FFB Braking

[Derek Speare]

Hiya gang,

So I have spent the better part of the past two weeks or so researching every possible way to get a better braking feel in racing sims. I have come to the conclusion that a FFB brake pedal is the way to give the correct feel of a real brake pedal and would also give the expected feedback we seek.

As it stands we get only a few options, but none are FFB. There are load cells, greater spring pressure and "stock" options. However, none of these have the true progressive feel a real life car brake pedal has and none give pedal feedback and brake "modulation" sensations. Additionally, a brake pedal has a fair amount of pedal travel, and the greater the amount of pressure you exert on your car's brake pedal, the more force it takes to exert more. Simply put, it's progressive.

My idea is to have some type of rack and gear mechanism connected to a FFB motor. The rack, or "linear gear" would travel laterally against the circular gear mounted to the FFB motor. That motor would take its commands from some FFB software generated by the game and turn those commands into more or less resistance against the brake pedal mechanism. The FFB motor would also give the brake mechanism braking pulses and so forth to simulate the feel we'd expect in various braking situations. I think this is the most logical solution, but it has some limitations.

One major limitation is that FFB braking isn't really supported. I do know that rFactor and Simbin's titles have provisions in their controller files to send braking signals either thru the FFB wheel or brake pedal, but I've not found anything substantiating if it would work. Certainly, there are other issues, but the sim has to support FFB braking most importantly.

So these are my thoughts on this subject of exponentially increasing braking forces. If you have some, please share them.

d

[lesthegringo]

I'd thought about doing this, but came to the conclusion that with the exception of when ABS kicks in, there is relatively little feel through the pedal itself. What there is is limited to the pressure applied, and the (very) slight vibration that is induced by the disc moving against the pads; in a good brake setup this is virtually nil.

Most of the braking feedback in a car comes from other senses, predominantly the longitudinal G sensed under braking. With threshold braking, you have a combination of hearing a lock up plus feeling the lessening of G or the pulling on the wheel caused by the reduced friction of a locked wheel.

It's a tricky one, becuse effective braking is often the key to getting the maximum from a lap time, and really important during overtaking manoeuvres.

Short of introducing some artificial (non-realistic) feel, I can't think of what to do. My initial idea was that the pedal can vibrate slightly, then the vibration stops when the wheels lock. Not real, but maybe possible?

[Derek Speare]

Good points.

I agree that the forces transmitted thru the brake pedal are slight. However, the necessary pressure to stop our car varies with the speed it goes. The applied pedal force needed to stop our car when it's going 100kph in the minimal amount of distance is not sufficient to stop it the same from 250kph. This is part of what I'd hope to simulate with a FFB brake pedal, and I believe it can be and would be accurately simulated.

While you've outlined numerous forces we process during this experience we call racing, I do think that a dynamically actuated brake pedal would increase the immersive effect and give us a better racing experience.

The essence of the matter is that it seems as if the pressure curve is an exponential one. Quite possibly, an eccentric cam adapter connected to a spring and the brake pedal mechanism would be what would work. If a mechanical system would increase the amount of resistance as the pedal travels from zero to max while still offering some pedal travel distance, then this would be a low tech solution.

I suggested a variable rate spring in a thread started by conticreative, and this is what got me to thinking about this whole thing. In my particular case, I have a very soft brake pedal, and it's very much unrealistic. Anything is better than a brake pedal that feels like one does when you bleed the system!

d

EDIT - it seems as if Frex has a hydraulic braking mechanism. Looks expensive too! :blink:

http://frex.xsrv.jp/xoops/modules/newbb/viewtopic.php?topic_id=317&forum=5

[lesthegringo]

I used foam, in a couple of densities, and also being careful with the geometry. Difficult to explain, so I think I'll have to use sketches to show you if you don't understand

Here goes though!

If you get some solid foam, I used stuff 25 mm thick, 25 mm wide, high density, then place it so that as your pedal turns, more area of foam is pressed by the pedal, you get a very exponential rise in 'spring' rate. When the pedal is at rest, maybe an area 10 mm x 25mm is being pressed by the pedal, so the pedal feels spongy. After the fist couple of degrees, there is something like 30 mm (x 25mm width) of foam being pressed, as more of the flat of the pedal contacts it, and if feels significantly harder. A few more degrees and I have about 70mm of the pedal in contact with the foam, and by that time, it has gone almost solid; there is still movement possible, but it is very small for a lot extra pressure.

Feedback? No, it doesn't give that. But it does feel like a proper car brake pedal.

If anyone doesn't understand it, I can certainly draw something to show you what I mean.

Don't give up on the idea of feedback though!

[Derek Speare]

I do get it and it's a creative and economical solution. The varying foam densities give the desired "progressive" feel. I got to thinking about the Frex hydraulic pedal, and I thought the same idea could be easily adapted to a load cell.

You can do this experiment at home by taking two syringes, one long with a narrow tube and the other with a much wider bore. Fill the thin one with water and connect it to the other one with a tube. Then inject the water into the other, much wider syringe and you will see that you get a lot of piston travel in the small bore one, and not much in the other. I think it's Bernoulli's principle that governs this, but this is the essence of hydraulics.

The piston on the long one would be fastened to a mounted load cell, and the load cell to an amp and the amp to a microcontroller. The whole thing has five components:

1. pedal mechanism
2. fluid pistons
3. load cell
4. load cell amp
5. USB controller

But the FFB still isn't there :blink:

d

[Stigasawus]

I think you've gone full circle & ended up back at the load cell with lots of extras. Not being picky, but I think you may be close with the comment about "bleeding". Maybe something like a hydraulic system with air in it (which is compressible, of course) would give the progressive feel, still ending up at the load cell, but more directly, ie., the slave cylinder or even just master cyl. actuating rod pushes on the load cell, with air in the system by experiment, enough to feel right.
One thing I dont agree on is the force needed to stop from a higher speed being greater, on the principle of "if your not accelerating or braking to the max, you mustnt be trying hard enough" (not my idea..just..as told to me).
Meaning, the braking force is the same, but you start braking earlier at higher speed. Just threw this in to help keep you on track. The pedal feel on track is very subtle when your pushing very hard & the feedback on the whole thing comes fromseveral other sources...brings us back to the motion sim idea does'nt it?
The foam idea sounds a lot like the squash ball principle I've seen mentioned.

[redi]

... The applied pedal force needed to stop our car when it's going 100kph in the minimal amount of distance is not sufficient to stop it the same from 250kph. ...
I'm not very familiar with car mechanics, but what you described here is true IMHO although it doesn't mean that the brake pedal should behave differently when going 100kph compared with when going 250 kph.

