Observer design for boom cranes with double-pendulum effect

Under certain conditions the payload oscillation inherent to all crane systems cannot be described by a single-pendulum but shows a double-pendulum like behavior. In that case anti-sway concepts have to be adapted to the new system. For the here given application case the rope angles of the double-pendulum have to be reconstructed out of gyroscope signals, in order to make the full state information available. Therefore an observer concept is proposed which considers the double-pendulum dynamics, measurement errors, and disturbances such as higher natural oscillations of the rope itself. As the observers are based on the linear payload dynamics a sufficient representation is derived applying the Euler-Lagrange formalism. The models are validated by evaluating measurements obtained form an experimental setup. The final observer concept is implemented at a LIEBHERR harbor mobile crane. The measurement results are presented and discussed to show the performance of the proposed observers.