Crane Control Using Cartesian Coordinates for Load Swing Damping
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Solution Overview
Problem
The calculation of control commands for cranes to dampen load swing is complex and imprecise, particularly when based on cylinder coordinates, and existing methods struggle with effective load sway damping.
Innovation Solution
A crane control system that calculates control commands for slewing, luffing, and hoisting gears based on target movements specified in Cartesian coordinates, using a physical model of the load and crane dynamics to invert control signals and incorporate sensor feedback for improved load swing damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control commands are calculated based on cylinder coordinates, then the control system can operate the crane mechanisms, but the calculation becomes complex and imprecise
Solution Approach 1:
The patent transforms the coordinate system from cylinder coordinates to Cartesian coordinates, changing the mathematical parameters used in control calculations. This parameter change simplifies the calculation of control commands for slewing, luffing, and hoisting gears while improving precision in load swing damping.
Solution Approach 2:
The patent introduces a coordinate transformation as an intermediary step between the control commands and the crane mechanisms. By converting cylinder coordinates to Cartesian coordinates through a transformation matrix, the system achieves simpler and more precise calculations without directly controlling the complex cylindrical system.
2Reliability
If traditional control methods are used for load swing damping, then the crane can operate, but the load sway damping is ineffective
Solution Approach 1:
The patent implements a feedback mechanism where the actual position of the load in Cartesian coordinates is continuously compared with the target position. The control commands are adjusted based on the position error and its derivative, creating a closed-loop control system that effectively damps load swing while maintaining operational reliability.
Solution Approach 2:
The patent replaces traditional mechanical swing damping methods with a computational approach using Cartesian coordinate transformations and mathematical modeling. This substitution of mechanical systems with computational methods achieves effective load swing damping without increasing physical system complexity.
3Ease of operation
If vertical and horizontal movements are coupled in control calculations, then the complete motion is controlled, but the control calculations become complex
Solution Approach 1:
The patent segments the control calculations by utilizing the Cartesian coordinate system, where vertical (z-axis) and horizontal (x-y plane) movements are mathematically decoupled. This segmentation allows independent control of lifting movements from swing damping, simplifying calculations while maintaining precise control over all motion dimensions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies and enhances load swing damping by decoupling vertical and horizontal movements, allowing for more precise control and effective oscillation damping, thereby improving crane operation and safety.
Implementation Method 1
The load swing damping of the control unit is based on the inversion of a physical model of the load hanging on the load rope and the crane, with the inverted physical model converting a specified movement of the load hanging on the load rope in Cartesian coordinates into control signals for the slewing gear, luffing gear and/or hoist gear
Implementation Method 2
The physical model includes the dynamics of the load hanging on the load rope, in particular the pendulum oscillation dynamics, so that extremely effective load oscillation damping can be achieved by inverting the model
Implementation Method 3
The crane advantageously comprises one or more sensors for determining one or more measured variables for the position and/or movement of the load and/or the crane, in particular for determining one or more of the variables radial cable angle, tangential cable angle, luffing angle, angle of rotation, cable length and their length Derivatives
Implementation Method 4
a first transformation unit is provided, which calculates the actual position and/or actual movement of the load in Cartesian coordinates on the basis of the measured variable or variables
Implementation Method 5
the control unit includes a load sway damping system, which dampens swaying of the load when the crane moves by suitable activation of the slewing gear, luffing gear and/or hoisting gear
Data Source
AI summary
The crane has a rotating mechanism and a luffing mechanism which is provided for luffing a cantilever arm. A lifting unit is provided lowering and lifting the load (9) hanging on a load cable. The calculation of the control instructions for controlling the rotating mechanism, luffing mechanism and lifting unit takes place on the basis of a reference-movement specified in Cartesian coordinate.