Get Yourself A Robot Who Can Do Both: Wearable Third Arm Can Punch Walls And Pick Fruit

The project is a collaboration between Createk, Exonetik and the Université de Sherbrooke, Canada. Createk Engineering Lab/Youtube

As three children recently found out, spider bites won’t give you superpowers, but a robotic third arm on the other hand may fulfill their dreams without the injection of venom.

A team of researchers led by Catherine Véronneau from the Université de Sherbrooke, Canada, and in partnership with Exonetik, have developed a “proof of concept” robotic arm that can pick fruit, play badminton, and even punch through walls. Combining the powers of Doc Ock with the Hulk smash, this extra limb is a great leap forwards in wearable robotics, usually limited to slow-moving and lightweight tasks. Somewhat detracting from the superhero vibe of the arm, however, is the tethered power-supply and its inability to move autonomously (it is currently controlled by a second person using a miniature version). Nevertheless, its myriad of abilities in three degrees of freedom is still pretty cool.


To get to this point the team has had to overcome numerous design challenges already. As described in their paper, published in IEEE Robotics and Automation Letters, the team’s robotic arm had to be lightweight, to avoid burdening the user, but strong enough to accomplish useful tasks (like punching a wall). Weighing in at just over 4 kilograms (8.8 pounds), the waist-mounted hydraulic arm has about the same mass as a human arm, and can itself lift 5 kilograms (11 pounds), enough to carry manual industrial tools.

With the potential to damage its user, it was important that the robotic arm could be quick enough to accommodate for the unpredictable motions of humans, but to not topple anyone over when doing so. Reaching a max speed of 3.4 meters per second (7.6 miles per hour), the robotic limb, powered by magnetorheological clutches and hydrostatic transmissions, has shown that in practical scenarios it can smoothly move at high speeds. As for the steadiness of its user, Véronneau told IEEE Spectrum that in her experience of wearing the arm, it depends on the activity.

“I get used to it quickly, and I can compensate for some of the movements (x, y, and z translational movements), but I still have some remaining issues to compensate for torsion movements (like if the arm is hitting a tennis ball with a racket), which is funny,” Véronneau said.

As well as exploring the field of autonomous control for the arm, Véronneau and her team have another task they want to achieve. They want to recreate this (faked) advert of a robotic arm that holds someone’s beer whilst they bust some moves but for real with their extra limb.


“The major challenges associated with this stunt is that we need hip positions and orientations (or the base of the arm) in real-time to stabilize the end-effector [hand] and having this measure implies an absolute way to measure it (cameras, or GPS, etc.),” Véronneau told IEEE Spectrum. “We are now working on it!”

I don’t know about you but the ability to avoid drink spillage and still dance wildly may be the greatest superpower I’ve ever heard of.

[H/T: IEEE Spectrum]