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Thread: kinematics + dynamics

  1. #1
    Junior Member
    Join Date
    Mar 2010
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    kinematics + dynamics

    Hi,

    Could anyone send me an example of a COLLADA file that uses both kinematics and dynamics (i.e., a file that specifies dynamics of an articulated body)?

    Thanks,
    Evan

  2. #2

    Re: kinematics + dynamics

    Hi,

    how about

    http://wikis.itec.uka.de/grasp/wiki/Robot_Editor

    see section "Export to COLLADA" -> "example.dae".

  3. #3
    Junior Member
    Join Date
    Mar 2010
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    2

    Re: kinematics + dynamics

    Thanks for responding! That file, example.dae, does indeed contain both kinematics and rigid body elements. However, the dynamic elements are all disabled (<dynamic>false</dynamic>). Additionally, the dynamics and kinematics elements are separated; there are no references from one to the other.

    Thanks,
    Evan

  4. #4
    Junior Member
    Join Date
    Apr 2009
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    16

    Re: kinematics + dynamics

    Hi Evan,

    the kinematics part of COLLADA 1.5.0 devides into four subparts:
    - joints: here you can define different kind of joints with its axes and limits
    - kinematic models: here you define one or more chains the model exists of. you can define some dependencies between joints by a closed loop or by a formula, too
    - articulated systems: here you can define some additional information for your model. You can define kinematics specific information (locking status, activity of joints, softlimits, ...) and dynamic specific information (speed, acceleration, jerk). The last one means e.g. what is the maximum speed allowed for joint xx.
    - kinematics scenes: here you define a scene of one or more kinematics models or articulated systems.

    The binding to visual scene is done while instancing the kinematics scene in the scene element.

    The dynamic element just describes if a rigid body can move in physics context.

    The difference between the physics context and the kinematics context is:
    the kinematics part describes moveable or better articulated objects that do the movement by theri own.
    The physics part decribes objects that are moved by some external forces e.g. gravity.

    The reference between those two models can be done by a visual scene, that only needs are node hierarchy if there is nothing to visualize.

    I hope this answer may help you.

    Feel free to ask more!

    Best regards
    Steffen

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