Device for controlling the transfer of a load suspended by cables from a carriage movable in translation in a lifting machine

A device for controlling the transfer of a load suspended by one or more cables from a carriage movable in translation in a lifting machine such as a travelling overhead crane or gantry crane comprising:

• control and dialogue means at the disposal of a machine operator;
• at least one horizontal travel motor associated with said carriage;
• means for sensing the suspension height, the sway angle and the angular speed of the load and the linear position of the carriage to provide respective signals L, .theta., .theta.', X;
• and
• a speed control system which, according to signals received from said sensing means, procures movement of the carriage minimizing load sway, said speed control system comprising:
• a carriage position corrector for receiving the measured position signals X and a target position value X.sub.B and for delivering an offset value relative to target position .DELTA.X weighted by a gain k.sub.1,
• a sway angle corrector for receiving the measured sway angle signal .theta. and a respective angular speed signal .theta.' and for assigning respective weighting values k.sub.2, k.sub.3 to said sway angle signal and said angular speed signal,
• a computing unit for determining by real time interpolation the values of the gains k.sub.1, k.sub.2, k.sub.3 according to the suspension height signal L, and
• a summing unit for summing the offset value, the weighted sway angle signal, and the weighted angular speed signal, for delivering a speed set point signal VC=k.sub.1 .DELTA.X+k.sub.2 .theta.+k.sub.3 .theta.' to a variable speed drive associated with a carriage displacement motor.