Rigid–flexible coupling dynamics modeling and fractional-order sliding mode control for large space solar power stations

Precise on-orbit assembly of Space Solar Power Station imposes great challenges on its effective rigid–flexible coupling dynamics modeling and low vibration control. This paper presents an integrated framework combining a reduced-order dynamics model and an improved fractional-order controller of Space Solar Power Station. The dynamics model, developed through Lagrangian equations and finite element methods, reduces system complexity from tens of thousands to tens of degrees of freedom while preserving essential dynamic properties. The fractional-order controller is proposed on this foundation, containing a robust fractional-order sliding surface for chattering suppression and the super-twisting algorithm for uncertainty and disturbance rejection. Simulations of three critical assembly phases are conducted to demonstrate the closed-loop behavior, simulation results show significant improvements in convergence time (reductions ranging from 44.6% for truss docking to 78.2% for antenna adjustment) and vibration suppression (vibration mode peaks decrease from 49 to 9 for ${\eta }_1$ and 65 to almost 0 for ${\eta }_2$) compared to the PID controller, verifying the effectiveness of the proposed control strategy.