Studies on the cable crane hung at three supports (IV)

On a method of simulation of the dynamic state

Abstract

Report III of this series reports on an analysis of control system by linearity theory for controlling the tension of wire rope, in the case of utilizing electromagnetic clutch. The result of the experimentation executed after that shows that the linearity theory is not suitable for the analysis of three wire rope system and that it is necessary to make a mechanical or electronic system for the tension control to simulate 3 dimensional non-linear system, which is originally so for three supports crane. Therefore the simulation program for computer of dynamic state was developed, and it is confirmed that it can trace the locus of the hoisting point of the crane nearly exact. The simulation is a step by step iterating method as follows. First, calculate at each instant the changing rate of length of each wire rope by acceleration or velocity of rounding of each drum based on the balancing relations among tension of wire rope, torque from engine driving drum, inertia of drum, viscosity and friction at each support and among three tensions of wire ropes, inertia and weight of hung load at hoisting point, adding behavior of automatic or manual steering from outside. Then compute the location of hoisting point at next instant from the calculated lengths of three wire ropes, assuming weights of those ropes are zero.