Main toolbar > Open Track View > Select a rotation track in the Track View Hierarchy. > Track View toolbar > Assign Controller > Smooth Rotation
Graph Editors > Track View > Open Track View > Select a rotation track in the Track View Hierarchy. > Track View toolbar > Assign Controller > Smooth Rotation
Use Smooth Rotation when you want rotation to have a smooth and natural look. Smooth rotation functions the same as Linear Rotation, but uses non-adjustable curved interpolation, and has the following characteristics:
Displays no controllers, key properties, or function curves
Move keys in Track View to change timing
Directly rotate objects in the viewports to change rotation values