  This paper presents the design of a small aerial robot for inhabited
microgravity environments, such as orbiting space stations (e.g., ISS). In
particular, we target a fleet of robots, called Space CoBots, for collaborative
tasks with humans, such as telepresence and cooperative mobile manipulation.
The design is modular, comprising an hexrotor based propulsion system, and a
stack of modules including batteries, cameras for navigation, a screen for
telepresence, a robotic arm, space for extension modules, and a pair of docking
ports. These ports can be used for docking and for mechanically attaching two
Space CoBots together. The kinematics is holonomic, and thus the translational
and the rotational components can be fully decoupled. We employ a
multi-criteria optimization approach to determine the best geometric
configuration for maximum thrust and torque across all directions. We also
tackle the problem of motion control: we use separate converging controllers
for position and attitude control. Finally, we present simulation results using
a realistic physics simulator. These experiments include a sensitivity
evaluation to sensor noise and to unmodeled dynamics, namely a load
transportation.
