How to animate smooth and fluid rotations of objects with bones and targeting?

 (by Jean-Sebastien Perron)

Watch the video

On the video

-The object on the right was animated with only the normal rotation channels

-The changes in rotation at keyframe points is choppy

-The object on the left is attached to a bone that track an animated sphere

-Now we have a smooth transition between change of directions

When do you need this technique?

-You need to animate a rotation on more than one axis and you don't want a complete stop at each keyframes

-Use it also for camera animation

The concept

-Since we don't have enough control on rotation

-We use the translation to control a rotation

Setup

-Create 2 bones starting at the centor of rotation of the object

-Create a sphere that will be used as a target for the bone

-Select the second bone

-In the "Links" section "Add Object" the object we want to rotate

-Set the inverse kinematic

-"Select IK Root" to the first bone

-"Select Target Object" to the sphere

-Check the "Bone is IK Chain End"

-Now set the bone to the "Green Running Man" this will activate the settings

-Animate the sphere and edit the motion path

-Be careful not to put the spheretarget too close to the bone

-Don't forget to set the spheretarget to invisible in the rendering by setting it to "Selection/Make Construction"

Animate a moving object

-If you need to move the object during the animation

-Put the object, the bones and targetsphere inside a group and move that group instead