ABSTRACT
There is increasing activity in space on a lot of fronts: launch, space stations, planetary rovers, satellite launch/ maintenance, asteroid prospecting, tourism etc. There is a lot of activity in the micro-gravity environment of Low Earth Orbit (LEO) and soon cislunar space: ISS, Hubble telescope, satellite maintenance, and other planned space stations. Today a lot of tasks in this micro-gravity environment, especially on the ISS, are done by humans (e.g. ISS construction, ISS battery replacement or Hubble telescope repair etc.). These tasks are ideally suited for robots, but current Earth based robots don’t work in space because of lack of gravity. There is need for free flying robots that can operate in the microgravity environment of space and perform needed tasks.
There are several challenges with getting robots to work in the microgravity environment of space:
This paper proposes a robot design that can effectively move, orient and maintain its position in microgravity. The robot has a cube structure for symmetry. The robot uses cold gas propulsion to control both translation and rotation motions. It has twelve cold gas propulsion nozzles on four out of six faces of the robot. The paper provides mathematical equations relating distance traveled and angle of rotation to the needed fuel (an inert gas, either N2 or CO2). The paper includes equations to calculate 3D routes that are either speed or fuel optimized. The paper also discusses methods to maintain robot position and attitude when the robot expands its appendages or turns, which is a challenge due to conservation of linear and angular momentum.
Additional research work is needed to design autonomous control and operation of the robot. 3D mapping is another area which needs work for the robot to be effective. These topics are not addressed in this paper, but are areas of research for the future.
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Micro-G Robots (pdf)
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