Kinematic chain

[2] Mathematical models of the connections, or joints, between two links are termed kinematic pairs.

[2][5] A system of n rigid bodies moving in space has 6n degrees of freedom measured relative to a fixed frame.

Specifically, hinges and sliders each impose five constraints and therefore remove five degrees of freedom.

[5] The constraint equations of a kinematic chain can be used in reverse to determine the dimensions of the links from a specification of the desired movement of the system.

[7] Perhaps the most developed formulation of kinematic synthesis is for four-bar linkages, which is known as Burmester theory.

His use of the newly developed computer to solve Freudenstein's equation became the prototype of computer-aided design systems.

The JPL mobile robot ATHLETE is a platform with six serial chain legs ending in wheels.
The arms, fingers, and head of the JSC Robonaut are modeled as kinematic chains.
Boulton & Watt Steam Engine
The movement of the Boulton & Watt steam engine is studied as a system of rigid bodies connected by joints forming a kinematic chain.
A model of the human skeleton as a kinematic chain allows positioning using forward and inverse kinematics.