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#cubli#reactionwheels#controltheory

The Cubli: a cube that can jump up, balance, and 'walk'

Gajamohan Mohanarajah (Gajan)

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Beginner. No background in the topic needed.

15M views12 years ago1 recommendation

HardwareSystems programmingEmbedded systemsElectronics

A demonstration of the Cubli, a robotic cube that uses reaction wheels to jump, balance on a corner, and walk.

The Cubli is a 15 × 15 × 15 cm cube that can jump up and balance on its corner. Reaction wheels mounted on three faces of the cube rotate at high angular velocities and then brake suddenly, causing the Cubli to jump up. Once the Cubli has almost reached the corner stand up position, controlled motor torques are applied to make it balance on its corner. In addition to balancing, the motor torques can also be used to achieve a controlled fall such that the Cubli can be commanded to fall in any arbitrary direction. Combining these three abilities -- jumping up, balancing, and controlled falling -- the Cubli is able to 'walk'. Lead Researchers: Gajamohan Mohanarajah and Raffaello D'Andrea This work was done at the Institute for Dynamic Systems and Control, ETH Zurich, Switzerland and was funded in part by the Swiss National Science Foundation (SNSF), grant number 146717. For more details visit: idsc.ethz.ch/Research_DAndrea/Cubli Other links: robohub.org/swiss-robots-cubli-a-cube-that-can-jump-up-balan… youtu.be/bMuCACqwI4s (Zurich.Minds talk on Cubli)

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1 person recommends this

What people say. Shared as a fascinating demonstration of control theory and reaction-wheel robotics achieving complex physical locomotion.

lh7777on Hacker News • Recommends

On “I designed a cube that balances itself on a corner”

> I plan to add mechanical brakes to the reaction wheels...This enables jump-up manoeuvers which in turn enable the cube to get to its equilibrium position on its own. Looking forward to this -- I always thought that was the coolest part of the Cubli project. Here's a video: link to this video

justifieron Hacker News • Mentions

On “The Science of the Missing Gravitational Waves”

> Consider the Bullet Cluster, which is two colliding galactic clusters. The gravitational center of mass is offset from the visible center of mass. This offset cannot be explained as potential energy of visible matter. There must be something else, invisible and massive, i.e. dark matter. i'd argue another possible explanation to add to your i.e. was addressed by the gp gp> then galaxies are not moving in the way we currently think they are. the movement of gyroscopes can alter a system's center of mass link to this video

venningon Hacker News • Mentions

On “Japan's zero-gravity space drone sends first pictures from ISS”

From a related video: the reaction wheels spin up while keeping total angular momentum at zero, then apply a rapid (magnetic) brake to transfer the momentum to the body (from the wheels). I'm assuming if you do that precisely enough (and in three dimensions), you can generate linear movement. EDIT: I'm probably very wrong about the movement. EDIT: The video: link to this video

jrussinoon Hacker News • Mentions

On “I designed a cube that balances itself on a corner”

In the old Cubli videos they go further, chaining together "jumping up", balancing, and controlled falling to demonstrate locomotion! link to this video