Three wheeled vehicle

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Finbar Argus

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Oct 11, 2021, 11:52:07 PM10/11/21
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Dear Users and Developers,

I am about to start a project where I need to simulate a three-wheeled (2 at the front, 1 at the rear) vehicle with rear steering.

Could you please advise on the best way to create an arbitrary user-defined vehicle? I also want each wheel to have its own torque input, so there will be no powertrain. Ideally, I would like to use python for the vehicle creation but I assume I will have to create the vehicle model in C++?

Many thanks,
Finbar Argus


Radu Serban

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Oct 13, 2021, 10:53:33 AM10/13/21
to Finbar Argus, ProjectChrono

Hi Finbar,

 

The current templates in Chrono::Vehicle do not allow a single “central” wheel per axle.  You will have to create the model “from scratch”.  For illustration of more complex models built this way, take a look at the rover models (in https://github.com/projectchrono/chrono/tree/develop/src/chrono_models/robot).   The Curiosity and Viper rovers implemented there use direct wheel actuation (so no powertrain/drivetrain).

 

Technically, PyChrono exposes enough of the Chrono functionality that you may be able to create the model in Python.  But for full flexibility and performance, I indeed suggest you create the model in C++ and then expose it to Python, using SWIG, like we already did with some of the above robot models (see https://github.com/projectchrono/chrono/blob/develop/src/chrono_python/robot/ChModuleRobot.i).

 

--Radu

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Finbar Argus

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Oct 14, 2021, 4:24:09 PM10/14/21
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Hi Radu, 

Fantastic, that will work perfectly! Will it be straightforward to swap the wheels in those models out for Pacejka wheels?

Cheers,
Finbar

Radu Serban

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Oct 15, 2021, 1:38:40 PM10/15/21
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Hi Finbar,

Certainly possible but maybe not very straightforward, the reason being that the tire models (Pacejka included) assume a Chrono::Vehicle model (in which the tire is associated with a "wheel" subsystem which in turn expects a "spindle" body - usually provided by a "suspension" subsystem). Having said that, we've done that kind of stuff in the past.  Once I merge some new stuff in Chrono (in a couple of weeks or si), that will have an example of connecting a Chrono::Vehicle tire to a plain Chrono model.

--Radu


From: projec...@googlegroups.com <projec...@googlegroups.com> on behalf of Finbar Argus <far...@aucklanduni.ac.nz>
Sent: Thursday, October 14, 2021, 11:24 PM
To: ProjectChrono
Subject: Re: [chrono] Three wheeled vehicle

Finbar Argus

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Oct 18, 2021, 12:04:15 AM10/18/21
to Radu Serban, ProjectChrono
Hi Radu,

Sounds great! Looking forward to seeing the new merge.

Cheers,
Finbar

Finbar Argus

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Dec 6, 2021, 4:11:09 PM12/6/21
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Hi Radu,

Could you please advise where I can find the example of connecting a Chrono::Vehicle tire to a plain Chrono model? 

Cheers,
Finbar

Radu Serban

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Dec 7, 2021, 3:45:23 AM12/7/21
to Finbar Argus, ProjectChrono

Hi Finbar,

 

The new code I mentioned previously is under chrono_vehicle/cosim/.  But that evolved beyond what I had back in October and no longer is a good example for what you asked.

 

However, I realized that there was already another perfect example for connecting a ChTire to some Chrono mechanism: that’s in the implementation of ChTireTestRig.  Look also at demo_VEH_TireTestRig for a demonstration.

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