– We are trying to replicate how a spacecraft moves in orbit, how to control it and how to coordinate it with other spacecraft, says Chris Nieto, PhD student in Onboard Systems.
– For example, we are simulating an automated docking scenario, in which one spacecraft needs to catch another one. This is similar to the case when a capsule docks to the International Space Station.
The experiments carried out with the platform will help the researchers to validate space components and control algorithms.
– The community will directly benefit in being able to perform more complex space missions while maintaining an acceptable safety level.
Experiments without friction
Frictionless platforms are used to emulate orbital dynamics in a laboratory. Air bearings support the platform to minimize the force that appears when two surfaces that are in contact move one relative to the other. Due to the lack of a “ground to stand on” in an orbital context, spacecraft do not experience such a friction force.
– The air bearings that support our platform create a layer of air, thinner than a piece of paper, that prevents any direct contact with the testbed surface. Such a surface must be very flat and leveled to minimize artificially induced forces that may disturb the results of the experiments, Chris Nieto explains.
– Additionally, eight air thrusters are distributed around the structure of the platform and they are used for changing the position and orientation of the platform in three degrees of freedom.
To drive all pneumatic components in the instrument, the system stores up to 300 bar of compressed air in a one-liter tank that allows for tests with a duration of ten minutes in normal conditions. That duration is enough to prove the most important dynamic behavior for spacecraft systems. Finally, an inertial measurement unit is constantly sensing the acceleration, angular velocity and magnetic field of the platform to feed the autonomous control algorithm.
– The uniqueness of our simulation environment is the size of the testbed area, fourteen squared meters, and the capability of combining our frictionless platform with a fixed-based robot manipulator and a moving-based robot manipulator.