A Compact and Low-Actuator Thrust System for Microgravity Flying Robot in Space Stations

Compact and low-actuator microgravity flying robots represent a promising avenue for narrow-area inspection in space stations. Thus, this article presents an annular attitude nozzle–duct fan thrust system for a compact and low-actuator microgravity flying robotic platform. The proposed thrust system features a more compact structure that reduces the number of actuators, achieving six-degrees-of-freedom (DOF) motion by only six actuators. However, achieving propulsion and precise attitude adjustments depends on the coordinated operation of these duct fans and nozzles. Thus, a coordinate allocation controller has been meticulously devised in this article to address this challenge. This controller autonomously regulates the rotational speed and direction of the duct fans. Additionally, dynamic models of a robotic platform are derived for the control design. Subsequently, a four-DOF helium balloon platform was also designed to validate the efficacy of the coordinated allocation controller and cut costs. The proposed platform maximizes the robot’s inherent symmetry along all three axes, thereby serving as an apt testbed for evaluating the feasibility of coupling attitude and propulsion control. The experiments verified the effectiveness of controllers for attitude control only, propulsion control only, and the coupling of attitude and propulsion control, thus demonstrating the robot’s excellent controllability performance.