General aviation force feedback yoke for Cessna sim

[Cessna172sim]

Something new that we are going to construct according to the plans below:
http://buggies.builtforfun.co.uk/Sim/FFB-yoke-1.php

Pictures will follow.. ;)

[iwik]

Hi Vectro,
Im about to embark on the same project. I built Ian motion platform, which works well, not fully tested yet. Had been waiting for his final FFB plans.
Are you buying your motors from Italy and is it being made out of wood?. I will be following your progres with interest.
Regards
Les

[Tom_G_2010]

OP,

I've been watching his site for a few months waiting for the release of the plans. I downloaded the plans, but will be adapting the concept to the actual Y bar of my 172 fuselage. I'm also going to see if I can adapt this to the rudder pedals. I hope to be purchasing parts for the mechanical linkages later this month. I don't know when the budget will allow for the purchase of the motors or controllers though.

Tom G.
Tom G.

[Cessna172sim]

OP,

I've been watching his site for a few months waiting for the release of the plans. I downloaded the plans, but will be adapting the concept to the actual Y bar of my 172 fuselage. I'm also going to see if I can adapt this to the rudder pedals. I hope to be purchasing parts for the mechanical linkages later this month. I don't know when the budget will allow for the purchase of the motors or controllers though.

Tom G.
Tom G.

Hi Les,

We are also going to connect the force unit axle directly to the current Y-bar mechanism with this kind of connection:
5604
5605
This way the original Y-axle can move freely. We ordered the controller cards (x2) for the motors last week from Ian and now we are going to order rest of the parts from Italy (encoders and the motors). Our friend have built a CNC cutting machine. With this machine we will cut all force unit frame parts from wood according to .DWG drawings.

The plans and the web page have been updated this month. We will only build this unit for the yoke.

[Tom_G_2010]

Do you have any additional pictures on your site? I'm having trouble seeing how that linkage works. I had a very different idea but don't have drawings done yet.

[Cessna172sim]

Do you have any additional pictures on your site? I'm having trouble seeing how that linkage works. I had a very different idea but don't have drawings done yet.
I only made this quick drawing about the connection. The basic idea is shown in the cockpit picture. We are going to connect the force unit directly to the rear end on the original C172 control yoke. The original Cessna Y-column remains completely intact.

The movement of the original Y-column is curved but the force unit movement is linear. That's why there needs to be a mechanical joint that connects the force unit and C172 control column. The picture I attached in my previous email is taken from a Frasca Beechcraft Bonanza trainer simulator control column.

[iwik]

Thanks Vectro,
Nice to know i want be the only one building it. Yes i built a small cnc machine a couple of years ago and will be using that to cut the wood.
Will an eye on this post.
Les

[Cessna172sim]

Once you are about to cut the wood parts, I can send you the drawings I received from Ian in .dwg format. These should be suitable for your cnc machine also.

[iwik]

Vectro,
Thanks
Have sent you a pm with email address

Les

[Tom_G_2010]

I only made this quick drawing about the connection. The basic idea is shown in the cockpit picture. We are going to connect the force unit directly to the rear end on the original C172 control yoke. The original Cessna Y-column remains completely intact.

The movement of the original Y-column is curved but the force unit movement is linear. That's why there needs to be a mechanical joint that connects the force unit and C172 control column. The picture I attached in my previous email is taken from a Frasca Beechcraft Bonanza trainer simulator control column.

You've got me re-thinking my design. Using more of Ian's original design as you are may far simplify things. The universal joint positioned where the FFB shaft connects to the 172 yoke answers the issue of angular change between the yoke shaft and the FFB shaft as the y column moves through its arc. How are you allowing for the change in the FFB shaft angle as this occurs back at the FFB chassis? Will you be mounting Ian's FFB chassis on a pivot?

[Cessna172sim]

You've got me re-thinking my design. Using more of Ian's original design as you are may far simplify things. The universal joint positioned where the FFB shaft connects to the 172 yoke answers the issue of angular change between the yoke shaft and the FFB shaft as the y column moves through its arc. How are you allowing for the change in the FFB shaft angle as this occurs back at the FFB chassis? Will you be mounting Ian's FFB chassis on a pivot?
I sent my suggestions to Ian couple weeks ago. He agreed that it could be possible to connect the force unit directly behind C172 Y-column with 2 pin joints. He actually made me a rough sketch that seems very logical. Here's the plan that we are now following:
5607

As we are using the original upper engine cowling the force unit will not be visible from the cockpit.

Also at this point we got so many electric components inside the fuselage and very near the control column it would be basically impossible to make extra room for new electronics, encoders and motors. With the current plan we don't need any extra space since the force unit will be behind all current electronic components.

