Realistic force feedback with coil & magnet ?

[Guest PhilippeV8]

I have had the honour of visiting a real CAE simulator a couple of months ago and since then there has been a thing running trough my mind. The 1 and only biggest thing I noticed different in the real sim compared to anything else I've had the oportunity of flying is that there is a lot of force needed in the real sim.I have been trying to work out a way in my mind to simulate this same thing in my home sim.To make it real, I would need little to no friction when the speed is close to 0kts. The faster the plane goos, the harder the controls become.I know that having a permanent magnet inside a coil makes it do weird stuff when power is turned on/off on the coil. I just read that power makes the magnet want to exit the coil. Can this be reversed ? I was thinking of putting a permanent magnet somewhere in line with the control colum link kables and have a coil around it. My idea is that when adding more power to the coil, the magnet should "want to stay inside the coil" more. If you understand my idea.Other brainstorms brought me to ideas of using a spring, but I have no idea how I can change tention of that spring dinamicaly via the computer.I found this "force feedback" to be so overwhelming in the real sim, that I can not imagine it missing from my setup. In fact, to fly the F50 manualy without using the trims .. you'd have to be as fit as M.Schumacher used to be! I tried and after +/- 3 minutes my arms started trembling from the phisical effort, which got me thinking I should dare to trim or I wouldn't hold on much longer.So .. any ideas ? Thoughts ? Possible solutions ? I'd greatly appreciate them !P.S. I'm looking into "magnetic brake systems" for home-trainer fitness things at the moment.

[Guest MikePowell]

Go here http://www.mikesflightdeck.com/old_stuff.htm and scroll down to the Aug 18, 2006 entry.Mikewww.mikesflightdeck.comwww.mikesflightdeckbooks.com

[Guest PhilippeV8]

Tnx Mike,I've been thinking about them magnets again and I don't think they are right way to go. They brake and make movement hard, but they don't center the controls ... which is what should happen, right ?

[Guest PhilippeV8]

I'm back at my original idea. The one with the heavy weight (like a hamer). The idea is, when you hold a hamer in 1 hand with the head down, close to the head, it's easy twisting your hand .. the further you hold it from the head, the harder it gets to twist.So, hanging a hamer with a servo motor which moves it up/down. Would that be the way to go to get realistic force feedback ?Or else I should throw open my microsoft force feedback race wheel and analyse how they do it.

[Guest MikePowell]

Phillipe,The concept drawing on my site is a torque motor, not a brake. The idea is to control the current through the windings to control the torque. A mechanical linkage couples the torgue to the flight controls to give computer actuated control loading.Tigert built a control loader based on a moveable weight pendulum. As I recall it worked reasonably well, but was noisy when the weight was being moved. Perhaps he can update us on the project.Response time is a factor to consider in a control loading scheme. A moveable weight system is slow to respond, so works best when all you need is control resistance that scales with average air speed. If you want bumps and shuddering in the control feel, you need to add soemthing else. You can either piggy-back on a slower system, or develop a faster system. You could, for example, add bass shakers to a moveable weight system. Commercial control loading systems are often based on servo motors to provide a controllable torque that produces forces on the flight controls. Servo motors respond rapidly and provide a more realistic control feel, incorporating shuddering due to turbulence along with the mushiness that comes with decreasing airspeed.It was this servo motor approach that I was considering on my site. I was looking for a low cost approach to making a torque motor that could be controlled by a PC.Mikewww.mikesflightdeck.comwww.mikesflightdeckbooks.com

[Guest PhilippeV8]

Hi Mike,Not sure I understand that concept. Could you write a "for dummy's" of that ? :s My english is not 100%

[kunzel4 0]

Gentlemen ,I am sending attached what I will do to my cockpit .As I am Mechanical Engineer I play a lot with mechanicals .From the drawing you can see that I will use one wheel,one spring ,one small bar thread ,one porca ,one electric motor (DC ) and one R/C servo .The idea is very simple , the Servo will follow the air speed of the aircraft and will turn on and off the electric motor ,more speed the spring will be more compressed and the friction between the wheel and the part A will increase , and vice-versa .Mechanically speaking, as the nut is fixed when the Electric motor run it slide up and down and the spring is decompressed or compressed respectively .The same system will be done for yoke concernig the aileron .Regards.Alberto Kunzel

[kunzel4 0]

