NASA - National Aeronautics and Space Administration
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Mobility Concepts

Centaur base

Though a highly capable robotic system, Robonaut must be able to locomote from one worksite to another in order to perform meaningful tasks. Several mobility options are under consideration as the team enters this new phase of system development.

For a robot, achieving mobility means much more than simply asking Dad for the car keys. Especially in remote environments, the robot must carry certain essential resources on board. These include a power source, a brain, control electronics (avionics), and communication equipment. Squeezing all of these modules into a compact humanoid requires innovations in miniaturization, packaging, energy conservation, and heat dissipation.

In order to take advantage of its mobility, the robot must be able to survive outside the clean, cool, and dry laboratory environment. Materials, motors, and electronic components must all be carefully selected to suit the target application. The choice of mobility platform, itself, is heavily dependent on the physical conditions into which the robot will be deployed. A wheeled robot designed to operate on the surface of Mars, for instance, will be completely ineffectual in the microgravity environment found on orbit.


As a highly capable robotic system, Robonaut must be able to move from one worksite to another in order to perform meaningful tasks. Several mobility options are currently being tested. For working outside the International Space Station, Robonaut can climb using the existing astronaut hand rails and then attach it’s foot into existing sockets on the Space Station. The foot then locks, freeing up its hands for performing tasks. In most urban environments, the RMP two-wheeled platform allows Robonaut to balance upright, maneuvering through doorways, aisles, and other tight spaces usually reserved for humans. The Centaur four-wheeled platform was designed for rough terrain. Its knobby tires and built in work space allows for exploration, sample gathering, and astronaut assistance.

Zero-G Leg

zero-g leg

The zero-g stabilizing leg allows Robonaut to attach to assist EVA astronauts. Robonaut can climb along astronaut handrails and then utilize the special latching foot to attach to the same WIF sockets used by the astronauts. The leg has seven degrees of freedom and can sense and control interaction forces with stiff environments like a spacecraft's hull.


RMP base

DARPA’s Mobile Autonomous Robot Software (MARS) Program and the US Navy have loaned the Robonaut team one of the first new Segway designed for use as a mobile robot.  Called the Robotic Mobility Platform (RMP), this two-wheeled vehicle can balance and hold position, while driving front to back and turning. 

The Robotics System combines the mobility and manipulation skills that are required for advanced EVA missions.  NASA recognizes that the unique mobility base is unlikely to operate in space, but is using this system as an inexpensive lower body for testing the Robonaut system.  Other more space relevant lower bodies are now in development and testing, such as the 0g stabilizing leg that has been produced for experiments with Robonaut on an air-bearing sled.

The Robonaut configured with a Segway RMP has been taken on travel to demonstrate it unique capabilities.  These trips have included to Hogg Middle School in the Houston area, NASA Headquarters and the DARPA IPTO fair held in November 2003.  Future trips include a visit to the DARPATech 2004 conference in March 2004.

The Robonaut team has made a number of upgrades to the system to make it an appropriate lower body for Robonaut B.  These include the following enhancements over the delivered RMP:

Software Upgrades


  • Position/attitude hold command
  • Ethernet Heartbeat drop out detection
  • Virtual limit switch using gyro data


  • NDDS interface for remote control
  • Telepresence interface (foot pedals)
  • Added RMP Model to RoboSIM


Electrical Upgrades


  • Wireless E-Stop for lower body
  • Wireless E-Stop for upper body
  • Tether Box for testing


  • Upper body power control unit
  • Wireless (4 Chan) cameras
  • Wireless Ethernet

Mechanical Upgrades


  • Adjustable training wheels
  • Failsafe skirt for extreme testing


  • Laptop pull out tray and suspension
  • Adjustable load (Stickman) for testing