To test our technology at Meta Futura, I had to develop a couple of floating platforms to test our algorithms in simulated microgravity.
Simulating microgravity in 2 dimensions (3DOF) is quite straight forward in theory, but reality makes it quite complicated.
The most common approach involves having a very flat surface and 3 graphite flat bearings. By supplying the bearings with compressed gas, this escapes through the porosity of the graphite, creating a very thin gas film that practically makes the bearing float with almost non existant friction.
If the surface is flat, the gravity force component that could push the platform side to side approaches zero. The reality is that the biggest the surface the harder it is for it to be flat.
The first tests we performed where done on a granite reference table at Surrey Space centre, that allowed us to test our thrust vectoring ability and the control algorithms.
This system used two compliant thrust vectoring mechanisms with cold gas thrusters to move around. Here's a simulated rendezvous manouvre. Movement is tracked with Qualisys motion capture system.
This was nice but we wanted more: more thrust, more weight, more space to move. We were able to develop a new bigger platform and test at the European Space Agency's Orbital Robotics Laboratory, one of the biggest in the world. The concept is the same, but instead of a graphite table, there's an ultra flat polished epoxy floor. Spoiler, it is not that flat, as the building foundation lay on sand and the facility is at the second floor! This means that the building moves and when the platform moves around (at up to 150kg) the floor bows.Â