Inverse kinematics is a technique used in the model of complex animation and motion rig with the a number of joints . The fundamental difference with the forward kinematics, inverse kinematics is determined from the movement of the bone based on the final corner of some joints that define the movement.
Inverse kinematics is generally applied to the figure defined from articulation of hierarchical bones which are connected by joints and each bone have a limitation to the movement. (see picture below).
Inverse kinematics is a technique that is very effective in shaping the movement of objects, especially in animating living body movement. Inverse kinematics techniques are be able to simplify the animation of the model that has many complex joints and realistic movements.
One simple example of inverse kinematics is the robot hand movement below, under the robotic arm rotates by 90 degrees based on its fingertips. While the upper arm will adjust to make the rotation of 45 degrees.
- The structure of chain-shaped hierarchy
- Limitation of movement contained in each bone
Articulation chains formed from the root chain (the chain’s core), number of joints and effector. Chain root is usually the first joints of the first segment. Chain root is the parent of all segments and joints of an articulated chain.
The figure below is an example of articulation chains contained in the blender. As you can see in the picture below, the joints in a chain spine1 root.
Joint are defined by the point of articulation where two segments meet each other. The figure below is a sample implementation of joint in Blender. Joint is a ball-shaped object that reconciles two bone segments.
The addition of restrictions on the each bone are useful for movement generated by inverse kinematics, with movement restrictions, each bone will move in accordance with the animation that we want.
Effector is a point of articulation is used to determine the position of the movement of the chains by using inverse kinematics. When effector moves, it will trigger the movement of inverse kinematics and motion of each joint transformation will be automatically calculated. Examples of effector is the end so the robot image above.