Force Torque Sensor Thermal Drift Compensation
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Solution Overview
Problem
Existing force and torque sensors with multi-axis capabilities are complex, costly, and difficult to manufacture due to the large number of strain gauges required, which can lead to robustness issues when downsized for measuring small forces and torques.
Innovation Solution
A sensor design featuring a load-bearing member with strategically mounted strain gauges, including a cylindrical flexure with six strain gauges symmetrically disposed about its longitudinal axis, and a signal conditioning unit that uses calibration matrices to calculate forces and torques, minimizing the impact of thermal drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of strain gauges are used to compensate for thermal strain in multi-axis sensors, then measurement accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The sensor measures forces and torques along individual orthogonal axes separately using dedicated strain gauge sets, rather than using a large number of strain gauges to simultaneously measure all six components. This segmentation allows thermal compensation to be performed independently for each axis, reducing the total number of strain gauges required while maintaining measurement accuracy.
2Measurement precision
If a large number of strain gauges are used to compensate for thermal strain, then measurement accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The sensor measures forces and torques along individual orthogonal axes separately using dedicated strain gauge sets, rather than using a large number of strain gauges to simultaneously measure all six components. This segmentation allows thermal compensation to be performed independently for each axis, reducing the total number of strain gauges required while maintaining measurement accuracy.
3Measurement precision
If the flexure is downsized to measure relatively small forces and torques, then measurement sensitivity is improved, but structural robustness deteriorates
Solution Approach 1:
The sensor measures forces and torques along individual orthogonal axes separately using dedicated strain gauge sets, rather than using a large number of strain gauges to simultaneously measure all six components. This segmentation allows thermal compensation to be performed independently for each axis, reducing the total number of strain gauges required 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 solution results in a compact, robust, and cost-effective sensor that accurately measures three orthogonal external forces and torques while being insensitive to thermally-induced drift, allowing for reliable operation across various load conditions.
Implementation Method 1
The strain gauges themselves undergo strain in response to the strain experienced by the flexure, and the strain gauges generate outputs responsive to this strain
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
Force and torque sensors (10, 10a) include a load-bearing element (12), and strain gauges (20, 22, 23) mounted on the load-bearing element (12) so that the strain gauges (20, 22, 23) generate outputs responsive to external forces and moments applied to the load-bearing element (12). The strain gauges (20, 22, 23) are configured, and the responsive outputs of the strain gauges (20, 22, 23) are processed such that the force and moment measurements generated by the sensors (10, 10a) are substantially immune from drift due to thermally-induced strain in the load-bearing element (12).