IK allows you to control the joint
rotations in a skeleton using an IK handle. You
pose the skeleton by positioning the IK handle (usually located
at the end extremity of the skeleton) and having the rotations for
the other joints calculated automatically by the IK
solver. In the steps that follow, you apply IK to the
To create an IK handle for the mechanical
- From the main menu, select
Skeleton > IK Handle Tool > .
The IK Handle Tool Settings window
for the Joint Tool appears. When the mouse
pointer is in the orthographic view its appearance changes to the tool's
cross hair cursor.
- In the IK Handle Tool Settings window,
do the following:
- Click Reset Tool to
set the tool to its default settings.
- Set the IK Handle Settings: Current
Solver - ikSCsolver.
The ikSCsolver setting
selects the IK Single Chain Solver. This
solver ensures that the joints in the skeleton will lie along a
single plane. This solver is well suited for the mechanical arm,
because the arm doesn’t need to twist, unlike a real arm.
- Working in the side view, starting from
the base of the mechanical arm, do the following:
- Click on the skeleton joint at the base
of the mechanical arm.
- Click on the skeleton joint at the tip
of the mechanical arm. (The IK Tool is
designed to attach to the joints closest to your selection point.)
In the side view, the
IK handle is drawn as a line from the start and end joints of the
- In the Hypergraph menu,
select View > Frame All.
In the Hypergraph,
two new nodes appear in the hierarchy that represent the IK chain:
an IK Handle node and an end effector
- In the Hypergraph,
select the node named ikHandle1.
Handle (in combination with the end effector) is used
by the IK solver to calculate the rotation of the joints in the
IK chain. By default, the IK Handle is
located at the last joint of the IK chain in the scene view.
- Select the Move Tool from
the Toolbox, and drag the Move Tool’s
Z axis manipulator (blue arrow) to reposition the mechanical arm.
When you drag the manipulator,
the skeleton and mechanical arm model are repositioned.
- Reset the mechanical arm to its previous
position by selecting
Edit > Undo, Redo, Repeat until
the mechanical arm is positioned into its previous orientation.
NoteWhen using the Undo feature,
do not undo so many times you inadvertently undo the IK handle you’ve
The next steps describe
how to manipulate the IK Handle using
a control object.