Sensor Sampling Frequency Coordination for Drivetrain Interference Reduction

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Solution Overview

Problem

Oral cleaning device sensors are susceptible to electromagnetic interference and mechanical vibration from the drivetrain, which can overwhelm sensor signals and interfere with accurate data sampling due to varying drivetrain frequencies producing harmonics above the Nyquist frequency.

Innovation Solution

Coordinating the sensor sampling frequency and drivetrain frequency by offsetting them by a predetermined value, using a controller to adjust the sensor sampling frequency in relation to the drivetrain frequency, ensuring they are synchronized to minimize interference, with possible multipliers such as 0.5, 1, or 0.75 to position the sampling frequency away from drivetrain harmonics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If sensors are placed close to the drivetrain to save space, then device compactness is improved, but sensor signal quality deteriorates due to electromagnetic interference and mechanical vibration

Engineering Contradiction:
Improvedevice compactnessVSAvoidsensor signal quality
Core Design Contradiction:
Volume of moving objectVSMeasurement precision

Solution Approach 1:

The system performs preliminary identification of drivetrain interference characteristics (frequency, amplitude, phase) before sensor signal processing. This allows the system to pre-calculate and apply appropriate filtering parameters, enabling effective interference rejection while maintaining compact sensor placement near the drivetrain.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system introduces an intermediary signal processing layer that mediates between the sensor output and the final measurement. This intermediary layer includes adaptive filters and interference cancellation algorithms that selectively remove drivetrain-related frequencies while preserving genuine sensor signals, thus decoupling the spatial proximity from signal quality degradation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If drivetrain frequency varies between modes to improve cleaning performance, then cleaning efficacy is improved, but sensor interference worsens due to varying harmonics above Nyquist frequency

Engineering Contradiction:
Improvecleaning efficacyVSAvoidsensor interference
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system implements dynamic adaptation where the interference cancellation parameters are continuously adjusted based on the current drivetrain operating mode. When the drivetrain frequency changes between cleaning modes, the system dynamically updates the filter characteristics and sampling synchronization parameters to maintain optimal interference rejection across varying operational conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes key parameters including sensor sampling frequency and filter cutoff frequencies based on the detected drivetrain operating mode. By synchronizing the sensor sampling rate with the current drivetrain frequency and adjusting filtering parameters accordingly, the system maintains effective interference cancellation while allowing the drivetrain to operate at optimal frequencies for different cleaning scenarios.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If traditional shielding and placement measures are used to reduce drivetrain effect, then some interference is reduced, but complete elimination is not achieved and sensor remains susceptible

Engineering Contradiction:
Improvedrivetrain interferenceVSAvoidsensor susceptibility
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The system employs feedback mechanisms where sensor signals are continuously monitored and compared against expected drivetrain interference patterns. The identified interference components are fed back into the signal processing pipeline to enable real-time cancellation, creating a closed-loop system that actively compensates for drivetrain effects rather than merely passively shielding against them.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system converts the harmful drivetrain interference into a useful reference signal for cancellation. By using the known drivetrain operating characteristics (frequency, amplitude, phase relationships) as a reference, the system generates an anti-phase signal that actively cancels the interference, transforming the harmful electromagnetic and mechanical vibrations into a beneficial cancellation mechanism.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentEP3539505B1Systems for minimizing drivetrain interference of sensors in an oral cleaning device
Publication Date: 2022.08.10 KONINKLIJKE PHILIPS NV
  • EP3539505B1 patent drawingFigure 1
  • EP3539505B1 patent drawingFigure 2~3
  • EP3539505B1 patent drawingFigure 4~5

AI summary

An oral cleaning device (10) minimizes drivetrain interference of a sensor and includes: a body portion (12); a brush head member (14) extending from the body portion, the head having a bristle face (18), where the bristle face is configured to move relative to the body portion; a clock (32); a sensor (28) in communication with the clock and configured to sample sensor data at a sensor sampling frequency (42) which is based on input from the clock; and a drivetrain (22) in communication with the same clock as the sensor, the drivetrain configured to generate movement of the bristle face at a first drivetrain frequency (40) which is based on input from the clock, where the sampling frequency and the first drivetrain frequency are coordinated to minimize drivetrain interference of the sensor.