A kinematic chain is an organized arrangement of interconnected links, specifically rigid bodies, that are either firmly interconnected or in direct contact with one another.
If a single link within the chain is immobilized, and the displacement of any other link to a fresh position results in the corresponding displacement of all other links to predetermined and predictable positions, then the system can be classified as a constrained kinematic chain. If the links remains fixed and the movement of any other link to a new position does not lead to the precise and predictable displacement of the remaining links, the system can be classified as an unconstrained kinematic chain.
Kinematic chains can also be classified as open or closed:
x