Virtual-Integrated Admittance Control Method of Continuum Robot for Capturing Non-Cooperative Space Targets

Abstract

Continuum robots (CRs) are highly effective in grasping moving targets in space through whole-arm grasping (WAG), offering broad applicability and reliable capture. These characteristics make CRs particularly suitable for capturing non-cooperative space targets. Compliant control plays a crucial role in ensuring safe and reliable interactions during the grasping process. This paper proposes a virtual-integrated admittance control (VIAC) method specifically designed to enhance WAG by CRs. By proactively adjusting the robot's trajectory before contact, the VIAC method effectively reduces the contact force exerted on the target during grasping, enabling compliant capture while preventing target escape and minimizing potential damage. This study first develops a mathematical model of the CR and addresses the inverse dynamics problem. Subsequently, the VIAC method is introduced to regulate contact force and improve grasping performance. This approach integrates virtual forces, derived from position information, with actual contact forces acting on the robot's links, facilitating trajectory replanning through an admittance controller. The virtual forces, constructed based on improved virtual potential fields, reduce the relative velocities of robot links with respect to the target during the approach, ensuring successful grasping. Simulation results validate the effectiveness of the VIAC method, demonstrating a significant reduction in contact force compared to conventional admittance control.