US 2002/0158036 A1 · Anti-sway control of a crane under operator's command

Abstract

A system is disclosed for eliminating sway of a load in a crane or crane-like system subject to operator's command. The load is suspended by a cable from a horizontally movable trolley 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.

Claims43

Dependent claims

A system for eliminating sway of a payload suspended by a cable attached to a hoist from a trolley, the position of said payload being vertically and horizontally adjustable, said system including means for receiving or for generating an operator's hoist velocity input signal for vertical adjustment of said payload and including means for generating an operator's trolley velocity input signal for horizontal translation of said payload suspended by said cable, said system comprising:

means for generating an adjusted operator's command acceleration signal from said operator's trolley velocity input signal;
means for generating a cancellation acceleration signal using the length of said cable, the time derivative of the length of said cable, and said adjusted operator's command acceleration signal;
means for generating an external factor reduction acceleration signal using a measured sway angle of said payload, a measured sway velocity of said payload, a model sway angle of said payload and a model sway velocity of said payload;
means for generating a velocity output signal based on said adjusted operator's command signal, said cancellation acceleration signal and said external factor reduction acceleration signal;
means for sending said velocity output signal to a means for controlling the velocity of said trolley;
and
means for predicting velocity change by generating a velocity change signal based on a collection of prediction model correction acceleration signals, from said anti-sway controller, comparing said velocity change signal to said velocity output signal, generating a velocity compensation signal from said comparison, and factoring said velocity compensation signal into said operator's trolley velocity input signal.

4 more elements

A system for eliminating sway of a payload suspended by a cable attached to a hoist from a trolley, the position of said payload being vertically and horizontally adjustable, said system including means for generating an operator's hoist velocity input signal for vertical adjustment of said payload and including means for generating an operator's trolley velocity input signal for horizontal translation of said payload suspended by said cable, said system comprising:

means for generating an adjusted operator's command acceleration signal from said operator's trolley velocity input signal;
means for generating a cancellation acceleration signal in an anti-sway controller, wherein said cancellation acceleration signal generation means comprises:
means for determining the length of said cable;
means for generating a cable length signal from said determination of the length of said cable;
means for determining the time derivative of the length of said cable;
means for generating a cable velocity signal from said determination of the time derivative of said cable length;
and
means for receiving said cable length signal, said cable velocity signal and said adjusted operator's command acceleration signal in said anti-sway controller to generate said cancellation acceleration signal based on a family of ordinary differential equations;
means for generating an external factor reduction acceleration signal in a means for controlling external sway, said external factor reduction acceleration signal generation means comprising:
means for measuring a sway angle of said payload;
means for generating a measured sway angle signal from said measured sway angle;
means for measuring a sway velocity of said payload;
means for generating a measured sway velocity signal from said measured sway velocity;
means for generating a model sway signal in said anti-sway controller;
means for generating a model sway velocity signal in said anti-sway controller;
means for receiving said model sway angle signal from said anti-sway controller into said external sway control means;
means for receiving said model sway velocity signal from said anti-sway controller into said external sway control means;
means for receiving said measured sway angle signal into said external sway control means;
means for receiving said measured sway velocity signal into said external sway control means;
and
means for generating said external factor reduction acceleration signal based on said model sway angle signal, said model sway velocity signal, measured sway angle signal and said measured sway velocity signal;
means for generating a velocity output signal in a means for generating velocity output, said velocity output signal generation comprises:
means for receiving said adjusted operator's command acceleration signal;
means for receiving said cancellation acceleration signal;
means for receiving said external factor reduction acceleration signal;
and
means for generating a velocity output signal in said means for generating velocity output based on said adjusted operator's command acceleration signal, said cancellation acceleration signal and said external factor reduction acceleration signal;
means for sending said velocity output signal from said means for generating velocity output to a means for controlling velocity of the said trolley;
and
means for predicting velocity change in a means for predicting velocity change, said velocity change prediction comprising:
means for generating a collection of prediction model correction acceleration signals in said anti-sway controller;
means for generating a velocity change signal using said collection of prediction model correction acceleration signals of said anti-sway controller;
means for comparing said velocity change signal to said velocity output signal;
means for generating a velocity compensation signal from said comparison;
and
means for factoring said velocity compensation signal into said operator's trolley velocity input signal.

