HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Sep 15, 2012, 09:20 AM
Registered User
daboz's Avatar
HB cali
Joined Apr 2006
4,030 Posts
Discussion
Interest In DS

some of you may find this interesting...

Chris

http://www.whoi.edu/oceanus/viewArticle.do?id=144090
daboz is offline Find More Posts by daboz
Reply With Quote
Sign up now
to remove ads between posts
Old Sep 15, 2012, 10:01 AM
setting CG with ceiling fan on
bluzharp's Avatar
USA, CA, Bakersfield
Joined Apr 2010
509 Posts
Cool! You better stock up on Dramamine, test pilot!
bluzharp is offline Find More Posts by bluzharp
Reply With Quote
Old Sep 15, 2012, 10:02 AM
Stay in it!!!!
Riverside, California, United States
Joined Aug 2004
5,052 Posts
I dont see DSing gliders on the ocean happening. Well, If the conditions were right I cant imagine being out there in it. Huge waves and high winds. Crazy. Good luck with the testing.
joe manor is offline Find More Posts by joe manor
Reply With Quote
Old Sep 17, 2012, 04:02 PM
Registered User
PeteSchug's Avatar
Elmhurst, NY (Queens in NYC)
Joined Apr 2004
7,061 Posts
Very tough since the robot has to "see" how far away the water is along with the wave height and speed and be able to calculate its arrival to coincide with the ideal position of the wave.

A bird can brush a wave because it's feathers will flex out of the way and are probably oily enough not to get wet. A glider should probably have a wire feeler at the wing tip to trigger an aileron response before its ridgid wing touches the water.

A lot of development could be done on a simulator with only brief trials at sea. I also don't think you have to go out to the roaring forties for every test.

Designing a simulator that can pass simulated wave heights to a simulated glider is already more work than I care to get into, but it beats being sea sick. As a small boat sailor and racer I ever had a twinge until the day I volunteered to go below and make sandwiches on a cruising boat. I quickly understood why a friend had brought along cheese whiz in a pressurized can and boxes of Ritz crackers.

The idea of a robotic glider doing dynamic soaring is really interesting.

I'm pretty sure a good model can outperform most sea birds, based on a few videos I've seen where nesting birds attack a glider being flown by someone too dumb to understand that the bird is trying to protect its young.

Pete
PeteSchug is offline Find More Posts by PeteSchug
Reply With Quote
Old Sep 19, 2012, 03:30 PM
Registered User
Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
29,117 Posts
Ultrasonic sensors in each wing would be easier than wire feelers, but it's still such a
tremendously dynamic environment that I don't see it being realistic.
What I'd want before even attempting the DS part is a plane that
simply refused to be pushed into the surface. That if you held a little
down elevator, it would just hold its altitude say a foot or two or three from the surface, no
matter how the surface changed. Could test it easily enough with a powered plane
over land, then over water and open waves (not breaking).

Then there's the problem of being able to control an RC plane in big wing/waves
when you can't see it below the waves.
Another DS member asked me about the feasibility of FPV piloting such
a plane. I think it would be hard as hell. Water blocks both video and control frequencies,
so you'd be unlikely to be able to pull it off unless you could get all your antennas up
very high (top of a very tall mast on a ship) or simply fly from a tall cliff overlooking a windy
stretch of ocean, where you might be able to maintain LoS to the plane out a mile or so.

And if your expensive FPV piloted DS plane does go in the ocean.. that's all she wrote.

ian
Daemon is online now Find More Posts by Daemon
RCG Plus Member
Old Sep 19, 2012, 08:24 PM
Registered User
PeteSchug's Avatar
Elmhurst, NY (Queens in NYC)
Joined Apr 2004
7,061 Posts
Quote:
Originally Posted by Daemon View Post
Ultrasonic sensors in each wing would be easier than wire feelers, but it's still such a
tremendously dynamic environment that I don't see it being realistic.
What I'd want before even attempting the DS part is a plane that
simply refused to be pushed into the surface. That if you held a little
down elevator, it would just hold its altitude say a foot or two or three from the surface, no
matter how the surface changed. Could test it easily enough with a powered plane
over land, then over water and open waves (not breaking).

Then there's the problem of being able to control an RC plane in big wing/waves
when you can't see it below the waves.
Another DS member asked me about the feasibility of FPV piloting such
a plane. I think it would be hard as hell. Water blocks both video and control frequencies,
so you'd be unlikely to be able to pull it off unless you could get all your antennas up
very high (top of a very tall mast on a ship) or simply fly from a tall cliff overlooking a windy
stretch of ocean, where you might be able to maintain LoS to the plane out a mile or so.

