Jörg Neupert

A heave compensation approach for offshore cranes

Offshore installations during harsh sea conditions results in rigorous requirements in terms of safety and efficiency for the involved crane system. Hence a heave compensation system based on heave motion prediction and an inversion based control strategy is proposed. The control objective is to let the rope suspended payload track a desired reference trajectory in an earth fixed frame without being influenced by the heave motion of the ship or vessel. Therefor a combination of a trajectory tracking disturbance decoupling controller and a prediction algorithm is presented and evaluated with simulation and measurement results.

Trajectory Tracking for Boom Cranes Based on Nonlinear Control and Optimal Trajectory Generation

The main objectives of crane automation are increasing the efficiency and safety of the transshipment processes. Therefore, advanced control strategies are applied for load sway reduction and trajectory tracking. The paper presents a nonlinear control strategy combined with a model-based optimal trajectory generation for the radial load movement of a boom crane. The results are validated by measurement results from a LIEBHERR harbor mobile crane.

A Nonlinear Control Strategy for Boom Cranes in Radial Direction

To increase the effectiveness of the cargo transshipment process is one of the most important objectives for the automation of cranes. Therefore new control strategies are applied. This paper presents a nonlinear controller in order to solve the trajectory tracking and disturbance rejection problem for a boom crane. A model of the crane dynamics in radial direction is derived considering the dominant nonlinearities such as the actuator kinematics. Further on, the coupling of a slewing and luffing motion is taken into account. This coupling is caused by the centrifugal acceleration of the load in radial direction during a slewing motion. Based on the nonlinear model a linearizing and disturbance decoupling control law is derived and discussed. Measurement results from the boom crane validate the good performance of the nonlinear controller.

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.

Modell-prädiktive Trajektoriengenerierung für flachheitsbasierte Folgeregelungen am Beispiel eines Hafenmobilkrans (Model-predictive Trajectory Generation for Flatness-based Nonlinear Tracking Control with Application to Boom Cranes)

Wesentliche Ziele der Kranautomatisierung sind die Erhöhung der Effektivität und der Sicherheit bei Verladeprozessen. Hierzu werden modellbasierte Methoden zur Lastpendeldämpfung, Trajektoriengenerierung und Trajektorienfolgeregelung entwickelt. Der Beitrag stellt eine Kombination einer nichtlinearen, flachheitsbasierten Folgeregelung mit einer modell-prädiktiven Trajektoriengenerierung für die radiale Lastbewegung eines Drehkrans vor. Die Ergebnisse werden anhand von Experimenten an einem Hafenmobilkran der Firma LIEBHERR bewertet. The main objectives of crane automation are increasing the efficiency and safety of the transshipment processes. Therefore, model-based control strategies are applied for load sway reduction and trajectory generation and tracking. The paper presents a nonlinear flatness-based tracking control strategy combined with a model-predictive trajectory generation for the radial load movement of a boom crane. The results are validated by measurement results from a LIEBHERR harbor mobile crane.