The only thing Ian pointed that the pin joint points must be tight enough (similar for the ones I pasted in my previous reply) for this setup to work properly. Although we might end up loosing some of the force from the motors you have to remember that the engines are still pretty powerful so I don't see this is a problem either.

[Tom_G_2010]

I sent my suggestions to Ian couple weeks ago. He agreed that it could be possible to connect the force unit directly behind C172 Y-column with 2 pin joints. He actually made me a rough sketch that seems very logical. Here's the plan that we are now following:
5607

As we are using the original upper engine cowling the force unit will not be visible from the cockpit.

Also at this point we got so many electric components inside the fuselage and very near the control column it would be basically impossible to make extra room for new electronics, encoders and motors. With the current plant we don't need any extra space since the force unit will be behind all current electronic components.

The only thing Ian pointed that the pin joint points must be tight enough (similar for the ones I pasted in my previous reply) for this setup to work properly. Although we might end up loosing some of the force from the motors you have to remember that the engines are still pretty powerful so I don't see this is a problem either.

THANKS! That pin joint on the back edge of the FFB chassis is what I was thinking about. This is so much simpler than what I was considering! AS for hiding it under the engine cowl. I've been on an e-Bay hunt for an affordable one for several months now with no luck. I'm going to start calling the junk yards around the U.S. and explain that all I need is an upper cowl skin and it does not need to be perfect or airworthy only clean enough to be repairable for my use. Maybe I'll get lucky . . .

[Cessna172sim]

Good luck for your hunt. I got mine with pure luck from Finland. The part was airworthy and I still got it with appr. 200$. There should be plenty of spares over there. I can still tell you that it makes a huge difference for flying when you can see the actual nose and virtual prop. especially in turns and landings.

Have you checked this one yet. I bought a door handle from them.
http://aircraftpartsandsalvage.com/

[Tom_G_2010]

. . . Have you checked this one yet. I bought a door handle from them.
http://aircraftpartsandsalvage.com/

I purchased a couple switches, a flap lever, and a landing gear lever form them. Great to do business with. They'll be among the first I go back to when I start the new hunt for the cowl.

[geneb]

Doesn't the base of that yoke connect to either a pushrod or a set of control cables that go to the elevator? If so, why not build a box at the back of the cockpit that uses the original connection system?
g.

[Tom_G_2010]

Doesn't the base of that yoke connect to either a pushrod or a set of control cables that go to the elevator? If so, why not build a box at the back of the cockpit that uses the original connection system?
g.

It connects to an ~18" pushrod that goes to a cam to convert it to a pair of opposing cables. I had looked at that but all the mechanical advantage favors the pilot (as you would expect) and going the other way which the FFB would need to do would require quite a bit of gearing down to reverse that and regain the leverage need to apply force at the controls. I didn't see that as practical.

Ian's documentation emphasizes free movement and minimal friction on the controls. I'm even concerned about the existing mechanical resistance in the factory aileron linkage between the two yoke shafts and pondering how to reduce that. The Y bar setup is designed to accomplish three things: 1. Provide linked dual controls; 2. Provide optimal mechanical advantage to the pilot/co-pilot; 3. leave clearance behind the MIP for all instruments and avionics.

Numbers 2 and 3 make for some interesting challenges when it comes to providing FFB to the controls. That's why I think OP's idea is better than the others I've considered. As I said, my only concern is the drag in the aileron linkage. It would be easy to simplify that linkage provided a direct cable between the yoke shafts cleared all the instruments and avionics when applying full up elevator, but I'm not sure that there is in fact enough clearance.

[Cessna172sim]

It connects to an ~18" pushrod that goes to a cam to convert it to a pair of opposing cables. I had looked at that but all the mechanical advantage favors the pilot (as you would expect) and going the other way which the FFB would need to do would require quite a bit of gearing down to reverse that and regain the leverage need to apply force at the controls. I didn't see that as practical.

Ian's documentation emphasizes free movement and minimal friction on the controls. I'm even concerned about the existing mechanical resistance in the factory aileron linkage between the two yoke shafts and pondering how to reduce that. The Y bar setup is designed to accomplish three things: 1. Provide linked dual controls; 2. Provide optimal mechanical advantage to the pilot/co-pilot; 3. leave clearance behind the MIP for all instruments and avionics.

Numbers 2 and 3 make for some interesting challenges when it comes to providing FFB to the controls. That's why I think OP's idea is better than the others I've considered. As I said, my only concern is the drag in the aileron linkage. It would be easy to simplify that linkage provided a direct cable between the yoke shafts cleared all the instruments and avionics when applying full up elevator, but I'm not sure that there is in fact enough clearance.
At the moment our yoke (elevator and aileron) is centered with normal springs. After FFB is connected all springs are removed to prevent any unwanted and opposite friction. According to the original plans there should be plenty of force available from the motors and referring Ian's email he adviced that it's even possible to double the force with extra cooling. Not tested but should theoretically be possible.

