Composite super-twisting control of an underactuated crane with partial-state measurements under parameter...

This work proposes a composite adaptive-gain sliding mode observer-based super-twisting control with integral sliding mode control (ASMO-STC-ISMC) strategy for sway damping and motion control of a crane system with only partial state availability. The technique integrates an adaptive-gain sliding mode observer (ASMO) with a robust state estimation scheme to accurately reconstruct unmeasured states and enable effective control synthesis. The proposed scheme is validated under various operational conditions and comparative benchmarks conducted with various case studies involving both experimental and simulation investigations. Moreover, control application experiments on a lab-scale crane confirm the superior robustness and adaptability of the proposed method compared to conventional sliding mode control (SMC) methods, model-free proportional derivative SMC (PDSMC) and prescribed performance control-based SMC (PPC-SMC). Experimental results demonstrate that the ASMO-STC-ISMC achieves a settling time of 3.4 s, representing a 47.7% reduction relative to the PDSMC method and superior convergence over the PPC-SMC benchmark. Furthermore, under ±50% cable length variations, the system maintains a maximum payload sway below 2.3^∘, while friction compensation eliminates steady-state positioning errors, confirming the strategy's effectiveness for high-precision industrial crane applications.