Friction Force Sensor Using Photointerrupter and Flexures
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing force sensors are inadequate for sensitive detection and measurement of friction forces in the millinewton range and for determining the friction coefficient between two specimens of different material properties.
Innovation Solution
A friction force sensor system utilizing a photointerrupter sensor, a flexible assembly with flexures, and a mounting element, which measures the displacement caused by friction forces and calculates the friction force and coefficient through calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional force sensors are used, then general force detection is possible, but detection sensitivity in the millinewton range is insufficient
Solution Approach 1:
The patent replaces conventional mechanical force sensing mechanisms with an optical detection system using a photointerrupter. The flexible assembly converts millinewton-range forces into displacements that block light beams, enabling highly sensitive detection through optical rather than mechanical means. This substitution achieves the required detection sensitivity while maintaining measurement reliability through calibration.
Solution Approach 2:
The patent transforms the measurement parameter from direct force detection to displacement detection. By using a flexible assembly, the system converts force in the millinewton range into measurable displacements that can be detected by the photointerrupter optical system, thereby achieving the required sensitivity threshold.
2Measurement precision
If simple sensing is used, then device complexity is reduced, but measurement capability is limited
Solution Approach 1:
The patent creates a multi-functional sensor system where the photointerrupter-based friction sensor can detect both static and dynamic friction forces. The same basic structure serves multiple measurement purposes, reducing the need for separate specialized sensors while maintaining high measurement precision for friction coefficient determination.
Solution Approach 2:
The patent introduces a flexible assembly as an intermediary element between the force application point and the photointerrupter sensor. This intermediary converts complex friction forces into simple linear displacements that the optical sensor can measure, enabling precise friction coefficient measurement without requiring direct complex force sensing.
3Measurement precision
If photointerrupter blockage method is used, then force sensing is achieved, but measurement and processing capability is limited
Solution Approach 1:
The patent implements a feedback mechanism where the photointerrupter detects light blockage caused by flexible assembly displacement, converts this into electrical signals, and provides feedback for automated data acquisition. This feedback loop enables the system to automatically process and record friction force measurements without manual intervention.
Solution Approach 2:
The patent employs a dynamic measurement approach where the flexible assembly continuously adapts to varying friction forces, and the photointerrupter system dynamically tracks displacements in real-time. This dynamic capability enables automated data acquisition across different friction conditions, from static to dynamic measurements.
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
The system effectively detects and measures friction forces in the millinewton range and determines the friction coefficient with high sensitivity, addressing the limitations of prior art sensors.
Implementation Method 1
A photointerrupter sensor is an electronic device which consists of a light emitter, a light transmitter and a light-sensitive receiver. The beam of light travels across a gap and is picked up by the receiver on the other end of the said gap. This transparent gap can be disturbed by a interrupter which can change the photo-transistor output, resulting in a means to deduce environmental changes caused by an external force
Implementation Method 2
a displacement or perturbance caused by an object in a sensory element calibrated appropriately to deduce force causing the displacement of the said object
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention generally concerns a friction force sensing system comprising one interrupter (10) with a blocking extension (13) and one flexible assembly (14) having a fixed end (17) and a free end (15), longitudinal flexures (18) extending between said fixed end (17) and free end (15), said interrupter (10) and said flexible assembly (14) being fixedly connected to each other by a mounting element (1) at the free end (15) of said flexible assembly (14).