blinked an ir led at a certain frequency. If the helicopter detects it, it could stop midflight.

propmod: http://www.propmodule.com/ and http://www.gadgetgangster.com/find-a-project/56?projectnum=160

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PG

CannibalRobotics

There was another UAV project some months ago that had an altitude issue. The problem with GPS is accuracy and landing. Being 20' off when your 200' in the air is one thing. Not knowing exactly where to flare in a landing is entirely another. I had suggested a hybrid approach. Use the GPS for flight altitude and an Ultrasonic ping for ground proximity.

Oh yeah, flying model helicopters is tricky and they can be very dangerous and expensive to keep rebuilding.

Sounds like a really cool project though, I have two old helicopters sitting in my shop and I've been thinking about the same project for a long time.

Good Luck!

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Signature space for rent!
Send $1 to CannibalRobotics.com.

Philldapill

If you want a good pressure sensor for detecting altittude, FreeScale Semiconductor makes some pretty sensitive ones. Heck, they offer them as free samples. too!

Philldapill

If you want a good pressure sensor for detecting altittude, FreeScale Semiconductor makes some pretty sensitive ones. Heck, they offer them as free samples. too!

copacetic353

Does anyone think it may be a good idea to try and use the ArduPilot for the autopilot and Propeller for the other things I may want to do? Is it possible to get the ArduPilot and the Propeller to communicate?

copacetic353

Nevermind, it looks like ArduPilot may not be up to the task. What would be the best method for attitude detection and correction?

w8an

A device by FMA Direct called the Co-Pilot "senses the difference in infrared signature between the earth and the carbon dioxide in the atmosphere" www.fmadirect.com/detail.htm?item=1489&section=20

I hooked one of these up to a very unstable fixed pitch electric helicopter several years ago and it really worked good. Perhaps this technology could provide your pitch and roll sensing.

Four IR sensors with necessary signal amplification and/or conditioning run into the Propeller for analysis.

..Steve

EDIT: Maybe you can use that AttoPilot XYZ Horizon Sensor as input to your Prop?

Post Edited (w8an) : 8/24/2009 4:57:04 AM GMT

w8an

The sensors seems to be readily available if you wanted to roll your own.
www.google.com/search?btnG=1&pws=0&q=MLX90247ESF-DSA

copacetic353

I don't think I want to spend $800 on the AttoPilot haha.

copacetic353

I would like to make everything on my own simply so that I can control and learn everything I am doing. I was about to click buy on the Co-Pilot but then I saw that it does not support CCPM so that little gadget is out. And the AttoPilot is really expensive and everything is already done, where is the fun in that? Any other ideas? Where do I learn how to use thermopiles for horizon / attitude detection?

copacetic353

Would it be better or easier to use gyros over thermopiles?

SRLM

I think you want to look at DIY drones. All these questions have been hashed over and over on the site. Things like the difference between an IMU and a theromopile, and the what the Attopilot XYZ sensor is (it's not an Attopilot, for one). BTW, I don't think Attopilot supports anything but a basic airplane.

copacetic353

Looking through DIY Drones, I came across this little chip on what appears to be their feeder site. Perhaps this would be a great choice for my application: http://www.sparkfun.com/commerce/product_info.php?products_id=8507

What do you think?

hover1

I'm not sure that module will solve your altitude issues. Quote: "The OS5000-S provides precise heading, roll and pitch data ideal for rapid attitude measurement."
I read altitude the first time but realised it was attiitude the second read through.·I have crashed, I mean flown, a few Helis in my time and they are pretty quirky especially when close to the ground and in "Ground Effect".
Read through Old Man Earl's posts. He started with a quad copter and then switched to a normal plane platform I believe.
http://forums.parallax.com/showthread.php?p=795698
http://forums.parallax.com/showthread.php?p=804807
http://forums.parallax.com/showthread.php?p=804939
But don't give up! Anything is possible!
Watch this:
http://www.youtube.com/watch?gl=HK&hl=zh-TW&v=Y4jtguSF0n4
Regards,
Jim

·

copacetic353 said...
Looking through DIY Drones, I came across this little chip on what appears to be their feeder site. Perhaps this would be a great choice for my application: http://www.sparkfun.com/commerce/product_info.php?products_id=8507

What do you think?

