Fulcrum points represent parts of the character that contact an obstacle (such as the gound, a colision object or another character).
These points play are used in many tools in Cascadeur:

By default, Fulcrum Points are not visible in the scene.
To enable them, click the Show fulcrum points button on the Toolbar:

Overview

A Point Controller is considered a Fulcrum Point when:

1. The point is close enough to the ground level. The Y coordinate for the point should not exceed the Collision radius value set for it:

2. Between the frames, the point does not move to a distance greater than the Max speed multiplied by the number of frames between the keys:

These parameters are parts of the Fulcrum point behavior which is by default applied to every Point Controller. They can be found on the Object Properties panel, under the Fulcrum Point tab:

Fulcrum state
Sets the conditions for when the controller should be considered a fulcrum point:
Fulcrum means the controller is considered a fulcrum point when the conditions are met. This is the default value.
Enforce means the controller is always considered a fulcrum point, even when the conditions are not met.
NotFulcrum means the controller is never considered a fulcrum point.

Max height
Sets the maximum vertical distance the Point Controller can be shifted without losing its properties as a fulcrum point.
Increasing this value can be necessary for fixing some errors in AutoPhysics simulations.
Set to 10 by default.

Max distance
Same as above, but defines the maximum horizontal shift.
Also set to 10 by default.

If an interval has at least one fulcrum point, the character is considered to be standing on the ground.
The Point Controllers that are recognized as Fulcrum points are marked with a green borders for the character model (but not for the physics ghost):

Examples of Using Fulcrum Points

Manipulating Fulcrum Points can greatly affect the behavior of the AutoPhysics simulation.
For example, the simulation can make the character jump when you’re trying to make a squat:

Why does this happen?
If you look closely at the character’s legs, you’ll notice that they slide on the ground, moving backward:

Because of this, the AutoPhysics tool does not recognize them as fulcrum points.
And where there’s no fulcrum points, there’s only one kind of motion possible: ballistic motion, i.e., jumping.

But if we copy the feet positions from the frame 0 to the whole interval, they won’t move anymore, and a fulcrum area will appear:

As you can see, squats work correctly when there are fulcrum points.