Crane and crane control method based on current and target boom tip and load positions

A crane controlling method in a crane comprising:

• a boom;
• an actuator of the boom;
• control circuitry for controlling the actuator of the boom based on a target speed signal indicating a moving direction and a speed of a load suspended from the boom by a wire rope and a suspending tool, to drive the boom and move the load;
• and an acceleration sensor configured to detect an acceleration of the suspending tool or the load, the method performed by the control circuitry, comprising:
• converting, every predetermined unit time, the target speed signal into a target position of the load relative to a reference position;
• computing, every unit time, a current position of a boom tip relative to the reference position from a swivel angle, a luffing angle and an extension/retraction length of the boom;
• obtaining, every unit time, a current acceleration of the suspending tool or the load from the acceleration sensor;
• computing, every unit time, a spring constant of the wire rope from a previously-computed position of the load the unit time before, a current position of a boom tip relative to the reference position and the current acceleration of the suspending tool or the load;
• computing, every unit time, a target position of the boom tip for the target position of the load from the current acceleration of the suspending tool or the load, the spring constant of the wire rope and the target position of the load;
• generating, every unit time, an operation signal for the actuator based on the target position of the boom tip;
• and
• controlling the actuator in accordance with the operation signal.