Crane Controller Anti-Sway via Rope Deflection Modeling
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Solution Overview
Problem
Existing crane controllers for semi-automatic control of rotary cranes do not effectively account for rope deflection, leading to increased strain on the crane structure and unsatisfactory sway control of the load during movement.
Innovation Solution
A crane controller that incorporates a model-predictive reference trajectory planning module, which takes into account the deflection of the rope in both tangential and radial directions, using an optimization unit to calculate a reference trajectory that minimizes rope deflection and sway, and includes a fallback trajectory planning module for situations where the optimization fails to provide a solution within a predefined time frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the optimization unit does not take into account rope deflection, then the calculation speed is faster and the system is simpler, but the strain on the crane structure increases and the sway control of the load is unsatisfactory
Solution Approach 1:
The optimization unit preliminarily considers rope deflection in tangential and radial directions when calculating the reference trajectory, before the actual crane movement occurs. This predictive approach allows the system to pre-compensate for expected deflections, reducing actual sway during operation while maintaining real-time performance.
Solution Approach 2:
The system changes the parameters considered in the optimization calculation by explicitly including rope deflection parameters (tangential and radial components) alongside traditional trajectory parameters. This expanded parameter set enables the optimization unit to generate trajectories that account for rope dynamics, improving sway control without excessive computational burden.
2Reliability
If the optimization unit takes into account rope deflection in tangential and radial directions, then the anti-sway control is improved and the strain on structure is limited, but the device complexity and calculation load increase
Solution Approach 1:
The optimization unit performs multiple functions simultaneously: it calculates the reference trajectory while concurrently considering rope deflection in both tangential and radial directions, and limiting strain on the crane structure. This multi-functional approach consolidates what could be separate control systems into a single integrated unit, managing complexity through functional consolidation.
Solution Approach 2:
The system manages complexity by changing the mathematical parameters used in optimization to efficiently represent rope deflection. By using tangential and radial components rather than more complex three-dimensional vector calculations, the system achieves accurate sway control with computationally efficient parameter representations.
3Object-affected harmful factors
If a feedforward-controller with anti-sway properties is used, then the load sway is limited during movement, but the system cannot effectively handle emergency situations or unexpected disturbances
Solution Approach 1:
The control system combines feedforward trajectory planning with feedback mechanisms. The optimization unit continuously receives feedback about the actual crane state and rope deflection, adjusting the reference trajectory in real-time. This feedback loop enables the system to handle emergency situations and unexpected disturbances while maintaining anti-sway performance during normal operation.
Solution Approach 2:
The system transitions from a static feedforward controller to a dynamic optimization unit that continuously adapts the reference trajectory based on current conditions. This dynamic approach allows the controller to respond to changing situations, including emergencies, by recalculating optimal trajectories that account for current rope deflection and system state.
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
The solution provides improved anti-sway control by limiting rope deflection and strain on the crane structure, ensuring stable and efficient movement of the load, even in emergency situations, while maintaining real-time responsiveness and safety.
Implementation Method 1
uses feedforward-controllers having anti-sway-control properties, and which take into account the pendulum dynamics of the load hanging from the crane in order to limit a swaying of the load during the movement of the crane
Implementation Method 2
this physical model may describe the pendulum dynamics of a load hanging on a rope from the tip of the boom
Data Source
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AI summary
The present invention shows a crane controller for the semi-automatic control of a rotary crane, the crane comprising at least a slewing actuator for creating a slewing motion of the crane and/or a luffing actuator for creating a luffing motion of the crane, the crane controller comprising an input unit which can be operated by a operator to provide a desired slewing speed and/or a desired luffing speed as an operator input and a model-predictive reference trajectory planning module comprising an optimization unit for calculating a reference trajectory that obeys the system dynamics and follows the operator input, and a feedforward-controller using the reference trajectory for controlling the slewing actuator and/or the luffing actuator. Further, the optimization unit takes into account the deflection of the rope in the tangential and/or radial direction when solving the optimization problem that provides the reference trajectory.