Special hybrid suspension in LOV ADAMS Car model

[grzyp413]

Hi everyone,


I'm working on mine master degree from automotive engineering. I'm trying to simulate a lightweight special-purpose vehicle model in Adams Car, featuring a hybrid suspension setup: a rocker-type dependent suspension and independent suspensions for each wheel.


The model builds without errors, and the static "Settle" simulation completes successfully after 2000 steps. However, the final position is clearly incorrect:

• The front tires do not make contact with the ground
• The rear suspension is heavily compressed
• The whole structure pitch and I am not able to find the reason why it happens

There is no drivetrain or powertrain included in the model. All joints and suspension geometries have been checked and seem correct.


Because the vehicle is incorrectly positioned after the static step, I’m unable to run any dynamic simulations — the solver fails due to lack of front tire contact.


Has anyone encountered similar issues with hybrid suspension systems or rocker-based axles? Could this be related to force transmission within the rocker mechanism, or an issue with tire-ground definition?


Any suggestions or diagnostic strategies would be greatly appreciated.
The time is running and I will be very thankful for some help.

Thanks in advance!

 

[GregLocock]

Where is your cg?

 

[grzyp413]

Where is your cg?

My center of gravity is located almost exactly in the center of the vehicle, within the rectangle defined by the wheels. I don't think the issue lies there.
Yesterday, I noticed that the solver consistently tries to set the vehicle with a camber angle of 0, despite the alignment being set to different values. As a result, I ran additional simulations, this time starting with an initial camber value of 0. In this case, the settle simulation finds a valid solution. Ultimately, the target camber should be around -1.3.
However, despite this simulation converging, the static simulation type straight still throw an error:

---- START: ERROR ----

Connector not found for force measure JPRIM(0,0,7,131)

Measure JPRIM(0,0,7,131), requested in call from VARSUB(124, 909, 400, 0, 7, 131, 2)

---- END: ERROR ----





acar/abg_ssserr

**** Error:



Problem computing value for VARIABLE/ 124

Could not obtain reaction torque for JPRIM/ 0





---- START: ERROR ----

Aborting Execution.

ID = 124



---- END: ERROR ----

 

[GregLocock]

I think you'll find in the first diagram the cg is vertically above the contact patch for the rear wheels. So due to some problem in your model the solver has found a geometry where static equilibrium is satisfied, but not the one you expected.

It seems to me you would be wise to look for JPRIM/0 and VARIABLE/124 and VARSUB(124 in the .adm file.

Sorry, can't help more than that I no longer have ADAMS.