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Does force feedback need to know wheel position?

Discussion in 'Direct Drive Wheels' started by Dav_Daddy, Apr 3, 2025 at 09:11.

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  1. Dav_Daddy

    Dav_Daddy New Member

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    My Motion Simulator:
    DC motor, Arduino, Motion platform
    I've been playing with the idea of building a hoverboard DD Steering wheel from scratch for a while now. However earlier tonight I had an idea. What if I add DD to my old TSW2 steering wheel instead? Other than adding force feedback to a Thomas Superwheel being sacrilege and all.

    Could I let the TSW handle positioning and button presses while using another board an Odrive 4.2 for example to just handle delivering the forces to the wheel? I don't think the forces delivered are dependent on wheel angle at all but I'm not 100% sure of that.

    If my memory serves me the first guys to try the whole DIY DD wheel thing did something similar with multiple boards but I don't recall what exactly the deal breaker was for this approach? I read through the huge 36 post thread on this topic but it jumps around so much with people trying different things with hardware and software and everything else. I'm not sure where to find what I'm after in there.

    If this is doable what modifications would I need to make to the hardware/software or firmware that handles all of this to get it to play nice?

    Thanks in advance.
    Dav_Daddy, Apr 3, 2025 at 09:11
    #1
  2. Aerosmith

    Aerosmith Active Member

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    My Motion Simulator:
    3DOF, AC motor
    Theoretically, the controller for the force feedback does not need to know the position of the wheel or the motor if (and only if) it has the ability to measure the motor current. Most cheap H-bridge drivers don't measure the current and therefore it is necessary to measure the motor speed to calculate back EMF to be able to at least somehow guess the motor current which is proportional to torque/force. Raw PWM only provides voltage control.

    If the controller has a torque mode which controls the motor current directly regardless of speed no encoder or other position feedback is necessary. I'm not 100% sure buit I think the Odrive is a full featured servo drive and should support torque mode.

    On the other hand, for brushless motors the controller needs to know the rotor position for commutation. But this requires less resolution and is usually done with hall sensors built into the motor.
    Aerosmith, Apr 3, 2025 at 11:23
    #2