Cranes with distributed-mass payload (DMP) have complex sway dynamics, and they are largely affected by changes in the DMP parameters. Although an input shaping technique has been utilised for sway control, it has low robustness to parameter uncertainties and mainly applied to cranes carrying a point mass payload. This paper proposes a robust shaper for efficient swing control of an underactuated overhead crane with a DMP under parameter uncertainties by using an output-based reference command shaping approach. The method has an advantage as it avoids the requirement for accurate measurements and estimations of the systems sway frequencies and damping ratios, which are difficult for DMP. In addition, the approach eliminates the need for controller re-design in cases of parameter changes. The effectiveness of the shaper is investigated using simulations and experiments under several scenarios involving varying cable lengths, changes up to 25% in the DMP masses and lengths, and different input profiles. The superiority and robustness of the shaper is confirmed with the highest hook and payload sway reductions in comparison to another multimode robust shapers. Under a robustness test with a different set of DMP parameters, and with experiments, the proposed shaper reduces the total sway by 46% and 24% as compared to the robust Zero Vibration Derivative (ZVD) and Equal Shaping-Time and Magnitude (ETM) shapers respectively. Interestingly, these are achieved by using only a single design and with a similar speed of trolley position response.
Bello et al. (Thu,) studied this question.