Link

连杆Essential

One of the rigid segments of a robot's body that joints connect together.

A link is the basic structural unit of a robot's mechanical body: a robot is a series of links strung together by joints (connections that allow relative motion), with motors driving the joints to move the links. For modeling purposes, a link is usually treated as a rigid body — one that doesn't deform under load. In a robot description file such as URDF, each link tag records that segment's visual mesh, a simplified shape used for collision checking, and its mass and moment of inertia; the joint tags record which two links a joint connects and its axis of rotation. Forward kinematics works by starting at the base and multiplying coordinate transforms link by link, joint by joint, all the way to the tip, to compute where the end effector is. Link length directly determines how far an arm can reach.

ExampleA serial arm with n joints has n+1 links, including the base — a 6-axis arm has 7 links. A human's upper arm and forearm are effectively two links, connected by the elbow joint.

Also called: Robot Link
Related: Revolute Joint · Prismatic Joint · Kinematic Chain · Rigid Body · Unified Robot Description Format · Degrees of Freedom (DoF)
Sources: Modern Robotics (Lynch & Park, 2017), Ch.2 Configuration Space
Wikipedia: Robot kinematics
ros/urdf_tutorial: 07-physics.urdf