Kinematic Chain

A kinematic chain is a series of rigid body links connected by joints that together form a robot's mechanical structure. An open chain (serial robot arm) has one free end (the end-effector), making FK straightforward. A closed chain (parallel robot, hexapod) has multiple loops that provide higher stiffness and speed but require more complex kinematics. The kinematic chain determines the robot's workspace, singularities, and the Jacobian matrix used for Cartesian control. URDF files describe kinematic chains as a tree of links and joints for simulation and control software.