Experiencing 3D Motion Study of Mechanisms

You can perform and experience the kinematic analysis of mechanisms. Using the various constraints between grouped items, you can construct rigid body mechanisms in Natural Shape.

With this time-motion study, you can perform the following activities:

  • Design and verify realistic and feasible mechanisms.
  • Move the parts to design and evaluate complex mechanisms in 3D.
  • Plot bodies at different positions during the motion to design housings and ensure clearance.
  • Add motors to produce realistic animations to design and understand complex mechanisms.

  1. Create a geometry with wires in Natural Shape.

    In this example, there are two edges and a propeller.



  2. To create a rigid set and represent a body of the mechanism, create a group for each geometry element.
    1. Select an edge and, on the context toolbar, click Group . Do the same for the other edge.
    2. Select the propeller and click Group .
    Three groups have been created.

    The origin and the absolute axis of the geometry are treated as immovable. One edge is used to create the angular constraint, the other one is the axis around which the propeller will rotate.

    Internal constraints of each body are irrelevant to the kinematic system. Only external constraints are considered for the kinematic relation between the bodies of mechanism.

  3. Anchor or ground the bodies to make them immovable using Fix .
  4. Use other Natural Shape capabilities to create a feasible mechanism.

    The nature of the relation between the bodies is a result of the degree of freedom between two bodies. The constraints you apply on the mechanical system decide the kind of motion between them. For example, the fixing of a body leads to its immobility whereas the coincidence and angle constraints lead to a revolute joint.

  5. From the Compass, click Play.
    • You are now in the motion study environment. Each body is colored uniquely.
    • The detected relation between the two bodies appears with the icon for a rotation-based relation and for a translation-based relation.
    • The Play section is added to the action bar.


  6. Select an individual body and drag along the ruler to change its position.


  7. To create an angular motor in the mechanism, click , and on the context toolbar.

    If a linear link is recognized for a joint, click , and on the context toolbar to create a linear motor in the mechanism.

  8. In the Angular Motor or Linear Motor dialog box, select the kind of profile to assign the motor.

    The different parameters needed to define for each kind of motion are as follows:

    ProfileParameters in Angular MotorParameter in Linear Motor
    Constant SpeedAngular Speed in turns per minuteConstant Speed in meters per second
    Distance
    • Start Time in seconds
    • Duration in seconds
    • Angular Displacement in degrees
    • Start Time in seconds
    • Duration in seconds
    • Linear Displacement in mm
    Oscillating
    • Phase Shift in degrees
    • Frequency in Hertz
    • Angular Amplitude in degrees
    • Phase Shift in degrees
    • Frequency in Hertz
    • Linear Amplitude in mm

  9. From the Play section of the action bar, click Play Forward.
    The mechanism can be now experienced. The propeller turns.

    The Play section includes the following commands:

    CommandDescription
    Step Backward
    Goes back to the beginning of the scenario.
    Play Forward
    Plays the scenario.
    Step Forward
    Moves to the end of the scenario.
    Decrease Speed
    Decreases the scenario speed.
    Pause
    Pauses the scenario.
    Increase Speed
    Increases the scenario speed.
  10. Optional: Select a motor and on the context toolbar the following options are available:
    OptionDescription
    Delete Motor Deletes the motor
    Lock Constraint Locks the selected constraint to stop free movement
  11. From the action bar, click Exit or from the Compass, click Play to exit the motion study environment.

    If you re-enter the motion study environment in the same session, the values you assigned are restored.

    Notes:
    • Since the values assigned to the motor are based on the constraints you apply to the geometry, the motor is reset if the concerned constraints are removed.
    • Delete the motor and assign new values to disregard the previous values assigned to the motor.