Anti-sway control of a crane under operator's command

Abstract

A system (10) is disclosed for eliminating sway of a load (30) in a crane or crane-like system subject to operator's command. The load is suspended by a cable (40) from a horizontally movable trolley (20) and can be hoisted vertically. The system uses the principle of cancellation to eliminate sway even when the crane has simultaneous trolley and hoisting motions. The system takes into account the full dynamical effect in computing cancellation signals. The use of a family of ordinary differential equations for the computation of the cancellation controls is a key component of the invention. In computing these controls, the differential equations are solved in real time using sensory measurement of the cable length and its time derivative. The cancellation controls handle the sway induced by the operator's command. Sway can also be induced by other factors, like wind load and external disturbances. This system also includes a feedback mechanism for eliminating sway due to such factors. The system ensures saturation limits, corresponding to the velocity and acceleration limits of the drive system of the trolley are not exceeded for proper functioning of the system.

Description

technical field [0001] The present invention relates to a system and method for controlling a rope-suspended payload transfer system, and more particularly, to a system and method for anti-sway control of a payload undergoing horizontal trolley and vertical lifting motion. Background technique [0002] Gantry cranes are widely used in port operations for the transfer of containers. Typically, the crane has two inputs in the form of speed commands. These two velocity commands independently control the horizontal carriage and vertical lift motion of the payload. Undesired swaying of the payload at the end of the transport is a difficulty in completing the transfer movement. Loading or unloading operations cannot be achieved while the payload is swaying. Currently, only experienced manipulators can effectively bring containers to a no-sway standstill. Other manipulators must wait for the swing to stop. Typically, the time spent waiting for the swing to stop or performing v...

AI Technical Summary

Problems solved by technology

[0017] While Virrkkumen's method is reasonable for two pendulums of fixed length, it is imprecise for a single pendulum or a single crane whose rope length undergoes changes

For example, the hoisting rate of the rope affects the sway angle, which is not considered in Virrkkumen's method

In addition, since the length may change continuously in typical horizontal movements, when determining the second rope length L 2 uncertainty in

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