Orbit-attitude coupled dynamics modeling and adaptive sliding mode control for detumbling large space debris

For non -cooperative large tumbling space debris, the use of detumbling techniques to reduce its angular velocity facilitates capturing and deorbiting operations. In our recent work, a new detumbling device combining three harpoons and a nanosatellite was designed. The device is released from the servicing satellite and attaches to the surface of the target. Then, the device's thrusters are actuated to reduce the target's angular velocity. In this paper, the dynamics and control issues involved in this strategy are further investigated. The collision model between the detumbling device and the target in the process of attachment is built based on the principle of momentum conservation. A high -precision orbit -attitude coupled dynamics model of the combined system during the detumbling mission is established, in which major external disturbances as well as inertial parameter variations due to the fuel consumption of the nanosatellite are taken into account. In addition, an adaptive sliding mode control scheme incorporating pulse -width pulse -frequency (PWPF) modulation is proposed for debris targets with parametric uncertainties and external disturbances. Finally, the effectiveness and robustness of the detumbling control scheme are demonstrated by numerical simulations. The results show that the detumbling device is capable of detumbling a large tumbling rocket upper stage within 4000 s.