Tool-Holder Force Module With Decoupled Multi-Axis Sensing
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Solution Overview
Problem
Existing force measurement systems using piezoelectric sensors are expensive and difficult to install, and they often face significant interactions between force components, making it challenging to accurately measure forces in multiple directions.
Innovation Solution
A force measurement module with a central core that decouples deformations around strain gauges, allowing independent measurement of force components by positioning strain gauges close to the neutral fiber and using specific hole shapes to reduce mutual interactions, such as 'I' or 'T' shaped central webs with elongated decoupling holes, to enhance sensitivity and stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are positioned close to the neutral axis to increase measurement sensitivity, then measurement sensitivity is improved, but the structure becomes more complex and manufacturing becomes more difficult
Solution Approach 1:
The holder body is segmented into multiple functional zones: a central core region where strain gauges are positioned close to the neutral axis for high sensitivity, and peripheral regions that provide structural support. This segmentation allows the sensitive measurement zone to be optimized independently from the structural requirements.
Solution Approach 2:
The holder employs an asymmetric cross-sectional design with a central core that is thinner than the peripheral regions. This asymmetric geometry enables the strain gauges to be positioned close to the neutral axis in the central region while maintaining adequate structural strength in the thicker peripheral regions.
2Adaptability or versatility
If multiple strain gauges are used to measure different force components, then measurement capability in multiple directions is improved, but interactions between force components increase and complicate measurements
Solution Approach 1:
The holder body is divided into distinct measurement zones with strain gauges positioned at specific locations: central gauges for one force component and peripheral gauges for other components. This spatial segmentation reduces the interaction between measurements of different force components.
Solution Approach 2:
Different regions of the holder are designed with different local properties: the central core region is optimized for measuring one force component with high sensitivity, while peripheral regions are optimized for measuring other components. Each region's geometry is tailored to its specific measurement function.
3Measurement precision
If the measuring body is thinned to position strain gauges closer to the neutral axis, then measurement sensitivity is improved, but the stiffness and strength of the holder may be reduced
Solution Approach 1:
The holder employs an asymmetric cross-sectional design with a central core that is thinner than the peripheral regions. This asymmetric geometry enables the strain gauges to be positioned close to the neutral axis in the central region while maintaining adequate structural strength in the thicker peripheral regions.
Solution Approach 2:
The holder body is segmented into a thin central measurement core and thicker peripheral support regions. This segmentation allows the central core to be optimized for measurement sensitivity while the peripheral regions provide the necessary structural strength and stiffness.
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
Enables precise and independent measurement of force components in multiple directions, reducing interactions and improving measurement accuracy and stiffness, thus overcoming the limitations of existing systems.
Implementation Method 1
Two measuring cavities are provided in the holder body. Strain gauges are arranged in these cavities to measure the shear deformation in order to evaluate the cutting force exerted on the insert holder.
Implementation Method 2
The strain gauges are arranged near the neutral axis of the insert holder and can be wired in a Wheatstone bridge configuration for good sensitivity and to limit the influence of other sources of insert holder deformation, particularly those related to feed, torsion, and penetration forces.
Implementation Method 3
The central core, shaped to decouple the deformations of the measuring body around the strain gauges, at least between the third and first directions, enables independent measurement of the force components in these directions by minimizing their interactions.
Implementation Method 4
The force measurement module may also include at least one third strain gauge fixed to the central web and configured to measure elongation-compression deformation in the second direction.
Data Source
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Figure 8~11
AI summary
The invention concerns a force measurement module (1) comprising: - a measurement body (2) comprising a central core (10) delimited by two cavities (8, 9) separating the central core (10) on either side of the central core (10), the cavities (8, 9) having a parallelepiped shape defining between them a first, second and third, mutually perpendicular direction (X, Y, Z), the measurement body (2) having an elongate shape in the second direction (Y), - at least a first strain gauge (13) attached on a side of the central core (10) and configured for measuring shear deformation in the third direction (Z), - at least a second strain gauge (14) attached on a parallel wall of one of the cavities (8, 9) and configured for measuring a deformation by elongation/compression or shear in the first direction (X), characterised in that the central core (10) is also delimited by at least two decoupling holes (11, 12, 16, 17, 18) shaped to decouple the deformations of the measurement body (2) around the strain gauges (13, 14), at least between the third direction (Z) and the first direction (X). The force measurement module is for example formed in a tool-holder or in an end of an industrial robot arm.