Damping of Oscillations of a Rotary Pendulum System

Abstract

This paper describes an innovative design based on the spectral approach of a novel shaper that eliminates frequency components that induce unwanted residual oscillations in various flexible mechanical systems, such as tower cranes or chain carousels, which are vital to many manufacturing and material-handling processes. However, their physical structure leads to flexible effects that limit their usefulness. Apart from the circular motion problem, control is provided by a single actuator, which makes it a so-called underactuated system. The input signal needs to be modified so that the spectral components from several interconnected degrees of freedom are considered together during shaper design, which increases the complexity of this task since one of its components induces nonlinear behavior. This means that traditional shaping techniques, based on linear theory, fail to provide good performance over the whole input range. The underdamped dynamics of the model and the effect of nonlinearities on the spectrum of the final signal are examined; the proposed method for application as a command shaping control technique is applied; and its effectiveness is analyzed by simulation and real-time implementation. The theoretical results verified on an experimental crane system confirm the expected oscillation phenomenon and show that the designed nonlinear shaper can reduce the payload swing significantly.

Data-Driven Identification of Crane Dynamics Using Regularized Genetic Programming

“…Load transportation is often performed by cranes using ropes, cables, or chains that incorporate the unactuated degrees of freedom to the system, making the transportation tasks more challenging in terms of safety and efficiency as the transient and residual swing of a payload suspended on a rope adversely affects the load positioning performances and may present a safety hazard for the personnel working on-site, the surrounding objects, and the transported cargo, as well as the crane's structure and equipment affected by the dynamic forces caused by the swinging of the payload. The aforementioned problem is extensively studied in the literature and addressed via different modeling approaches and various anti-sway open-loop and closed-loop control strategies [1][2][3][4]. An accurate dynamic model of a crane system, ensuring the precise prediction of actuated and unactuated states, especially in model-predictive control strategies, is crucial for improving crane operational and energy efficiency, as well as to mitigate the safety hazard.…”