A brake system is just a pedal compressing a fluid that pushes against a cylinder or something that makes the brake claws push against the brake disc. How pushing the brake pedal down feels, has nothing to do with how fast the car is going. The resistance change as a function of brake pedal travel will not depend on the actual speed of the car, and the maximum physical brake pedal travel that is possible is also not dependent on the actual speed of the car. Hence, brake pedal characteristics are completely independent of car speed.

When a car does 100 kph, there is a certain maximum force you can exert on the pedal (i.e. a certain brake pedal travel) before a brakes start locking. In order to do maximum braking at 250 kph, you may have to push the pedal in deeper, but the feel of the brake pedal will not change with that, i.e. when you would have pushed the brake pedal down the same amount when going 100 kph, it would have felt the same (only maybe the wheels would have locked while at 250 kph they won't, I don't know really).

Hence, I think that the feel of a brake pedal does not change at all with how fast the car is going, only the brake pedal travel you need to brake at maximum power will vary.

So, what you're looking for is a pedal that gives progressively increasing resistance with pedal travel, but the actual maximum brake power (i.e. the maximum brake pedal travel) allowed before locking the brakes at a certain speed will come from the simulation, not from the pedal.

[Stigasawus]

I'll drink to that, wish you'd written my reply...you said it better

[lesthegringo]

The foam idea sounds a lot like the squash ball principle I've seen mentioned.

Yes, though the way it works can be tailored to give different rising rates, so maybe a little more sophisticated if used right

[phntomF16]

As you investigate candidate solutions it could help to test existing solutions from other manufacturers. If budget allows or if you know others with aftermarket pedals you could see if there are pedals that behave the way you desire.

I would say the ECCI Trackstar 6000 pedals behave quite closely to your ideal as described in this thread. It is an open loop system, so the racing software does not produce feedback into the ECCI pedal. But with proper calibration the brake pedal and braking behavior in sims are a very good approximation of pedal feel in real life.

[Derek Speare]

Thanks for the comments, gang. Remember that friction is what overcomes the shear forces when the pad mates against the brake disk. More pressure = more friction to the point of lock up. I think maybe a progressive spring is the "down and dirty" mod for a brake pedal. The commercial solutions are just too cost prohibitive to have any mainstream consumer applications.

Back to the drawing board.

[Stigasawus]

Gotta google the Trackstar pedals now, maybe I've seen & forgotten them!
I reckon the load cell MUST be the right central point, with anything else built around that. Thought the load cell operation would give a progressive actuation, forgot the feel part. So next question, what is a good "thing" to pirate a progressive spring from. I can only think of suspension struts & thats way too big.
My experience is that the first thing to give on a real car is the tyre to road contact & even with power assist on say a V8 monster, you push damn hard & sense the lock-up coming from the rest of the cars reaction..not too much feel from the pedal (and the disc area is prone to losing grip from heat). Dont forget that there arent many ideal surfaces out there...ie the braking area is usually far from a billiard table & some are wild rides...another factor esp. of late is using the braking to put the front end on the ground & get traction back to turn in after the lift of acceleration or just aero (lack of).
"Tuning" a sim is getting a lot like the real car for the time in the pits...seems like mines always there...or the next stop is being planned !!

[clockit]

I was perfectly happy with my load cell, 'til I started reading this thread.
I've got the AP mod which works brilliantly at high pressures, but not quite so well at low pressures. It's hard to just brush the brakes. I'm having to apply more pressure in my sim, than I do in a road car.

[brucepts]

Just a random thought . . . a real car master cylinder and caliper with a load cell between the piston caliper and the caliper housing. So the load cell would be where the pads and rotor sit, could be done with a drum brake cylinder also, which would be very cost effective.

An answer for the progressive spring question could be an inner spring of a shorter length that would come into play at a certain depth of pedal, could be adjustable and a few could be used of varying lengths.

As an edit: you could also use the master and slave from a car that uses a hydraulic clutch. Slave would press the load cell.

[Bruno-F1]

The Fanatec "ClubSport Pedals" have what you search for:

(excerpt from the features list)
- Vibration feedback motor on brake pedal to indicate blocking tires. The driver software calculates this moment based on the telemetry data received from the games.

- Pressure sensitive load cell sensor on the brake. Control the brake force with muscle tension instead of movement. Realistic brake pedal dampening created by special PU foam made in Germany and used in the car industry in shock absorbers. Ultra strong and smooth.

You can use any racing wheel together with the ClubSport pedals.

See:
http://www.fanatec.de/html/index.php?id=293&lang=en

[Derek Speare]

I'm not convinced the Clubsport hardware will deliver what I seek. They specifically call it "Vibration feedback". While it may deliver some feedback, I don't think it will deliver from what I have read and seen of it.

I like brucepts' idea! It's very original and out-of-the-box :)

Here's a sketch I made up of what I see in my mind:

http://i962.photobucket.com/albums/ae109/derekashley1967/NFS%20Shift/FFBBrakeMechanism_1.png

The FFB software would modulate the pressure and progressive feel at various speeds. Now all we need is the software...and the support for it!

Derek

[redi]

The FFB software would modulate the pressure and progressive feel at various speeds. Now all we need is the software...and the support for it!

Derek
What I've been trying to tell you is that AFAIK a real brake pedal does not show varying brake pressure and feel with varying speeds. Only the response of the car to the same brake input varies with speed, but that is the realm of the simulation you're playing. Of course I'm not a car mechanic or race driver so I could be wrong, but I think you should make sure that what you have in mind in fact has a connection with reality...

[Stigasawus]

What I've been trying to tell you is that AFAIK a real brake pedal does not show varying brake pressure and feel with varying speeds. Only the response of the car to the same brake input varies with speed, but that is the realm of the simulation you're playing. Of course I'm not a car mechanic or race driver so I could be wrong, but I think you should make sure that what you have in mind in fact has a connection with reality...

You got it, theres not as much feel in the brakes of a purpose built race car as a road car & even with power assist you push hard as poss. still keeping the tyres gripping & set up your own braking points using markers or "scenery". The braking distance is the variable. Road cars are much more forgiving to allow for different needs & driver ability.

[Stigasawus]

Remember that fluids dont compress, so a hydr. system in a sim wont give any feel without any car or reality involved so you HAVE to have something compressible or your going to do a lot of work to end up with what youve already got!

