Optimisation of tower crane rotation mechanism force acceleration mode at steady payload hoisting

The process of optimisation of the force acceleration mode of the rotation mechanism of the tower crane with the beam jib at steady payload hoisting was examined in the presented paper. The crane rotation mechanism was presented as a dynamic model with 4DOF in which the main motion of the rotation and payload hoisting mechanisms is considered as well as oscillations of the rotation part of the crane and the payload in the plane of slew. For such a dynamic model, a mathematical model which is a system of ordinary second order differential equations was formulated. The system of equations was reduced to the angular coordinate of the payload slew and was represented by the sixth order equation. The optimisation of the rotation mechanism’s acceleration mode at steady payload hoisting was carried out based on the RMS of the drive torque criterion considering constraints on the drive torque and drive power. The optimisation criterion as well as the constraints were reduced to the generalised criterion. When optimising , the movements and velocities of the generalised rotation mechanism coordinates in the beginning and in the end of the acceleration process were chosen as motion boundary conditions. The acceleration mode of the crane rotation mechanism at steady payload hoisting was obtained as the result of optimisation. The obtained mode minimised the action of the dynamic payloads and decreases the maximum values of the crane’s mast deformation, drive power, and deviation of the payload cable from the vertical. At that, the crane’s elements’ and payload’s oscillations upon reaching the steady motion mode were eliminated. The results of the study may be used in automation systems for controlling the rotation mechanisms of tower cranes, which ensures improved efficiency and stability of work during payloads hoisting