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Dextre: a helping hand in space March 11, 2008

Posted by eyegillian in Canada, design, explore, science, space, technology.
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Space station mobile servicing systemThis morning’s launch of the shuttle Endeavour also launched the career of a new astronaut: Dextre.

The Dextre manipulator (or Special Purpose Dexterous Manipulator), a sophisticated dual-armed robot, is part of Canada’s contribution to the International Space Station (ISS). Designed for servicing the Station, Dextre can remove and replace small components on the Station’s exterior that require precise handling.

Like a mechanic in space, Dextre can pivot at the waist, and its shoulders support two identical arms with seven offset joints that allow for great freedom of movement. It is equipped with lights, video equipment, a stowage platform, and four robotic tools.

At the end of each arm is an orbital replacement unit/tool changeout mechanism, or OTCM-parallel jaws that hold a payload or tool with a vice-like grip. For fine manipulation tasks, Dextre has a unique technology: precise sensing of the forces and torque in its grip with automatic compensation to ensure the payload glides smoothly into its mounting fixture. To grab objects, each OTCM has a retractable motorized socket wrench to turn bolts and mate or detach mechanisms, as well as a camera and lights for close-up viewing. A retractable umbilical connector can provide power, data, and video connection feed-through to payloads.

Dextre in cargo bay of space shuttle EndeavorThe cargo bay of Shuttle Endeavour with the Canadian robot Dextre and the pressurized component of Kibo, the Japanese Experiment Module.

Dextre can accomplish tasks that require high precision and a gentle touch such as removing and replacing Station components, opening and closing covers, and deploying or retracting mechanisms. Some of the many tasks Dextre will perform include installing and removing small payloads such as batteries, power switching units, and computers, as well as manipulating, installing, and removing scientific experiments.

A typical task for Dextre would be to replace a depleted battery (100 kg) and engage all the connectors. This involves bolting and unbolting, as well as millimetre-level positioning accuracy for aligning and inserting the new battery.

Like the Canadarm2 and the Mobile Base System, Dextre can be controlled from a workstation inside the space station or by controllers on the ground in mission control centres in Houston, Texas and at Canadian Space Agency headquarters in Longueuil, Quebec. Its five cameras, including two pan/tilt cameras below its rotating torso, provide operators with multiple views of the work area.

Dextre, Canadarm2 and the Mobile Base System form a robotic system called the Mobile Servicing System (MSS). The MSS is built for the Canadian Space Agency by the Canadian company MD Robotics.


(Information and illustrations: Canadian Space Agency)

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1. Richard - March 13, 2008

I’m amazed at the accuracy of this machine – you say to milimeter accuracy, which is amazing for something so large.

I suppose the only bad thing is it means there will be less spacewalks, because Dextre can replace much of what spacewalks used to do. Anyway, it will be very interesting seeing Dextre in action. It’s nice to see the Canadians doing something in space too. 🙂

2. eyegillian - March 13, 2008

I know spacewalks are fun for us to watch, but the preparation and execution time is a lot of effort for the astronauts, and with the shuttle program ending, I think the space station crew will want to focus on other work…

And, yes Canadians in space – yeah Canada – by “doing something in space”, I presume you mean besides the 8 Canadian astronauts who have been on shuttle missions so far, the Canadarm and the rest of the Mobile Servicing System…!

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