how to move my custom Side-by-side 2 wheel mobile robot?

[dedoogong]

Setup
Describe the setup you are using to run CARLA along with its version:

• CARLA version: 0.10.0 unreal 5.5 built from source
• Platform: Windows 11
• Python version: 3.10
• GPU: 4090
• GPU Drivers: 532

Describe the bug
I have used Carla UE5-dev branch without problem with the provided vehicles.
Recently I added 2 wheel robot FBX file exported from blender.
After the adding custom asset into carla following the tutorial, I finally could add it.
but when I run manual_control.py --filter my_mobile_robot,
the mobile robot is spawned correctly but I can't move it! why?

for more information,

The 2 wheels are located side by side (left and right side of the mobile robot body).
When I opened the imported asset, it showed same skeleton trees in the skeleton mash editor as blender's armeture and bones like below(Bone_Body, Bone_Wheel_L, Bone_Wheel_R);

but it doesn't show the same structure in the physicsasset editor like below (it shows only Bone_Body. I dont know why. maybe? the wheel is inside the robot so any separate collision boxes for the wheels doesn't need to exist for covering them?)

the mesh/bone/armature structures in the blender panel is as below

anyway, when I setup all bones, phsics assset properties, and created a new BP_my_robot and copied 2 wheel BPs from Carlas asset and set them to my robot like below;

and then added it vehicle factory with "number of wheels" equal to 2,
but frankly I'm not sure Carla support 2 side by side wheel mobile robot and settings like that works or not. Please give me some guide.

Steps to reproduce
same as above

Expected behavior
running a normal simulation

Logs

Scripts
Add any scripts relevant for the reproducibility of the error.

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context
Add any other context about the problem here.

[Blyron]

We do not understand very well what it looking your BP due to the language.
CARLA does support two wheels vehicles. But we would need more details like. Dimensions the pivot point etc. If you could send your files that would be very helpful for us

[dedoogong]

@Blyron thank you for your fast reply!
I recreated phsics asset from skeletal mesh with some modified option like "minimum bone size == 0.0" and found the all bones are now set correctly in the new physics asset". and I regenerated collision spheres for each wheels, but I still can't move the robot in the simulation. One thing I didn't touch is adding Animation because there is no human driver for my robot. I hope this anim part is not the cause of this issue. I thought the anim part is optional.

here is the simple version of the FBX file

Around_Simple_Rigged_v2.zip
if you succeed to move it in the simulation after import the FBX file, please please share the settings in detail!
Thank you so much!

[dedoogong]

Hello @Blyron , I found one strange thing (I hope this is the right cause of the problme) that,
I used BP_VehicleFactory following the tutorial to add my custom robot in the simulation like

My BP_Around(BaseVehiclePawn) has BP wheel class references for the 2 wheels like below;

If I don't set the classes like above and run the simulation, "wheelnum<0" assertion error occurs.
Assertion failed: Wheels.Num() > 0 [File:C:\Users\USER\Documents\CarlaUE5\Unreal\CarlaUnreal\Plugins\Carla\Source\Carla\Vehicle\CarlaWheeledVehicle.cpp] [Line: 286]

I checked other Carla's assets and I found something strange!
All BPs(BaseVehiclePawn) like BP_Audi_Etron or BP_CitroenC3 has no settings for wheel configuration like below;

bone names are "Bone_Wheel_L" and "Bone_Wheel_R" which are different from the bone names from the bone names of skeletal mesh or physics asset(actually I think it should be "Wheel_Front_Left" and "Wheel_Front_Right").

I tried to add 2 more wheels and set each wheel configuration for the BP_Audi_Etron one by one

then I set the BP_Audi_Etron to the vehicle factory BP.

and then I run the simulation with the provided BP_Audi_Etron,

and now I can't move the spawned Audi too!( I used python manual_control.py --filter mine_test )

but when I run just python manual_control.py (without --filter option), it automatically spawned randomly provided vehicle and I can move it.

I think the problem must be related to the wheel configuration.

Please help me.
how to solve it??

[dedoogong]

Hello @Blyron ! I also found that carla python example(manual_control.py) shows no support for 2 wheel vehicle like yamaha bike!
I inserted BP_Yamaha(carla provided asset) into the vehicle factory and then I run simulation and the script with autopilo mode, and it doesn't move the bike at all too!
plus the UElog shows
...
[2025.04.19-20.16.50:538][445]LogCarla: Error: Number of WheelPhysicsControl is not 4.
/Game/Carla/Maps/UEDPIE_0_Town10HD_Opt.Town10HD_Opt:PersistentLevel.BP_Yamaha_C_0"
...

thank you!

[Blyron]

We were trying to implement the two wheel vehicle using this tutorial and we are nearly there but we are missing the rider
https://www.youtube.com/watch?v=ofwC1LGAJ3s&t=1849s&ab_channel=MarcoGhislanzoni