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Zen Design!
O-man waves his hand through 60 degrees of motion
By Design News Staff -- Design News, May 16, 2004
When you turn Ojarumaru Man on, he says something (in Japanese) about the firefly on his hat and waves his tiny, 9-gram plastic arm up and down through 60 degrees of motion. Because of O-Man's peaceful, Zen-like demeanor, engineers wanted a completely silent method of actuation that would be cost-competitive with an inexpensive, single-speed motor. (In fact, the original design called for a traditional electromagnetic motor, but engineers rejected it because it was too noisy.) In this simple application, engineers mounted Oman's arm to the output shaft of a Nano-Muscle RS-70-CE actuator, which runs off of two AA batteries and uses shape memory alloys (SMAs) as the motive force. SMAs undergo a solid-state phase change when their temperature drops below a specific transition point, providing constant power output across the entire stroke length and a force-to-weight ratio on the order of 15 kgf/m2.
| WEB Resources | ||
| Nanomuscle offers a new commercial development kit for its RS-70-CE actuator for $199.95 or toy development kit for $179.95. For details, go to http://rbi.ims.ca/3849-563 | ||
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APPLICATION:Ojarumaru Man—a toy modeled after a famous animated character that is currently sold by McDonald's restaurants in Japan. O-man (as he's fondly referred to) waves his hand through 60 degrees of motion.
LOCATION: Sold at McDonald's Restaurants, Japan
DESIGN ENGINEERS: Ransom Lui, VP of Engineering Creata, Hong Kong Katie Broughton, Principal Engineer NanoMuscle, Antioch, CA
ENGINEERING CHALLENGE: Find a way to move O-man's 9-gram plastic arm that is completely silent (so not to drown out his voice) and cost competitive with a traditional rotary motor.
NANOMUSCLE RS-70-CE ACTUATOR SPECS:
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Operating voltage: 3V (runs off 2 AA batteries)
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Operating current: 200 mA (average)
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Nominal Torque: 12 g-cm
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Rotation angle: 60 degrees
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Actuator Dimensions: 50 × 12 × 10 mm
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Run time per charge: 4 hours
