Patent ID: 8005598

Claim:
A method for controlling a crane drive unit so as to suppress sway of a load suspended by a rope of a crane, which sway occurs when the load has been transported from a first position to a second position, the control being made by operating a controller having a filter unit using a feedforward control program, comprising: removing a component near a resonance frequency by the filter unit from a transportation command for the load, in which command a maximum value among at least one of transportation speed, transportation acceleration, and transportation jerk is limited, under the resonance frequency sequentially computed from a rope length that is a distance from the center of rotation of the sway of the rope to the center of gravity of the load and under parameters that relate to a control unit of the crane drive unit and that are previously computed so as not to exceed a performance of the crane drive unit; wherein based on expression (1) or (2), the component near the resonance frequency is removed by using parameters a i (f) and b j (f), which are determined by a simulation under a constraint condition that maximum speeds in the transportation command do not exceed a limitation of a maximum value of the crane drive unit y ⁡ ( t ) = b 0 ⁡ ( f ) ⁢ x ⁡ ( t ) + b 1 ⁡ ( f ) ⁢ x ⁡ ( t - 1 ) + b 2 ⁡ ( f ) ⁢ x ⁡ ( t - 2 ) + … ⁢ ⁢ - a 1 ⁡ ( f ) ⁢ y ⁡ ( t - 1 ) - a 2 ⁡ ( f ) ⁢ y ⁡ ( t - 2 ) - … ⁢ ⁢ y ⁡ ( t ) = ∑ j = 0 m ⁢ ⁢ b j ⁡ ( f ) ⁢ x ⁡ ( t - j ) - ∑ i = 1 n ⁢ ⁢ a i ⁡ ( f ) ⁢ y ⁡ ( t - i ) Expression ⁢ ⁢ ( 1 ) where a i (f) and b j (f) are parameters mediated by the resonance frequency f sequentially computed for the varying length of the rope, and F ⁡ ( S ) = Y ⁡ ( S ) X ⁡ ( S ) = b 0 ⁡ ( f ) ⁢ S 0 + b 1 ⁡ ( f ) ⁢ S 1 + b 2 ⁡ ( f ) ⁢ S 2 + … a 0 ⁡ ( f ) ⁢ S 0 + a 1 ⁡ ( f ) ⁢ S 1 + a 2 ⁡ ( f ) ⁢ S 2 + … = ∑ j = 0 m ⁢ ⁢ b j ⁡ ( f ) ⁢ S j ∑ i = 0 n ⁢ ⁢ a i ⁡ ( f ) ⁢ S i Expression ⁢ ⁢ ( 2 ) where expression (1) is obtained by carrying out a Z-transformation to the transfer function of the filter shown in expression (2), and S is a Laplacian operator, and inputting the transportation command from which the component near the resonance frequency is removed into the crane drive unit, thereby controlling the crane drive unit so that the load does not greatly sway when the load is transported from the first position to the second position.