Input Shaping Techniques for Anti-sway Control of a 3-DOF Rotary Crane System

This paper presents development of input shaping for anti-sway control of a 3 degree-of-freedom (3-DOF) rotary crane system. A nonlinear equation of motion in a state space form obtained using Euler-Lagrange technique is considered for the crane´s tower in order to control and reduce the sway angle during the rotation. An unshaped square-pulse current input is implemented to determine the characteristic parameters of the system for design and evaluation of the input shaping control techniques. Positive and modified Specified Negative Amplitude (SNA) input shapers with the derivative effects are designed based on the properties of the system. Simulation results of the response of the rotary crane system to the shaped inputs are presented in time and frequency domains. Performances of the control schemes are examined in terms of sway angle reduction and time response specifications. Moreover, the robustness of the feed-forward control schemes is discussed. Finally, a comparative assessment of the proposed control techniques is presented and discussed.