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Hello Everyone, I am trying to perform a full vehicle simulation; however, when I replace the default rear suspension with my rear suspension model, the simulation fails. I have attached the model and the video file.
Hi @premkumar_07,
If you deactivate the default body clamp joints (shown below) everything looks to run just fine:
Those joints exist to help stabilize the simulation in a static setting, then are deactivated once the transient simulation begins. Since your rear suspension pops afterwords, they are actually doing more harm than good.
Hope this helps!
Adam Reid
You can manually create this plot in HyperGraph by loading the PLT and selecting the X Source as toe angle and Y Source as the vertical displacement. You can always select a plot that is generated in a Standard Report and click the Define Tool to see what was used to generate a plot you may be familiar with using:
Suspension travel is the wheel center vertical travel.
It can be seen in the Instrumentation system (for assembly models) for more detail:
That is usually the cause of your powertrain not supplying any power to your vehicle. You will want to double check that the Driver Model is generating a Throttle Demand and that signal is being propagated through to your wheels.
It looks like the initial position of your vehicle model causes an erratic starting orientation. In rare cases, the Static simulation that begins these Standard Driving Events does not reach an ideal starting orientation before the maximum step number is reached. This may be due to some non-linearity of your custom vehicle model. If you deactivate the Run Initial Static option in the Entity Browser for the DLC event, the model will skip this static simulation and initialize with 1-2 seconds of equilibrium needed. Alternatively, you can increase the Maximum Number of Iterations in the Static Global Simulation Settings or the Static Settings in the event definition.
I tried increasing the number of iterations; it worked at 36 km/h, but at 72 km/h the model started to float in space.
Did you try deactivating the Run Initial Static option in the Entity Browser?
hello, I am not able to find that option.
In version 2026, it appears as shown:
Therefore, you must be using an older version. Which version of HyperMesh Desktop do you currently have deployed?
I also see you are running this as Real Time Compliant. Have you tried running without that enabled?
I used the Default Analysis without the Driver active to see how your model initializes.
Your vehicle looks to jump considerably at initialization:
I would investigate your suspension settings to increase your model stability.
hello, I am using the 2025 version, and I have tried without real-time compliance.
This time I did not imported my suspension model , I kept the default rear suspension and just changed the hard point which reflects my model and the error reamained the same
Hello, Thank you for resolving the issue. What could be the possible cause of the rear tire hop? I would also appreciate it if you could suggest a few debugging approaches.
It's not wheel hop, it's your suspension extending rapidly. Based on the steady state values, your front suspension wants to extend about 25 mm and the rear almost 40 mm.
Hello, How can I plot camber-toe angle vs. wheel vertical displacement for the full-vehicle simulation? And in the suspension travel plot (in this case, rear suspension travel left), what does the plot represent, as wheel center vertical travel or shock travel?
Thank you for the prompt reply, When I load the plt file, I can't see the request ID for camber, toe and caster angles.
That is correct. In the image I attached in the last post, the channels displayed are for REQ/71000025. This can also be seen below:
It should be noted that Solver Variables for toe are usually featured by default, as they are used in other calculations. You could very easily create an expression-based Output that uses these Solver Variables to make your own, more explicit, toe angle output:
Hello, I was able to plot camber and toe angle vs. wheel vertical displacement. Thanks for helping out. In the constant-radius turn simulation, the vehicle doesn't accelerate from its initial velocity to its final velocity. But when I ran the default vehicle template, the velocity changed.
Hello, You are correct, the driver model is generating throttle demand, but it is not propagating through to the wheels. I have attached the plot for your reference.
So, in my vehicle model, I have modified the power train. I used a linear torque-mapping powertrain. I have made changes in the force> differential force.
You are not displaying the Throttle Demand, but regardless the results should look like the following for this event:
Based on your plot the Differential Torque is not applied correctly.
Your Differential Torque definition looks to only apply torque to the left wheel. Do you have another signal to also apply torque to the right wheel?
Also, what signal is used in your TZ expression? (ID = 32300500) By default it should be the Solver Variable "Drive Torque" (sv_torque_output).
Torque is applied only to the left wheel; there is no signal to the right wheel. In the TZ expression, I am using the same ID you have mentioned. I have attached the throttle plot. So, we are using hub motors, one motor per wheel. And I am trying to model the same.
Hello, I figured out the issue. I entered the wrong torque value. Thank you.
