Control of Torsionalpendulum on Containercranes

by Bäck, Pär

A container crane of STS-type, Ship To Shore, consists of a spreader hanging underneath a railrunning trolly. As the container is under the influence of wind, it is likely that it starts to turn in a torsional pendulum. This report handles how the torsional pendulum of a container crane can be damped. A number of different models have been developed to analyze how different placement of the actuators affects the system. Two differens types of controllers, LQG and MPC, have been developed and applied to these models. The different models and controlers were evaluated and compared by studying simulation results in timedomain. Moreover in order to make the simulations more realistic, a wind model has been developed and applied. The models and controllers have been analyzed with bodediagrams and sensitivity functions. The analyses shows clearly that the best placement of the actuators for control of the torsional pendulum on an STS-crane is in the trolly, pulling and relaxing the wires. This control is best handled by a state feedback control (LQG). Furthermore, the control should in this way, with addition of in the horizontalplane movable suspensions in the trolly, work acceptably in the whole operational area of a STS-crane. Nyckelord Keyword STS-crane, skew-angle, torsional pendulum, MPC-control, LQG-control, statefeedback control, kalman estimation Sammanfattning En containerkran av STS-typ, Ship To Shore, best?ar av en spreader som hänger i ett flertal linor under ett rälsg?aende ?akdon, som kallas trallhuset. När lasten p?averkas av olika yttre störningar, t.ex. vind, är det vanligt att spreadern börjar vrida p?a sig i en torsionspendel. Denna rapport behandlar hur denna torsionspendel regleras p?a bästa sätt. Ett flertal olika modeller har designats för att utreda hur olika placering av ställdonen p?averkar systemet. Till dessa modeller har tv?a olika typer av regulatorer, LQG- och MPC-typ, tagits fram och applicerats i simuleringar. För att göra simuleringarna mer realistiska har en vindmodell designats och applicerats. Dessa simuleringar har använts för att studera prestanda för systemet i tidsplanet. Modellerna och regulatorerna har även analyserats med hjälp av bodediagram och känslighetsfunktioner. Analyserna visar entydigt att den bästa placeringen av ställdonen för att reglera torsionspendeln p?a en STS-kran är i trallhuset s?a att linorna kan förlängas och förkortas. Denna reglering sköts bäst med en tillst?ands?aterkoppling (LQG) som regulator. Regleringen bör p?a detta sätt, med tillägg best?aende av i horisontalled rörliga upphängningspunkter i trallhuset, fungera tillfredställande inom hela arbetsomr?adet för en STS-kran. Nyckelord STS-kran, skew-vinkel, torsionspendel, MPC-reglering, LQG-reglering, tillst?ands?aterkoppling, kalmanfilter i Abstract A container crane of STS-type, Ship To Shore, consists of a spreader hanging underneath a railrunning trolly. As the container is under the influence of wind, it is likely that it starts to turn in a torsional pendulum. This report handles how the torsional pendulum of a container crane can be damped. A number of different models have been developed to analyze how different placement of the actuators affects the system. Two differens types of controllers, LQG and MPC, have been developed and applied to these models. The different models and controlers were evaluated and compared by studying simulation results in timedomain. Moreover in order to make the simulations more realistic, a wind model has been developed and applied. The models and controllers have been analyzed with bodediagrams and sensitivity functions. The analyses shows clearly that the best placement of the actuators for control of the torsional pendulum on an STS-crane is in the trolly, pulling and relaxing the wires. This control is best handled by a state feedback control (LQG). Furthermore, the control should in this way, with addition of in the horizontalplane movable suspensions in the trolly, work acceptably in the whole operational area of a STScrane.