Nonlinear Backstepping-like Feedback Control for Deploying Space Tethered Satellite

In this paper, a novel nonlinear control approach is proposed for deploying the space tethered satellite (STS), via the backstepping-like feedback control (BFC). By using the Lagrangian mechanics theory, the STS model in elliptical orbit is presented, taking the actual situation of deployment mission into account. Then, a BFC controller is developed by means of the Lyapunov method, which can be applied into non-strict-feedback system and can effectively improve the control performance, compared with traditional backstepping methods. In addition, given the external disturbances of STS system, an observer-based BFC scheme is proposed to eliminate the influence of disturbances and complete the tether deployment mission within a finite time. Finally, the effectiveness of the proposed controller is verified by simulation results.