Disney uses store-bought conductive thread to build robot muscles


Researchers have developed an inexpensive way to make artificial muscles using off-the-shelf supplies.


They say Disney World is the most magical place on Earth, but we’d argue that it may come second to their research lab. From 3D-printed plush toys to autonomous sand drawing robots to bipedal droids that walk like animated characters, the Disney Research team continues to dream up some impressive innovations that blend fantasy with the real world.

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In an effort to make robotic arm automation more lifelike, a group of Disney engineers have found a way to develop strong, artificial muscles using inexpensive, store-bought conductive sewing thread coiled into a shape that resembles somewhat of a DNA helix.

“Natural muscles exhibit high power-to-weight ratios, inherent compliance and damping, fast actuation and high dynamic ranges. Unfortunately, traditional robotic actuators have been unable to attain similar properties, especially in a slender muscle-like form factor. Recently, super-coiled polymer (SCP) actuators have rejuvenated the promise of an artificial muscle,” the researchers write.

Movement is facilitated through the heating and cooling of the off-the-shelf strings. As the strands fluctuate in temperature, the cables contract and expand like a human muscle, which in turn, pulls the fingers causing the artificial hand to close. While the researchers initially set out to find a low-cost way to create artificial muscles, their project yielded controlled forces in less than 30 milliseconds — actually outperforming the capabilities of a human muscle.

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“The average human skeletal muscle has a twitch cycle of over 100 ms, and reaches a steady-state force in hundreds of milliseconds. Furthermore, the peak power- to-weight ratio of mammalian skeletal muscle is 0.32kW/kg, whereas these actuators have been shown to generate up to 5.3kW/kg,” the team adds.

For their demonstration, Disney Research employed a 3D-printed robotic hand — which had been crafted using an AVR powered Makerbot Replicator 2 machine — comprised of four fingers and a thumb with actuators on each tendon enabling a full range of motion. The muscles were strewn along the forearm of the robot to mimic the physical locations of a human arm, while four small computer fans were used to cool the actuators during relaxation. As for its electronics, the arm was driven by an Arduino Nano (ATmega328) along with some simple MOSFET PWM-switching supplies.

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“The robot arm was able to perform various grasping maneuvers. The grasps were performed in under a second without the benefit of any feedback sensor, using a lead compensator to improve the speed of finger motions. Each finger can be manipulated individually, and there was no noticeable crosstalk between actuators.”

Does this mean that in the future we’ll see more realistic movements by Disney automations at its parks worldwide? As we wait to find out, you can read its entire paper here.

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