ATTENUATION OF INITIAL OSCILLATION IN BRIDGE CRANES VIA INPUT-SHAPING-BASED FEEDBACK CONTROL METHODS

Crane payloads are frequently subject to oscillations in-duced through movement and external disturbances. These oscil-lations degrade performance and can be dangerous. Input shap-ing is an effective method to move cranes without creating os-cillation, however it is not effective on initial swing. This paper develops a feedback control system, with two operation modes based on input shaping, that allows a crane operator to remove initial oscillations while retaining control over the crane move-ment direction. The system is shown to be simple to implement, and the effectiveness of the two operation modes is verified ex-perimentally on a scale bridge crane. NOMENCLATURE θ(t) angle of deflection from vertical degrees ζ damping ratio ωa actual frequency of payload oscillation rad/sec ωd damped frequency of payload oscillation rad/sec ωm measured frequency of payload oscillation rad/sec ωn natural frequency of payload oscillation rad/sec g acceleration due to gravity m/s2 b damping constant Ns/m L hoist length m La actual hoist length m Lm measured hoist length m Aa actual oscillation amplitude m/s Ai ith impulse amplitude m/s Am measured amplitude m/s ∗Address all correspondence to this author. AR requested velocity amplitude m/s T oscillation period sec Tm measured oscillation period sec mp payload mass kg V magnitude of step velocity input to trolley m/s Vmax maximum trolley velocity m/s V (ωn,ζ) residual vibration amplitude m/s x linear displacement of payload as measured by overhead camera m xa actual linear displacement of payload as measured by overhead camera m ti time of ith impulse sec c actual to measured frequency rati