Model-based velocity-tracking-control of self-erecting industrial tower cranes

Although crane control has been a research field for decades, active sway damping control for tower cranes is not yet established in industry. For different reasons, the concepts (mainly validated with laboratory cranes) cannot be applied to large-scale tower cranes. In this paper, a model-based control concept under consideration of the elastic deformation of the crane structure is presented and validated using an industrial self-erecting tower crane. Different to most other crane control concepts in the literature, the elasticity of the crane structure is considered in the model, which is used for feedback control. Nonlinear flatness-based feedforward control and linear state-feedback control is applied. A new low-cost sensor concept and subsequent pendulum angle estimation strategy is presented using inertial measurement units mounted at the hook block and at the crane structure. The robust stability is analyzed by calculating the disk margin considering uncertain double pendulum parameters and kinematic drive constraints. Therefore, the nonlinear constraints are linearized using the harmonic balance method. The qualitative results of the theoretical robustness analysis are validated experimentally. The main goal of this paper is to close the gap between decades of research and industrial application of sway damping control for tower cranes. To the best of our knowledge, it is the first publication including measurement results for feedback control of a self-erecting industrial tower crane. The presented control concept is suited to be the basis of assistance functions for industrial tower cranes driven by an operator in future.