In our solution there will be minimum amount of extra cables, gearing, etc. that I would assume to create more friction = more power needed from the FFB motors. As far as I remember, when there's no any springs or cables connected to the Y-column and all parts are clean/greased, the friction (aileron + elevator) is not so big.

(If) the FFB motor power is anything like the GA Frasca trainers I have been test flying you have to use huge amount of opposite force against the yoke if the plane is not trimmed correctly. With this kind of force the yoke friction is nothing. Of course I cannot tell what's the case with this DIY unit.

As far as I can remember from real life PPL flying, in C172 the most powerful control surface forces affects the elevator. This should be the one that should be working as real as possible. Then comes the ailerons and at the end the rudders.

[IanH1960]

Hi OP,

Sorry I haven't looked in earlier - been busy.

The forces generated by the unit in its default setup are described on the web page - elevator push/pull to about 9 kgf (~20lbs), aileron one handed force about 4.5kgf (~10 lbs). On my test yoke these levels of force are quite tiring to sustain for any length of time and there is a stong urge to trim the forces out when they arise in flight. These forces are however a good deal less than in commercial CL systems - but I guess their use in commercial systems is for flying with simulated systems failures - eg engine out etc, where sustained loading at high levels might be experienced.

In general the most effective way to increase the loading would be to increase the gearing ratios - eg fitting planetary gearheads to the motors would provide a factor of 2, 3 or 4 on the loading without additional electrical loading on the cards and motors. The cards however have capacity for 2x loading by changing their programming - although this will take the current draws above their ( and the motor's) continuous ratings - so would need care and forced air cooling to prevent overheating in circumstances where the higher loads were sustained for more than the length of a normal flight manouevre.

I'm going to test this once I get my hands an a suitable PC style fan that I can fit over the card heatsinks.

On the effects of mechanism on the force feel I was concerned that existing friction, cogging or general stickiness etc in the control mechanisms would affect adversly the force feel because I felt they have made a difference in my various experiments. However a 747 sim builder in Dublin has just finished retro-fitting his existing flight controls with the FFB system - I've made up a quick web page showing some details -

http://buggies.builtforfun.co.uk/Sim/BFF-FFB-System-Customers.php

The force feel on this retro-fitted approach is very smooth (I visited on Tuesday) - better than I thought it might be given all the existing mechanism. So my feeling now is that so long as the existing control mechanisms are themselves smooth and friction free there is a good chance the FFB system will perform well when fitted retrospectively. But there will always be a need for care in the design and interfacing. And we did a bit of tuning to get things set up properly - I altered the card programming slightly to increase the vibration magnitudes to deal with the added inertia of his existing control mechanisms.

PS the builder of the 747 sim finds the vibration effects the FFB brings as one of the biggest suprises - simulated engine and ground vibration comes up through all the controls and varies in intensity with engine thrust, runway speed etc. Throttling up on takeoff for example feeds vibrations/shaking through to your hands and feet - and to an extent up through the flight deck structure. It sort of brings the controls to life - I can still picture the big grin on his face!

Ian

[Cessna172sim]

Hi OP,

Sorry I haven't looked in earlier - been busy.

The forces generated by the unit in its default setup are described on the web page - elevator push/pull to about 9 kgf (~20lbs), aileron one handed force about 4.5kgf (~10 lbs). On my test yoke these levels of force are quite tiring to sustain for any length of time and there is a stong urge to trim the forces out when they arise in flight. These forces are however a good deal less than in commercial CL systems - but I guess their use in commercial systems is for flying with simulated systems failures - eg engine out etc, where sustained loading at high levels might be experienced.

In general the most effective way to increase the loading would be to increase the gearing ratios - eg fitting planetary gearheads to the motors would provide a factor of 2, 3 or 4 on the loading without additional electrical loading on the cards and motors. The cards however have capacity for 2x loading by changing their programming - although this will take the current draws above their ( and the motor's) continuous ratings - so would need care and forced air cooling to prevent overheating in circumstances where the higher loads were sustained for more than the length of a normal flight manouevre.

I'm going to test this once I get my hands an a suitable PC style fan that I can fit over the card heatsinks.

