An Omnidirectional Robot Moves by Scooting, Shuffling, Climbing

A team of researchers from the University of Michigan has created SKOOTR, a three-legged robot that skates and shuffles, enabling it to roll as it walks. SKOOTR can maneuver in any direction and is capable of ascending to overcome obstacles.

The concept for the SKOOTR project, short for SKating, Omni-Oriented, Tripedal Robot, originated from assistant professor Talia Y. Moore at the University of Michigan’s Evolution and Motion of Biology and Robotics (EMBiR) Lab.

Inspiration from Everyday Movement

“I conceived this idea while moving around on my office chair amidst groups of students,” Moore explained. “I noticed how effortlessly the passively rolling office chair could rotate in any direction, allowing me to execute various maneuvers while maintaining stability. This omnidirectional agility reminded me of how brittle stars alter their swimming direction.”

Adam Hung, one of Moore’s students, took on the task of designing and constructing a robot with similar capabilities, with support from Challen Enninful Adu and Moore. While three-legged robots excel at maneuvering, elevating one leg for movement can lead to “inefficient and dynamically unstable locomotion.” To address this limitation, Hung incorporated a freely rotating sphere into the design.

SKOOTR comprises a central structure functioning as a control hub, housing an Arduino Uno board, inertial measurement unit, and Li-Po battery. Additionally, it features an underslung cage equipped with spherical bearings interacting with the sphere at four points.

Each leg attached to this hub is equipped with two planar rotational joints, operated by off-the-shelf servos. At the tip of each leg lies a “hybrid end effector,” where a small servo extends a spherical bearing for rolling contact or retracts it, allowing a rubber cap to make contact with the floor to propel or pull the robot.

Enhanced Stability and Obstacle Navigation with the Central Sphere Mechanism

The prominent central sphere serves as an additional point of contact for the robot during movement, enhancing its stability. Moreover, this mechanism allows the robot to grip the ball, elevate it from the ground, enabling the legs to navigate over obstacles like steps or clutter, before lowering it back and propelling forward.

“Thanks to the combination of the central sphere and multiple legs, SKOOTR exhibits remarkable stability,” explained Moore. “Through numerous experiments, we’ve observed that it’s virtually impossible to overturn SKOOTR while it’s operational. Additionally, its capabilities extend beyond what may be apparent from its ‘skooting’ gait. By leveraging its legs to lift the sphere, SKOOTR can overcome obstacles that would pose challenges to other rolling robots. It’s even capable of ascending stairs.”

The project offers open-source access to its build plans, CAD files, and code, with many of the robot’s components 3D-printable using PLA filament and readily available off-the-shelf parts purchasable online. The estimated cost of the project is approximately US$500.

The EMBiR team envisions various potential applications for the robot, including mapping and exploration of challenging indoor environments, payload delivery, and serving as a cost-effective educational resource. Future developments involve integrating sensors for autonomous localization, motion planning, and mapping.

Further information about the project is available on arXiv, and additional insights can be gleaned from the accompanying video.

Read the original article on: New Atlas

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