Gajamohan Mohanarajah (Gajan)
1 HN recommender · recommended in 3 months, 2016–2024
2:37 · 16M views · Dec 17, 2013
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.
Brought up whenever reaction wheels or self-balancing cubes come up, with the jump-up maneuver singled out as the coolest part.
4 comments from Hacker News
> 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
> 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
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
In the old Cubli videos they go further, chaining together "jumping up", balancing, and controlled falling to demonstrate locomotion! this video