FRDP: A Micro Free-Flying Robot With Dual-Vector Propulsion in Space Station

This article details the design, modeling, and control of the FRDP, a novel free-flying robot with an innovative dual-vector propulsion structure for space station. Compared with the existing free-flying robots, FRDP achieves a significant reduction in weight and size by decreasing the redundancy of the propulsion module, while maintaining stronger mobility when carrying more sensing and computing modules. A new control allocation method for this dual-vectored propulsion structure is presented, enabling the generation of thrusts and torques in six degrees of freedom (DOFs) using four actuators. To adapt to various mission requirements, FRDP features both energy-saving mode and performance mode. The dynamic modeling and controller design for both modes are described, and the maneuvering performance and energy efficiency of the two modes are analyzed and compared. Simulation and real-world experimental results fully validate the effectiveness of the designed dual-vector propulsion structure and dual-modal controller, demonstrating FRDP’s potential for task execution in space station environments.