A Predictive Input Shaping Control for Swing Suppression of an Overhead Crane System Subjected to Non-Zero Initial Condition and Payload Hoisting

Non-zero initial conditions in flexible systems can significantly degrade control performance, often resulting in excessive payload swing. Payload swing is a critical issue in crane operations which an uncontrolled payload swing may lead to collisions and potential damage to the payload or crane system itself. This thesis proposes a predictive Unity Magnitude Zero Vibration (PUMZV) input shaping technique to suppress payload swing in an overhead crane system under conditions of non-zero initial conditions, payload hoisting, and payload mass variation. The PUMZV is designed using a neural network trained by genetic algorithm to minimize payload swing under these conditions. Unlike traditional shapers that are designed for a crane system with fixed system parameters, the proposed technique could predict and directly update the shaper’s parameters in real time to handle the effects of the aforementioned conditions. These shapers lack adaptability, often resulting in residual vibrations and limited robustness in real applications. In contrast, the proposed technique predicts and directly updates the shaper’s parameters in real time, enabling it to effectively handle the effects of the aforementioned conditions and achieve superior swing suppression. To evaluate the performances of the proposed method, two tests of simulations and experiments were carried out. For Test 1, based on experiment and simulation results, the superiority of the proposed method is confirmed by reductions of at least 34.78%
and 44.27% in the overall and residual swing responses, respectively, over a conventional UMZV shaper designed using an average operating frequency and a robust shaper namely Zero Vibration Derivative-Derivative (ZVDD). Meanwhile, in Test 2, the performance improvements of the proposed method, as measured by overall and residual swing responses, exceed 50% and 53%, respectively, in all experimental and simulation cases, over comparative control methods, with fast shaper response. In addition, the significant reductions are achieved with a less shaper duration resulting in a satisfactory speed of response. It is anticipated that this open-loop control approach will be beneficial in minimizing oscillations and vibrations in various applications of flexible systems that having non-zero initial condition.