Hi Radu, Thanks for your message, I will check the documents again and figure it out!
Bests, Chen On Monday 9 September 2024 at 05:38:41 UTC+8 Radu Serban wrote: > Hi Chen, > > > > You may want to read up a bit on the design of Chrono::Vehicle and > understand the difference between the subsystem templates (parameterized > models) and concrete subsystem models (an instantiation of one of these > templates for a particular vehicle). > > > > You can start with the description on the Chrono::Vehicle documentation > page <https://api.projectchrono.org/manual_vehicle.html> and look at the > Chrono::Vehicle paper > <https://projectchrono.org/assets/white_papers/chronoVehicle_IJVP.pdf>. > > > > Bottom line is that a concrete HMMWV tire model (whether implemented as a > derived class or specified through a JSON file) has the parameter values > (including the tire radius) **fixed**. These parameters must be > consistent with each other. Having said that, the OBJ files for the HMMWV > are used for visualization only, and so they may have slightly different > dimensions than the physical tire model. > > > > If you want a tire of a different radius, you must provide a different, > alternative HMMWV tire model. This is exactly what you would do in real > life: you replace the tire on your car, you do not change the radius of the > tire you already have. > > > > --Radu > > > > *From:* [email protected] <[email protected]> *On > Behalf Of *ychen_441 > *Sent:* Thursday, September 5, 2024 9:34 AM > *To:* ProjectChrono <[email protected]> > *Subject:* [chrono] Re: How to modify tire size? > > > > For the two observations mentioned in the last message: > > > > - The footprint seems reasonable when I do the same thing to > "tractor_wheel". > > > - For stress distribution, I think they are generated in the same way > as models in demos provided. Methods can be found in SCM paper. > > > > Some further question is that the radius and width defined in ".json" file > do not match the dimensions in Blender. For instance, "HMMWV_rim.obj" used > in "HMMWV_wheel.json". > > The one in ".json" states: radius: 0.268, width: 0.22, while in Blender, > the dimension of the wheel rim is (0.285, 0.484, 0.484), indicating radius: > 0.242 and width: 0.285, I assume? > > > > Anyone has any idea about this? Again, sorry if this is an obvious and > stupid question lol. > > > > Chen > > > > On Thursday 5 September 2024 at 13:24:05 UTC+8 ychen_441 wrote: > > Updates on this question for who may headache about this: > > > > I have tried to read header files and modify several ".json" files to see > if those could help and finally, > > the solution was to directly scaling (it's a nasty way for test, if you > want to model your vehicle, you should > > design a new one by yourself) the ".obj" file, and the tire size changed > which you can obviously see in the picture below! > > > > > > > > It is easy to see from the footprint that the width doesn't match well to > the new size, so that might be something you need to deal > > with ".json" file or others. Also, the stress distribution seems already > changed (color difference), the reason of it is still unknown. But, anyway, > > questions about tire size are solved now, hope this will help those who > have the same confusion about this like me. > > > > Best, > > Chen > > > > On Wednesday 4 September 2024 at 16:38:48 UTC+8 ychen_441 wrote: > > Or maybe modifying the parameters in the ".json" file indeed changes tire > properties but at the same time, > > visualization is governed by ".obj" file so I can't see any differences? > > > > Chen > > > > On Wednesday 4 September 2024 at 16:13:36 UTC+8 ychen_441 wrote: > > Hey colleagues, > > > > Might be a dumb dumb question but it cost me a little bit longer time than > I expected. > > > > How to modify the size of a tire? > > - When I was trying the demo "demo_VEH_DeformableSoil.py", there was a > "Dlobal parameter for the tire", but the operation of changing the value > there only led to the starting position of the tire changed. > > > - How to change the tire size here? I have noticed that there was a > ".obj" file used in the later codes of that demo but the file seems to > be > more of a mesh generation stuff I guess? Is the tire size fixed by the > ".obj" file? > > > - In another case, when playing HMMVV and citybus demos, I saw their > tire type is set by the function "SetTireType()" and details can be found > in CPP reference. So I thought this might be a ".json" settings, and I > changed the value of tire radius and width in "HMMVV_RigidTire.json" but > nothing happened. > > > - What about this scenario? Is there a way to change tire size within > a vehicle system? (different from the former one using a single wheel) > > Forgive me being stupid but I will be grateful if anyone can provide some > suggestions. > > > > Thanks, and all best, > > Chen > > -- > 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 [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/projectchrono/4181a7e3-d7b8-4d64-8950-a94b59d444a4n%40googlegroups.com > > <https://urldefense.com/v3/__https:/groups.google.com/d/msgid/projectchrono/4181a7e3-d7b8-4d64-8950-a94b59d444a4n*40googlegroups.com?utm_medium=email&utm_source=footer__;JQ!!Mak6IKo!JlmyDCUSWYmIxLqXmz_ZPMCfpIOVSsPGyZKVsssBaxup11PHPfm0jlBuzyzC6wk8qUkVC_EdJVb6vKHjAd4$> > . > -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. 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