For a character model with humanoid avatar, how can I control the character with script freely? For instance, for the Unity Chan model, I want to realize that when I press button W on my keyboard, I want to let the character rotate its left arm clockwise 90 degree at a certain speed. When I press button U on my keyboard, I want to let the character rotate its left arm clockwise 45 degree at a certain speed. I do not want to use the animation to let the character to execute a certain series of actions. I want to just use some buttons to directly rotate parts of the character body. Which interfaces, methods, or plugins should I use to realize this effect?
You can for example assign the target bones of your character to a serializeable member variable and rotate them in script with onbuttondown-events.
Rotation is handled with quaternions in Unity.
You can use the slerp method for smooth rotations, here the corresponding documentation with an example: