Compensated Angle Determination for Work Machine Joints
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Solution Overview
Problem
Existing methods for determining the position of elements or joints in mobile work machines, such as excavators, are affected by hysteresis due to mechanical play in the angle sensors, leading to inconsistent and erroneous angle measurements.
Innovation Solution
A method that involves a calibration phase to determine a hysteresis angle value by recording sensor angle values at end positions, and an application phase where the compensated angle is calculated by correcting sensor angle values based on the hysteresis angle and pivot direction, thereby compensating for errors caused by mechanical play.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor angle values are measured directly with an angle sensor coupled to the component and reference component, then the measurement process is simple, but the measurement precision deteriorates due to hysteresis caused by mechanical play in the coupling
Solution Approach 1:
The calibration phase is performed in advance to determine the hysteresis angle value and establish correction relationships before actual angle measurements are taken. This preliminary characterization of the mechanical play allows subsequent measurements to be corrected systematically, improving precision without adding complexity to the ongoing measurement process
Solution Approach 2:
The method transforms the raw sensor angle values into compensated angle values by applying corrections based on the hysteresis angle value and pivot direction. This parameter transformation compensates for the mechanical play effects, converting imprecise measurements into accurate angle readings while maintaining a relatively simple measurement setup
2Measurement precision
If the calibration phase is performed to determine hysteresis angle value, then the angle measurement accuracy is improved, but the time required for setup and maintenance increases
Solution Approach 1:
The calibration phase can be performed periodically or at specific intervals rather than continuously, establishing hysteresis correction parameters that remain valid for extended periods. This periodic approach maintains measurement accuracy while minimizing the time spent on calibration activities
Solution Approach 2:
The system automatically performs the calibration process and applies corrections without requiring manual intervention during normal operation. The computing unit autonomously determines the hysteresis angle value and applies the appropriate corrections, reducing the time burden on operators
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 method provides consistent and accurate compensated angle values that are independent of the pivot direction, effectively addressing the issue of hysteresis in angle measurements, and enabling precise feedback and control in work machines.
Implementation Method 1
hysteresis due to mechanical play in the angle sensors, leading to inconsistent and erroneous angle measurements
Data Source
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AI summary
The invention relates to a method for determining a compensated angle (αcomp) of a component (2) of a work machine which can be pivoted relative to a reference component (4) between a first and a second end position, wherein there is a known end position angle difference between the first and the second end position, wherein an angle sensor (8) is provided which is coupled to the component (2) and the reference component (4) and which is designed to measure sensor angle values of the component relative to the reference component.The method comprises a calibration phase, including pivoting (110, 16) of the component (2) into the first end position and detecting a first sensor angle value (αSens(αmin)) in the first end position, pivoting (120, 18) of the component (2) into the second end position and detecting a second sensor angle value (αSens(αmin)) in the second end position, and determining (130) a hysteresis angle value from the sensor angle difference between the first and the second sensor angle value and from the end position angle difference, and an application phase, including detecting (140) a sensor angle value for a determination time, determining (150) whether a positive or a negative pivot direction of the component is present at the determination time, and determining (160) the compensated angle (αcomp) by correcting the sensor angle value at the determination time by a value dependent on the hysteresis angle value and Angle correction depending on the swivel direction.