Humanoid & robot atlas
RHex
Photo: Gadlopes at English Wikipedia, Public domain, via Wikimedia Commons
ResearchUnited StatesAssisted

Boston Dynamics · legged machine

RHex

A cockroach-inspired hexapod whose curved, compliant legs spin like spokes, letting it run, climb and cross mud. Specs shown are for the Boston Dynamics commercial version.

Price
—Not published
Height
20 cmTaller than 14%
Weight
12.5 kgHeavier than 32%
Payload
—Not published
Speed
9.7 km/hFaster than 84%
Battery
6 hRuns longer than 100%
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Why it matters

Showed that six simple, springy rotating legs (one motor each) could carry a small robot fast over rough ground, inspiring a long family of robots.

Real-world use

Boston Dynamics sold a ruggedised commercial version (listed in its legacy robots from 2007); the X-RHex research version continues at the University of Pennsylvania.

Timeline

First shown
2001
Released
2007
Original RHex completed by the consortium (built 1999-2001)

Maker

Boston DynamicsCompany · founded 1992 · Waltham, Massachusetts, United States

Owned by Hyundai Motor Group since June 2021 (80% stake bought from SoftBank for about $880M; SoftBank kept about 20%).

How it stacks up

Against other legged & novel that publish the figure. Pick a measure.

  1. Walking Forest Machine (Plusjack)Plustech Oy (Timberjack R&D unit, later John Deere) · 1999450 cm
  2. Tri-ATHLETE (ATHLETE second generation)NASA Jet Propulsion Laboratory · 2009400 cm
  3. Dante IICarnegie Mellon University Field Robotics Center (for NASA) · 1994305 cm
  4. i-footToyota · 2004236 cm
  5. ATHLETE (All-Terrain Hex-Limbed Extra-Terrestrial Explorer)NASA Jet Propulsion Laboratory · 2005200 cm
  6. BEAR (Battlefield Extraction-Assist Robot)Vecna Robotics · 2005180 cm
  7. RHexDARPA-funded consortium (University of Michigan, McGill University and others); commercial version by Boston Dynamics · 200120 cm
  8. ACM-R5HTokyo Institute of Technology (Hirose lab); product version by HiBot · 200512 cm

RHex is taller than 14% of the 22 other legged & novel that publish a height. Bars show the 7 closest in date.

Height 20 cm 5 cm450 cm #20 of 23 · taller than 14%

Not published by the maker: payload, price.

Public attention

How much public attention RHex gets, from open data.

  • No Wikipedia article of its own yet
  • 2 news stories from reputable press listed on this page

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 · 6 joints
How it runs
Assisted. Usually steered by an operator with a remote control while its spinning legs and gait handle rough ground on their own; labs also tested autonomous behaviours.
Actuators & motors
Six DC motors, one per compliant C-shaped leg (6 DoF).
Sensors & vision
Cameras, gyroscope, accelerometer; motor position, current and temperature sensing; optional payload sensors.
Compute
Intel-based main computer plus optional payload computer.
Battery & power
Two 144 Wh lithium-polymer packs, about 6 hours (commercial version).
Materials & build
Aluminium and carbon-fibre body; dust- and waterproof commercial version.
AI & software
Linux; control code in C, Python or Matlab.
Other details
About 12.5 kg (8.6 kg X-RHex); over 2.7 m/s in some versions; climbs slopes over 45 degrees, swims and climbs stairs. Family includes Rugged RHex, X-RHex, T-RHex and MiniRHex.

Lineage

Every DARPA-funded consortium (University of Michigan, McGill University and others); commercial version by Boston Dynamics machine in order.

  1. RHexRHex2001Research
  2. BigDogBigDog2005Retired
  3. LittleDogLittleDog2005Retired
  4. RiSERiSE2006Retired
  5. Sand FleaSand Flea2012Retired
  6. LS3 (Legged Squad Support System)LS3 (Legged Squad Support System)2012Retired
  7. CheetahCheetah2012Retired
  8. WildCatWildCat2013Retired
  9. Spot (now called Spot Classic)Spot (now called Spot Classic)2015Retired
  10. SpotMiniSpotMini2016Retired
  11. HandleHandle2017Retired
  12. Handle (logistics version)Handle (logistics version)2019Retired
  13. SpotSpot2019Commercial
  14. StretchStretch2021Commercial
  15. Spot Enterprise and Spot ArmSpot Enterprise and Spot Arm2021Commercial

Boston Dynamics also makes 5 humanoids. See every Boston Dynamics robot

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
Multiple research and commercial units
Sold or delivered
A ruggedised commercial version was sold by Boston Dynamics (listed with 2007 on its history page)
Where it is sold or used
University of Michigan, McGill and partners; commercial version Boston Dynamics, Massachusetts
Customers and pilots
DARPA (about $5 million over five years from 1998); University of Pennsylvania Kod*Lab continues X-RHex research

News

The latest 2, newest first. Summaries are ours; tap through for the original.

  1. RHex does parkour at Penn

    IEEE Spectrum covered Penn's X-RHex Lite leaping gaps and climbing obstacles across campus, from an ICRA 2013 paper.

    IEEE Spectrum
  2. RHex shows acrobatic leaps

    IEEE Spectrum showed video of a RHex variant performing jumps and flips.

    IEEE Spectrum

Sources

Figures come from press coverage. Every link below backs something on this page.

Boston Dynamics Legacy robots Carnegie Mellon University Robotics Institute RHex: A Simple and Highly Mobile Hexapod Robot (Saranli, Buehler, Koditschek; IJRR 2001) The International Journal of Robotics Research / Carnegie Mellon University repository RHex: A Simple and Highly Mobile Hexapod Robot Boston Dynamics Boston Dynamics History & Legacy — Handle

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