On the effects of mechanism on the force feel I was concerned that existing friction, cogging or general stickiness etc in the control mechanisms would affect adversly the force feel because I felt they have made a difference in my various experiments. However a 747 sim builder in Dublin has just finished retro-fitting his existing flight controls with the FFB system - I've made up a quick web page showing some details -

http://buggies.builtforfun.co.uk/Sim/BFF-FFB-System-Customers.php

The force feel on this retro-fitted approach is very smooth (I visited on Tuesday) - better than I thought it might be given all the existing mechanism. So my feeling now is that so long as the existing control mechanisms are themselves smooth and friction free there is a good chance the FFB system will perform well when fitted retrospectively. But there will always be a need for care in the design and interfacing. And we did a bit of tuning to get things set up properly - I altered the card programming slightly to increase the vibration magnitudes to deal with the added inertia of his existing control mechanisms.

PS the builder of the 747 sim finds the vibration effects the FFB brings as one of the biggest suprises - simulated engine and ground vibration comes up through all the controls and varies in intensity with engine thrust, runway speed etc. Throttling up on takeoff for example feeds vibrations/shaking through to your hands and feet - and to an extent up through the flight deck structure. It sort of brings the controls to life - I can still picture the big grin on his face!

Ian

Hi Ian,
Thank you once again for your detailed information. I'm sure there will be many happy grins here also when the FFB unit is built and operational. ;)

[Cessna172sim]

BTW, can you independently control the 'shaker' option of the FFB unit?

Since our sim is full of fragile electronic connection, like DIY avionics the control column shake could deattach solderings and cable connections.

Of cource if you could adjust the shake functions to minimal but still senseable level it would be ideal.

For the rest of the cockpit shaking we use ButtKicker 2.

BR,
OP

[IanH1960]

Morning OP,

All the vibrations effects can be adjusted or disabled completely. Run the BFF_CL_Setup application, open your config file and go to the Vibration 1 & Vibration 2 tabs - tick the checkboxes for the vibrations you wish to disable. You can also alter the magnitude and frequency gains to adjust the vibration effect strengths.

Ian

[Cessna172sim]

Sounds too good to be true.

[IanH1960]

Hi OP,

...all the force effects are adjustable. I suggest you start with the "Bonanza" config file in the software zip package - and then tune this to suit your requirements once you get your system commissioned and operating.

There's a bit of work required to do this as there isn't a single set of settings that will suit all cockpit builds and aircraft. I hope to write a step-by-step "tuning" guide soon to help builders through it.

Ian

... it's not as complicated as I'm making it sound!

[Cessna172sim]

Maybe there could also be C172 flight dynamics as a default since (I think) it is most commonly used GA flight model. How about it? ;);)

[IanH1960]

Maybe there could also be C172 flight dynamics as a default since (I think) it is most commonly used GA flight model. How about it? ;);)

... once you get your configuration settings sorted I could include it as the default C172. :wink:

Ian

[Tom_G_2010]

. . . As far as I remember, when there's no any springs or cables connected to the Y-column and all parts are clean/greased, the friction (aileron + elevator) is not so big.

(If) the FFB motor power is anything like the GA Frasca trainers I have been test flying you have to use huge amount of opposite force against the yoke if the plane is not trimmed correctly. With this kind of force the yoke friction is nothing. Of course I cannot tell what's the case with this DIY unit.

As far as I can remember from real life PPL flying, in C172 the most powerful control surface forces affects the elevator. This should be the one that should be working as real as possible. Then comes the ailerons and at the end the rudders.

Over the weekend I made some very basic force measurements on the controls in my fuselage. I have the full Y bar with the 3 pulley pairs linking the aileron movement between the yokes, the ~18" push rod and cam are still there from the elevators, and both rudder bars. With no return springs the force needed to overcome mechanical friction and move the Y for elevator control will be less than 2 pound. For the rudder pedal about 1 pound. However, it took just under 10 pounds of force to rotate the yoke shaft at the chain linkage for aileron movement.

So that 9 to 10 pounds is what has my attention. I suspect with a more thorough cleaning and additional lubrication I could reduce that some, but it does seem like a lot of mechanical friction to me. Rolling the yokes by hand feels relatively smooth so there's ample mechanical advantage at the yoke handle to overcome the friction. However back at the shaft were I measured it a rotational force of 9 to 10 pounds was needed.

I may have this all wrong (I have a background in Electrical Engineering, not a Mechanical), but if I read the FFB spec correctly the system was designed to create about 9 LBF of aileron feedback force. So, does that mean, in my case, that most of it's normal output would be consumed just to overcome the mechanical resistance and rotate the yokes before providing any appreciable feedback? If so, can it handle producing 18 LBF to deliver a net 9LBF of feedback to the controls? If not, I may need to rework that linkage to reduce mechanical friction.

