Control of motorcycle

Cpapagiann
Cpapagiann Altair Community Member
in Community Q&A

I face a problem in a model that I build. I have a motorcycle as the example of Altair, but with different mass and inertia properties. I have the problem where I want to make a 3d analysis but I can't keep the motorcycle stable because of not handling the motorcycle as it should be. The control of it I believe is the main reason. I started to test different values of kp,ki,kd and look ahead time, but I couldn't find the solution. Is it possible to find a solution in this problem?

Thank you in advance.

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Answers

  • Vishvam
    Vishvam
    Altair Employee

    Hi @Cpapagiann,

    Could you explain a bit more about the issue you are facing? I am assuming you are working with Motionview for multibody simulation. Any more info with the type of event that you are working with might help.
    If possible please share the model so that the issue can be looked first-hand.

  • GTT Adam
    GTT Adam
    Altair Employee

    Hi @Cpapagiann,

    You are correct in that the steering and lean parameters should be adjusted for a motorcycle of significantly different mass and inertia properties. They should also be adjusted depending on the type of event you are trying to complete.

    If we look at the Electric_Sport_Bike example model, you can see that when a double lane change, a slalom, and a throttle off in corner event are introduced, a different set of leaning PID parameters are initialized:

    Double Lane Change:

    image.png

    Slalom:

    image.png

    Throttle Off in Corner:

    image.png

    From these examples, it should be noted that the parameters for the lateral error control (steer control) remain constant and the modifications per event are only made to the lean controller. Also, the Ki is constant across all 3 events, so it is likely that only Kp and Kd need to be modified.

    If you are having significant issues with having your custom motorcycle complete events, there are a few strategies to deploy:

    1. Double check that the overall mass, center of gravity, and inertia of your motorcycle is realistic and matches your configuration target. Compare your overall configuration with that of the example models to see the % difference in those key areas to make sure you have not accidentally defined bodies incorrectly.
    2. Using the default Kp and Kd values, manually adjust the parameters based on the performance you are seeing. If the vehicle simply falls over, then the proportional constant may simply need to be increased.
    3. Rather than manually adjust the two variables, you can also use HyperStudy to vary the two parameters for you with an objective function of maximizing the longitudinal distance travelled (if using a DLC< for example). This would ensure the end of the course has been reached.
      1. The implementation of a driven event has seen significant improvements in the last few releases with respect to HyperStudy, so please use version 2025.0 at least for this type of optimization process.

    Hope this helps!

    Adam Reid

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