Method for damping load oscillations on a crane

DETAILED DESCRIPTION Therefore, it is a primary object of the present invention to provide an open loop method for damping load oscillations by using a computer to shape the speed signals sent to the variable speed drive of the carriage motor.
Another primary object of the invention is to provide a general method for controlling a crane with a pattern to cause load oscillations to be damped.
Another primary object of the invention is to provide an open loop method for damping load oscillations that responds to changes in input speed commands at arbitrary times.
Another primary object of the invention is to provide an open loop method for damping load oscillations that responds to a rope length signal.
Another primary object of the invention is to provide an open loop method for damping load oscillations over a broad range of rope lengths without the need for a rope length sensor.
Another primary object of the invention is to provide an open loop method for damping load oscillations over a broad range of rope lengths, eliminating the need to adjust the rope length signal for different sling lengths.
These and other objectives are accomplished by the present invention which is a method of damping load oscillations during a traversing run of a load suspended by a hoisting rope from a movable carriage on a track.
The carriage is powered by a motor controlled by a motor drive.
A motion reference signal, representative of a desired motion of the carriage, is generated.
The motion reference signal is recorded at different times.
A damping signal, r(t), is formed based on a linear combination of the recorded motion reference signals.
The damping signal, r(t), is coupled to the motor drive to control carriage motion and the damping signal causes load oscillations to be damped.
The motion reference signal may be a speed reference signal s(t).
A pattern characterizing the type of desired damping is applied to the motion reference signal to produce the damping signal.
The hoisting rope length may be sensed and used to affect the rate at which the motion reference signals are recorded