[brucepts]

So you swap over to a closed airclyinder pressing on a load cell or pressure sensor? You would have to play with cylinder diameters and strokes to get the right pressures a bleed valve could be used to tune the desired pressures. My problem has been fitting it into the area of my G27 pedals. Plus I don't want to pull my set of pedals apart as it would render my simseat unusable for a time being (too addicted to this now for that to happen). Anyone have a set apart they could share the measurements?

I have to many other projects going and for what the AP Electrix setup costs is it really worth the hassle for me to design something else are my thoughts? I also like the adjustability of the Clubsport Pedals.

[phntomF16]

At the risk of seeming immodest, I'll summarize my motorsports experience for the sole purpose of establishing some measure of credibility in the readers' minds. I have held FIA Karting, FIA Road Racing, and FIM Road Racing licenses, I have completed 100+ car trackdays and 100+ motorcycle trackdays, and I have instructed with the BMW Car Club of America, National AutoSport Association, Porsche Club of America, and several other organizations. I also hold a degree in aerospace engineering from the US Air Force Academy. I do not claim to be an expert, so please feel free to add to, correct, and critique my ideas below.

As I see it, simulating real world braking behavior is best if divided into 2 separate key components: accurately modeling the pedal pressure vs braking torque relationship (load cells), and accurately modeling feedback indicative of threshold braking, impending brake lockup, and locked brakes.

. . . How pushing the brake pedal down feels, has nothing to do with how fast the car is going. The resistance change as a function of brake pedal travel will not depend on the actual speed of the car, and the maximum physical brake pedal travel that is possible is also not dependent on the actual speed of the car. Hence, brake pedal characteristics are completely independent of car speed.

. . .the actual maximum brake power (i.e. the maximum brake pedal travel) allowed before locking the brakes at a certain speed will come from the simulation, not from the pedal.

redi is essentially correct in his assessment of brake pedal behavior in real world cars. The pedal force required for a given braking torque is relatively constant and it is independent of vehicle speed.

There are already numerous pedal designs and pedal mods on offer - many of them incorporating load cells - that accurately simulate the pedal pressure vs braking torque relationship. For example, here is an excerpt from the description of ECCI's TrackStar 6000 pedals (a model I may seem partial toward because I own several sets):

PMB-II NEXT GENERATION PRESSURE MAPPED BRAKE PEDAL

Another ECCI exclusive innovation. As an integrated solution for our 6000 pedals, the PMB-II is an entirely new design from our previous PMB modules. The PMB-II offers not only the very highly progressive feel of the brake in a "real world" auto, it also provides highly progressive braking response that exactly matches the feel. Two key adjustments are available: maximum braking force level and initial preload.

INDIVIDUALLY ADJUSTABLE PEDAL TENSION

The TRACKSTAR 6000 has an independent spring pack for each pedal that offers two critical adjustments. Widely adjustable maximum braking force, and initial preload. This allows the user to set the force required to actuate gas, brake, and clutch to appropriately differing levels. The preload adjustment sets the amount of force needed to initiate pedal movement.

http://ecci6000.com/6000_pedal_01.htm

Let me reiterate: numerous pedal designs already accurately model real world brake pedal pressure vs braking torque.

So solutions already exist for the first key component: pedal pressure vs braking torque relationship.
-----------------------------------

The second component involves modeling feedback to the driver indicating threshold braking, impending brake lockup, and locked brakes. Locked brakes present obvious and easily modeled indications (skid noise, tire smoke, loss of directional control). Sims do a fine job of modeling locked brakes.

Approaching but short of lockup the driver receives subtle sensations that include but are not limited to:

1. Diminished steering response felt through the steering wheel as understeer when the front brakes begin to lock,

2. Diminished rear end stability, sometimes felt as oversteer, as the rear brakes begin to lock,

3. Cyclic braking vibrations passed through the steering wheel,

4. Cyclic braking vibrations passed through the brake pedal.

The steering and brake pedal cyclic vibrations arise from the brake calipers clamping brake pads against rotating brake rotors.

The first three sensations are covered in quality sims using car balance, car behavior, and steering FFB; therefore our focus is on the 4th item.

For reference, think of what one feels on a pedal bike through the brake levers when hand braking: The cyclic vibrations a driver feels through the brake pedal are similar to the sensations felt through the hand brake levers on a pedal bike.

So we have identified what sensations remain to be modeled in our brake pedal: the cyclic braking vibrations matched to the brake rotor rotations of our simulated vehicle.

The cyclic sensations manifest as pressure changes felt through the brake pedal. These subtle pressure changes are rapid in frequency (matched to braKe rotor RPM) but relatively small in amplitude compared to the total brake pedal pressure applied by the driver under effective braking. Also, the intensity of the cyclic sensations increases with increasing overall pedal pressure.

The driver’s foot feels the cyclic sensations overlaid on top of the overall pedal pressure; this is the primary reason why I think it is best to separate the pedal pressure vs brake torque behavior component from the threshold/impending lockup/full lockup behavior component when designing a simulator brake pedal.

Another key indicator of approaching lockup is the amplitude and frequency of the cyclic sensations in the brake pedal fall off sharply to match the brake rotor rotation approaching zero.

In summary, we need to vibrate an existing brake pedal in the latter portion of pedal travel with a small cyclic vibration that slightly increases in amplitude as the driver applies more pedal pressure, up to the point of decreasing amplitude and frequency as the brake rotors begin to lock, and finally falling off to zero cyclic vibration at brake lockup.

Thus, we simply need to map pedal vibration amplitude and frequency as a function of brake pedal position and brake rotor speed, design a small vibration module that behaves as such, and attach it to a quality existing pedal design.

--------------

The vibration feature of the Fanatec Club Sport Pedals represents a good first effort at simulating cyclic braking vibrations passed through the brake pedal, but there is room for improvement, IMHO. The CSPs need a stiffer brake pedal and the vibration needs to account for brake rotor speed. (I also own a set of the Club Sport Pedals).

[Derek Speare]

I must disagree, respectfully on the issue of pedal force and pressure. Increased vehicle speed increases brake disk rotation. The pressure of the brake pad against the disk creates friction, and friction is what stops the car. This is no different of a force than if you were to suspend two different weights from separate ropes over your balcony. If you had a 10# and 50# weight, you'd have to hold the heavier one with more grip pressure. Our brake caliper is this principle.

My idea is focused on simulating this characteristic, but first we'd need to agree that the force and pedal pressure may, for clarity, not be used interchangeably. To keep the concept simple, my assertion is that the amount of pressure needed to stop our race car (in the shortest distance in the minimal of time without wheel lock = most efficient) when it is going 100kph is insufficient when our car is traveling 250kph. I consider that this can be simulated in a FFB brake mechanism like I have sketched out above.