33 more elements

A method for eliminating sway of a payload suspended by a cable attached to a hoist from a trolley, the position of said payload being vertically and horizontally adjustable, said method including means for generating an operator's hoist velocity input signal for vertical adjustment of said payload and including means for generating an operator's trolley velocity input signal for horizontal translation of said payload suspended by said cable, said method comprising:

generating an adjusted operator's command acceleration signal from said operator's trolley velocity input signal;
generating a cancellation acceleration signal using the length of said cable, the time derivative of the length of said cable, and said adjusted operator's command acceleration signal;
generating an external factor reduction acceleration signal using a measured sway angle of said payload, a measured sway velocity of said payload, a model sway angle of said payload and a model sway velocity of said payload;
generating a velocity output signal based on said adjusted operator's command acceleration signal, said cancellation acceleration signal and said external factor reduction acceleration signal;
sending said velocity output signal to a means for controlling the velocity of the said trolley;
and
predicting velocity change by generating a velocity change signal based on a collection of prediction model correction acceleration signals from said controller, comparing said velocity change signal to said velocity output signal, generating a velocity compensation signal from said comparison, and factoring said velocity compensation signal into said trolley velocity input signal.

4 more elements

generating an adjusted operator's command acceleration signal from said operator's trolley velocity input signal;
generating a cancellation acceleration signal in an anti-sway controller, wherein said generation of said cancellation acceleration signal comprises:
determining the length of said cable;
generating a cable length signal from said determination of the length of said cable;
determining the time derivative of the length of said cable;
generating a cable velocity signal from said determination of the time derivative of said cable length;
and
receiving said cable length signal, said cable velocity signal and said adjusted operator command acceleration signal in said anti-sway controller to generate said cancellation acceleration signal based on a family of ordinary differential equations;
generating an external factor reduction acceleration signal in a means for controlling sway due to external factors, said external factor reduction acceleration signal generation comprising:
measuring a sway angle of said payload;
generating a measured sway angle signal from said measured sway angle;
measuring a sway velocity of said payload;
generating a measured sway velocity signal from said measured sway velocity;
generating a model sway signal in said anti-sway controller;
generating a model sway velocity signal in said anti-sway controller;
receiving said model sway angle signal from said anti-sway controller into said external sway control means;
receiving said model sway velocity signal from said anti-sway controller into said external sway control means;
receiving said measured sway angle signal into said external sway control means;
receiving said measured sway velocity signal into said external sway control means;
and
generating said external factor reduction acceleration signal based on said model sway angle signal, said model sway velocity signal, measured sway angle signal and said measured sway velocity signal;
generating a velocity output signal in a means for generating velocity output, said velocity output signal generation comprises:
receiving said adjusted operator's command acceleration signal;
receiving said cancellation acceleration signal;
receiving said external factor reduction acceleration signal;
and
generating a velocity output signal in said means for generating velocity output based on said adjusted operator's command acceleration signal, said cancellation acceleration signal and said external factor reduction acceleration signal;
sending said velocity output signal from said means for generating velocity output to a means for controlling velocity of said trolley;
and
predicting velocity change in a means for predicting velocity change, said velocity change prediction comprising:
generating compensation signals in said anti-sway controller;
generating a velocity change signal using said compensation signals of said anti-sway controller;
comparing said velocity change signal to said velocity output signal;
generating a velocity compensation signal from said comparison;
and
factoring said velocity compensation signal into said operator's trolley velocity input signal.

33 more elements

Dependencies are inferred from the claim text.

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

Life of this patent

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

Life of this patent

Abstract

Claims43