Cars Honda NSX 3.6.5

[ArchTheSecond]

It's been about a year since the last update, so I'm going over the physics again, adding some features and updating conventions to current standards.

Major new features are primarily COSMIC suspension which allows for features like physics based alignment (caster as well, for example), better implementation of installation stiffness, variable motion ratios, chassis torsion flex, a limited elastokinematic modeling and helper springs independent from bumpstops, alongside other minor features and improvements implemented into the NSX.

I've externally simulated a simplified 3D kinematic and elastokinematic model of the NSX-R rear suspension based on some data from Honda (without things like wheel rim compliance) and I've implemented in-game a dramatically simplified rear suspension toe deflection based on that model. The trend is stabilizing toe-in on the outside wheel in cornering and braking.

The front compliance pivot is theoretically doable, but it didn't produce very useful effects especially compared to the CPU use it requires, so I've opted to leave that out as the majority of the neutral toe and caster behavior is already present in the rigid modeling. Front suspensions also need to generally be rigid at AC's 333Hz to avoid minor vibration in the FFB output. The reasoning for not opting for a more comprehensive rear elastokinematic modeling or chassis bending flex is also primarily due to the 333Hz rate.

I've also updated tire modeling to the current standard and I intend to verify and improve the tire SAT modeling for the public release. Slipcurves are also more realistic, and I will implement hopefully slightly more accurate thermal behavior for tires and brakes (WIP).

On top of that, there's FFB Tweaks 'Realfeel' support for steering torque and brake pedal force that includes a basic brake booster simulation.

The next update is unlikely to include changes beyond physics changes. It will require CSP 0.2.3 minimum.

 

[ArchTheSecond]

Update is reaching completion, not much more left on the agenda but some of it needs to be confirmed in many different models so it takes a few man hours.

I spent the last few weeks working on tire SAT, powersteering and TCS in addition to steering U-joint nonlinearity and demystifying the NSX's steering rack parameters and adding progressive racks to the cars. Thanks to some (a lot) of help the implementation is complete. (thanks to mclarenf1papa and the usual suspects)

The steering rack deflection per degree of steering wheel angle is linear in vanilla, but that's not how most real cars work.

Due to the steering wheel being attached to the steering rack via a system of U-joint(s) and intermediate shaft(s), and due to the U-joints rarely being able to be packaged in such a way so as to produce an output identical to the input, the steering rack deflection per degree of steering wheel turn varies with steering wheel turning and will oscillate.

The implications are mainly having to do with how it feels to turn the wheel into a corner and out of it, it can make the slipcurve feel more or less linear/the car handling feel more or less sensitive. It'll also affect the correct rate for steering motions.

I believe that often the steering is designed to be nonlinear on purpose so as to cause a specific kind of handling feel near center and in the usable range when cornering. Having it be more linear wouldn't result in a correct feel. Many cars seem to use a nonlinear rack in addition to aggressive U-joint angles so as to produce specific handling effects, like the NSX does.

ETA when it's done. Maybe a week, or two, or three, I dunno.

 

[ArchTheSecond]

Slight delay to the update as I was busy correlating Toyo RR tire temperatures and making a Honda S2000 model to use during the correlation. The results of the work will guide the parameter tuning for the update and result in overall more realistic and consistent temperature behavior. I am almost done with the work itself, hopefully within one or two stints and analysis.

After the work is done, some further work needs to be done to convert the thermals to be more suitable for heavier treaded tires such as the ones included in these cars.

No ETAs this time, but I don't foresee it taking terribly long.