Jointdefinition

Jointdefinition is a term used across engineering, biology, and computer graphics to describe the specification that defines how two or more components connect and move relative to each other. The concept is central to modeling, simulation, and control, providing a formal description of the connection, motion, and constraints that govern a linkage or articulation.

In robotics and mechanical design, a joint definition specifies the type of connection (for example revolute, prismatic, fixed, spherical), the reference frames for motion, and the axis or direction of movement. It also includes limits on position, velocity, and effort, as well as dynamic properties such as damping, stiffness, friction, and actuation. A complete joint definition enables the construction of a kinematic chain, supports simulation, and guides real-world control and manufacturing.

In human anatomy, a joint definition describes an articulation where two or more bones meet, enabling movement and load transfer. Joints are classified structurally as fibrous, cartilaginous, or synovial, and functionally by range of motion and type of movement. Components often cited include articular cartilage, a joint capsule, ligaments, synovial membrane, and synovial fluid. Understanding joint definitions is essential for medicine, biomechanics, and physical therapy.

In computer graphics and animation, a joint definition rigs characters by detailing how bones connect, their local coordinate frames, and the allowed movements and limits. This supports realistic motion, inverse kinematics, and procedural animation within virtual environments.

In standard robotics formats such as URDF and SDF, a joint element constitutes a joint definition with fields for type, parent and child links, origin, axis, and limits. Across domains, the core purpose of a jointdefinition is to enable consistent modeling, simulation, and control of connected parts.