Thrust control of tethered satellite with a short constant tether in orbital maneuvering

Abstract

Tethered satellite with chemical propulsion has broad application prospects in the space debris removal, the orbital transfer of space detector and the orbital rescue of malfunctioning satellite. In orbital maneuvering, tethered satellite with a short constant tether can avoid using certain windlass mechanism of base satellite, which is helpful for the implementation of project. In this article, based on a dumbbell model of tethered satellite, dynamic equations of tethered system in orbital maneuvering are established. Furthermore, taking elastic strain of the tether into account in the dynamic model, as the slackness of tether occurs, the effects on tethered satellite of the degree of slackness, initial states of librational angles and the variation of thrust acceleration are analyzed. To avoid several adverse phenomena aroused by the slackness of tether, such as tether winding or collision between satellites, a thrust control method of tethered satellite with a short constant tether in orbital maneuvering is proposed. In this method, the thrust acceleration imposed on the base satellite can be adjusted to avoid the slackness of tether and damp out the librational angles; meanwhile, it is required that the regulating value of thrust acceleration meets with accuracy requirements of orbital trajectory in practical engineering; therefore, a continuous thrust controller is presented based on the feedback of tether tension; besides, considering in practical engineering that the continuous thrust is always replaced by an impulse thrust, the ranges of impulse thrust parameters, such as impulse width and duty cycle, are studied. Afterwards, an orbital transfer case between two circular orbits is studied to demonstrate the effectiveness of the tethered satellite with a short constant tether in orbital maneuvering. In this case, an orbital transfer strategy for tethered satellite is designed based on a continuous thrust. Numerical simulation results show that the slackness of tether can be eliminated and the librational angles are damped out according to the thrust control scheme in orbital maneuvering; in addition, the stability of tethered system could be guaranteed by the designed thrust controller, which is useful for flight safety.

Optimal Control Scheme of the Tethered System for Orbital Transfer under a Constant Thrust

“…Linskens and Mooij focused on the preliminary design of a guidance and control system to achieve space-debris removal as well as on the influence of different tether parameters on mission performance [9]. Sun et al derived analytical solutions of the librational angles; besides, a method of hierarchical sliding mode tension control and a method of thrust control are presented to solve the control problems of the tethered system under a thrust, respectively [10][11][12]. Huang et al studied the coupling dynamics modelling of a tethered space robot, explored a space tethered towing method which utilizes thrust to fulfill transfer, and bounded tension to stabilize tether heading; besides, Huang et al studied the dynamics analysis and a controller design for maneuvering a tethered space net robot and also discussed the design, measurement, control, and experiment of a dexterous tethered space robot [13][14][15][16].…”

Anti-sway control of tethered satellite systems using attitude control of the main satellite

“…Many studies have been conducted to reach this goal by using various actuator and control methods. Thrusters on satellites [18][19][20][21], tether tension control [22], tether rate control, and attachment point position control [4] are among the methods that are used to reduce the librational motion of tether. Sometimes the last phase is retrieval which is known to be unstable.…”

Dynamics modeling and model selection of space debris removal via the Tethered Space Robot

“…A simplest, but reasonable dynamics model of the TSS has been derived by several researchers, by treating two end-bodies as massive points, the connecting tether as rigid and uniform in mass, and assuming a circular Keplerian reference orbit for the center of mass of the system. 6,7 This simplest model can be extended directly when the longitudinal flexibility or elasticity of the tether is taken into account, 8–10 and it is also can be used for momentum exchange 11 and orbit transfer. 12 These models are widely used for dynamics analysis and control scheme design during deployment and retrieval because of the well description of basic characteristics of the system, and the simplicity in mathematics.…”