Position Encoder Sensor Array Harmonic Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing position encoder systems face challenges in achieving high resolution position information due to the complexity and cost of implementing techniques that require accurate weighting of sensor signals, particularly in suppressing higher harmonic components like the third harmonic, which affects measurement accuracy.
Innovation Solution
A scanning device for a position encoder that uses a summation unit to combine selected subsets of sensor signals, eliminating the need for Fourier weighting coefficients and multiple value resistors, by arranging sensor elements as multiples of three and four per scale period to suppress third harmonic contributions, and optionally fifth harmonics, using integer weightings for summation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Fourier weighting coefficients are used to suppress higher harmonic components, then measurement precision is improved, but device complexity increases and manufacturing cost increases
Solution Approach 1:
The patent changes the spatial arrangement parameter of sensor elements from arbitrary positioning to specific periodic patterns (multiples of 3 and 4 per scale period). This parameter change causes the third harmonic components to naturally cancel out through the periodic summation of sensor signals, achieving harmonic suppression without requiring complex Fourier weighting coefficients or multiple value resistors.
2Measurement precision
If multiple value resistors are used to implement Fourier weighting, then measurement precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent changes the sensor configuration parameter to use integer multiples of 3 and 4 elements per scale period. This allows the summation unit to use simple integer weightings (adding or subtracting sensor signals) rather than requiring multiple precision resistors with different values, greatly simplifying the electronic implementation while maintaining the ability to suppress third harmonic components.
3Measurement precision
If the number of sensor elements is increased to suppress harmonics, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the sensor elements into specific periodic groups arranged at integer multiples of 3 and 4 elements per scale period. This segmentation creates a structured pattern where each group contributes to canceling third harmonic components. The segmented arrangement achieves effective harmonic suppression with a moderate number of sensors, avoiding the need for excessive sensor elements.
4Measurement precision
If complex weighting schemes are implemented, then sine and cosine signal accuracy is improved, but ease of operation deteriorates
Solution Approach 1:
The patent changes the weighting parameter from complex Fourier coefficients to simple integers based on the periodic sensor arrangement. The summation unit can then combine sensor signals using simple addition and subtraction operations, making the system easier to operate and implement while still generating accurate sine and cosine signals with suppressed third harmonic distortion.
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 cost-reduces the implementation of position encoder systems, providing accurate sine and cosine signals with reduced harmonic distortion, enabling high-resolution position measurement without the complexity of prior art methods.
Implementation Method 1
the scanning device may comprise multiple, spaced apart, Hall sensor elements that each output a sensor signal of a voltage that is indicative of sensed magnetic field strength
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A scanning device ( 150) for a position encoder is described that comprises a plurality of sensor elements (16;H) for generating a plurality of sensor signals (S). A summation unit (34) is also provided for generating at least a first summation signal (Sin) and a second summation signal (Cos) that provide information on the relative alignment of the scanning device and an associated scale (14;152). The first summation signal (Sin) is generated from a first subset of the plurality of sensor signals (S) and the second summation signal (Cos) is generated from a second subset of the plurality of sensor signals (S). The plurality of sensor elements (16;H) are substantially evenly spaced apart from one another and N sensor elements are provided per period (p) of an associated scale (14), wherein N is an integer value and a multiple of three and four, hi this manner, the third harmonic contribution to the summation signals (Sin/Cos) is suppressed.