And if your expensive FPV piloted DS plane does go in the ocean.. that's all she wrote.

ian
There might be a problem with how ultra sonic sensors are oriented depending on how directional they may or may not be.

The main thing is that this is not an FPV platform or even an RC platform. It's supposed to be an autonomous robotic craft. RC would be purely an override for entering and leaving the autonomous state.

Commands would be mostly in the form of tasks to accomplish rather than direct control.

The glider could probably be made waterproof enough to take a dunking or two between takedowns for maintainence.

Nice idea , starting out with something that can autonomously avoid getting wet while cruising at low altitude under power or dealing with smooth waves. You might have to treat the motor as expendable with the rest of the plane waterproofed. I'm sure the first sea birds did very little more than that.

Something like the AS3X system coupled to a three axis magnetometer and a GPS could actually calculate wind speed based on heading vs. track made good. That would also help make sense out of the wave patterns most of the time.

I look forward to hearing more about this.

Maybe one of these days I can just sit at home watching the ocean on my TV screen as my bird flies around. (except I don't have a tv!)

Pete
PeteSchug is offline Find More Posts by PeteSchug
Reply With Quote
Old Sep 19, 2012, 09:19 PM
Registered User
PeteSchug's Avatar
Elmhurst, NY (Queens in NYC)
Joined Apr 2004
7,061 Posts
Adding a quick two cents.

A lot of gliders, bot full sized and model, use a TEK probe (don't ask me what the K in TEK stands for) to get total energy vario readings. This slight baffles me as something more than a touch retro. If you know how fast you are going and how high you are you have total energy right there.

You can calculate it in real time.

The interesting part of this is it also explains dynamic soaring. When your airspeed goes up without doing anything else your total energy goes up also, which is exactly what happens when you cross a sheer line.

Part of the problem of getting an autonomous model to soar dynamically will involve getting it to "recognize" a sequence of operations that boost the TE.

This may be easier to do on a slope than out in the ocean.

Maybe there should be record keeping not just for gyro and non-gyro, but piloted and autonomous.

Yup, I think the first attempts should be made over land and when we have a robotic glider that can DS a relatively small slope and/or cliff top etc. and know its location as well as any car with GPS and is thus able to consistently fly the same track, give or take very little then it's time to head for the ocean.

Pete
PeteSchug is offline Find More Posts by PeteSchug
Reply With Quote
Old Sep 19, 2012, 11:42 PM
R.I.P
josh18's Avatar
Australia, QLD, Toowoomba
Joined Jan 2010
3,581 Posts
Maybe a simpler idea would be to fit a camera to and train some wandering albatrosses to do the job for you.....
josh18 is offline Find More Posts by josh18
Reply With Quote
Old Sep 20, 2012, 12:10 AM
In Foam We Trust
Aerogance's Avatar
United States, CA, Ventura County
Joined Sep 2008
2,793 Posts
Birds can do it therefore it works.

You don't need wind with swells, they generate their own apparent wind. This apparent wind can be 20-30+ mph depending on the swell size and interval.

Birds make it work in virtually no sea state, so in huge swells it should be that much easier with a glider.

As for seeing the plane, its obvious you would need to be in a fast boat riding on the crest or trough of the wave you are DS'ing.

Its gonna work great, get out there and video this!
Aerogance is online now Find More Posts by Aerogance
Reply With Quote
Old Sep 20, 2012, 12:23 AM
Registered User
PeteSchug's Avatar
Elmhurst, NY (Queens in NYC)
Joined Apr 2004
7,061 Posts
The goal is not to DS waves, it's to make a robotic glider that can DS waves without help.

The best place to start is on a DS site with a glider that can retrace its path once started and find its own optimum groove. Ultimately it should be able to assess a slope and figure out how to DS it without help.

Then it has to learn (or be taught) to do it over water.

If it needs a pilot it's NOT a robotic aircraft.

