B7 Mura 990 Small lean angles create large lateral oscillations

[h106frp]

I'm not sure if its just a bug rather than a physics problem, if you have the rumble on at low speed you can sense the rumble triggering as you lean through a small lean and back to vertical although visually you do not see a large reaction it appears to be the the same source of the more extreme issue at speed.

[Vini]

Those 'random' wobbles that happen at the Monza or Magnycourse back'straight's (probably better called tank slappers) can be avoided if you are extremely (unrealistically) smooth on the steering.

The wobbles you get when accelerating out of a corner while straightening the bike up are different and unless you can keep the front wheel in the air until you are well out of the corner there is nothing you can do about it.

[h106frp]

I have tried very gentle steering but for this it does not help, with a small lean you get a very small initial vibration that will gradually build until it throws the bike of the track, it more like the reaction you get from an underdamped control loop when the input is very small and the control loops starts to oscillate.

There are known issues with control loops; Best to solve the problem of the initial source first i.e. the vibration for no obvious reason then tune the loop



Wiki..

Applying too much impetus when the error is small and is reducing will lead to overshoot. After overshooting, if the controller were to apply a large correction in the opposite direction and repeatedly overshoot the desired position, the output would oscillate around the setpoint in either a constant, growing, or decaying sinusoid. If the amplitude of the oscillations increase with time, the system is unstable. If they decrease, the system is stable. If the oscillations remain at a constant magnitude, the system is marginally stable.

[C21]

Or send me the replay file and I'll make and upload the video.

Will do it tomorrow.

[Vini]

I have tried very gentle steering but for this it does not help, with a small lean you get a very small initial vibration that will gradually build until it throws the bike of the track, it more like the reaction you get from an underdamped control loop when the input is very small and the control loops starts to oscillate.

I have managed to ride the long rider hander at the beginning of Magnycours without any wobble which I thought was impossible but that was only once or twice and as I said it is unrealistic how careful you have to be.
Does not really change the situation but maybe it's important to know that it's not some more fundemental bug.

[Napalm Nick]

Hockenheim 97 on GPBOC 1 server really highlights the small lean/oscillation problem due to the tracks long, fast sweeping curves.

Buckaroo. 

[Napalm Nick]

BUMP - this problem is still present in Beta 8 and is a game killer. 

https://www.youtube.com/v/5aYtId8bViE

[doubledragoncc]

You can say that again Nick, This and Core problems are not being worked on, or at least never says about it in daily update.

DD

[Blackheart]

Watching the suspension motion, here is the problem, are moving in a completely abnormal way 

[Hawk]

I would suggest this could be a bike physics problem rather than core GPB physics problem? In which case it would be the bike physics author to sort it out. We all know that the bikemods are better setup physics-wise than the default bikes, right. 

Hawk.

[Napalm Nick]

But as the video says it applies to all bikes including the stock ones.  I just tried it on the Murasama too, to double check. If it only happened on some Mod bikes or only happened on the stock bikes then I would agree, but it affects all of them.

[Blackheart]

Look to 0.53 in my video with Varese, is definitely less than in the Nick clip, but is present. 

https://www.youtube.com/v/kFuf-974ix8

[Hawk]

But as the video says it applies to all bikes including the stock ones.  I just tried it on the Murasama too, to double check. If it only happened on some Mod bikes or only happened on the stock bikes then I would agree, but it affects all of them.

It's still present in the updated beta 8 mod bikes too? Sorry, I haven't had chance to test any yet. 

Hawk.

[Vini]

It is and it is even worse than on the Murasama.
Even a heavy tank won't stabilize the front and avoid wobbles.

[Napalm Nick]

It's still present in the updated beta 8 mod bikes too? Sorry, I haven't had chance to test any yet. 

Hawk.

I don't know about the updated Beta 8 bikes because we don't really have any fully released ones yet , only the stock bikes and Beta 7 Mods. If it is not present on the Beta 8 bikes then that will be a small Triumph (geddit?) but only means the problem at the heart of the bike has been tuned out.

Just been taking the Varese around the A1 Ring and its a wobble fest