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Frame from The Cubli: a cube that can jump up, balance, and 'walk' Plays via YouTube's privacy-enhanced embed

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

Gajamohan Mohanarajah (Gajan)
Demos
YouTube
1 HN user recommended this demo1 month2016–2024 score 1
Years with an HN recommendation, 2007–2026

Brought up whenever reaction wheels or self-balancing cubes come up, with the jump-up maneuver singled out as the coolest part.

A demo of the Cubli, a 15 cm cube that uses reaction wheels to jump up onto a corner, balance there and fall in a controlled way to move. The video shows these three abilities chained into locomotion.

“I always thought that was the coolest part of the Cubli project.” (HN, 2024)

1 recommendations · 3 citations · Demos

4 Hacker News comments

From the HN archive; up to 20 kept per video, favoring different commenters. Recommendations first.

@lh7777 Feb 2024 Recommends
on HN thread 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: [this video]
Cubli jump-up maneuver is the coolest part

Citations, criticism and jokes

@justifier Jul 2016 Cites it
on HN thread 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 [this video]
Gyroscopic reaction wheels shifting center of mass
@venning Jul 2017 Cites it
on HN thread 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: [this video]
Reaction wheels with braking transfer momentum to the body

Video list and Hacker News comment labels from HackerTube (prompted by @karpathy), released under ODC-By 1.0, built on the open-index/hacker-news archive. Hacker News data is provided by Y Combinator; comments remain the work of their authors. Video titles, channel names and thumbnails belong to their creators and are shown via YouTube. HackerTube Watch is an unofficial edition. Data export of 2026-10-31.

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