>Gentlemen ,>>I am sending attached what I will do to my cockpit .>>As I am Mechanical Engineer I play a lot with mechanicals .>>From the drawing you can see that I will use one wheel,one>spring ,one small bar thread ,one porca ,one electric motor>(DC ) and one R/C servo .>>The idea is very simple , the Servo will follow the air speed>of the aircraft and will turn on and off the electric motor>,more speed the spring will be more compressed and the>friction between the wheel and the part A will increase , and>vice-versa .>Mechanically speaking, as the nut is fixed when the Electric>motor run it slide up and down and the spring is decompressed>or compressed respectively .>>The same system will be done for yoke concernig the aileron .>>Regards.>>Alberto KunzelGentlemen ,Where reading " one porca " , please read "one nut "RgdsAK

[Guest rolandvanroy]

Most FF joysticks use a motor that is powered via software to push against any stick deflection from the refence center. The software basically acts as a servo feedback loop, where the feedback gain (stick stiffness)is modified depending on airspeed etc. I hacked a logitec FF stick succesfully, added a power amp for driving bigger motors, and build an enlarged version of flight stick and also yoke. Both work satisfactory, not to the point where my arms get sore, but good enough for some nice force feedback. More force would just require bigger motors and more power. Ofcourse with your own software, a D/A converter and position feedback via A/D converter you could do it yourself, including some nice additions like vibration, bumps, ect. for some details see http://www.simprojects.nl/adding_force_feedback.htmhttp://www.simprojects.nl/flight_stick.htmRoland

[Guest PhilippeV8]

Excellent stuff Roland !Which motor did you use there ? I thought of a motor to power windscreenwipers for a car. Is it the same ? I used one of those once in a project for school.I'll start looking around for FF joysticks and what they cost lately. I know that my beloved Gillemaut FF race wheel, which I bought for

[Guest rolandvanroy]

The motors for such a FF system need some consideration: First of all, they mostly work in stalled condition, so they generate more heat w/o much cooling. Use bigger motors than you would think.second, for good firm feel, there cannot be much 'give' in the motor-stick linkage. Too many gear wheels could cause too much give.Third, use a motor with many anchor contacts. These are nomally lower speed motors, with more torque. Stall torque is the important parameter. For pitch I used a industrial type from junkyard, with torque rating 50 inch-oz (0.353 Nm)Keep in mind that you must be able to work the motor in reverse against its powered direction. The gear needs to be able to take this, so worm-gear (not sure that's the expression) is not suitable.It's an interesting experiment, but requires lots of tweaking. Roland

[Guest MikePowell]

Philippe,The general concept of control loading that I was considering is well described by Roland's posts. You connect motors to the flight controls through some sort of mechancial linkage (gears, pulleys, push rods, etc.) You control the power to the motors to control the forces the pilot feels on the controls. The algorithm that controls motor power can take as input the aircraft speed, turbulance, the current position of the flight controls and so on. So, the farther from center the pilot moves the controls, the more power is applied to the motor and the harder the control pushes back against the pilot's movement of the control. Similarly, as the airspeed changes the force required to move the controls is changed.The specific concept I was exploring was the possibility of making a motor suitable for control loading at a lower cost than buying one. Mikewww.mikesflightdeck.comwww.mikesflightdeckbooks.com

[Guest Robid]

>Gentlemen ,>>I am sending attached what I will do to my cockpit .>>As I am Mechanical Engineer I play a lot with mechanicals .>>From the drawing you can see that I will use one wheel,one>spring ,one small bar thread ,one porca ,one electric motor>(DC ) and one R/C servo .>>The idea is very simple , the Servo will follow the air speed>of the aircraft and will turn on and off the electric motor>,more speed the spring will be more compressed and the>friction between the wheel and the part A will increase , and>vice-versa .>Mechanically speaking, as the nut is fixed when the Electric>motor run it slide up and down and the spring is decompressed>or compressed respectively .>>The same system will be done for yoke concernig the aileron .>>Regards.>>Alberto KunzelAlberto, I can't open your attachment. I have it as a .txt file. That can't be right. Do you have a website to see your concept.ThanksDavid

[Guest PhilippeV8]

*hint* it's a pdf ! ;) save target as, then rename it .. it should work.

[Guest Robid]

Nope, it's saving dcboard.htmAny other suggestions.Is everyone else getting it open?