3D One-Legged Hopping Machine

A one-legged robot with a pneumatic leg and hydraulic hip that hopped freely on an open floor, controlling hopping height, speed and body attitude separately. The work was funded by DARPA and published in 1984.

Price: —Not published
Height: —Not published
Weight: —Not published
Payload: —Not published
Speed: —Not published
Battery: —Not published

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Why it matters

Showed that a robot could balance actively by hopping on a single leg in three dimensions, a foundation for later dynamic legged robots including Boston Dynamics' machines.

Real-world use

DARPA-funded research

Timeline

First shown: 1983
Released: Not yet

Built at CMU's Leg Lab; described in DARPA report CMU-RI-TR-83-01

Maker

Carnegie Mellon University Leg Lab (Marc Raibert)University lab · founded 1980 · Pittsburgh, Pennsylvania, USA

DARPA research contracts

Public attention

A historic robot: no longer sold or in use, so it is not ranked against current machines.

No Wikipedia article of its own yet
No recent press stories listed yet

Measures how much people read and write about a robot, not how good it is. Measured 2026-10-13; same method for every robot. How it is measured

What’s inside

The parts the company has talked about publicly.

Movement: Walks on legs
How it runs: Assisted. Its controller kept it balanced and hopping on its own while an operator could set the speed and direction it travelled.
Actuators & motors: A simple pneumatic springy leg positioned by a hydraulic hip.
Sensors & vision: Not detailed in the sources used.
Compute: Off-board computer running a three-part controller (hopping height, forward speed, body attitude).
AI & software: Raibert's decomposed balance controller, generalised from the earlier planar (2D) hopper; let the machine hop in place, run at a set speed and follow a simple path without support.
Other details: Ran and balanced on an open floor with no mechanical constraint; described in CMU-RI-TR-83-01 and in the International Journal of Robotics Research (June 1984).

From the maker

3D One-Legged Hopping Machine is the only machine from Carnegie Mellon University Leg Lab (Marc Raibert) in the atlas.

Made, sold and where

Unit counts are usually company figures; analysts often disagree.

Price: Not published
How to get one: No official buying page found
Built: Research machine (one)
Sold or delivered: not sold
Where it is sold or used: Carnegie Mellon University Leg Lab, Pittsburgh; the lab moved to MIT in 1986
Customers and pilots: DARPA-funded research

Sources

Figures come from a published paper. Every link below backs something on this page.

Robotics Institute, Carnegie Mellon University Experiments in Balance With a 3D One-Legged Hopping Machine Robotics Institute, Carnegie Mellon University Dynamically Stable Legged Locomotion: Second Report to DARPA Carnegie Mellon University Robotics Institute Dynamically Stable Legged Locomotion Progress Report: October 1982–October 1983

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