[IanH1960]

Hi Tom,

I'm not properly familiar with the details of your mechanism. Can I assume that the "chain linkage" force you measured for the Aileron friction is effectively the chain tension needed to induce rotational movement of the aileron?

If so then you would expect it to be higher than the hand force required at the control wheel. In rotational systems it is torque we are primarily interested in. Torque off course is force x distance - so the 2lbs control wheel force x the larger control wheel diameter should (all things being equal) = the 10lbs chain tension force x the chain sprocket pitch circle radius. If you need 2 lbs at the wheel but 10 pounds at the chain it suggests your wheel radius is about 5 x the PCR of the chain sprocket.

The aileron figure I gave is the force output at the wheel - ie in a low friction system the FFB aileron drive will produce a force of approx 10lbs at the wheel (when it is held single handed). So you would compare your measured 2lbs at the wheel to the 10lbs spec of the FFB system.

In general however it is will be wise to try and remove as much friction as possible from the mechanism so as to not loose any low level subtle force cues and not to inhibit low level vibration effects from coming through to the pilot's hands.

Incidently the aileron force level is based on a speed reduction ratio of 3:1 between the motor shaft and the yoke tube - this is a convenient ratio for DIY belt drives so suits the DIY yoke. If this gearing ratio is increased then the FFB force level goes up in direct proportion - significantly greater force levels could be obtained by designing-in different gearing in the transmission....

Ian

[Tom_G_2010]

Hi Tom,

I'm not properly familiar with the details of your mechanism. Can I assume that the "chain linkage" force you measured for the Aileron friction is effectively the chain tension needed to induce rotational movement of the aileron?

If so then you would expect it to be higher than the hand force required at the control wheel. In rotational systems it is torque we are primarily interested in. Torque off course is force x distance - so the 2lbs control wheel force x the larger control wheel diameter should (all things being equal) = the 10lbs chain tension force x the chain sprocket pitch circle radius. If you need 2 lbs at the wheel but 10 pounds at the chain it suggests your wheel radius is about 5 x the PCR of the chain sprocket.

The aileron figure I gave is the force output at the wheel - ie in a low friction system the FFB aileron drive will produce a force of approx 10lbs at the wheel (when it is held single handed). So you would compare your measured 2lbs at the wheel to the 10lbs spec of the FFB system.

In general however it is will be wise to try and remove as much friction as possible from the mechanism so as to not loose any low level subtle force cues and not to inhibit low level vibration effects from coming through to the pilot's hands.

Incidently the aileron force level is based on a speed reduction ratio of 3:1 between the motor shaft and the yoke tube - this is a convenient ratio for DIY belt drives so suits the DIY yoke. If this gearing ratio is increased then the FFB force level goes up in direct proportion - significantly greater force levels could be obtained by designing-in different gearing in the transmission....

Ian

Ian,

Thanks for the additional info and clarification. Your assumption about my measurement at the chain linkage is correct. I'll be working on reducing the mechanical friction and proceed from there.

Again, Thanks!
Tom G.

[Cessna172sim]

Some pictures of the project so far: (all wood parts were cnc-machine cutted)
5684
5685
5686
5687
5688

[Cessna172sim]

Still one more new image from the first 'loose-test' fitting:
5689

[iwik]

Hi Vecto,
Thanks for the pics. Im just starting to cut my plywood. Motors and boards wont be here till late Oct. So ive got plenty of
time. Be great to see your one finished and hear how well it works.
Keep the imfo comming.
Les

[Cessna172sim]

Sure. Will post new pics again when we have finished the assembly.
Send us all some pics of your project pics also when you make some progress.

//OP

[iwik]

Will do.
Les

[Cessna172sim]

Some progress here:
5735
5736
5737
5738
5739

[Cessna172sim]

5740
5741

[Cessna172sim]

Construction in test bench completed. Next we will start calibration and software settings setup.
5809

[iwik]

Hi,
Nice to see your progress, my one nearly ready for testing, motors arrived yesterday.
When its assembled will post my pics.
Did you mount all your motors front and back with angle ally?.
Be interested to see how this mounting holds up. Ian used straps, your idea seems easier.
I havnt got to the stage of mounting motors. Are you running it off batteries or a Power supply?.
Keep us posted
Les

[Cessna172sim]

Hi,
Nice to see your progress, my one nearly ready for testing, motors arrived yesterday.
When its assembled will post my pics.
Did you mount all your motors front and back with angle ally?.
Be interested to see how this mounting holds up. Ian used straps, your idea seems easier.
I havnt got to the stage of mounting motors. Are you running it off batteries or a Power supply?.
Keep us posted
Les
Hi,
All motors are mounted with angle ally. The unit is running with power supply.

