Time-varying Input Shaping Applied to Anti-swing Control of Overhead Cranes

Input shaping technology is widely used to reduce residual vibrations of flexible systems. But in designing time-varying systems, the conventional input shaping method is not very effective because of the restrained robustness. Zero placement method in the frequency domain was utilized to work out optimal arbitrary time-delay filter (OATF), on the basis of which time-varying input shaping was studied, with application to anti-swing control of overhead cranes. The time locations and amplitudes of the impulses of the time-varying input shaper were adjusted based on online feedback of the oscillation frequency and damping ratio of the crane in order to reduce the residual vibrations efficiently. Simulation results verify the fine performance of the proposed TVIST. Compared with the conventional input shaping method, the proposed method is more robust to the parameter variations, and can reduce the residual vibrations more efficiently. Besides, the time-varying input shaper is of shorter duration, and able to improve the operational efficiency.