Sonic Transducer Surface Type Detection Using Ringdown Signal Analysis
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Solution Overview
Problem
Existing devices that move on or operate on surfaces face challenges in accurately detecting surface types, particularly due to interference from ringdown signals, which can obscure returned sonic signals, making it difficult to determine surface characteristics like hardness, softness, wetness, or cleanliness.
Innovation Solution
The implementation of a technique that estimates a 'void ringdown signal' by sampling early ringdown points and extrapolating using a decay factor, allowing for the comparison with actual ringdown signals to generate metrics for surface type detection, using sonic transducers that transmit and receive signals in infrasound, acoustic, and ultrasonic ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sonic transducers are used to detect surface types, then surface characteristics can be determined, but ringdown signals interfere with and obscure returned sonic signals
Solution Approach 1:
The patent applies the 'Blessing in disguise' principle by using the ringdown signal itself as a reference to characterize surface types. Instead of treating ringdown interference as purely harmful noise that obscures returned sonic signals, the invention extracts useful information from the ringdown signal's decay characteristics. By comparing the ringdown signal properties with returned signal properties, the system can determine surface characteristics such as hardness, softness, wetness, or cleanliness, thereby converting the harmful interference into a beneficial detection mechanism.
2Length of stationary object
If ringdown distance is reduced to improve surface detection, then closer surfaces can be detected, but ringdown interference becomes more severe
Solution Approach 1:
The patent applies the 'Mechanics substitution' principle by replacing traditional time-based signal separation methods with a frequency-domain approach. Instead of relying on temporal separation between ringdown and returned signals, the invention uses Fast Fourier Transform (FFT) to convert signals into frequency spectra. This allows the system to distinguish between ringdown and returned signals based on their frequency characteristics rather than timing, enabling detection at shorter distances without being overwhelmed by ringdown interference.
3Device complexity
If traditional signal processing is used, then simple processing is applied, but returned signals cannot be discerned from ringdown interference
Solution Approach 1:
The patent applies the 'Another dimension' principle by transitioning from one-dimensional time-domain signal analysis to two-dimensional frequency-time analysis using FFT spectrograms. This dimensional change allows the system to visualize and differentiate between ringdown and returned signals based on their frequency evolution over time. The spectrogram representation reveals distinct patterns that are not apparent in the time domain, enabling accurate signal discrimination while maintaining manageable processing complexity through efficient frequency-domain algorithms.
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 method effectively discerns returned signals from ringdown interference, enabling devices to accurately determine surface types, facilitating improved operation and surface interaction, such as adjusting movement or cleaning actions based on surface conditions.
Implementation Method 1
a sonic transducer (which may be part of a sensor assembly) that transmits sonic signals toward a surface and receives corresponding returned signals reflected from the surface
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A robotic cleaning appliance includes a sonic transducer and a processor coupled with a housing. The sonic transducer transmits sonic signals toward a surface within its ringdown distance and receives corresponding returned signals. Following cessation of the sonic signals, the processor samples the ringdown signal generated by the sonic transducer during an early portion before the corresponding returned signals have reflected back to the sonic transducer, and during a later portion which includes the corresponding returned signals. The processor utilizes the sampled early portion to estimate a void ringdown signal of which represents performance of the sonic transducer in absence of returned signals being received. The processor compares the estimated void ringdown signal to the later portion of the ringdown signal and generates a metric based on the comparison. The processor utilizes the metric to determine a type of the surface, out of a plurality of surface types.