Impact Location Determination Using Frequency Domain Signal Analysis
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Solution Overview
Problem
Existing touch-sensitive devices face limitations in determining the location of impacts, particularly when signal-to-noise ratios are low or multiple impacts occur simultaneously, as they struggle to accurately identify and distinguish between touch events.
Innovation Solution
The method computes a representative value that accounts for both predetermined acoustic properties and real impact properties, using reconstructed source signals and error energy calculations to determine the location of impacts, even under unfavorable conditions, by comparing measured signals with reconstructed signals in the frequency domain and applying filtering to improve signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signal normalization and phase information comparison is used to determine impact location, then the method functions well in normal conditions, but measurement precision deteriorates when signal to noise ratio is low or multiple impacts occur simultaneously
Solution Approach 1:
The patent transforms the measured signals and system response into the frequency domain using Fourier transformation, changing the parameter domain from time to frequency. This allows for frequency-dependent weighting and filtering that improves signal-to-noise ratio and enables reliable impact location determination even under adverse conditions. The frequency domain representation reveals characteristic patterns that are obscured in the time domain when multiple impacts occur simultaneously.
2Device complexity
If traditional signal comparison method is used, then computational complexity is low, but the ability to distinguish multiple simultaneous impacts is insufficient
Solution Approach 1:
The patent introduces a frequency dimension by transforming signals from the time domain to the frequency domain. This additional dimension allows for frequency-dependent analysis and weighting, enabling the system to distinguish between multiple simultaneous impacts based on their characteristic frequency signatures. The frequency domain representation provides extra information that is not available in the time domain alone.
3Measurement precision
If frequency domain transformation and frequency-dependent weighting is applied, then accuracy under unfavorable conditions improves, but computational power requirements increase
Solution Approach 1:
The patent applies frequency-dependent weighting rather than processing all frequency components equally. By identifying and emphasizing the frequency ranges that contain the most useful information for impact location determination, the system achieves high accuracy without the need to process the entire frequency spectrum with maximum computational effort. This selective approach reduces computational energy consumption while maintaining precision.
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 enables precise identification of impact locations, including multiple simultaneous touches, with improved accuracy and speed, even in low signal-to-noise environments, by minimizing computational power and effectively filtering noise.
Implementation Method 1
the location of an impact on a surface of an object, e.g. a touch screen or any other input device, is determined by analyzing acoustic signals which are captured by acoustic transducers, like piezoelectric sensors
Data Source
AI summary
The invention relates to a method for determining the locations of one or more impacts or touches on a surface of an object including two or more transducers which improves the precision of localisation even for low signal to noise ratios and furthermore provides the possibility to identify multi touch or multi impact situations. To achieve these objects the method comprises the steps of: a) receiving a signal, in particular an acoustic signal, from each one of the transducers, wherein the signals correspond to at least one impact at least one location on the surface; b) determining a representative value based on the signals received in step a) and predetermined properties, in particular acoustic properties, of the object at a given location on the surface of the object; and c) deciding whether the at least one impact at the at least one location on the surface of step a) corresponds to the given location on the surface based on a comparison of the representative value and the corresponding value of the at least two signals.