Please note that I am not an expert, but I do drive :) Stigasawus makes a perfect point in that fluids do not compress. Fluid dynamics is an area of my knowledge, and the only compressable fluids - practically - are gasses. Hydraulic fluid would be useless if it compressed!

Anyhow, there are some great points in my scans of the recent replies, and I want to take more time with them to understand the ideas and concepts. My hope is that we can flesh out the needed braking behaviour and then hope to have someone write the software to make the idea come alive.

More will follow from me soon, but I have to go shopping :) Thanks for the replies :)

[jeroenvdb]

Are real life brakepads and -disks compressable or completely stiff?

IMO there are 3 things to deal with:
1) Measuring the force applied to the braking system.
2) How the pedal moves as force is applied or released.
3) How the car reacts to the force on the brake.

3 is IMO something for the simulation to deal with and the pedal should just tell the sim how hard it is being pushed.
1 would be done best with a forcesensor (like a load cell) somewhere in the pedal.

Regarding 2:
First the pedal would move a short distance against a returnspring while no force is applied to the sensor, this simulates the brakepads moving inside the caliper from their restposition to the brake disk. As long as the pads do not touch the disk there will be no braking. The driver will feel a small gradually increasing force.
Eventually the pedal will touch the forcesensor and stop moving when more force is applied. This simulates the brakepads reaching the brakedisk.
Any extra force applied after this point will be read by the sensor and sent to the simulation.
http://img97.imageshack.us/img97/4547/brake.gif

To simulate vibrations fed back from the brakes we could attach a little vibratormotor or -better- a bass shaker to the pedal.
With a motor we could only control it's speed (frequency) while a bass shaker would allow us to control both frequency and amplitude.
Then we would need to write some software that calculates a signal for the shaker based on pedalforce and wheelspeed.
The way I understand phntomF16's post it would be like this:
frequency based on wheelspeed and amplitude based on brake force, right?

[Derek Speare]

Remember that a FFB mechanism would alter the pedal travel distance, pressure needed to affect pedal travel and give the feedback sensations, most like a FFB wheel but for brakes. A load cell is simply static and accepts pressure. It does not respond to anything from the sim; the sim responds to it.

This line from Simbin's PLR file is what got me thinking about the concept of FFB braking:

FFB Brake FX on steer axis="0" // 0 = Brake effects on brake axis, 1 = brake effects on steering axis.

An automotive brake mechanism pedal is a lever and the hydraulics mutiply the pedal pressure. The pedal will travel farther at braking during high speeds than it will at low speed braking due to some expansion of fluid in the master cylinder and increased braking pressures needed at high speed. To slow a car from very high speeds requires the calipers to exert high claming forces on the disks, and high clamp forces are generated by increased pedal pressure.

If I had a simple spring that could give me an exponential compression curve, then I'd not really have anything to speak about :blink: But because springs are mostly linear, an electromechanical FFB device may be the solution.

Anyhow, maybe logitech will develop something like this.

d

[redi]

I must disagree, respectfully on the issue of pedal force and pressure. Increased vehicle speed increases brake disk rotation. The pressure of the brake pad against the disk creates friction, and friction is what stops the car. This is no different of a force than if you were to suspend two different weights from separate ropes over your balcony. If you had a 10# and 50# weight, you'd have to hold the heavier one with more grip pressure. Our brake caliper is this principle.

...
Look at it this way: if what you say is true that the brake resistance changes with the car's velocity, it would mean that the brake disc pushes back at the cylinder/claw, depending on the car's speed. Since the brake force (friction) is parallel to the brake disc and the force you exert on the brake cylinder/claw is perpendicular to the brake disc, this is impossible.

[Derek Speare]

My point is that we know all of the components are incompressable. However, this does not mean that more pressure cannot be applied to the system. Water in the open ocean is an example, and the deeper the water, the more pressure being exerted. The brake pedal in a real car has some length of travel because a braking system trades piston travel distance for system pressure.

Either way, though, my idea is only aimed at giving a sim racer a more realistic braking feel than what is found currently. The essence of the sensation in a car is that it takes increasingly more effort to press down the brake pedal to the point when the system reaches its maximum. I consider this to be an exponential relationship, and that is precisely what we can simulate with the system I sketched out above.

This is the essence of it:

http://i962.photobucket.com/albums/ae109/derekashley1967/NFS%20Shift/progFFB_1_1.png

d

[jeroenvdb]

What exactly do you mean by 'system resistance'?

Do you mean force?
Newton says that this would be a linear relation.
If I apply 1 pound of force to the pedal then the pedal will 'resist' with exactly 1 pound, if I apply 10 pounds the pedal will push back with 10 pounds.

Or do you mean movement?
In that case the pedal would only move while the brakepad is moving towards the disk and in that phase there would be no braking.
Once the pad is on the disk it no longer needs to move and, if the system is incompressible, neither would the pedal.

[Data]

Look at it this way: if what you say is true that the brake resistance changes with the car's velocity, it would mean that the brake disc pushes back at the cylinder/claw, depending on the car's speed. Since the brake force (friction) is parallel to the brake disc and the force you exert on the brake cylinder/claw is perpendicular to the brake disc, this is impossible.

It actually is possible.

Think of it this way:
You have a master and slave cylinder, the slave cylinder piston presses against the load cell in its center and at the same time the outer side of it presses against another slave cylinder.
You have the second slave cylinder work against a second master cylinder, that is controlled by a motor instead a pedal.
The faster you go, the higher the pressure on the second master cylinder before it moves backward like a seesaw.
It could also be done with a gear rail and a motor, where the rail is pressing against the outer rim of the slave cylinder.
How strong the reverse force of the motor is, could be taken from the steering wheel input, the force that changes the steering wheel turning pressure.
I hope you understand what I'm trying to say.

[Derek Speare]

The physical property here is the same as wind drag against a car. For example, drag increases to the square of vehicle speed. With the case of friction in our braking system, the same principle applies. The necessary pedal pressure increases to the square of the disk rotational speed. It is not a linear relationship.

d

[jeroenvdb]

Wouldn't you need less force on the brakepad to get the same amount of friction if friction increases with speed?

[redi]

The physical property here is the same as wind drag against a car. For example, drag increases to the square of vehicle speed. With the case of friction in our braking system, the same principle applies. The necessary pedal pressure increases to the square of the disk rotational speed. It is not a linear relationship.

d

All that this only means that you have to push harder on the brake to slow down as fast as possible when you're driving at high speed. But that doesn't mean that the brake pedal feels stiffer if you drive faster, that is not what happens in a car, you can feel that for yourself.

