Axial Force Sensor Diaphragm with Optical Signal Pairs
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Solution Overview
Problem
Existing single-axis load cells are sensitive to manufacturing tolerances, temperature changes, and impact loads, requiring frequent recalibration and are susceptible to assembling errors due to off-axis loads.
Innovation Solution
An axial force sensor with a sensing diaphragm comprising an inner and outer ring connected by a compliant element, utilizing multiple signal pairs of emitters and receivers for precise axial force measurement, enabling off-axis load cancellation and temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are used to measure deflections in single-axis load cells, then the sensing structure can detect axial forces, but the sensor becomes sensitive to manufacturing tolerances, temperature changes, and impact loads, requiring frequent recalibration
Solution Approach 1:
The patent replaces the mechanical strain gauge system with an optical sensing system using laser displacement sensors. This substitution eliminates the need for physical strain gauges that are sensitive to temperature and manufacturing tolerances, while maintaining the ability to measure axial forces through optical deflection detection of the diaphragm structure.
Solution Approach 2:
The patent changes the measurement parameter from electrical resistance change (strain gauges) to optical displacement measurement (laser sensors). This parameter change allows for non-contact measurement that is immune to temperature effects and manufacturing tolerances, improving sensor reliability while maintaining measurement precision.
2Measurement precision
If multiple strain gauges are installed exactly opposite one another to compensate for off-axis loads, then off-axis load compensation is achieved, but the sensor becomes susceptible to assembling errors
Solution Approach 1:
The patent replaces the mechanical strain gauge arrangement with optical sensors positioned to detect diaphragm deflection. This eliminates the need for precise mechanical alignment of multiple strain gauges opposite each other, as the optical system can detect off-axis loads through deflection patterns without requiring tight assembly tolerances.
Solution Approach 2:
The patent introduces the diaphragm as an intermediary element that translates off-axis load effects into detectable deflection patterns. The optical sensors measure the diaphragm's deformation, which inherently provides off-axis load information without requiring direct mechanical alignment of multiple sensors, thus reducing assembly error susceptibility.
3Stability of the object's composition
If a rigid sensing structure is used, then the sensor structure is stable, but the sensor cannot accurately detect axial force-induced deflections
Solution Approach 1:
The patent applies local quality by making only the diaphragm portion flexible while keeping the rest of the sensor structure rigid and stable. The diaphragm is specifically designed with appropriate flexibility to detect axial force deflections, while the mounting structure and housing provide overall stability, thus resolving the contradiction between structural stability and deflection detectability.
Solution Approach 2:
The patent segments the sensing structure into a flexible diaphragm component and a rigid support structure. This segmentation allows different parts to have different mechanical properties - the diaphragm provides the necessary flexibility for deflection detection, while the support structure maintains overall stability and positioning of the optical sensors.
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 axial force sensor achieves precise measurement of axial forces while minimizing the impact of off-axis loads and temperature changes, ensuring accurate and stable readings.
Implementation Method 1
Each signal pair includes a signal emitter and a signal receiver. The signal emitter is coupled to one of the inner ring and the outer ring. The signal receiver is coupled to the other of the inner ring and the outer ring.
Data Source
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AI summary
An axial force sensor, a robot gripper and a robot are provided. The axial force sensor includes a sensing diaphragm and at least two signal pairs. The sensing diaphragm includes an inner ring, an outer ring and a connecting element connected between the inner ring and the outer ring. The connecting element is more compliant in a direction of the axial force to be detected than in other loading directions. Each signal pair includes a signal emitter and a signal receiver. The signal emitter is coupled to one of the inner ring and the outer ring. The signal receiver is coupled to the other of the inner ring and the outer ring.