Steered Wheel Position Detection Using Variable Arc Coding
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Solution Overview
Problem
Existing methods for detecting the actual position of a steered wheel in electric steering systems for industrial trucks are prone to inaccurate arc length measurement during homing movements, leading to incorrect position determination and increased tire wear, especially in vehicles with multiple steered wheels.
Innovation Solution
A device and method that utilize a coding element with sections of differing arc lengths, where the sensor detects transitions between sections and corrects for systematic measurement errors by comparing recorded arc lengths with reference values, allowing for precise position determination by setting sections with the same arc length in relation to those with different arc lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If incremental position determination is used without a sensor on the steered wheel, then the device complexity is reduced, but the measurement precision deteriorates due to inaccurate arc length measurement during homing movements
Solution Approach 1:
A coding element with sections of different arc lengths is introduced as an intermediary between the sensor and the steered wheel position. This coding element provides reference markers that enable accurate determination of the homing position and systematic error compensation without requiring a sensor directly on the steered wheel, thus maintaining low device complexity while improving measurement precision.
Solution Approach 2:
The coding element uses sections with varying arc lengths as changeable parameters to encode position information. By measuring the arc lengths of these sections and comparing them to reference values, the system can determine the homing position accurately and compensate for systematic errors, thereby achieving high measurement precision with simple incremental measurement.
2Ease of operation
If the sensor is not optimally set during homing movement, then the ease of operation is improved, but the measurement precision deteriorates leading to incorrect position determination
Solution Approach 1:
The system measures the arc lengths of sections in the coding element and compares them to reference values to detect deviations. This feedback mechanism allows the system to identify incorrect homing positions and compensate for systematic errors, ensuring accurate position determination even when the sensor is not optimally set during homing movement.
Solution Approach 2:
The coding element with pre-defined sections of different arc lengths is prepared in advance to provide reference information. This preliminary encoding allows the system to automatically detect and correct homing position errors without requiring manual sensor adjustment, maintaining ease of operation while ensuring measurement precision.
3Productivity
If arc length measurement is performed during homing movement, then the productivity is improved by enabling position determination, but the measurement precision deteriorates due to systematic errors
Solution Approach 1:
The system continuously measures arc lengths of coding element sections and compares them to reference values, providing feedback on systematic errors. This feedback enables real-time compensation, allowing fast position determination (high productivity) while maintaining accurate measurements despite systematic errors during homing movements.
Solution Approach 2:
By using sections with different arc lengths as variable parameters, the system can quickly identify position information during homing movement. The comparison of measured arc lengths with reference values allows rapid detection of systematic errors and their compensation, achieving both high productivity and measurement precision.
Data Source
Figure 1~2
AI summary
Device for detecting the actual position of a steered wheel in an electric steering system for a forklift truck, comprising: - a steering drive that positions the steered wheel, and - a detection device comprising a coding element with a plurality of sections of different arc lengths and a sensor moving relative thereto, - wherein the coding element comprises two types of sections, the sections of a first type having different arc lengths compared to other sections and the sections of a second type having the same arc length compared to other sections of the second type, - the steered wheel and the coding element are arranged relative to each other such that at least one of the sections of the first type is completely traversed and its arc length is detected, wherein the detected arc length of the section(s) of the first type has been corrected before a position determination.