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Cables

Cables


INTERACT can help you to simulate cables by using physical properties. We use a beam finite element model to process flexible cables.

Cable generator component

Tutorial

Check the interactive tutorial on cables to discover cable features. Tutorials > Show Tutorials > Cables.

There are two ways of generating a cable:

  • from a CAD model,
  • from a spline.

When your cable is generated, you can customize its shape, length, position, radius and more.

Create a Spline

If the cable geometry is not yet available in your product design, you might consider using INTERACT to help you define your cable routing.

To do so :

  1. Use the toolbar menu GameObject > Spline > Draw Splines Tools,
  2. Define your knots by clicking in the scene view
  3. Press Esc when done.

For more information about how to create a Spline and manipulate it, click here.

Spline doesn't appear

If you created a Spline, and the Spline object appears in the hierarchy but not in the scene view, you probably unchecked the toggle visibility of all Gizmos in the Scene view. In the top right corner, activate the visibility by clicking this icon.

Physics

At this step you have only created a spline with no physics behaviour. To simulate the bending of your spline, check the following create cable section.

Create Cable

To apply physics to your cable geometry (whether it is from CAD or a spline) :

  1. Select the cable geometry in the hierarchy or game view,

  2. Click on INTERACT > Physics > Create Cable.

    Selected objects

    If you select one or more objects when creating one or more cables, they are automatically added to the GameObjects, but you can still edit them by deleting an object or adding one in the Selected Objects area.

  3. Configure your cable :

    • Number of nodes: The number of nodes used by our finite element method to compute the physics of the cable. This can be edited after the cable has been created in the Cable Generator component.
    • Radius (m) for the Splines only: cable radius in metres.
    • Material: You can use presets to configure the physical properties of your material. These presets can be changed when using Custom materials.
    • Density, Young modulus and Poisson ratio are physical properties commonly found for a material. Units are measured using the International System of Units.
    • Preformed cable

Geometry

To recognize shapes for a cable's parameters, you need to use either an open deformed cylinder or a closed surface. Tessellation should be quite detailed in order to perform well.

Cable properties

The XdeCircularBeam component contains all the information relating to the cable's physical material and simulation properties.

You can find it in the Cable GameObject's components, which is a child of the spline or CAD model that the cable has been generated from.

  • Beam info: Cable radius (in mm) and total length (in m). The average segment length (in m) is the length between two nodes.
  • Number of Nodes: Number of nodes used by our FEM to compute the physics of the cable.
  • Attach Points: When your cable is created, it only has start and end attach points, but any new Attach Point will appear here.
  • Collision Group: Like any physicalized object, you can define a collision for your cable to make it collide with other objects.

Edit the cable

Cables generated from a CAD model or a spline have a Spline Container. This is very useful in the event that you would like to lengthen, shorten or even move your cable.

  1. Select the gameobject you generated a cable from (the one with the Spline Container in its components).

  2. Select the Move tool, then the Spline icon as shown in the picture.

  3. Select the Knot you want to move and move it.

    Knot

    When you create the spline, you add knots by clicking on the view scene in order to place points. When you create it from a CAD model, the knots are automatically added based on the curvature.

Preformed Cable

In order to compute a cable's deformation, we need to set up two states:

  • The initial configuration, which is the initial starting position of each point in the cable.
  • The reference configuration, which is the position with no internal stress on the cable. For a straight cable, initial and reference positions are the same.

The preformed property allows users to set the reference configuration :

  • If unchecked, the reference configuration of the cable is a straight line. If the current shape of the cable is not straight, it means this cable is already affected by internal forces. When playing your simulation, if the cable is not attached, it will try to take the straight position.
  • If Preformed is checked, initial positions and reference positions are the same. So when playing the simulation, its reference shape will be the one you gave it in Editor mode. Use this for beams or cables that have been built with a specific shape.

Example

Consider two identical cables, with the left one being preformed and the right one not having this quality. Unweld the CableEndAttach and play the simulation.

Notice that the first one is affected by gravity but keeps its initial shape (following the points 1,2,3,4,5). The other one is also affected by gravity but is now a straight line.