Braking: Understand the Subject BEFORE Critiquing

I read so much nonsense re the braking not being correct in this sim yet am have no issues myself. I keep reading that such a car's brakes lock up too easily, yet when I go and test, I can't replicate the issue.

Understanding the subject:

How your brake pedal works and how it's set up in the sim is massively important. The best kind of brake pedal for racing sims in a pressure sensitive load cell. If you're using potentiometers that just register movement/position then send that value to the sim, you are going to struggle with threshold braking and brake modulation unless you have rubber resistance damper to push against.

The ingame sensitivity value is very important. If you're using a load cell then values closer to zero are best and it's a case of playing with the sensitivity until you get the best feel. When you change the sensitivity value you are really redrawing the response curve. 50% is linear, while values either side are nonlinear. Values closer to zero produce a bell curve which is always going to be closer to what a real braking system does. It's easier to develop muscle memory when braking with a load cell and sensitivity set closer to zero. If your locking up too easily with a load cell then you have the sensitivity too high.

Please note that things like rubber and foam dampers will wear out over time and need replacing. This happens slowly over time, so you might not notice. Sim brakes need to be maintained just as real braking systems do.

 

I agree with most of what you said apart from that. For a load cell you should have the sensitivity set to 50%, i.e. linear. You want a linear response given to the sim, the sim will then apply that to the simulated braking system which may be non-linear and will also change per car, if it has power assistance or not, etc.

 

Real braking systems aren't linear. No need to change per car either because servo assistance is just there to reduce the amount of pressure required. A car like a Caterham with no servo will require similar levels of pressure as a car with a servo. The Caterham has small brakes, a low mass so no servo is needed.

A load cell doesn't need much pressure to reach its full value hence the need for a lower value closer to a nonlinear bell curve.

 

It's important to note that many of the comments, mine included, were made before the latest couple of updates. If you go and test the game today, those comments are now irrelevant, as there has been a definite adjustment made to the braking, so the 'early locking' issue is no longer an issue.

I don't need a lesson on how to understand the subject. It was just a plain and simple comparison with numerous other sims and real cars (including karts and race cars) - the brakes in AMS2 DID lock up far easier in comparison, and it WAS definitely not right. I'm aware of the various options and adjustments that can be made, but as a default setting it was, in my opinion, not close enough to realistic.

However, the latest update has definitely adjusted the brake behaviour and now it feels like a much better default setting.

 

The sensitivity is not applied to the braking system, it is a modifier of the pressure applied to the pedal reported to the game. You do not want the pressure you apply to be modified when you already have a linear load cell reporting the correct pressure to the game.

Modifying the sensitivity value would be like adding a non-linear lever arrangement between a real car's brake pedal and your foot. Not a good idea.

It is only useful for people that are using rubber mods on potentiometer based pedals as the movement becomes non-linear when you hit the rubber stop and you need the game to account for that.

 

No, you do what it modified. You can be very precise with pressure and a nonlinear curve is longer than a linear one so you'll get more precision. Whatever to appling the force to the cell when you press the pedal will also change the cure if it's compressible. If there's a solid rod pushing on the cell then your foot pressure will reach max braking with light pressure so you'll want a nonlinear sensitivity value closer to zero to give you more control and precision.

 

What!? The length of the curve in this case does not affect the precision. The input axis stays the same length, you don't magically extend the input axis or the output axis precision or dynamic range. The curve just maps one axis to another. What you do end up with is more precision in one part of your input and less in another. If you "decrease" the sensitivity what you are essentially doing is making the brake react less when you apply 0%-50% but then react more from 50%-100%. This is actually making your precision worse at higher braking pressures as you are losing dynamic range - compressing the dynamic range into the upper part of the input.

I've been building and using load cell brakes for a few years now. You might want to take the advice you gave earlier. In all the forums with in depth discussions on LC brakes the consensus is to use linear brake sensitivity. Of all the available load cell brakes available, the pressure reported by the load cell is linear to the pressure applied to the pedal. The sensitivity value is for people using rubber mods on potentiometer pedals and those using game pads. Changing the sensitivity will decrease the precision in part of the pedal travel.