[iwik]

Thanks for the update. What did you use for the P/supply?. Linear or switch mode and what current/voltage.?
Les

[Cessna172sim]

Thanks for the update. What did you use for the P/supply?. Linear or switch mode and what current/voltage.?
Les
Sorry for the wrong information. I just confirmed the power source. We are using 2 x 28Ah batteries and charger.

[iwik]

Thanks,
not sure what i will end up with, have batteries and have some switch mode supplies also.
Les

[IanH1960]

... I recommend batteries, even in the first instance. They produce very smooth current output, even under higher draws.

If you use a power supply be sure of the voltage output, and keep an eye out for electrical roughness at higher current draws - you will feel this through the FFB system if it is there.

Ian

[iwik]

Hi Ian,
Yes i have read all docs and will use batteries first and then compare to power supplies, then use the best option.
Ian, i see Vectro used angle ally for mounting the motors. Do u think this would adequate hold for the motors.
Les

[IanH1960]

Hi Les,

Yes it looks a good solution. Leave a bit of sideways adjustment at the fasteners to allow some tinkering with the belt tension and motor alignment.

Ian

[Cessna172sim]

Here's our battery pack:
5811

[iwik]

Hi Vectro,
Thanks,
Are you able to show me a close up of the mounting brackets fitted to the motors.
Les

[Cessna172sim]

Hi Vectro,
Thanks,
Are you able to show me a close up of the mounting brackets fitted to the motors.
Les
I'll ask my brother to take you some closeup pics of the brackets tomorrow.

[iwik]

Thanks,
I have some ideas but would like to see what you have done.
LES

[iwik]

Hi OP,
Will post my attempt shortly. Just got to mount one more motor. I just had athought while i had the Carriage assembly off.
Did you consider adding screws to add extra strength to the front and back supports on both the base and Carriage assembly.
Just a bit worried the glue may let go. What are your thoughts.
Have you tested your unit yet.
les

[iwik]

Hi Olli,
Have PMed you please take a look.
Thanks
Les

[iwik]

Hi Olli ans All,
Ive attached some pics of my completed FFB Yoke and plans and details can be found here.
http://buggies.builtforfun.co.uk/Sim/FFB-yoke-1.php

Anybody interested in serious simming just has to build one of these. I cannot say enough how much
more immersive my simming has become since completeing this. Options available to tweak to ones liking
is phenominal. I cant go into the w/s and do anything untill i fire up my crappy 15" laptop and fly.
To hear the engine sounds and have the contant vibration of RPM and flying forces is incredible. I know its more
expensive than a conventional yoke but the rewards are unmeasureable.
Please go to Ians site and download the plans and have a look, he has the software available and the driver boards
for the Brushless Motors( these have to be sourced, links are given) used.
Also consider the possibility of building the yoke and upgrade it to FFB when you can afford it.
The yoke itself is extremely smooth which i cant say applies to any of the Ch, Saitek or PFC ones i own.Im sure one could
add springs to get by till the upgrade.
If you guys can build Shells and Panels then im sure you can cut out 12mm ply to make one. Or a local woodworking
place could cut one for u. Costs to make the basic yoke is very little ,bearings i sourced from VXB.com.
Anyone want anymore details please ask as Ian monitors this board and is more than happy to help. His support is
fantastic.
No i dont have any association with his company but have built his Motion Platfform and can vouch for his plans.
You heavy metal people are not missing out, the unit has been fitted to these columns as well and works well.
So give some serious thought you wont regret it.

Regards
Les

[Cessna172sim]

First of all, Les, great stuff! :cool: I can also very warmly recommend this yoke solution.

Few pictures of the instrument /electronic/battery casing:
6122
6123
6125

+ Finished force feedback yoke assembly:
6124

Everything is running smoothly in the test bench already. During the spring we will move the unit to it's final place to the C172 sim fuselage.

[Cessna172sim]

Here's the joint between C172 yoke and force feedback unit:
6326

[iwik]

Hi Olli,
Nice work, hopefully will do the trick for you.
My one has been going well, found a couple of bugs so keep an eye on Ian's site
and update your software.

Regards
Les

[Cessna172sim]

The unit is now connected to the C172 control yoke. Some pics here (upper cowling removed):
http://www.lentosimulaattori.1g.fi/kuvat/Force+Feedback+yoke+project/IMG_0753.JPG

[iwik]

Olli,
Very nicely done,how does it feel?. Since last talking with you i have had a chance to try the
Flight Illusion one. Not impressed with the feel unpowered quite gritty feeling.
Powered wasnt to bad and had someone else try both and his preference was for Ian's one.
Still very pleased with it.
Les

[Cessna172sim]

Hi Les,

We still haven't had time to test the unit but will advice as soon as we have tested it.