Pete
PeteSchug is offline Find More Posts by PeteSchug
Reply With Quote
Old Sep 20, 2012, 01:03 AM
In Foam We Trust
Aerogance's Avatar
United States, CA, Ventura County
Joined Sep 2008
2,793 Posts
...
Aerogance is online now Find More Posts by Aerogance
Last edited by Aerogance; Sep 20, 2012 at 01:05 AM. Reason: oops
Reply With Quote
Old Sep 20, 2012, 01:43 PM
Registered User
Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
29,117 Posts
I disagree that training a robot plane how to DS a hill, is the best
starting point. The hill doesn't move. The circuit is relatively fixed, and the speed
and continuous bank angles would be much much higher. That's more of a navigational
challenge. It bears very little resemblance to albatross flight.

The challenge for open ocean DSing starts with negotiating the constantly moving
waves and simply staying out of the water. If we're modelling the Albatross flight, the goal is to
go somewhere, not just fly around in circles. As such, I'd start with an efficient powered plane
and train it how to do close terrain following utilizing ultrasonic sensors (they've been used
on multirotors to maintain a fixed distance to the ground). Start on open flat ground
then introduce some variety of terrain, and finally fly it over water with swells, building
up from small to big. I think this is the largest single challenge. The ultimate goal
here should be to keep the plane close enough to the surface to exploit the benefits
of ground effect (about half span or less from the surface) to effectively raise the L/D.

Once that part is rock solid, teach it how to detect wind direction and changes
in wind speed. Assumption is plane has full suite of sensors (GPS, altimeter, airspeed,
IMU w/ gyros/accelometers/magnetic compass). Determining wind direction should be fairly
easy. Climb up a few meters above the waves into the wind and execute a constant bank angle
360 degree turn and then average the plane's position to see which way it has drifted.
Knowing wind speed and direction above the shear is essential to knowing which way
to turn to start and finish the DS turns. Initially wind speed/direction could be programmed
in, but ultimately it'll need to figure this out own it's own.

Now you set the plane on some constant speed course (probably directly
crosswind) in terrain following mode (still powered at this point), then have the plane turn
into the oncoming wind direction, let it climb to the top of the next swell it encounters and
when it detects the wave dropping away continue to pull up until it detects a largish increase
in wind speed indicating it's crossing above the wind shear. At peak airspeed, bank
hard (can calculate desired bank angle based on airspeed and desired turn radius), and pull
a 180 degree turn directly downwind, and immediately dive back down into terrain following
mode with a gradual turn back onto original course. Coast down to original cruise airspeed, Rinse, repeat.

Train it do this all while flying under power until it has the maneuvers down solid. Then try
turning the motor off (brake to ensure the prop folds back to lower drag) right
at the moment it starts climbing through the shear. Execute the DS turn to gain ground speed,
dive, and go back on course and let the airspeed bleed off until you need to restart the
motor. Measure the gain in airspeed and time/distance spent coasting from the DS turn
and then figure out at what point you have enough energy to transition from coasting
on course, to turning back into the wind, climbing up the next swell and into the wind
to execute the next DS turn, without turning the motor on. Once it can complete the
cycle a few times with the motor off, you've proven it's possible (where a lot of
scientific papers would stop).

That's the basics. After that, you have to teach it how to handle a variety of different
courses, how to tack upwind, and downwind. How to adjust for changing wind direction
and speed over time. To exploit random strong gusts (climb instantly, bank, and turn
downwind). To coast in the troughs (this one might be impossible without forward vision).

ian
Daemon is online now Find More Posts by Daemon
RCG Plus Member
Old Sep 20, 2012, 02:09 PM
Registered User
daboz's Avatar
HB cali
Joined Apr 2006
4,030 Posts
You can tell Aarons a surfer.

Quote:
Originally Posted by Aerogance View Post
Birds can do it therefore it works.

You don't need wind with swells, they generate their own apparent wind. This apparent wind can be 20-30+ mph depending on the swell size and interval.

Birds make it work in virtually no sea state, so in huge swells it should be that much easier with a glider.

As for seeing the plane, its obvious you would need to be in a fast boat riding on the crest or trough of the wave you are DS'ing.

Its gonna work great, get out there and video this!

A buddy and I have been talking to Phil for a while. I'ts been fun sharing our hobby/sport/game and see this interest in Dynamic Soaring and from a world renowned scientist. Phill is a pretty cool dude, He wants to do the robot thing and it would be awesome to see but I was thinking it would be nice to “just” get started, (got walk before you run, right?) First try sloping the wind created, or added to light off shore winds by “somewhat predictable” large waves.