Guns of Fun

6. F.A.C. + GPS Loc to Loc Capability with Obstacle avoidance
You·could use a camera and laser range finder on a gimble.· This would give you the distance and·angle from helicopter.··You would have to have a wide angle low power mode for scanning and a·narrow angle and high power mode for tracking.···A radar would be better, but that is taking it to a whole different level.


7. F.A.C. & Full GPS + Target Aquiring/Tracking

Same principle as above but installed on a freely rotating turret.· Think Predator Drone or Kiowa Warrior.

Sounds fun.· Keep us posted.

Javalin

copacetic353 said...
Looking through DIY Drones, I came across this little chip on what appears to be their feeder site. Perhaps this would be a great choice for my application: http://www.sparkfun.com/commerce/product_info.php?products_id=8507

I wouldn't rely on a magnetic compass on a helicopter platform personally.· GPS all the way.

GPS's don't work well for altitude - all its able to give is your distance +/- the datum at your position.· Effectively your distance away from the satalite's - sorta.

James

TreeLab

If you are using an absolute pressure transducer (which is easily able to measure heights to a few cm in a static system), do you have to worry about how the air flow around the aircraft is changing the measured pressure? Bernoulli and so on?

Plus, if you were landing at a (x,y) position different from take-off (where you would zero the P sensor), then the zero of pressure-based-elevation would change, no?

I would have thought a Ping-type module would be just about perfect for the landing phase.
Cheers!
Paul Rowntree

jazzed

I hate to bring it up, but I've tried this, and one of the great challenges of an autopilot for a traditional helicopter is vibration. Vibration noise induced in an accelerometer even with a Kalman filter and gyro reference is difficult on the platform. I do hope you end up with a workable solution.

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--Steve

Propeller Tools

• Propalyzer: Propeller PC Logic Analyzer
• BMAD: An on-chip PASM Debugger
• SPUD: Spin Source Level Debugger for Linux/Cygwin

w8an

Simple-- assign a cog the task of active vibration suppression.

Scott, you haven't told us what craft you are planning on using for this experiment? How big is the motor and what is its power source? Tell us a bit about the flying machine.

..Steve

SRLM

w8an said...
Simple-- assign a cog the task of active vibration suppression.

I doubt it will be that simple. Assuming the OP is using the Parallax 3-axis accelerometer, the accelerometer has a frequency response of 500 Hz. A model helicopter blade rotates at about 2,500 RPM (see here), so, according to the Nyquist rate it would be impossible to accurately measure the vibrations.

Dr_Acula

I doubt it will be that simple. Assuming the OP is using the Parallax 3-axis accelerometer, the accelerometer has a frequency response of 500 Hz. A model helicopter blade rotates at about 2,500 RPM (see here), so, according to the Nyquist rate it would be impossible to accurately measure the vibrations.

That could still work. 2500 rotations per minute is 41 rotations per second. 500 hz is 500 samples per second. So you can sample over 10x per rotation. Take all those samples and do a rolling average, maybe over two or three rotations, say 50 samples or 0.1secs. That ought to give a smooth value but at the same time update fast enough for real time control.

BTW - great little project, please keep us posted.

SRLM

Dr Acula said...
That could still work. 2500 rotations per minute is 41 rotations per second. 500 hz is 500 samples per second. So you can sample over 10x per rotation.

Do-oh. I expected to be working in seconds, so that's what I thought of and forgot that I was using two different timescales. Thank you for catching that. w8an, I apologize.

w8an

NP. Typically for vibration suppression we use soft rubber like ZEAL vibration absorption tape

The question about the type of craft is important, however. I have several model helicopters from small electric to .90 size gas. These things are engineered to lift their own weight, some required electronics and not much more. So weight consideration is a big issue. A gimbal mounted tv camera, gps, 3-axis gyros, computers, batteries... this all means more weight.

..Steve