BR,
OP

[IanH1960]

HI OP,

...just back from my travels and had a first look at your unit photos.

Are you still using the original Y-bar in the mechanism - I can't see it? If so, you will need to use a pinned joint between the force unit underside and the "table" it is mounted on otherwise the FFB unit will be over-constrained. The FFB unit would need to be free to pitch nose up/down slighty as the Y-bar rocks back and forward as the elevator is controlled.

...sorry if I am viewing it wrongly......

Ian

[Cessna172sim]

Hi,

Instead of metal pin joint we are using flexible polyurethane suspension that is attached into the bottom of the unit. This should do the same trick.

You can see the polyurethane joints here (blue color):

http://www.lentosimulaattori.1g.fi/kuvat/Force+Feedback+yoke+project/IMG_0759.JPG

BR,
OP

[IanH1960]

...neat idea, let us know how it goes when you get it powered up....

Ian

[Cessna172sim]

Will do! And late reply to your previous post; yes, we are using the 100% original C172 dual control yoke Y-bar.

[Efe Cem Elci]

Great work. I'm going to scrap the 737 and get cracking on a GA, and this will be on the drawing board. Once I offload the stuff I have at hand.

[Cessna172sim]

Force Unit remote control to the cockpit:
6645

[Cessna172sim]

Hi,

We have finally completed all hardware and software installations. Is there any change to get your config files to our C172. Since almost nobody of us have a real life flying experience it would help us a lot to get some pre-programmed configure file. Feel free to send me some mail: robots[at]jippii.fi

Thanks in advance,
BR,
OP

[IanH1960]

Hi OP,

...have emailed.

Ian

[Cessna172sim]

Hi everybody,

Just wanted to tell you that the unit is now fully functional. We had a real life C172 pilot visiting the sim yesterday and we made small adjustments to the software settings appr. 6 hours. Few clips here:

http://www.youtube.com/watch?v=DhGzIhR_-pE&list=UU78niMlxa3rP65NEw0ksYEw&index=8&feature=plcp

http://www.youtube.com/watch?v=Aj72zEhvq_8&feature=relmfu

Also some general updated videos here:
http://www.youtube.com/user/Cessna172sim?feature=watch

Next we would like to start working with the force rudders.

I still need to add some lubrication to the yoke shaft. As you can see it's VERY dry.
Best regards,
OP

[iwik]

Congratulations,
Looks awesome and its great to use isnt it.
What are you doing re the Force rudders?.
Les

[Cessna172sim]

Hi,
The concept really gives our sim a complete new life. You really have to use the trim to find the 'sweet spot' from the yoke and keep the plane trimmed. Also the vibration effects are super smooth. We would primarly want to build Ian's rudder pedal prototype and connect this to our current pedals. According the concept pictures it seems to be fairly easy to connect to the C172 rudder pedals via control rods.
http://bffsimulation.com/FFB-pedals-1.php

[IanH1960]

Hi OP,

Thanks for the update - great to hear it is making a difference to your sim experience.

Can you send me your modified config file - I'd love to see how close the lighter cessna config I sent you was to what your pilot expected...

I've not had any time to do more work on the pedals - this steel FFB yoke kit is consuming all my time... I got as far as making the components for the FFB rudder prototype and they've just sat in the workshop for 6 months!

Ian

[Cessna172sim]

Hi Ian,

Sure, we can send the config file for you. The only thing that is not yet working is the autopilot. From some reason it turns on OK, but after few seconds it disengages and you have to fly manually. I tried to raise the pry-file autopilot elevator and aileron setting value from 20 to 60 but no help. Should this value be even higher?

Also I tried invert AP button from the config settings. Any idea about this? Could it be that the small amount of friction disengages the autopilot, or something else..

Looking forward for those rudders also.

[IanH1960]

Hi OP,

In the first instance try in the Pry_S.cfg file setting the elevator and aileron disengage values high - say 200 each. This will effectively disable the AP disengage feature and let you see what the basic AP following movement is trying to do.

Try this and see what happens - if it still disengages then can you zip up and send me the Logs folder - I'll have a look and see what the software is saying... I'll also be able to see what chip firmware versions you have on the cards.

Ian

[Cessna172sim]

Perfect. I'll send your advices to Ville and ask him to try to raise the values first and if this doesn't help, will send you the files.

