Skip to content
buildrobots.io
LearnStart

HumanoidAgility Robotics2017US

Cassie

Torso-less bipedal research robot spun out of Oregon State University and sold to research labs. Superseded by Digit, which reuses its leg design.

discontinuedResearch onlyL2 Sim-verifiednot buildable

Difficulty index

8.5/13
8.5
Index breakdown
Classhumanoid+5
Costunknown · midpoint+1.5
DOF10 DOF+1
Partsunknown · midpoint+1
How the index works

Top of the ladder. This robot lives on the humanoid domains.

Specimen photographs

8 items
  • Cassie studio render, three-quarter front view
    Studio render of the published MJCF, keyframe pose from the model. Geometry only; colours are the model's own materials.Rendered by Hyperspawn from mujoco_menagerie/agility_cassie (MIT) · Hyperspawn render · source
  • Cassie studio render, side view
    Side view of the same MJCF render, keyframe pose from the model.Rendered by Hyperspawn from mujoco_menagerie/agility_cassie (MIT) · Hyperspawn render · source
  • 4 s turntable of the MJCF studio render.Rendered by Hyperspawn from mujoco_menagerie/agility_cassie (MIT) · Hyperspawn render · source
  • Cassie bipedal robot walking on a forest trail next to its operator
    Via Wikimedia Commons (CC BY-SA 2.0).Oregon State University, via Wikimedia Commons · CC-BY-SA-2.0 · source
  • Cassie bipedal robot, front view of pelvis and legs, outdoors
    Via Wikimedia Commons (CC BY-SA 2.0).Oregon State University, via Wikimedia Commons · CC-BY-SA-2.0 · source
  • Meet CassieAgility · official video, embedded · source
  • Cassie Sets World Record for 100M RunAgility · official video, embedded · source
  • OSU Bipedal Robot First to Run 5KOregon State University · official video, embedded · source

Spec card

2/13 known
Degrees of freedom
10
Price
not for sale

Not in the registry: height, mass, payload, speed, runtime, battery, bom total, part count, actuators, compute, sensors. Left blank rather than guessed.

What you learn building it

  • +Whole-body control
  • +Dozens of actuators on one bus
  • +Balance and fall handling
  • +Safe bring-up of a full-size machine
  • +Testing in simulation (URDF/MJCF) before touching hardware

Openness

20/100
  • not publicCAD
  • not publicBOM
  • not publicFirmware
  • publicSim model
  • not publicSoftware
  • not publicPolicies

Score 20/100 computed from what is public: CAD 25, BOM 20, sim 20, firmware 15, software 10, policies 10.

Repos & models

MJCF ↗MuJoCo Menagerie ↗
Docs

Build it

Discontinued.

humanoidrobot.build/agility/cassie · Closed hardware; no public CAD or BOM.

Simulate

Load it in the browser simulator and train a policy before building.

Open on humanoidrobots.training ↗

Next rung

None. This is the top. Find people building it on humanoidrobots.team.

This is the top of the ladder.

NoteRan an untethered 5K (2021) and set a Guinness record for fastest 100 m by a bipedal robot, 24.73 s (2022, OSU). agilityrobotics/cassie-doc is archived; osudrl/cassie-mujoco-sim last pushed 2023. DOF = actuated joints in menagerie model (5 per leg).

Sources

  1. [1]Wikipedia - Agility Roboticschecked 2026-09-24
  2. [2]OSU - Cassie 5Kchecked 2026-09-24
  3. [3]MuJoCo Menagerie agility_cassiechecked 2026-09-24