Crane control method and crane

A control method of a crane configured to automatically convey a load along a conveyance path given as point group data including at least coordinates of a passing point of the load and a passage order of each passing point by controlling a luffing operation of a boom, a slewing operation, and a feed-in operation and a feed-out operation of a wire rope, wherein the control method comprises steps of:

• a first step of setting a target conveyance time of the load in a section defined by two passing points adjacent to each other in the passage order on the point group data;
• a second step of calculating a target conveyance speed of the load in the section based on a distance between the two passing points and the target conveyance time in the section;
• a third step of calculating, from the target conveyance speed, target speeds of a luffing speed of the boom, a slewing speed of the boom, and a feed-in/feed-out speed of the wire rope in the section for achieving the target conveyance speed;
• a fourth step of calculating maximum speeds of the luffing speed of the boom, the slewing speed of the boom, and the feed-in/feed-out speed of the wire rope in the section;
• a fifth step of comparing the target speeds and the maximum speeds of the luffing speed of the boom, the slewing speed of the boom, and the feed-in/feed-out speed of the wire rope in the section;
• and
• a sixth step of limiting, when there is a target speed greater than a corresponding maximum speed in the fifth step, to be smaller than the maximum speeds, the target speeds of the luffing speed of the boom, the slewing speed of the boom, and the feed-in/feed-out speed of the wire rope by multiplying the target speeds of the luffing speed of the boom, the slewing speed of the boom, and the feed-in/feed-out speed of the wire rope by a same coefficient having a value greater than 0 and smaller than 1, and controlling the crane based on the target speeds that are limited,
• wherein, in the fourth step, the maximum speeds of the luffing speed of the boom, the slewing speed of the boom, and the feed-in/feed-out speed of the wire rope in the section are calculated on a basis of a condition of supplying operation oil in a hydraulic circuit configured to operate a first actuator to luff the boom, a second actuator to slew the boom, and a third actuator to perform feed-in/feed-out of the wire rope, and
• wherein, in the sixth step, the target speeds and the maximum speeds of the luffing speed of the boom, the slewing speed of the boom, and the feed-in/feed-out speed of the wire rope in the section are compared, a target speed that exceeds a corresponding maximum speed out of those is extracted, and the coefficient is calculated by dividing the corresponding maximum speed by a corresponding target speed.