Experimental evaluation of estimated sway angle of payload in crane systems

Nowadays, the world trade volume is increasing. In many countries, the demand for container cranes is very high in order to handle the boomimg trade. The object of the crane system is to load containers between ships and shore. Operators need to convey containers safely and efficiently. However, operation of the crane system requires expert skill because of its underactuated system. Information of the sway angle of the payload is needed to accomplish operators´ tasks, but many sensors are used to get the sway angle information. They cost a lot. Therefore, there is demand for the crane system which requires no sensors. In this paper, an estimation method for the sway angle is proposed by using reaction force observer (RFOB) instead of sensors. In the experiments, a method to compensate static friction between the trolley and the rail is proposed because there exists static friction which prevents the trolley from moving on the rail. The efficiency of this method is verified by simulations and experiments.