 

Which is what i want because it's how real brakes work. I want 75% of my braking force to be applied in a nonlinear bell curve over the last 30% of my pressure. The accuracy and precision comes with our ability to better judge pressure than moment.

 

I don't agree with that statement. The sensitivity adjustment is for anyone that finds value in using it regardless of their hardware. I have Protosimtech pedals and use brake sensitivity with the Madness engine around 30-35. Now, with that, I could adjust the pedals themselves to be less sensitive or adjust the sim to get the exact feeling I desire (i.e. I could adjust the pedals so a sensitivity of 50 feels like 35 does now). In the end, it doesn't matter which side I adjust. For convenience, it's nice to have in the sim so I don't have to be on the floor fiddling with he pedal adjustments.

 

That's a fair point, I over stated that part as it is one of the things it is very useful for. Of course anyone can use it to tune the response to their liking.

I also make the electronics boards for load cell pedals with adjustment sensitivity. From what I can tell the Protosimtech use the method to change the sensitivity. The type of adjustment is not the same as the sensitivity adjustment in the game. The load cell sensitivity adjuster will change the maximum pressure required on the pedal to provide the maximum output to the game whilst keeping the response linear. What the game will do is keep the min and max values the same but change the response curve to make it feel like you have more (or less) range in the first region of braking. However as it is now non-linear you will reach a point where you will get a sudden increase in the braking for the same amount of increase of force as earlier in the application.

 

I'm well aware how the sensitivity setting works (started with WMD for PC1 in 2011). It's really a "game" you play with most consumer sim pedals. Most load cells while allowing users to use pressure rather than pedal length still don't replicate real pedals. The main issue is that real pedals combine both length and pressure where as load cells typically don't have much pedal travel. The sensitivity option helps offset the lack of travel.

 

It isn't how real brake input works at the pedal and in is certainly not a bell curve unless the braking drops off after you apply even more pressure.

You don't seem to understand how the input chain works here.

1) Pedal input
2) Pedal driver maps pedal input value (pressure or position) to output value
3) Game receives pedal driver output
4) Game applies brake sensitivity value mapping
5) Mapped value is now passed to brake simulation algorithm
6) Brake simulation algorithm applies non-linear transformations to decide how much braking force is applied to the wheel.

You have taken a little bit of knowledge and applied it to something else. The brake sensitivity value is solely for tweaking the input feeling. The non-linearity of the braking system still exists as it is modelled elsewhere in the processing chain. For you, you might prefer to alter the braking sensitivity but it is certainly not what "should" be done for load cell pedals and will not give you a more realistic response, if anything it will take you further away from the realistic simulation provided by the game.

 

I remember you from your moderator days on the pCars forums.

Do you still record and upload your Mazda (sic) /sports car, track days ?

 

What sensitivity does that represent, or what do you have set? Oh, BTW, what Brake pedals/Load Cell do you use?

 

Just tested 50% and it was awful. Brakes were too grabby and lacked a progressive feel. It was difficult to threshold brake and to modulate. It's like driving with over servoed brakes.

No wonder people have been complaining about locking up if they've been running load cells like that.

 

That was with Fanatec V2 Clubsports. My other pedals are HPP and I have them closer to zero than the V2s which I have at 20%.

 

Thanks. The Mazda is long gone but I still have the S2000 race car. It's been down the last year waiting for a new engine. Engine is here, I just lack motivation. However, I have been tracking my Alfa 4C a bit which has been fun just no competition driving for a while.

 

Shame. Must be a massive buzz to race for real in your own car, although being close to someone who may cause you to crash if they arent so great at racing must be a nerve wrecking experience when its your own wallet that has to pay for it all

 

I expect that is because you are used to an altered sensitivity. I've been using linear on all the sims I use and have never had any issue with brakes locking up or modulating. I run a 50kg load cell and have to use most of that to hit max pressure. Maybe you have your load cell set in the driver / control panel to be very light in which case it would feel like it is over servoed.