Transforming Linear Movement to Rotational Power - Piston

The Motors of the L1 Force category of the Physics Toolbox contains motors that can be used as wheels, which drive movement in a custom structure. However, by using the controls in the Sliders category, you can also convert linear movement into rotational power.

Preparing a Wheel to a Shuttle

  1. Apply an Infinite Plane from the Physics Props library as the surface for the segway to move along.
  2. Apply a cylinder and transform it into a wheel.
  3. Set it as Dynamic rigid body with the Object Physics Setting panel (Shortcut: Shift + F9). Assign its bound type as Cylinder - Y axis.
  4. Switch to the Local Move tool to observe the direction of the pivot of the cylinder.
  5. Open the Constraint Settings panel and apply a Generic constraint to the cylinder. Set the values of the constraint according to the illustration shown below:
    • Temporarily connect the cylinder to the World.
    • Set the (X, Y, Z) in the Move section to (Lock, Lock, Lock) to keep the cylinder fixed to its parent.
    • Set the (X, Y, Z) in the Rotation section to (Lock, Free, Lock) so that the cylinder can rotate around the Local Y axis.
  6. Apply the Shuttle dummy from the L1 Force category of the Physics Toolbox. Transform it and relocate it to the same height as the wheel.

Setting the Structure

In order to trigger the wheel to rotate according to the movements of the shuttle, you need to connect the wheel to the shuttle with a designated structure as shown in the steps below:

  1. Apply another cylinder as the bolt, transform and align it to the top center of the wheel.
  2. Apply a box and transform it into a bar. Position it at the same height as the shuttle.
  3. Move the pivot of the bar to the left-center because a Hinge constraint will later be applied to it in order to allow for free rotation of the bar.
  4. Rotate the bar so that the other end is raised to the position of the bolt.

Transferring the Power

After the structure is set, you need to transfer the force from the shuttle dummy to the wheel in order to rotate it. By setting constraints to the parts of the structure, the piston behavior can be formed.

  1. Select the bar and the bolt, set them as Dynamic rigid body in the Object Physics Settings panel (Shortcut: Shift + F9).
  2. Apply Hinge constraints to the bar and the bolt in the Constraint Settings panel (Shortcut: Shift + F10).
  3. Set the bar to target to the shuttle and set the Local Y to Free.
  4. Set the bolt to target the bar and set the Local Y to Free.
  5. Apply a Generic constraint to the bolt. The constraint will be used to fasten the bolt to the wheel.
  6. Set the target of the new generic constraint to the wheel and Lock every setting so that the bolt is fixed to the wheel.
  7. Click the play button in the Physics Control to start the simulation. The power will then be transferred to the wheel. However, since the range of the shuttle is not adjusted, the movements of the shuttle cause the structure to be unstable.

Setting Moving Range of the Shuttle

  1. Double click on the blank area of the physics control to open the Advanced Panel of the shuttle.
  2. Adjust the Range value and close the Advanced Panel.
  3. Play the play button in the Physics Control to simulate again (you may need to fine-tune the position of the wheel so that the power can drive it to rotate in the right direction).

Setting The Structure Free

Because the wheel and the shuttle dummy are constrained to the World, the structure is fixed at the original position. By picking another physics rigid body that is able to move along a free local axis as a target, the entire structure can then move along while the wheel is rotating.

  1. Apply a box and position it next to the shuttle dummy.
  2. Designate the box as a Dynamic rigid body in the Object Physics Settings panel (Shortcut: Shift + F9).
  3. Apply a Slider constraint to the box via the Constraint Settings panel (Shortcut: Shift + F10).
  4. Adjust the settings of the constraint according to the illustration below:
    • Connect the box to the World.
    • Set the Local X to Free so  that the box can only move along the Local X axis.
  5. Individually select the wheel and the shuttle dummy. Open the Constraint Settings panel (Shortcut: Shift + F10) and pick the box as their target. This step will set the entire structure free.
  6. Select the shuttle and Attach it to the box. This step is crucial to ensure the shuttle will always use the box to determine its relative center position.
  7. Increase the Mass of the box and the Friction of the wheel so that the box will not be affected by the vibration of the shuttle and the wheel will not be slippery. In this case, (40 and 250).
  8. Click the play button on the control panel to simulate again. The shuttle will act like a piston to trigger the wheel to rotate, which in turn will cause the structure to move forward.