The fact that kinetic energy increases with the square of the velocity has NOTHING to do with the fact that the brake pedal gets progressively stiff when you push it down. Those two things are completely unrelated. The brake pedal gets progressively stiff because it's a hydraulic system with an (almost) incompressible fluid, and that has nothing to do with the car's speed. It gets equally progressively stiff when standing still or when driving 250 kph. You only need to press the brake less hard to stop when driving 50 kph compared to when driving 250 kph, and that's what makes braking at 250 kph harder.

Hence, all you need to do is to make a brake pedal that gets progressively stiff in a realistic fashion, compared to a real hydraulic system. The car's speed is completely irrelevant in this. FFB in the brake pedal only comes into the picture if you want to simulate ABS.

[Derek Speare]

...Hence, all you need to do is to make a brake pedal that gets progressively stiff in a realistic fashion, compared to a real hydrolic system. The car's speed is completely irrelevant in this. FFB in the brake pedal only comes into the picture if you want to simulate ABS.

This is precisely what I have been saying all along! Whatever laws govern the forces at work in a braking system notwithstanding, I do know that my brake pedal in my cars and on my motorcycles get progressively stiffer as I press them. This is what I wish to see in a FFB brake pedal.

Certain vibrations and modulations can be articulated thru the pedal as a result of ABS, lockup and so forth, but the essence is the progressive nature. I'd even suggest some pedal vibrations when braking to help the user "feel" it; some exaggerations are necessary to compensate for the absence of gravity effects on the driver in a sim. It is my claim that more braking pressure is needed to stop a car the faster it travels.

Anyhow, we're back to the beginning :)

d

[redi]

It actually is possible.

Think of it this way:
You have a master and slave cylinder, the slave cylinder piston presses against the load cell in its center and at the same time the outer side of it presses against another slave cylinder.
You have the second slave cylinder work against a second master cylinder, that is controlled by a motor instead a pedal.
The faster you go, the higher the pressure on the second master cylinder before it moves backward like a seesaw.
It could also be done with a gear rail and a motor, where the rail is pressing against the outer rim of the slave cylinder.
How strong the reverse force of the motor is, could be taken from the steering wheel input, the force that changes the steering wheel turning pressure.
I hope you understand what I'm trying to say.
You're saying that you can make a progressively stiff brake pedal with this, which is good :) I was stating that the brake pedal doesn't get stiffer because the car tracels faster, but only because you'r epushing it down further :)

[phntomF16]

Gentlemen, maybe there is a misunderstanding in this thread. The high downforce levels generated by some classes of race cars (open-wheelers with ground effects, aero devices, and wings for example) do affect braking behavior. It is true that race cars that generate high levels of aerodynamic downforce produce greater tire grip due to this downforce at higher speeds. For this class of cars higher pedal force is required for maximum threshold braking at higher speeds when higher grip due to downforce is available.

Please note that quality sims model this downforce vs grip vs maximum braking relationship rather well; quality sims simply require higher braking torque and therefore increased pedal pressure to achieve maximum threshold braking at these increased grip levels.

In other words, it is true that "at higher speed more braking pressure is needed to maximum brake a high-downforce car".

DeeMoNay, is this what you are talking about?

[pjj1180]

I wonder how much of the pedal feel is related to expanding brake lines. Brake fluid shouldn't compress, so why would the pedal feel any different the farther it is pushed? Is the valving progressively different in the caliper, or is the master cylinder providing less multiplication the farther the pedal is pushed? LOL, you guys got me :P

[redi]

Gentlemen, maybe there is a misunderstanding in this thread. The high downforce levels generated by some classes of race cars (open-wheelers with ground effects, aero devices, and wings for example) do affect braking behavior. It is true that race cars that generate high levels of aerodynamic downforce produce greater tire grip due to this downforce at higher speeds. For this class of cars higher pedal force is required for maximum threshold braking at higher speeds when higher grip due to downforce is available.

Please note that quality sims model this downforce vs grip vs maximum braking relationship rather well; quality sims simply require higher braking torque and therefore increased pedal pressure to achieve maximum threshold braking at these increased grip levels.

In other words, it is true that "at higher speed more braking pressure is needed to maximum brake a high-downforce car".

DeeMoNay, is this what you are talking about?
I think the misunderstanding has been cleared already :) From the first postings I was under the impression that the FFB in the brake pedal was used for making the brake pedal stiffer when the car in the sim was traveling faster, but from the last postings I gather that all DeeMonay wants is a brake pedal that gets progressively stiffer when you push it down. He was thinking of doing that with a FFB motor, but it probably is easier by doing it through a passive contruction using, for example, different materials that make brake pedal resistance stronger the further the pedal is pushed.

[Derek Speare]

Gentlemen, maybe there is a misunderstanding in this thread...[original redacted]

...In other words, it is true that "at higher speed more braking pressure is needed to maximum brake a high-downforce car".

DeeMoNay, is this what you are talking about?

Yes, this is precisely what it is that I wish to have simulated in a FFB braking mechanism. This is represented in my curve sketch above.

:)

I wonder how much of the pedal feel is related to expanding brake lines. Brake fluid shouldn't compress, so why would the pedal feel any different the farther it is pushed? Is the valving progressively different in the caliper, or is the master cylinder providing less multiplication the farther the pedal is pushed? LOL, you guys got me :P

Most of the expansion is taken up by the master cylinder and the caliper pistons receiving brake fluid. Brake fluid, like all solid fluids, do not compress. We'll assume that a race car is outfitted with metal brake lines to prevent any unintended expansion of the system.

Additionally, it is important that the pedal travel distance can mislead us into thinking that there is quite a bit of movement in the actual hydraulic system itself. This is not the case, and the amount of fluid traveling into the cylinders of the brake calipers is not much. Remember that the brake pedal mechanism is a lever with a fulcrum point very near the actuator piston in the master cylinder. The master cylinder then converts its piston travel distance to pressure at the caliper, and it is the Bernouli Principle that governs this; that principle is exactly analogous to mechanical gearing.

Hydraulic braking system:

http://en.wikipedia.org/wiki/File:Hydraylic_disc_brake_diagram.jpg

Brake Pedal levering system:

http://www.cannonsimulationtechnologies.com/user/cimage/Black-Brake-Pedal-Assembly.JPG

So when we push the brakes deeper to the floor our brake system builds more pressure. That three or four inches of movement is converted to fractions of inches at the wheel disk, and that conversion multiplies the pressure in the system many, many more times over...

