Force-position collaborative optimization of rope-driven snake manipulator for capturing non-cooperative space targets

With the rapid development of space activities, non-cooperative space targets increase swiftly, such as failed satellites and upper stages, threating normal spacecrafts seriously. As there are some problems in the capture process, such as excessive collision and fast tumbling of targets, manipulator with redundant Degrees of Freedom (DOFs) can be used to improve the compliance and therefore solve these problems. The Rope-Driven Snake Manipulator (RDSM) is a combination of hyper-redundant DOFs and better compliance, and therefore it is suitable for capturing mission. In this paper, a snake manipulator mechanism is designed, and the complete kinematic model and system dynamic model considering RDSM, target and contact is established. Then, to obtain the configuration of joint with hyper-redundant DOFs, an improved motion dexterity index is proposed as the joint motion optimization target. Besides, the force-position collaborative optimization index is designed to adjust active stiffness, and the impedance control method based on the modified index is used to capture the space target. Finally, the proposed force-position collaborative optimization method is verified by virtual prototype co-simulation. The results demonstrate that based on the proposed method, the collision force is reduced by about 25% compared to normal impedance control, showing higher safety.