When using the minimum unbalance torque as the objective function to establish the optimization mathematical model of pulley block compensation in luffing mechanism, the dimensional optimal solutions do not have extension applicability. To solve this problem, a new optimization mathematical model, using the horizontal trajectory deviationas function, was established through geometric method. The working length of the movable arm was taken as measurement, and the geometric parameters of the

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... nism were transformed into dimension less parameters, and the function was linearized. As the mathematical model was solved, this article got a universal dimensionless optimal solution which is suit to different kinds of luffing mechanism. The application example shows that the optimal result using this method is obviously better than that using the minimum unbalanced moment as the objective function.