I think the misunderstanding has been cleared already :) From the first postings I was under the impression that the FFB in the brake pedal was used for making the brake pedal stiffer when the car in the sim was traveling faster, but from the last postings I gather that all DeeMonay wants is a brake pedal that gets progressively stiffer when you push it down. He was thinking of doing that with a FFB motor, but it probably is easier by doing it through a passive contruction using, for example, different materials that make brake pedal resistance stronger the further the pedal is pushed.

Essentially this is the idea, but a completely mechanical system would not simulate the feel of brake fade, ABS feedback, wheel lock, brake failure or vibrations. An electromechanical system controlled by software would allow us to have more simulated accuracy than a progressive rate spring; a progressive spring was my first idea, but I tossed it away feeling that this idea would have more utility and boost the realities we wish to experience in our sims. A FFB braking system would be dynamic and a passive system only static.

If I was unclear, please accept my apologies. I do not claim that the pedal stiffness increases with car speed. We just need more brake pedal pressure to stop our car the faster it travels - and when I indicate "stopping", I mean braking efficiency where we can slow the car to a desired speed in the fastest amount of time, in the shortest distance while preventing wheel lock.

phew!

Thanks again for the thoughts and comments. Now we need Logitech to come along and make it! Oh, and pay us for the idea :)

Derek

[Derek Speare]

Seems like these folks have a spring like I have been suggesting for a strictly mechanical system:

http://www.f1driving.it/images/stories/arc_brake/ARC_Brake.jpg

d

[Stigasawus]

Yup thats a progressive spring & looks like some Logitech too. Gee I thought there was gonna be a brawl there until everyone started agreeing.
The whole thing revolves around, if you have the money to throw at it, there is a system out there...bet the Red Bull pro. sim as used by the team has one. Then theres the , how can we do this & still feed ourselves approach. Not something for nothing but how can we DIY a solution (well thats what keeps me amused anyway).
Welcome all engineers, who can help...isnt that what a forum is for.
My "idea" (only!) is that a pedal conn. to a master cyl. filled with fluid & actuating rod, pushing a load cell (maybe a hyd. clutch master cyl. even) WITH a very small amount of air inside the hydraulics, for the "feel" & pedal movement, sounds like a possible.
If you sit in your road car & push the pedal with nothing running & handbrake off. Then try again with the motor running, then again at various speeds...yes there will be a difference, but I bet the first one will give a dead pedal.
There is a lot of modulation of braking in road travel situations, but on the track you try to always use max. braking from a suitable marker before the corner...which leads to one thing that has probably been covered, sort of. The movement in the disc end of the system is hopefully minute, but there is a little thing called "knock-off" where the disc rotation can make the pads separate from the disc & this will cause a lack of pedal feel until the take up happens...not nice either.
So, to sum up, we want to improve the low price gear at a low price eh!

[ptclaus98]

I used foam, in a couple of densities, and also being careful with the geometry. Difficult to explain, so I think I'll have to use sketches to show you if you don't understand

Here goes though!

If you get some solid foam, I used stuff 25 mm thick, 25 mm wide, high density, then place it so that as your pedal turns, more area of foam is pressed by the pedal, you get a very exponential rise in 'spring' rate. When the pedal is at rest, maybe an area 10 mm x 25mm is being pressed by the pedal, so the pedal feels spongy. After the fist couple of degrees, there is something like 30 mm (x 25mm width) of foam being pressed, as more of the flat of the pedal contacts it, and if feels significantly harder. A few more degrees and I have about 70mm of the pedal in contact with the foam, and by that time, it has gone almost solid; there is still movement possible, but it is very small for a lot extra pressure.

Feedback? No, it doesn't give that. But it does feel like a proper car brake pedal.

If anyone doesn't understand it, I can certainly draw something to show you what I mean.

Don't give up on the idea of feedback though!

I'd like to know more about this. What foam did you use? How much did it cost? How did you keep it in place?

[lesthegringo]

It cost me about 3 euros, and I bought it at a place that sold foams in Hong Kong when I lived there. It was a self adhesive strip 25mm x 25mm, and was just fairly basic black high density foam. Most places that do DIY will have something that you can use, even if it's by cutting a piece of that floor mat type stuff. It's the way you use it that makes the difference.

Even that stuff they use in packing will do, so long as is it foam that is rubbery, not the stuff that crushes.

I held it in place using tie-wraps, by drilling a hole through it and threading through, and it is very effective.

I will draw some diagrams to show the geometry, and then will post them here.

[lesthegringo]

right, I have some diagrams of the 'lesthegringo' progressive pedal setup I have made, but they are in .pdf file format, I can't convert them to .jpg so that I can post them - can anyone help me put them up here? They are five pictures, each about 200kb

[phntomF16]

Les, you could use the PrintScreen button (PrtScr). Open the .pdf file to the desired diagram and press the PrtScr button to take a snapshot of your desktop. This will place the snapshot onto the editing Clipboard.

Next, open your photo editing software, create a new document, then Paste the snapshot you took of your desktop. Now you can edit, resize, crop the picture you took of the .pdf diagram and then post it here.

[lesthegringo]

Good tip, phntomF16, and it works. For anyone interested then, here is the 'Lesthegringo pedal' setup!

There are four pictures, each with progressively more brake pedal movement. The diagrams are not accurate for dimensions or angular movement, they are for illustrative purposes only. The beauty of this setup is that you can carve the foam, or add more or less to give the pedal feel and travel you want, and all it costs is some cheap foam

On the left of the pictures is the support for the medal mount, with the pedal and its pivot point on the right. Between them is a block of high density foam. The block is square edged, the only reason that at rest the top right hand part is not squared off is because it is jammed up in such a way that the 25mm area is being compressed between the pedal and the support. This serves two purposes, one to help locate the block, and two to give an initial, soft, feel to the pedal. You will still have to restrain the block, I used tie wraps through holes cut into the foam. You will also probably have to use a return spring and a rest postition stop for the pedal

In the second picture, the pedal had been moved by 10 degrees, which 'takes up the slack' in the pedal movement and has that soft feel you have right at the start of the pedal movement, but by this point you can start to feel extra resistance. Note how the area of foam being crushed is greater, so not only have you crushed it more, you also have more foam pushing back against the pedal.

