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Question Tuning a dedicated surge axis

Discussion in 'DIY Motion Simulator Projects' started by alex928gt, Oct 15, 2020.

  1. alex928gt

    alex928gt New Member Gold Contributor

    May 2, 2020
    +0 / 0 / -0

    You'll find below my settings. As you can see they are very simple for the purpose of focusing on my horizontal actuator's behavior.

    The only force I'm using is Surge - no filter at all - and it's sent to my horizontal surge actuator. In the control center I used 2 different settings for Surge max/min, +3/-3 and +10/-10.

    With these very simple settings I'm getting the same odd behavior, of course with different intensity for different max/min levels (no video, sorry, since I don't have a Youtube account I could use):

    - when just releasing the throttle the tray goes backwards whereas if you think about it it should not since I'm not actually braking, i.e. not generating negative surge, I'm just letting surge go back to 0.
    - likewise, when just releasing the brake the tray goes forwards whereas I'm not accelerating, i.e. not generating positive surge, I'm just letting it go back to 0.

    Getting for instance such move forward when you are just releasing the brake and not accelerating is very disturbing. When you just release the brake the car should continue on its track at constant speed and you should therefore not be pushed forward by a surge actuator.

    This said, you're right, I'll create a new thread to discuss this topic but - if I may - I really would meanwhile appreciate constructive views on my point since I believe I now made it pretty clear and I also believe it could be useful for lots of users of horizontal surge actuators.


    Game Engine.png
    Control Center - Surge +3-3.png Control Center - Surge +10-10.png
  2. Ads Master

    Ads Master

    +0 / 0 / -0
  3. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

    Jul 13, 2014
    Innovative tech specialist for NGOs
    St Helens, Tasmania, Australia
    +9,125 / 46 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    To help with tuning advice can I please confirm my understanding of your motion profile aims.

    What I understand you want is significant surge effect on acceleration, with the surge axis moving forward, and to simulate sustained surge in a return to light throttle, in other words there is not an abrupt return of the surge axis, but rather a gradual reduction. Under braking your expectation is that the surge table will have a significant surge effect moving backward, but you want a softer response when braking is released.

    If my understanding is correct filters may come into it later for refinement, but initially what you want to find is the best compromise where the horizontal surge axis has 100% Axis Allocation, and you want fast acceleration but slower deceleration responses. You can initially start by differentiating the Max/Min values in the Tuning Center. In the Tuning Center the check boxes are Green by default, which means the Min and Max values will default to the same value, Blue is to capture values and uncheck them to Pink (Off) to manually enter values. So change yours to Pink and manually fine tune the horizontal surge actuator by differentiating the Max/Min values to the point of the fastest deceleration return you can live with. The larger the value the softer the response over a greater axis range, so you want larger values to slow the effect for lighter throttle and getting off the brakes. I suggest the fastest deceleration you can live with in anticipation of what you may do with other actuators.

    At this point I just want to differentiate a little here, for tuning clarity, as you have a surge table, which has a physical range and is a surge axis, but you also have 4 vertical actuators that can, if you want, somewhat simulate surge, but do not actually provide a surge axis. So once you are happy with the horizontal surge tuning if you intend the vertical axis to contribute a simulated surge effect then enable surge only on the vertical actuators, no other axis. In fine tuning the vertical actuators you want to find the minimum Axis Allocation value you can live with. The reason for that is that it will minimise the differentiated Max/Min effects in the Tuning Center as much as possible, but contributing in a way that may enhance the simulation. A byproduct of having differentiated Max/Min values is that with your vertical actuators it can be used to emphasize gear shifts via simulated surge: https://www.xsimulator.net/community/faq/snappy-gear-change-motion.121/

    After all that some judicious use of filters may be helpful for final tweaks, in particular Washout for your surge table actuator, because your surge axis has a finite range, but those tweaks should be very much secondary to getting the main profile as good as it can be in the first place.

    As an aside I hope SimTools V3 will make differentiating settings much more flexible, given @yobuddy's comment here: https://www.xsimulator.net/communit...next-for-development.13062/page-6#post-206041
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    Last edited: Oct 15, 2020