A Numerical Model for the Attitude Manipulation of Twin-Hoisted Object

Hoisting an object with two crane hooks is sometimes applied when the pitch attitude of the hoisted object is necessary to be adjusted. The pitch attitude can be manipulated by changing the length difference of the two crane cables that connect the object with two hooks at two different positions. However, this twin-hoisted approach is impractical for crane operators who must be highly experienced and capable of adjusting the crane based on their visual measurement. This implies that the safety of workers and operation efficiency may rely on the physical and mental state of the operator. Furthermore, for the automation of the hoisting process, the method to precisely adjust attitude is required. In this research, a numerical study is carried out by a model that enables the attitude manipulation of a twin-hoisted object. By specifying a pitch attitude and lifting height of the object, the model can take the geometrical limitations of hoisting process into consideration and then determine the lengths of the two crane cables in real - time. In this study, the developed model is validated using a mobile crane both through a virtual environment and a lab-scale experiment. The proposed model not only can be implemented with a guiding interface established to guide crane operators in real time but also contributes to the development of automated crane control method.