Semantic Robot Description Format (SRDF)

An XML file that adds planning groups and collision exceptions on top of a URDF.

SRDF is an XML format used by MoveIt (ROS's motion-planning framework) alongside URDF (the Unified Robot Description Format, which describes links, joints, and geometry). URDF only describes what the robot looks like; SRDF adds the semantic information motion planning needs: planning groups (for example, which joints make up the “arm” group versus the “gripper” group), end effectors, named poses (such as home or ready), virtual joints (which fix the robot to the world frame, or to a mobile base), passive joints, and pairs of links for which collision checking should be disabled. Links that are adjacent or can never physically touch don't need self-collision checks, which noticeably speeds up planning. It's usually generated automatically with the MoveIt Setup Assistant and then fine-tuned by hand.

ExampleWhen generating a MoveIt configuration for a Franka arm, the SRDF defines a panda_arm group containing its 7 joints and a named pose called ready, and lists the adjacent links panda_link1 and panda_link2 as exempt from collision checking.

Also called

SRDF, .srdf file

Related

Unified Robot Description Format · MoveIt Motion Planning Framework · Xacro (XML Macros) · Self-Collision Checking · Motion Planning · MJCF (MuJoCo XML Format)

Sources

ROS Wiki: srdf
MoveIt Docs: URDF and SRDF