Adaptive control for 5-DOF varying-cable-length tower cranes with multivariable state constraints

For 5-DOF varying-cable-length tower cranes, a novel adaptive controller is presented with multi-variable state constraints in this paper. To meet safety and transportation requirements, it is essential to ensure that all actuated state constraints are satisfied theoretically and practically. For this purpose, some auxiliary terms are designed elaborately to constrain all actuated state variables within suitable ranges. Considering parametric uncertainties, an adaptive controller is proposed to estimate uncertain/unknown friction-related parameters as well as compensate for friction. Notably, an elaborate adaptive law is introduced to precisely estimate unknown payload masses through online identification. To the best of our knowledge, this article should be the first closed-loop controller considering for 5-DOF tower cranes that all actuated state variables are restricted within preset limits. The Lyapunov technique and LaSalle’s invariance theorem are employed to prove the system’s stability theoretically. Hardware experiments are carried out to demonstrate the satisfactory control performance and significant robustness of the proposed controller.