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Wheels continuously trembling RRS feed

  • Question

  • Hi, guys... first of all I want to thank this community for the help I've found here for developing my MRDS project. I'm glad of communicating that it is almost complete :).

    To all those who haven't read any of my previous posts, the project consists in a custom robot (Pioneer P3AT) with a SickLRF that can be controlled externally (can be stopped, driven, rotated using commands...) by an application developed in C Unix via sockets (it's a little more complicated but that is enough for summing up).

    In my development I've used the strategy followed in chapter 6 of ProMRDS for a quad differential drive, adapting it to my version of MRDS (2008 academic version)

    As I said, it's almost complete, but I have some little (or not so little) problems that I need to solve:

    1) In simulation, the wheels (and, by the way, the whole robot) are continuously trembling, even when the robot is "stopped". If the camera is enough far, you don't notice that trembling, but doing a zoom it's clearly appreciable.

    The curious thing is that even the example in ProMRDS have this problem (in a minor magnitude), so I suppose that is something that is not related to the code. What is more, even the pioneer3DX example that comes with MRDS have this behaviour (but only after you drive it a little with the simple dashboard).

    Additionally, when you change to physics render mode, the wheels are changing of colour all the time. It changes from white (controlled by the simulator) to red (kinematic, if I'm not wrong) and viceversa

    2) Given a point, I need to move the robot to the original position (0,0,0). I do this with

    entity.PhysicsEntity.SetPose( 
                new Pose(new Vector3(0, 0, 0), 
                TypeConversion.FromXNA(xna.Quaternion.CreateFromAxisAngle(new xna.Vector3(0, 1, 0), 0))) 


    the point is that for some strange reason (to me), the robot moves to that position, but suddenly a force is applied to it and move brusquely (sometimes it stays near, or sometimes it flyes all over the scenario...). It seems to me like if something is colliding with the ground plane and the simulator aply a force to separate them. But of course, nothing of that happens (or at least is not visible in the physics render mode)


    Well, that's all. Again, thank you and excuse my bad english.

    Regards,

    Zen
    • Edited by Zen1981 Wednesday, March 11, 2009 6:40 PM
    Sunday, March 8, 2009 1:51 PM

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