Load swing damping in overhead cranes by sliding mode technique

Moving a suspended load is not an easy task when strict specifications on the swing angle and on the transfer time need to be satisfied. Nevertheless, these type of requirements are always present in industry because they are related to operation safety and cost. Intuitively, minimizing the cycle time and the load swing are conflicting requirements, and their satisfaction requires proper control actions, especially if some uncertainties in the system dynamics are present. In this paper we propose a simple control scheme based on second order sliding modes which is proved to be effective also in the case of poor knowledge of the system dynamics and/or parameters. Such controller has been tested on a laboratory-size model of an overhead crane by means of commercial devices, and some experimental results are reported within the paper