Vibratory Personal Care Device Force Detection Using IMU Sensors
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Solution Overview
Problem
Existing personal care devices, such as electric toothbrushes, rely on dedicated pressure sensors to detect force applied by cleaning elements, which increases complexity and cost, while inertial motion unit sensors are underutilized for determining vibration and pressure.
Innovation Solution
Utilizing inertial motion unit sensors, such as accelerometers and gyroscopes, to detect the vibration of cleaning elements and analyze frequency and amplitude to determine the force applied, eliminating the need for dedicated pressure sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated pressure sensors are used to detect force applied by cleaning elements, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies multi-functionality by enabling IMU sensors (accelerometer and gyroscope) to perform both their original function of detecting device motion and orientation, and a new function of detecting vibration characteristics to determine applied force. This eliminates the need for dedicated pressure sensors while maintaining force detection capability, directly resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent changes the detection parameter from direct pressure measurement to vibration parameter measurement (frequency and amplitude). By analyzing how vibration characteristics change under different force conditions, the system infers applied force indirectly. This parameter transformation allows existing IMU sensors to provide force detection without requiring additional dedicated pressure sensing components
2Measurement precision
If dedicated pressure sensors are used to detect force applied by cleaning elements, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent makes existing IMU sensors perform multiple functions including force detection through vibration analysis. By reusing components already present in the device for motion tracking purposes, the system eliminates the need for additional dedicated pressure sensors, thereby reducing component count, assembly complexity, and manufacturing cost while maintaining force detection capability
Solution Approach 2:
The patent enables the IMU sensor system to serve itself by using its own vibration detection capability to infer applied force. The same sensors that detect device movement during normal operation also detect vibration changes caused by force application, allowing the system to extract force information without requiring separate sensing hardware, thus reducing manufacturing costs
3Device complexity
If inertial motion unit sensors are used to detect vibration and determine force, then device complexity is reduced, but measurement precision may be affected
Solution Approach 1:
The patent exploits mechanical vibration principles by analyzing changes in vibration frequency and amplitude of the cleaning elements when force is applied. The IMU sensors detect these vibration characteristic changes, and through signal processing and analysis, the system determines the magnitude of applied force. This vibration-based approach enables force measurement using existing motion sensors without compromising accuracy
Solution Approach 2:
The patent implements a feedback mechanism where the IMU sensors continuously monitor vibration characteristics, the processor analyzes these signals to determine applied force, and this information can be used to provide real-time feedback to the user. This closed-loop approach ensures accurate force determination while using only the existing IMU sensor system, maintaining measurement precision without increasing device complexity
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
Accurately determines the force applied by cleaning elements, providing feedback to users for improved cleaning habits and reducing device complexity and cost.
Implementation Method 1
a sensor unit configured to detect a vibration of the cleaning elements as the cleaning element engages with the surface of the user
Implementation Method 2
Inertial motion unit (IMU) sensors (i.e. an accelerometer and a gyroscope)
Implementation Method 3
a processor configured to analyse the detected vibration in order to determine a force exerted by the cleaning elements on the surface of the user
Data Source
AI summary
Proposed are schemes, solutions, concepts, designs, methods and systems pertaining to aiding and/or improving a vibratory personal care device having cleaning elements that are adapted, in use, to vibrate. It has been realized that, by analyzing a vibration of the cleaning elements as they engage with a surface of a user, a force exerted by cleaning elements on the surface may be determined. That is, the vibration of the cleaning elements are indicative of a force exerted by a user on a surface via the cleaning elements. In this way, there is no need for a dedicated pressure sensor for determining the force for feedback to the user.