I’ve spent a lot of time on the North Shore of Hawaii in the water, in big waves with light offshore winds. There’s places where steep waves form up, “or peak”, but don’t break. The wave passes over a reef and back into deep water. There’s a few advantages to this, close to shore, smooth ocean conditions, huge amounts of power, and most importantly predictability. I would think one could position a boat or jet ski between two peaks in a wave train, (set), learn to slope the wave and then DS. The way I envisioned DSing the waves would be to place the vessel between two large waves and keep its forward speed the same as the set of waves basically in the trough but moving sideways relative to the direction the waves travel.

Any surfer who’s duck dived a huge wave has felt the power of the wind over the back of the wave. A good steep wave has the perfect cross-section shape for ds, it makes its own wind and with a slight off shore could have huge power.

I hope Phil gets the funding because I know there’s a few of us dying to do it.,..
daboz is offline Find More Posts by daboz
Reply With Quote
Old Sep 20, 2012, 02:36 PM
Registered User
PeteSchug's Avatar
Elmhurst, NY (Queens in NYC)
Joined Apr 2004
7,061 Posts
When I say Hill, I do not mean Weldon etc. I also said.

Yup, I think the first attempts should be made over land and when we have a robotic glider that can DS a relatively small slope and/or cliff top etc. and know its location as well as any car with GPS and is thus able to consistently fly the same track, give or take very little then it's time to head for the ocean.

Note, small hill or cliff.

Just something to get by on.

I agree it has to be able to fly close over water without getting wet, but over water is not the place to "learn DS."

I also pointed out that track made good (GPS location) vs. heading gives you wind speed. Maybe heading is too simple an explanation. It's really dead reckoning location vs. GPS. You constantly calculate position inertially and constantly compare that to GPS and you have true wind speed and direction. Maybe our phraseology is different but we mean the same thing.

My feeling is that it has to be able to handle flying over waves before it can DS, but I think it also has to fly DS someplace simple before tackling it over water.

I also think the first DS over water is going to be simply staying aloft. Once it can do that then it's time to go where the albatross goes and know what the albatross knows.

Two major steps are, learn to fly over water and learn to DS preferably on a minimal slope. The next step is to combine them and the final step is to expand merely DSing over water into traveling by DSing waves.

I also think the goal is not to write a paper about it but to make a practical robotic, DSing UAV to use for research, search and rescue and whatever other tasks might be useful.

Pete (not arguing, just trying to clarify my thoughts on the subject)
PeteSchug is offline Find More Posts by PeteSchug
Reply With Quote
Old Sep 20, 2012, 03:01 PM
Registered User
Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
29,117 Posts
Even with your clarifications, I still don't really see any significant value in trying to teach it how to
DS over land behind hill, cliffs or otherwise. Fly yes.. DS no. Everything about the scale,
speed, and shape of the terrain and shear and circuit is totally different. Over the ocean,
the shear is created more by overall drag created by a rough surface, than traditional rotors
behind "hill shapes". The wind near the surface (including at the tops of the waves) is lower
speed, than the wind higher up, because it's dissipating its energy pushing on the waves
themselves. Instead of flying above the hill, and behind the hill as we do, the albatross
transitions from "very close to the waves" where the wind speed and drag in ground
effect is low to "high above the waves" where the wind speed and energy potential
is high. It executes DS turns after each transition.

This video has been posted before, but shows what I'm talking about nicely.
Albatross (5 min 10 sec)

In the 2nd vid segment, the albatross's average course is almost straight upwind.
At 3:22ish can see it pop up into the wind, bank hard, pull more than 90 degrees away from
the camera (the power part of the DS turn), dive back down to the waves and then turn
back to original upwind course while skimming the waves.
The individual waves are all but irrelevant to its flight pattern although I'm sure
they're more useful when they're big.

ian
Daemon is online now Find More Posts by Daemon
RCG Plus Member
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Ds site in the news mr_editor Dynamic Soaring 5 Aug 29, 2012 04:00 PM
Wanted Fatshark base goggles in good shape. $150. I'm not interested in any other brand. traderdmb FPV Equipment (FS/W) 0 Jun 04, 2012 06:44 AM
Discussion Interesting "cook up" on the DS forum PeteSchug Scratchbuilt Indoor and Micro Models 10 Apr 24, 2012 01:51 AM
Discussion Administration "Not Interested" In Lower Fuel Prices Real Ira Life, The Universe, and Politics 36 Mar 02, 2012 03:02 AM
Question Anyone interested in 1.4m Foam Hellcat Kits SWR246 Electric Warbirds 5 Feb 26, 2012 05:17 PM