Impulsive Super-twisting Sliding Mode Control for Space Debris Capturing via Tethered Space Net Robot

Tethered Space Net Robot (TSNR) has been proposed as a promising method for active space debris capturing and removal since space debris have posed a big threat to operational satellites and astronauts. After contacting the debris, the net cannot naturally wrap around the debris, especially when the debris does not contact the net in the center. Thus, it is worth investigating the net closing control of TSNR. Two requirements should be satisfied in the net closing control algorithm. First, the control algorithm should make the net close around the debris in a very short time to avoid the escape of the debris. Second, the control input should be continuous to avoid the oscillations of net tether caused by high-frequency control instructions. Based on the two requirements, an impulsive adaptive super-twisting (IASTW) sliding mode control scheme is proposed to complete the net closing action. The control scheme can drive the state vectors convergence to the origin in a short time and keep it there thereafter. The numerical simulation results illustrate the efficiency of the proposed control algorithm, in which the two requirements are all satisfied.