An improved robust adaptive NFTSMC-STA control for nonlinear
double-pendulum tower cranes
Abstract
When the hook mass of tower crane can not be ignored, the dynamic system
presents double-pendulum characteristics, which brings great challenges
to the dynamic characteristics analysis and controller design of the
crane systems. In this paper, an improved non-singular fast terminal
sliding mode control with super-twisting algorithm (NFTSMC-STA) scheme
is proposed to address the issues of double-pendulum effect,precise
positioning,swing suppression and unexpected disturbances in crane
systems. In order to reduce the chattering effect, a modified
super-twisting algorithm (STA) is designed to ensure that the state
variables reach the surface of the sliding mode in a finite-time. At the
same time, a non-singular fast terminal sliding mode surface is
established to ensure the finite-time convergence of the state variables
on the sliding mode surface, and ultimately the finite- time convergence
of the system state is guaranteed. In addition, adaptive compensation
terms are employed to counteract the effects of unknown frictions. The
stability of the closed-loop system is theoretically proved by using the
Lyapunov technique. Simulation results and analysis show that the
proposed method not only improves the chattering suppression effect
significantly, but also has good positioning and swing suppression
performance. And it has strong robustness to model uncertainties and
external disturbances.