Impact Stabilization of Spinning Tether Systems After Nonideal Rendezvous

Spinning tether systems are considered a good platform for payload transportation and active removal of space debris. Such maneuvers require rendezvous with targeted objects. Due to the inevitable maneuvering error, rendezvous usually happens not at a designated ideal position, but within the acceptable capture range; that is, the rendezvous is usually nonideal. Nonideal rendezvous have impacts on both orbital and spinning motions of spinning tether systems. This paper studies the dynamics and control of nonideal rendezvous maneuvers. Tension force, aerodynamic force, and damping (friction) force are considered. The assumption of distributed parameters (flexible lumped model) is proposed to calculate the instantaneous impact of rendezvous. Analysis indicates that the orbit of a tether system drops after rendezvous, and a catastrophic sudden peak of tension force forms right after a nonideal rendezvous, which leads to the breakage of the tether. The aforementioned impact is most significant at the boundary of the available rendezvous range and neglectable at the ideal position. To deal with the sudden peak, a nonlinear sliding mode controller with the double-power reaching law is proposed to stabilize the impact of rendezvous by adjusting tether length. Numerical results validate the effectiveness of the proposed sliding mode controller for stabilizing the impact of nonideal rendezvous. The capture envelope is enlarged by five times. The aerodynamic force has small but ongoing perturbations on orbital motion but insignificant influences on instantaneous spinning motion after rendezvous.