KDL

Kinematics and Dynamics Library (KDL) is an open-source software library for performing kinematic and dynamic computations on robotic systems. Originating within the Orocos project, KDL is designed to be lightweight, portable, and suitable for integration into real-time control pipelines. The primary implementation is in C++, but the library is designed to be usable from other languages through bindings or adapters. It is widely used in robotics research and development, including projects that use the ROS ecosystem.

KDL provides data structures and algorithms to describe robots as chains of segments and joints, and to perform common calculations such as forward kinematics, inverse kinematics, Jacobians, and dynamics computations. Core concepts include Chain, Segment, Joint, Frame, Twist and Wrench. The library exposes solver interfaces for forward kinematics (end-effector pose from joint angles), inverse kinematics, and Jacobians, as well as dynamic computations like joint torques given motion, inertia, gravity, and external forces. Its modular design allows swapping solvers while keeping a stable model representation.

KDL serves as a lightweight alternative to more comprehensive middleware stacks, and is used in planning and control components of robotics systems, particularly where portability and a small footprint are valued. It has evolved through contributions from researchers and practitioners in academia and industry and continues to be maintained as part of open-source robotics tooling.

Note: KDL also stands for other terms in different domains, but in robotics the Kinematics and Dynamics Library is the best-known reference.