Now look at the third picture with only a couple of degrees more movement. The area of foam in contact with the pedal has increased a lot. Another factor comes into play as well; the further away from the pivot the foam is, the 'harder' it apparently feels as you don't have the mechanical advantage. So now, you have a lot more area, and the foam working on the lower part of the pedal feels harder, so those extra couple of degrees took a lot more effort to compress.

Last picture now - virtually all the foam is in contact with the pedal, now we have well over three times the original area being compressed, AND we have the foam in contact with the lower pedal feeling over three times as tough because of the distance from the pivot. To move that final degree may need 9 times the effort required to have moved the last couple of degrees.

You can see that this gives an exponential rise in rate of pressure, using an inversely exponential amount of pedal movement.

The foam can be moved around to increase the area initially in contact, or increase the rate at which the pressure rises.

A couple of extra tips. Using this method you will exert a LOT of pressure on the brake, so you need to make sure that the brake pedal, the pivot, the support behind it and the seat attachment are all strong enough. My first attempt ended up with both the pedal mount and the seat mounts twisted.

Hall effect sensors work pretty well with this setup because of the rather more exponential way that their movement is sensed, although I happily used potentiomenters and adjusted the mid point with DXTweak to suit.

A rest stop, and a 'soft' full movement stop are good to have. my ones are made from blocks of nylon and so are not noisy, plus the full travel stop also doesn't feel like it's bottoming out.

Set the max (100%) braking for just before the stop

Hope this helps someone, and I'm happy to answer any questions on it

Les

[Stigasawus]

Yes, though the way it works can be tailored to give different rising rates, so maybe a little more sophisticated if used right

Well & clearly described. Seems far better than the "squash ball"..damn & I'd found one too. Cant be much harm in experimenting with whatever type of foam is available in your part of the world, except it sounds like it could be a Logitech pedal killer..is that what your using? I dont have much faith in the strength of them just from the looks.
Still hasnt quite addressed the original thread starter idea, but at least follows the K.I.S.S. principle & little $$'s too.
Which helps prevent divorces (actually allows the $'s to be spent on other sim stuff, but I didnt say that!)

[lesthegringo]

The pedals I made to use in conjunction with the foam progressive feel setup in a post above were constructed from metal, and were not difficult or expensive. Here's a picture, the lengths and so forth are just cut to suit your rig. I did my first ones all by hand

Basically some 3mm aluminium sheet, some 90 degree extrusion, and some 20mm square thick wall tube, plus some 4mm nuts, bolts and countersunk screws. All these parts are available in Home Depot, B&Q, Wickes, and most other hobby/DIY/modelling shops

All you need in terms of tools is a drill, a hacksaw, a file and some things to measure out. If you want, you can draw it on sticky back paper and stick it to the bits so you know where to drill and cut.

The only hole to be careful with is the pivot hole, try and get this as square as you can, but careful marking and maybe borrowing someones bench press drill (lots of people have them at home) will save you hassle

Les

[Derek Speare]

Looks good! :)

[conticreative]

As far as FFB on the brake pedal, couldn't the rumble pad from a cheap controller work if attached to the back of the pedal? I would think that with a bit of software to filter the input, it may be able to give some semi-realistic feeling on the cheap. Has anyone thought about this?

[lesthegringo]

Yes, in fact one of the earlier iterations of my gear stick and pedal input circuit boards came from a joypad that included a vibration motor that could have been used, but I just couldn't see what feel would be right. I never took it any further

[stagman]

Just throwing my 2 cents worth in here:

I have a hydraulic master and caliper system on my cockpit thing. System is currently 100% clutch/brake fluid as other things I tried never worked right.
Water caused the cylinders to seize - probably the seals not liking the lack of lube.
Vegetable oil turned the lot into a gooey mess.
Air in system didn't produce the desired effect. Maybe if you spend a lot of time mucking about with it you may have success but you need very little air and a tiny fraction too much or little is enough to throw the proverbial spanner in the works.

I eventually got the right feel by fitting a very strong spring between the two caliper pistons. Still not exactly brilliant but my best result so far.

Signal is still via linkage and pot as I never found a oil pressure sensor of the right rating for few $$$. Most cost a packet or were not suitable. In the end I ran out of interest due to the whole system no longer being recognised by MS Win7 - so no more sim racing for a while as real cars are far more interesting to work on....

Also, I have never felt anything through a brake pedal in all the various vehicles I have driven other than the brake line pressure resistance.
If I were to feel vibration, pulsing or what not, the brake system is certainly not OK. Therefore I still wonder why anyone would want to introduce a feeling that would point to the lot being broken.

Edit: That bit about the strong spring didn't last either. Just looked at the setup and noted I had dumped idea in favour of two polypropelene plates with a 3mm bit of wire jammed in between on an angle. Even less rocket science but the best feel I ever got. I base this on my experience with non-servo assisted brakes - as pretty much all race cars have no assisted brakes that is what I was aiming for. Feels a fair bit different than the assisted brakes all modern road cars have.

[guybo]

I just picked up a set of the Fanatec Clubsport Pedals and the diff between them and my old G25 pedlas is like night and day. The CSPs have a load cell brake AND a spring. Its progressive and feels a lot like a real car. When you first press down, you are compressing the spring and this puts pressure on the load cell. When the spring bottoms out you start to press directly on the load cell and you can apply that much more force. The real secret is that you jam on the brakes when you are at speed and need the extra pressure to take off speed then when the car slows you can ease off the brake pressure so you are right on the edge of lock up the entire time. It makes a HUGE difference.

The prob I have is knowing when I do lock them up. How can I tell? This is where a ffb system would help. Yeah the CSPs have the ffb motor on the brake pedal but it only works when they are plugged into a Fanatec wheel and you lose resolution. And it only works in 3 games. We need an independent system to work with any sim. If the ffb was on the pedals, attached to my chair or even if its a light or a sound that'd be fine.

[Stigasawus]

Just re-read the lot & think that stagman comes close. The idea might be a load cell replacing the disc but the feel would still not be right on without some sort of fiddle because the master is only operating 1 "disc" not 4.
The idea of using similar braking pressures at different speeds & varying the braking distance also helps when you are using heel & toe (which is actually ball of foot on brake & side on accel. pedal) as you have taken up any slack & only push harder or softer from there....but the hard/soft part only really changes in response to feed back BUT not from the pedal ...from the rest of the car. Sort of similar in a pre select but they now have electronic engine rev control...then theres left foot braking...ho hum!
Unfortunately, the only way I can see to get the right feel is from a motion(gravity) sim, so I'd be happy to go the load cell way & not worry about an FFB pedal....maybe just get the feel right with a progressive spring or similar to simulate taking up the knock off & maybe work on the relationship to the accel. pedal to get the heel & toe bit working happily.....Hmm the accel pedal springs need a bit of work but lets not go there!

