Brittle stars (Ophiuroidea) crawl by coordinating five or more segmented arms, with no fixed front and a decentralised nervous system. In BRT every arm segment has an in-plane and an out-of-plane joint, and the number of arms and segments, their sizes and actuation are set in the morphology specification.
Drag to orbit, right-drag or shift-drag to pan, scroll to zoom. Physics runs in your browser with the official MuJoCo WebAssembly build.
The default five-armed brittle star in the brittle_star/undirected_locomotion aquarium, rowing
with an open-loop gait: every segment traces an oval, the strokes are mirrored across arm 0, and a phase lag
along each arm makes a travelling wave. The disk moves about 2 m in 10 s, and the simulation
restarts every 20 seconds. The controller is a fixed pattern, not a trained policy.
brittle_star/undirected_locomotion: move away from the start as far as possible, in any direction.brittle_star/directed_locomotion: reach a target position on the floor.brittle_star/light_escape: move from light into shade, sensed by the arm segments.Read the brittle star README for the biology, the morphology specification and the observation and action spaces.