Monolithic Flexure Dynamometer with Photointerrupters
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Solution Overview
Problem
Existing force sensing technologies, such as those using photointerrupters and piezoelectricity, often lack the accuracy and reliability needed for precise three-dimensional force measurement, particularly in applications like high-speed micro-milling, and can be costly, limiting their widespread adoption.
Innovation Solution
A triaxial monolithic flexure-based dynamometer with a central force exertion point and three light blocking structures positioned to represent three-dimensional Euclidean space, cooperating with three photointerrupter sensors for even force distribution and accurate force detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If photointerrupters are used for force sensing, then the device complexity is reduced and unit cost is lowered, but the measurement precision and reliability are insufficient for accurate three-dimensional force measurement
Solution Approach 1:
The force sensing function is segmented into three independent measurement axes (X, Y, Z), each with its own photointerrupter sensor and light blocking structure. This segmentation allows each sensor to measure force in a specific direction independently, enabling accurate three-dimensional force measurement while keeping each individual sensor simple and low-cost.
Solution Approach 2:
Light blocking structures serve as intermediaries that translate mechanical displacement of the flexure into optical signals detectable by photointerrupters. These structures are positioned to interrupt light paths when displaced by force, converting mechanical deformation into measurable optical changes without requiring complex sensing elements.
2Reliability
If a monolithic flexure with three light blocking structures is used, then the reliability and accuracy of triaxial force measurement are enhanced, but the device complexity increases compared to single-axis sensors
Solution Approach 1:
Three separate force sensing functions along orthogonal axes are merged into a single monolithic flexure structure with three light blocking structures. This integration allows simultaneous measurement of three-dimensional forces while maintaining structural rigidity and reducing the number of separate components, thereby improving reliability without excessive complexity increase.
Solution Approach 2:
The monolithic flexure structure serves multiple functions: it provides mechanical support, enables three-axis force sensing, and positions the light blocking structures. This multi-functionality reduces the need for additional components and simplifies the overall system architecture while enhancing measurement reliability.
3Adaptability or versatility
If three photointerrupter sensors are positioned to cover three-dimensional space, then the adaptability for various force directions is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The three photointerrupter sensors are positioned symmetrically around the central force application point, creating equipotential measurement conditions for forces applied in any direction. This symmetric arrangement ensures that each sensor operates under comparable geometric conditions, reducing the impact of positioning variations and simplifying calibration.
Solution Approach 2:
The light blocking structures are asymmetrically positioned on the flexure arms to optimize their leverage and displacement characteristics for each axis. This asymmetric design compensates for manufacturing tolerances by creating inherent mechanical advantages that enhance measurement sensitivity while maintaining adaptability to various force directions.
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 solution provides enhanced reliability and accuracy in force measurement across three dimensions, ensuring precise control mechanisms while maintaining a lower unit cost, making it a more accessible and effective solution for industrial applications.
Implementation Method 1
A photointerrupter sensor is an electronic device which consists of a light emitter, LED to transmit the light 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 gaps can be disturbed by a combination of light blockers which can change the photo-transistor output
Implementation Method 2
a flexure as a load-bearing element which is displaced under strain or a force applied
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention generally concerns a monolithic triaxial dynamometer for machining applications comprising one flexure frame (1) with three flexural arms (4) and three light blocking extensions (5) protruding three different photointerrupter sensors (19) housed in specially designated sensor placement slots (8) situated on the sensor stand (7), the bottom of which lands on the floor (16) of the external mounting structure (17), which is aligned and connected with the said top flexure frame (1) using first (3) and third group screw holes (15), thus bringing together a dynamometer used for force sensing in various industrial applications.