[guybo]

IRL your whole body gets that feedback. In a racing sim at your own home we have only the arcadey feedback path to follow. That's why IMHO anything that indicates lockup has occured will suffice. Right now I just have my sound settings set so I can hear the tires lockup and I have all other sounds turned way down. A "lockup light" would be fine even.

Frex has a (very expensive) pedal add-on that adds ffb to your pedals (simple vibration) when you lock 'em up. It works with a lot of racing sims- rF, Simbin games iRacing and others. So its possible. It works over USB. So how does Frex do it? Id like to make my own lockup light but I have no clue at all how to.

[guybo]

IRL your whole body gets that feedback. In a racing sim at your own home we have only the arcadey feedback path to follow. That's why IMHO anything that indicates lockup has occured will suffice. Right now I just have my sound settings set so I can hear the tires lockup and I have all other sounds turned way down. A "lockup light" would be fine even.

Frex has a (very expensive) pedal add-on that adds ffb to your pedals (simple vibration) when you lock 'em up. It works with a lot of racing sims- rF, Simbin games iRacing and others. So its possible. It works over USB. So how does Frex do it? Id like to make my own lockup light but I have no clue at all how to.

[Derek Speare]

Frex does it because the GMotor sims (GTR2/GTL/Evo and rFactor) have outputs for FFB to the device. Take a look at the FFB values in your .plr file and see it there.

FFB Brake FX on steer axis="0" // 0 = Brake effects on brake axis, 1 = brake effects on steering axis.

If other sims have that function, I do not know.

d

[Stigasawus]

Well Dee you started this one do you think you've got the "feel" you were looking for yet, after 2 pages of circular motion & a lot of physics lessons?

[Derek Speare]

Yes, I have a few things up my sleeves ;) Keep watching for details to emerge :

d

[brucepts]

I went with the AP Electrix mod to my G27 pedals, got it on Friday and it suits my needs for now . . . 30-45 minutes max install and I was up and running again and enjoying the ease at which I could control my braking.

Will take some time to get the "feel" of the brakes and how the car reacts at differing speeds, am able to hit lockup and then back off a tad to gain traction again and feel it happening. Could not do that with the stock brake pedal.

Now, I'm a newbie to all of this so take it for what it's worth, but the load cell pedal has changed my experience with rFactor.

Would love to sometime down the road build my own set of pedals based off the Manu-Factory pedals if I could only figureout what pressure sensor they used???

[Kazumi]

IRL your whole body gets that feedback. In a racing sim at your own home we have only the arcadey feedback path to follow. That's why IMHO anything that indicates lockup has occured will suffice. Right now I just have my sound settings set so I can hear the tires lockup and I have all other sounds turned way down. A "lockup light" would be fine even.
isn't there a way to visualise when the ABS system engages in HUD?

then you have the light and can just deactivate the ABS function in chassis file (at least in GTR2, rFactor that could work)

[brucepts]

I can feel lockup in my steering wheel in rFactor? Steering does not react to rotary input when the front wheels lockup. Release a little pressure and steering comes back, "leg muscle motion" lets you learn how hard you can or can not press the brake before lockup occurs with the load-cell pedal I am finding.

[guybo]

isn't there a way to visualise when the ABS system engages in HUD?

then you have the light and can just deactivate the ABS function in chassis file (at least in GTR2, rFactor that could work)

That's what I'm thinking- a lock up light.

[Christopher Snow]

Most will know, but some may not, that effects like "brake vibe" or "throttle vibe" in the wheel can be easily changed in rFactor.

To do this, first find the file "controller.ini" in your USERDATA folder and copy and save the original version...perhaps with a name like "controller_original.ini," before making any changes so you can revert back to what you had before in case you don't like the changes or new effects.

Then open controller.ini in a text editor (like Windows Notepad or Wordpad), and scroll down to the [ Force Feedback ] section about 2/3rds of the way down...and find this line (to change or alter brake effects in the wheel, for example):

FFB Brake FX on steer axis="1" // 0 = Brake effects on brake axis, 1 = brake effects on steering axis.

The comment probably explains it clearly enough, but if not, set the line to "=1", then save the changes to the file and restart rFactor to bring brake effects to your wheel axis.

This section a bit further down is where the actual parameters can be changed:

FFB brake vibe freq mult="0.90000" // Scales actual brake rotational frequency to force feedback vibration frequency.
FFB brake vibe zero magnitude="0.10000" // Magnitude of brake vibration at 0mph (reference point).
FFB brake vibe slope="0.00000" // Slope of line defining magnitude as a function of frequency (used with FFB brake vibe zero magnitude).
FFB brake vibe wave type="0" // Type of wave to use for vibe: 0=Sine, 1=Square, 2=Triangle, 3=Sawtooth up, 4=Sawtooth down.
FFB brake vibe update thresh="0.05000" // Amount of change required to update brake vibe (0.0 to 1.0)

That as posted ^ are the parameters I use with my very old Logitech Formula Force wheel in our CSGT/WSC70 mod, and I suspect someone using the popular G25/G27 would settle on something quite different.

It's been a long time since I changed anything here, but I do recall too that the shape of the waveform has a pretty dramatic effect on "feel" so it might be worth trying those options.

A perusal of this section will show that "throttle FX" as well as other effects can be changed in the same way.

---

I hope this helps anyone who may not have been aware they have fine control over what they feel this way.


Christopher Snow

[Dimebag]

ok, got halfway into this thread, and then my brain started to hurt... :D

I'd just point out, that D is right about the thing about the amount of forces needed to stop the rotating disc increases with the disc's speed...
I think it sounds clever and all, when you pull out your Newton's and all, but you seem to forget that these rules DO NOT apply with moving parts WITH A SLIP...
...and that's exeactly how a brake-disc functions... ;-)

Ok, Dime out; back to your Newton's.... ;-)

[Hitman_M3]

That's what I'm thinking- a lock up light.

For those who have Fanatec CS Pedals it should be quite easy to do, as they have a FF motor in the brake. While its effect is unnoticeable due to pedal stiffnes, even if racing with socks, you could rewire them easily to a LED that you can put anywhere you want ... instead of giving current to the FF motor, you would get the current to the lamp and even would get a visual clue of the lock pulse (Which IIRC changes depending on lock up status) :thumbup:

[guybo]

It only works with 4 games and only when attached to a Fanatec wheel. We really need an independent peripheral.