I wanted to give a brief update. I tried getting SCM terrain to work with the default settings. I think I set things up correctly by looking through the source code to see what I have to do. And I am STILL seeing this weird problem. The problem seems to be that when the tire force/torque is reported as zero, the wheel spindle torque can sometimes be non-negligible (on the order of hundreds in magnitude) and causes the wheel to rotate beyond its limit. It's like the applied torque to the spindle is as if the tire is in collision, but the collision hasn't occurred yet. That's my best guess.
I tried changing some of the collision parameters that I am aware of, but this had no effect whatsoever. Any help would be greatly appreciated. Ted On Sun, Jan 12, 2025 at 1:35 PM Ted Sender <tsen...@umich.edu> wrote: > Hi Dan, > > I realized there was no video attached. The system wouldn't let me attach > it for some reason and it said someone had to approve the post before I > could edit it. Here is the video. Let me know if you have trouble viewing > it. > > I'd like to use SCM terrain, but I'm using someone else's setup that they > provided to me and I have no idea how to get SCM to work. > > Ted > > > On Sun, Jan 12, 2025 at 10:19 AM Dan Negrut <neg...@wisc.edu> wrote: > >> Ted – there was no video attached… >> >> >> >> One thing that might be worth trying is to use SCM deformable terrain. If >> you have a couple of hours, give it a try – folks in our lab have had good >> success with that. >> >> >> >> Dan >> >> --------------------------------------------- >> >> Bernard A. and Frances M. Weideman Professor >> >> NVIDIA CUDA Fellow >> >> Department of Mechanical Engineering >> >> Department of Computer Science >> >> University of Wisconsin - Madison >> >> 4150ME, 1513 University Avenue >> >> Madison, WI 53706-1572 >> >> 608 772 0914 >> >> http://sbel.wisc.edu/ >> >> http://projectchrono.org/ >> >> --------------------------------------------- >> >> >> >> *From:* projectchrono@googlegroups.com <projectchrono@googlegroups.com> *On >> Behalf Of *Ted Sender >> *Sent:* Saturday, January 11, 2025 10:32 PM >> *To:* ProjectChrono <projectchrono@googlegroups.com> >> *Subject:* [chrono] Tires Rotating Beyond Mechanical Limits >> >> >> >> Hello, >> >> >> >> I am currently using Chrono for vehicle simulations with a polaris >> vehicle. I am using rigid tires on rigid terrain. I am noticing that with >> certain terrain profiles one or both of the front tires rotate very quickly >> beyond its mechanical limit when the vehicle drives over a harsh bump/dip. >> >> >> >> These are the current settings I am using: >> >> Solver: Barzilai-Borwein, tolerance 1e-6, max iters 400, time step 1 ms >> >> Collision: Bullet, default suggested envelope 1 mm, default suggested >> margin 1 mm >> >> Terrain: Rigid, coeff friction 0.6 >> >> >> >> I have tried using different solvers, but they did not seem to work (some >> just failed to perform the calculations or crashed the program). I tried >> lowering the time step from 1 ms to 0.2 ms, but that did not work either. >> >> >> >> Attached is a video showing an example of the problem I am having. Right >> around t = 6 seconds, the front right wheel drives over a dip and then the >> wheel suddenly rotates clockwise well past its mechanical limit (the limit >> is about 0.48 radians, but the wheel rotates like 2 radians). >> >> >> >> I also logged some force/moment values to the terminal to see what was >> going on, thinking that it could have been a problem with the tire forces. >> Attached is a .txt file showing the tire's steering angle, tire force and >> torque values, and the applied force and torque to that wheel's spindle (I >> believe all forces/moments are expressed in the global frame). >> >> >> >> From this data, it seems that when the tire has no reported force/torque, >> the spindle still has some applied force/torque. At t = 5.1 seconds, this >> occurs, but is not a problem as the spindle torque is rather small. >> However, at t = 5.90 seconds, the tire force is zero but the spindle torque >> starts to increase and then the wheel rotates beyond its limit. >> >> >> >> Does this seem like a problem with the collision model/settings or is it >> caused by something else? Any help is greatly appreciated. I hope the data >> provided is helpful, but if you need some more values, let me know. >> >> >> >> Thanks, >> >> Ted >> >> -- >> You received this message because you are subscribed to the Google Groups >> "ProjectChrono" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to projectchrono+unsubscr...@googlegroups.com. >> To view this discussion visit >> https://groups.google.com/d/msgid/projectchrono/38e5d8a2-5ccc-47bf-93cb-bb0f6ff6e327n%40googlegroups.com >> <https://urldefense.com/v3/__https:/groups.google.com/d/msgid/projectchrono/38e5d8a2-5ccc-47bf-93cb-bb0f6ff6e327n*40googlegroups.com?utm_medium=email&utm_source=footer__;JQ!!Mak6IKo!IWB4NaZMiARYuUywzXWMFmkLZzGIyuN5qnFl3Q6IJPyX-E8W4TJaXJwRH3RrQod2PHaq9IZU0O17gy62$> >> . >> > -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. To unsubscribe from this group and stop receiving emails from it, send an email to projectchrono+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/projectchrono/CA%2Byw%3DfpS4T6-Rg%3DbdnHVH-L%2BEqnJDoV5sNxZU80%3DHwhi3Vth3A%40mail.gmail.com.
