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Sophisticated computer programs enable automatic operations or allow the astronaut to operate the arm in several control modes, ranging from complete end-point control (where the astronaut "flies" the end of the arm) to moving one joint at a time. The arm also has a contingency back-up mode that can be used to complete missions, if the primary control system fails.

The Canadarm is capable of maneuvering payloads of nearly 30 000 kg mass in space at speeds (depending on the payload mass) of up to 60 cm/s. It can place such payloads in any position, with an accuracy of approximately 5 cm. Each joint is powered by an optically commutated, brushless DC motor driven by a specially designed servo-power amplifier. To obtain the high joint torques needed from the small, high-speed joint motors, a high-reduction gearbox with an epicyclic/planet system is used in each joint. Gear ratios range from 1842:1 to 739:1 on different joints.

Demanding stiffness and strength requirements, coupled with volume constraints imposed by the shuttle, dictated extensive use of the latest AEROSPACE materials (eg, TITANIUM, stainless steel, ultra-high modulus graphite epoxy). The harsh environment necessitated special attention to thermal design and lubrication. The arm is entirely covered with a multilayer insulation system, consisting of alternate layers of goldized kapton, dacron scrim cloth and a beta cloth (fibre glass) outer covering. In extremely cold conditions, thermostatically controlled electric heaters protect critical electronics.

The Canadarm was designed to have a minimum lifetime of 10 years and to be used for up to 100 missions. It weighs under 450 kg and cannot support itself in normal gravity; hence, a complex simulation facility (SIMFAC) had to be developed to verify its operation in space before its first flight and to facilitate astronaut training. On Earth, the assembled arm could only be tested in one plane at a time by using a special air-bearing cradle operating on a specially designed flat-floor area.

The $110-million Canadarm development program was largely carried out by Canadian industry, under the direction of the NATIONAL RESEARCH COUNCIL OF CANADA. The industrial team, led by SPAR AEROSPACE LIMITED, included CAE Electronics Ltd and DSMA Atcon Ltd. The export-oriented, industrial returns achieved to date include the sale and maintenance of 4 Canadarm systems to NASA (one of the 5 built was donated); the sale of robotic components to Japan and Europe; the sale of simulators; and the development of robotic systems for the nuclear industry. Canadarm has allowed the establishment in Canada of an industrial capability in the HIGH-TECHNOLOGY fields of advanced manipulator systems and ROBOTICS.

The arm first flew in November 1981 on the second space shuttle flight and performed well, exceeding all design goals. It was declared operational one year later, after 3 successful test flights. Since it first flew, Canadarm has become an important symbol of Canadian prowess in technological fields. In the first 80 flights of the shuttle between 1981 and 1997, Canadarms have flown 47 times. The best-known tasks carried out with Canadarm have been the capture, repair and deployment of several satellites, including 2 missions to the Hubble Space Telescope; the docking of the space shuttle to the Russian Mir space station; and the knocking-off of ice growths that were causing a blockage to a waste exit on the shuttle. The Canadarm, along with the Mobile Servicing System also being developed by Canada, will be essential for building the International Space Station.

Canadarm in Action
(courtesy NASA)

Canadarm
Canadarm2 after its installation on the International Space Station by CSA Astronaut Chris Hadfield and the STS-100/6A crew (courtesy Canadian Space Agency).

Author KARL DOETSCH and GARRY LINDBERG

Links to Other Sites
Canadian Space Agency
A fascinating website devoted to Canada's far-reaching space program. Check out the latest news about Canadian astronauts, Canadarm and Canadarm 2, recent space missions, and more. Also features "Canadian Space Milestones" and educational resources for students and their teachers.

Canadarm - A Technology Star
This CBC website features amazing video clips of the Canadarm and Canadarm2 robotic arms working in outer space.

Canada and the International Space Station
This CBC website focuses on the operational role of the new Canadarm 2 which is now part of the International Space Station.

Canadarm Wrestling
Get a handle on the differences between the Canadarm on the Space Shuttle and the newer version on the International Space Station (ISS). An educational feature from NASA.

The Canadarm
A slightly more technical description of the design and operation of the "Shuttle Remote Manipulator System," commonly referred to as the “Canadarm.” From the website for the Institute of Electrical and Electronics Engineers Canada.

Garry Lindberg
A video profile of Garry Lindberg, Canadarm project manager. From the University of Alberta.

Lloyd Pinkney
A video profile of Lloyd Pinkney, who devised the vision system used on Canadarm. From the University of Alberta.