Posted by: robotnews | April 1, 2006

Maintenance & Repairs in Space – Rangers

u0204781 Peh Meng Wee

“Hello International Space Station maintenance. What! Sector 4 has been hit by an asteroid! We’ll send in the robot maintenance crew to take a look immediately.”

Does the previous scenario entice you? Or does the image of R2D2 repairing Luke Skywalker’s fighter in “Star Wars” amazes you. Well, soon these scenes will not be science fiction stuff but would be played out right above our heads. in space

Since the beginning of time, humans have looked to the stars for guidance and dreamed of ascending to the heavens. However, hostile conditions in space have impeded mankind’s development and knowledge in this area. The construction of the international space station (ISS) represents a leap in mankind’s determination to explore and conquer the last unexplored frontier. However, following the Challenger disaster, there has been an upsurge in interest to use robots to replace humans in doing dangerous jobs like repair/maintainence in space. Unforseen circumstances like space debris, radiation makes it dangerous for astronauts to work outside their ships or structrues. Moreover, robots do not need to eat and sleep and will not tire, thus making them better suited for “living” in space.

After the lengthy introduction, I must introduce you to the Ranger, a space repair and maintenance robot. The Ranger system include four manipulators: two 7-DOF bilateral dexterous manipulator(one a normal arm and one an engineering arm), a 6-DOF grappling manipulator for worksite stability, and a 5-DOF camera positioning manipulator to locate a pair of stereo video cameras. A second video camera on the vehicle centerline will provide a stable visual reference for free-flight maneuvering and autonomous docking.

Unfortunately the rangers system is still in development. Only prototypes are available. However the prototype has shown that it is capable to do heavy tasks like opening hatch doors and menial tasks like tightening of a bolt under neutral buoyance. The fact that it can do this 2 totally different kind of tasks shows that the precision and control involved in the system is very advance and state-of-the-art. Those intersted in the specfications of the Ranger prototypes can be go here.

This short clip will simulate portions of the removal and replacement of a Hubble Space Telescope electronics control unit (ECU). In the clip, the Ranger engineering arm moves back to get the bare bolt drive which is mounted on a tool post. With the bare bolt drive attached to its wrist, the arm moves to one of the ECU keyway slot bolts. After turning the bolt, the arm moves away from the bolt and places the bare bolt drive back on a tool post. The parallel jaw mechanism is retrieved which has a set of “fingers” that fit around the tether loop. The “fingers” are closed around the tether loop as the video ends.

A lengthier video of the prototypes under buoyancy tests performance various tasks can be seen here.

However, sad to say, the rangers are not autonomous but rather teleoperated. They can be controlled either from Earth or from a base station in space. But then, sometimes it might be better to put your lives in the hands of another human being instead of a robot.

I believe that the Rangers will make the headlines soon when the question of prolonging the lifespan of the Hubble Space Telescope comes up. The Rangers would most probably be called upon to do the job and when that time comes, it will mark a new era in roles of robots in the exploration and development of outer space.

For more information, please visit this websites.
NASA Telerobotics Program Overview
Ranger Robotics Program

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Responses

  1. U0204511 Tan Chin Hiong

    This will definitely reduce the cost of space maintainence. Up till now, a maintainence crew is sent up to space when maintainence is required. Now, a Ranger can be permanently stationed in space (which a human cannot do). Whenever repairs is needed, the Ranger will be there for prompt actions. This will be much faster and cheaper than having to launch a space shuttle to space every time maintainence is needed.

  2. U0204808 Li Junsheng

    Hmmm, as much as it helps in maintenance and repairs, these robots still need to be sent to space and perhaps brought back from time to time. After all, who will upgrade, maintain and repair the Rangers themselves? Until people come up with AI and control at the level of C3PO and R2D2, I think humans are still very much an essential factor in maintenance and repair.


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