Force Moment Sensor Miniaturization via Deformation Element Transducer Placement
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Solution Overview
Problem
Existing force/moment sensors are complex and expensive to manufacture, have large size limitations, and suffer from material volume constraints that hinder miniaturization and can be affected by attachment-induced tension, which impairs measurement accuracy.
Innovation Solution
A force/moment sensor design featuring an inner and outer annular holding element connected via multiple deformation elements, with deformation transducers arranged on these elements rather than the holding elements, allowing for miniaturization and reduced attachment-induced tension, and utilizing flexure hinges for connection without separate joints, enabling production simplification and improved measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are arranged laterally on the beam for force/moment measurement, then measurement capability is achieved, but the outer dimensions increase and miniaturization becomes impossible
Solution Approach 1:
The patent moves the strain gauges from a lateral arrangement on the beam surface to a topological arrangement on the deformation elements themselves. By placing strain gauges on the top and bottom surfaces of the deformation elements rather than laterally on the beam, the sensor achieves miniaturization to an outer diameter of less than 20 mm while maintaining measurement capability through the deformation elements' inherent geometry.
Solution Approach 2:
The patent extracts the strain gauge arrangement from the lateral beam surface and relocates it to the deformation elements. This separation allows the beam to be minimized in lateral dimensions while the deformation elements, which are essential for force transmission, carry the strain gauges on their top and bottom surfaces, enabling compact sensor design.
2Area of stationary object
If the material volume at clamping points is reduced for miniaturization, then sensor size decreases, but twisting of the structure occurs which impairs measurement results
Solution Approach 1:
The patent applies different structural characteristics to different parts of the sensor. The deformation elements are designed with specific geometric properties (such as varying thickness or cross-sectional shape) that provide both stiffness and flexibility where needed. This local optimization allows miniaturization at the clamping points while maintaining the structural integrity and measurement accuracy through carefully designed deformation characteristics in the measurement regions.
Solution Approach 2:
The patent employs composite construction where the sensor body and deformation elements are formed from materials with appropriate mechanical properties. The use of flexure hinges with specific material characteristics allows the structure to be both compact and resistant to unwanted twisting, while the deformation elements provide the necessary flexibility for accurate force and moment measurement.
3Device complexity
If outer holding elements are used as deformation elements for force measurement, then structural efficiency is improved, but attachment process induces tension that adversely affects measurement results
Solution Approach 1:
The patent separates the holding function from the deformation measurement function. The outer holding elements are dedicated to providing structural support and clamping, while separate deformation elements are introduced specifically for force measurement. This segmentation prevents attachment-induced tension from affecting measurement results, as the deformation elements are designed to be free from attachment stresses, while maintaining structural efficiency through the holding elements.
Solution Approach 2:
The patent introduces deformation elements as intermediary components between the holding elements and the measured structure. These deformation elements serve as pure measurement sensors that are not directly subjected to attachment forces, thereby eliminating the problem of attachment-induced tension while still enabling force measurement through their controlled deformation.
4Ease of manufacture
If a monolithic construction is used for force/moment sensor, then manufacturing simplicity is achieved, but the manufacture becomes extremely complex and expensive
Solution Approach 1:
The patent divides the sensor into distinct functional components: holding elements, deformation elements, and flexure hinges. This segmentation allows each component to be manufactured separately using optimized processes, then assembled together. The holding elements can be produced from appropriate materials for structural support, while deformation elements are manufactured with integrated strain gauge mounting features, reducing overall manufacturing complexity compared to a true monolithic construction.
Solution Approach 2:
The patent designs components with multiple functions to reduce the total number of parts. For example, the deformation elements serve both as structural connectors and as mounting platforms for strain gauges. The flexure hinges provide both flexible connection and force transmission. This multi-functionality simplifies the overall manufacturing process while maintaining measurement accuracy.
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 design achieves significant miniaturization to an outer diameter of less than 10 mm, reduces attachment-induced tension, and enhances measurement accuracy by eliminating lateral strain gauge placement and using flexible connections, facilitating easier production and improved structural stiffness.
Implementation Method 1
The two holding elements are connected to each other via at least three, preferably at least six deformation elements
Implementation Method 2
On said rods, strain gauges are arranged. With the aid of the strain gauges, three orthogonal forces and three orthogonal moments can be determined
Data Source
AI summary
A force/moment sensor for measurement of three orthogonal forces and three orthogonal moments, comprises an inner holding element which is surrounded by an outer holding element. The two holding elements are connected to each other by deformation elements. For each deformation element, at least one deformation transducer is provided. The force/moment sensor is preferably monolithic, and the deformation transducers, formed as strain gauges, are preferably arranged in one plane or in two preferably parallel planes.