Design and control strategy of a self-growing flexible variable stiffness robotic arm for space debris capture

Space technology is a valuable contribution to the development of human science and technology and is the basis for human exploration of the vast universe. To guarantee the safe operation of space personnel and equipment, a space debris capture technology, a space hazardous matter removal or transfer technology, has been proposed under increasingly frequent human space activities. Fast-developing space debris capture equipment has provided the basis for realizing this technology. Existing capture methods, such as rigid robotic arms, nets, and balloons, limit the adaptability to space debris of different distances and sizes. Additionally, there is a lack of a capture device and strategy that can cope with various types of space debris. To address these problems, in this paper, a new type of spatially self-growing flexible variable stiffness robotic arm is designed and promoted using the variable stiffness characteristic of curved-shell beams, which realizes a wide range of adjustability of the working space of the robotic arm. On this basis, the kinetic analysis of this new type of robotic arm is performed, which leads to the principle of equal moments for the distribution of the robotic arm lengths and further the corresponding algorithms. We also proposed a series of strategies oriented toward the capture of space debris of various sizes and adopted the methods of sampling obstacle avoidance and spline curves for trajectory planning of the robotic arm. Finally, we simulated the proposed control method for a self-growing flexible variable stiffness robotic arm and verified its feasibility.