//OP

[iwik]

Hi OP,
I too are waiting for Ian's ffb pedals. Re the AP i think i found the same thing
and cant remember what my setting was but found increasing the value somewhat can get you to a point where quite a lot of resistance is required
for ap to release.
Les

[Cessna172sim]

Thanks for the info. In our case we didn't even need to touch the yoke before the autopilot disengaged. It took appr. 3 seconds until the autopilot dropped off and went back to manual steering. We will first try what Ian already suggested and raise the value from 20 up to 200. Like said, we only tried to run the autopilot with the value increased from default 20 to 60. In our case the system might need a bit more resistance to disconned since there are more mechanical joints to cause extra friction. We actually added few drops of silicon based lubrication to C172 yoke shaft and now it's slick like a bacon in the belly. :D

Will report tomorrow. Until then, cheers from cold, rainy and chilly Pirkkala, Finland. :)

//OP

[iwik]

OP,
It works well when going.Look forward to how it goes.
From a lovely Frosty Sunny Morning in New Zealand.
Les

[IanH1960]

Hi OP,

Once you have tried the change I suggested and we see what happens there are a couple of other things we'll look at.

The amount of effort the system puts into trying to follow the AP is controlled by other settings, and I tended to set these to default at fairly light forces to keep forces low and limit the possibility of damage in DIY systems. It may be that with the additional effort to move your real Cessna control mechanisms the default AP following effort is a bit low and the controls aren't following properly - so the auto disengage (which is triggered by the size of the position error ie the difference between the positon demanded by the AP and the actual position of the controls at any moment) triggers and switches the AP off.

One factor controlling this is the PID settings which control the position following movement - increasing the elevator P term in the Pry_S.cfg file is one possibility. The bigger this P term is the more force is generated when a position error appears. It may be the default P gain is too low for your heavier system. (This may be term Les is thinking off - increasing the P gain also causes a bigger force to be required by the pilot to move the controls away from the demand position when they are in AP following mode).

The other is the overall cap level applied to the position following forces - this is set in the 20X2 chip firmware as a safety feature but can be adjusted by changing the programming and re-flashing the chip.

Once Ville has tried with the large trigger error settings and he can see the movement then we'll know a bit more...

Ian

[Cessna172sim]

Hi Ian,

Thanks for the info. I just received info from Ville that the AP value is now raised to 200 and AP now works OK and doesn't disengage anymore. :)

I also received the latest log and config files. Could you kindly drop me email to my robots[at]jippii.fi address so I can send the files for you to check.

BR,
OP


Hi OP,

Once you have tried the change I suggested and we see what happens there are a couple of other things we'll look at.

The amount of effort the system puts into trying to follow the AP is controlled by other settings, and I tended to set these to default at fairly light forces to keep forces low and limit the possibility of damage in DIY systems. It may be that with the additional effort to move your real Cessna control mechanisms the default AP following effort is a bit low and the controls aren't following properly - so the auto disengage (which is triggered by the size of the position error ie the difference between the positon demanded by the AP and the actual position of the controls at any moment) triggers and switches the AP off.

One factor controlling this is the PID settings which control the position following movement - increasing the elevator P term in the Pry_S.cfg file is one possibility. The bigger this P term is the more force is generated when a position error appears. It may be the default P gain is too low for your heavier system. (This may be term Les is thinking off - increasing the P gain also causes a bigger force to be required by the pilot to move the controls away from the demand position when they are in AP following mode).

The other is the overall cap level applied to the position following forces - this is set in the 20X2 chip firmware as a safety feature but can be adjusted by changing the programming and re-flashing the chip.

Once Ville has tried with the large trigger error settings and he can see the movement then we'll know a bit more...

Ian

[IanH1960]

Hi OP,

Okay...

If you don't need the control movement AP disengage feature then you can probably continue with the higher position error trigger settings.

If you do want to be able to AP disengage by moving the controls then these are the checks you'll need to go through..

1. Use the Zero button on the CL software each time you start it - after the cards have been calibrated and after a successful Ping has been done to ensure the cards are responding. This will instruct the cards to drive the yoke to what it thinks the true yoke zero position is and the CL software will compare this to the joystick axis zero position. The AP following position demands will then be calculated more accurately.

2. Try reducing the trigger error settings in steps and each time re-starting the CL software (repeat the Ping and Zero's each time you restart the software) until you start to see the false disengage behaviour returning.

3. If the trigger settings are still above about 50 say then the control movement AP disengage probably won't feel satisfactory - ie you'll have to move the controls further than you want to get the AP to disengage. In which case....

4. Try increasing the P term gains in the Pry_S.cfg file to sharpen up the position following effort. But don't go much above doubling the existing value... If this doesn't allow smaller trigger settings to be used then you may need to try 5.....

5. ...raise the position following force cap level by re-flashing the 20X2 chip - I can help with the appropriate settings if you get this far...

If you are happy using the normal instrument buttons for AP disengage then you don't need these tests..

I've dropped you an email.

Ian