My Personnal Web-Pages — Aymeric BRUNOT

Hang-Glider Simulator

 

This web-page quickly describes the hang-glider (HG) simulator I have built in my garage.

This is a quite simple system, with one main objective : provide some of the sensations of hang-gliding, by puting the pilots in an environment similar to the one experienced when hang-gliding.

This means :

· The Pilot is in a typical hang-gliding harness, hanged as it should.

· The regular HG piloting actions of the pilot (weight-shifts) is captured by the system.

· These piloting actions control a computer flight-simulation in front of the pilot.

Also, with a set-up that should be as simple as possible (small, trasportable), and require very little specific  equipement. Personnally, I think that the set-up can be built in a single rainy afternoon. (This is how I built the first version of the simulator).

 

What you need for a basic set-up :

· A hang-gliding harness

· A place where you can hang the harness (should be a strong attach : ex. a chin-up exercice bar) AND where you can have a fixed horizontal bar for the pilot to hold and perform the weight-shifts for piloting.

· A PC computer, with :

· The GREAT free softwares FREETRACK (http://www.free-track.net) and PPJOY (is also contained in the freetrack package)

· a flight-simulator software (ex. HangSim, MicroFlight, Condor, maybe MS Flight simulator…)

· A web-cam (USB)

· The only thing you need to « build » (basic electronics) : an Infrared Light Emiting Diode (IR LED) connected to a proper alimentation source.

 

The principle of the Hang-Gliding Simulator is simple and is mostly a side-product of the excellent FREETRACK software.

FREETRACK provides a cheap/free alternative to a commercial product like TrackIR (http://www.naturalpoint.com/trackir/) that enables to use the head motion of the player to control the point of view of the camera in a computer game. For example: when the player turns his head right in front of his screen, the computer screen shows him what’s on his right side in the game.

To do this, FREETRACK uses IR LEDs placed on the head of the player (ex. on a baseball cap): the computer web-camera records the motion of the head, and FREETRACK software processes the images to identify the motions of the IR LEDs (bright points). After some computations, the soft can then deduce the position of the head… and tell the simulation program how to turn the camera in the game…

The great thing is that this output can also be used to simulate a Joystick, thanks to another small (but very useful) software : PPJoy (http://ppjoy.bossstation.dnsalias.org/).

 

The Hang-gliding simulator does not use FREETRACK to detect the motion of the head, but rather the motion of the center of gravity of the pilot, and turns this into a joystick input for the computer flight simulation. This is consistent with the piloting of « soft » hang-gliders, where the weight-shifts (motion of the center of gravity) pilots the aircraft.

It only requires the simple single-LED set-up for Freetrack (2 degrees of freedom). All the information about building a single-LED FREETRACK set-up, and how to use a Web-Cam with it, can be found on the FREETRACK web-site (tutorials, Q&A, forums) : http://www.free-track.net/

 

After some trials, I personnally used a IR LED, in serial with a 40 Ohm resistor, and plugged in a 4.5V AC-DC power adapter (former mobile-phone charger). This gives me a 70mA intensity in the Diode. Cost : 2 Euros, apart from the charger.

My initial set-up used my every-day web-cam. But it required to be operated almost in the dark for freetrack to work well… So I bought a 6-Euros web-cam, removed its IR filter and added a « floppy-disk » filter (see instructions on the freetrack web). I can now operate the simulator in daylight.

 

The overall set-up is displayed at the top of the web-page (I built a crossbar, but a simple hanging point is sufficient).

 

The web-cam is positionned near the hanging point, pointing down. The set-up could be much simpler, but I wanted to be able to mount/dismount it from a chin-up bar in a matter of seconds :

 

The IR LED (tracker of the center of gravity), is on the karabiner or on the bottom of the rope going upward from the karabiner. This is better than putting the LED on the harness because the change of pilots in the simulator leads to different spread of weights, and thus different positions of harness… which requires re-calibration with each pilot. But the karabiner and upward rope are always very close to the CoG !

 

Once the « hardware » part done, Freetrack and PPjoy are installed and configured. The Virtual Joystick created by PPjoy is centered and calibrated (in Windows).

You can then just launch the flight simulation, check that the joystick input works and…. GO FLYING !!

 

See this small video for a demo (UTube) :

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Flight simulations to simulate Hang-Gliding

I tried several commercial flight simulators with this set-up :

· HangSim (Wilco Software—15-30 Euros, not distributed any more)

· MicroFlight 5.0 (successor of HangSim—approx 30 Euros)

· Condor (40-50 Euros) : glider simulation

· X-Plane (Demo) : an opened-up MS Flight Simulator. But I did not like at all the dehaviors of the HG models I found in it .

I like Hangsim/Microflight because they are quite adapted to simple HG simulation : micro-aerology, thermals, etc.. One drawback, although they are HG models in the sim, their behaviors in turns are not representative : you should maintain the « turning action » to maintain the turn, which is not the case in a HG. This will apparently be corrected in the next version of Microflight.

Condor (Competition Soaring simulator) : a great GLIDER (not Hang-Glider) simulation, with good aerology models (dynamic  soaring, thermals, etc.) and an active multiplayer mode (on the Internet). No HG models here :-( but if you forget the difference of speed range, of gliding ratio, of inertia, if you remove the cockpit from the display, you can make interesting cross-country races while in your HG harness… Now if a HG was created as part of the next plane packs… it would be a dream !! ;-) Not very likely to happen though :-(

I left aside MS Flight simulator : it requires a lot of computer ressources and FREETRACK already use some of them. In addition, aerology conditions (thermals, dynamic wind, etc.) appear not to be supported. Thus I did not buy/test it.

 

 

Just a last word… Unfortunately nothing in this word comes really for free. Although freetrack and PPjoy are « free » software, a (small) donation to their authors can help further developement… and show your appreciation ! :-)

Also, Microflight is a nice piece of software, not expensive compared to some other, more « industrial », products…  Think about it and about supporting diversity ! Author claims free upgrade to the new version to come (ex. HG neutrality in turns)...

 

Enjoy !!

Aymeric

A_brunot « at » club-internet « dot » fr