Compact Kibble Balance With Flexural Arms for Absolute Mass
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Solution Overview
Problem
Existing mass measurement technologies, such as the NIST-4 Kibble balance, are large, expensive, and require periodic calibration at national metrology institutes, making them inconvenient and costly for researchers and manufacturers.
Innovation Solution
The development of a second generation NIST Kibble balance, a compact tabletop instrument that measures masses with high accuracy and versatility, allowing on-site calibration and reducing the need for frequent trips to national metrology institutes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional NIST-4 Kibble balance is used, then mass measurement accuracy is maintained, but device size and cost increase significantly
Solution Approach 1:
The Kibble balance is divided into modular components including a balance beam assembly, electromagnetic actuator assembly, and measurement assembly. Each module can be independently calibrated and maintained, enabling compact design while preserving measurement accuracy through modular precision engineering
Solution Approach 2:
Traditional mechanical linkages and physical calibration weights are replaced with electromagnetic actuators and capacitive sensors. The electromagnetic actuator uses magnetic fields to balance gravitational forces, eliminating complex mechanical transmission systems and reducing overall device size while maintaining measurement precision
2Reliability
If periodic calibration at national metrology institutes is performed, then measurement reliability is ensured, but time loss and operational inconvenience increase
Solution Approach 1:
The instrument incorporates self-calibration capabilities using built-in reference standards and automated calibration routines. The system can perform self-diagnosis and self-adjustment of calibration parameters, eliminating the need for frequent trips to national metrology institutes while maintaining measurement reliability
Solution Approach 2:
The device includes pre-calibrated reference masses and electromagnetic field references that are integrated into the measurement system. These preliminary calibration elements allow for quick verification and adjustment of measurement accuracy without requiring external calibration services
3Measurement precision
If high measurement accuracy is achieved, then uncertainty is reduced, but device complexity and environmental requirements increase
Solution Approach 1:
The system dynamically adjusts measurement parameters such as electromagnetic field strength, balance beam position, and sensor gain to optimize measurement accuracy for different mass ranges. This adaptive parameter tuning reduces measurement uncertainty across varying environmental conditions without requiring stringent environmental controls
Solution Approach 2:
Capacitive sensors provide real-time feedback on balance beam position and electromagnetic actuator displacement. This feedback is used to compensate for environmental disturbances such as temperature fluctuations and vibrations, maintaining high measurement accuracy in less controlled environments
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 second generation NIST Kibble balance provides accurate mass measurements with uncertainties less than 1/3 of ASTM E617 Class 3 weights, offering a cost-effective and user-friendly solution for calibration laboratories, capable of measuring a wide range of masses with reduced uncertainty and environmental requirements.
Implementation Method 1
the central flexural bridge... flexes in response to pivotal motion of the lever bar relative to the main body
Implementation Method 2
the mass arm flexural bridge... flexes in response to pivotal motion of the lever bar relative to the main body
Implementation Method 3
the reference arm flexural bridge... flexes in response to pivotal motion of the lever bar relative to the main body
Implementation Method 4
measuring a first change in voltage required by the actuator to maintain the specific position
Data Source
AI summary
A second generation NIST Kibble balance includes: a main body including a main body fulcrum node; a lever bar in mechanical communication with the main body and that pivots about the main body fulcrum node; a central flexural bridge in flexural mechanical communication with the main body and the lever bar; a measurement mass arm mechanically coupled to the main body via the lever bar, the central flexural bridge, and a mass arm flexural bridge; the mass arm flexural bridge in flexural mechanical communication with the measurement mass arm and the lever bar; a reference force arm mechanically coupled to the main body via the lever bar, the central flexural bridge, and a reference arm flexural bridge; and the reference arm flexural bridge in flexural mechanical communication with the reference force arm and the lever bar.