Chaos vehicle skipping gears

Development World Creation
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1

Hello,

We just recently decided to migrate from PhysX to Chaos (UE 5.3), and we are now trying to change the vehicle behaviors to match a somewhat realistic acceleration and braking profile. The way we do this is by acceleration a vehicle from 0 to 100 km/h and monitoring its time, distance and gear changes.

By default, vehicles take 20-25 seconds to reach it, and to increase that, we started increasing the Max Torque parameter in their VehicleMovementComponent. The issue comes when, after certain values of torque, the vehicle starts skipping gears, jumping from the 1st to the 3rd, 4th, or even higher gears, instead of the 2nd one.

This obviously results in unexpected and unrealistic acceleration profiles. This seems to us like it was not an issue in PhysX due to the GearAutoboxLatency which forced the vehicle to say at a gear for a minimum time, and which is not there in Chaos but to many parameters have changed to say for sure.

So the question is, how could we avoid this? We’ve tried changing other parameters to fix it, but those end up with unrealistic values, and will have most likely have unexpected consequences in other behaviors.

Thanks in advance for any information,

Guillermo

2

In a non automatic setting it is not uncommon to just skip gears.

That said, in a 0 to 100km speed dash that is likely not normal.

The way i see it, you have 2 optipns.

  1. build from source, swap back to phys x. And live happy.

  2. build from source, audit and modify chaos to make it work. Realize it will never work and will always perform way worse than what Physx did. Go back to point 1 after having wasted months of dev, or release a game that wont work right on 90% of computers.

Someone may actually give you some tip to get chaos working - but the gear skip is probably the last of the problems to worry about when your vehicle feels like a doughtnut bouncing around the screen and when you get 10fps with 40 vehicles in a race…