Full-vehicle MBD analysis. Problem with vehicle system oscillating under lateral load during cornering
I am trying to do some full vehicle MBD analysis research for my Master degree.
The object of my study is a Go-Kart model. I've set up the non-wizard kinematic model of a Kart using Altair Driver and now I'm trying to do some tests. When performing Straight Line Acceleration/Braking events - everything is fine. Kart accelerates and brakes just as it should, no problem with oscillation can be observed. The same happens when performing the Slalom event with basic settings. The Kart accelerates and turns just like it should.
But when I'm trying to perform some events that require steering more than a couple of degrees (for instance, ConstantRadius turning event) - I mean any event with long corners, something incorrect happens with the analysis.
Firstly, the Solver Log shows ERRMES:
<< ALTAIR DRIVER :: Steering Controller : Computed predicted path error > allowed path error of 1 mm.
Proceeding with the best approximation.
Possible Reasons:
1. Vehicle has spun out.
2. Path is not smooth
3. Steering wheel angle has reached saturation
and
<< ALTAIR DRIVER :: Steering Controller : Computed predicted path error > allowed path error of 1 mm.
Proceeding with the best approximation.
With basic settings of the event, the analysis crashes immediately after this ERRMES. If to perform some custom event with custom .adf (altair driver file - the 8-shaped track cornering event - I can share it if needed, but can't attach it to this message) and if to decrease the "LOOK AHEAD TIME" parameter of "FEEDFORWARD TRACTION" from basic 0.5 to 0.1 or lower, the analysis may be prolonged till further crash, but to no good results.
Secondly, while observing the resulting H3D file some weird oscillation may be spotted during cornering (I'm attaching the gif-file of the cornering results). The attached GIF shows the Kart oscillation in the 15-meter Radius corner with speed just of 1 m/s. The Kart behaves in an incorrect way and I'd like to fix it and do my further research.
Some details about the Kart: both frame and suspension is rigid. There are no dampers and shocks in this type of vehicle. The only damping mechanism in this system is Tire. I believe that the key to solution is in Tire settings file. Maybe you could give me some advise how to set it up correctly for light vehicle analysis?
I'm attaching:
.mdl file - MotionView model
.gif - visualisation of vehicle oscillation results
.step - CAD-geometry of Kart frame
How can I fix this issue and perform the Go-Kart cornering anaylsis? Is there anything I'm doing incorrect? If you could provide any advise (especially for tire setup for light vehicle analysis), I'd be really grateful.
Thanks,
Alex
