Aluminum Flange Torque Sensing for Cost-Effective Robot Joints
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Solution Overview
Problem
Existing torque sensors for robot joints are complex, expensive, and difficult to manufacture due to the use of stainless steel, making accurate torque measurement challenging and costly.
Innovation Solution
A torque sensing system using a flange made of aluminum or aluminum alloy, equipped with miniaturized torque sensor devices and a stiffening region, which reduces complexity and cost while providing accurate torque measurements by using silicon or foil strain gages and a Wheatstone bridge circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stainless steel is used for the circular body/diaphragm in torque sensor devices, then measurement accuracy and reliability are improved, but manufacturing cost and device complexity increase significantly
Solution Approach 1:
The torque sensor device is divided into separate components: a flange (can be aluminum) and a torque sensor device proper (stainless steel). This segmentation allows the complex stainless steel portion to be minimized to only where absolutely necessary while the larger flange structure can be made from cheaper aluminum material.
Solution Approach 2:
The patent introduces an intermediate aluminum flange structure that mediates between the torque transmission requirement and cost reduction goal. The flange serves as an intermediary component that can be made from aluminum while still enabling accurate torque measurement through its specific geometric design featuring a thinned sensing area.
2Reliability
If stainless steel is used for the circular body/diaphragm, then structural strength and measurement reliability are improved, but manufacturing cost increases
Solution Approach 1:
Instead of making the entire flange from expensive stainless steel, the patent applies local quality by creating a thinned sensing area (reduced thickness) in the specific region where torque measurement occurs, while other portions of the flange maintain standard thickness for structural support. This localized modification enables accurate measurement with cheaper aluminum material.
Solution Approach 2:
The patent changes the geometric parameter (thickness) of the flange in the sensing area to create a more sensitive region for torque measurement. By reducing the thickness in this specific area, the flange becomes more compliant and responsive to torque-induced deformation, enabling accurate measurement without requiring expensive stainless steel throughout the entire structure.
3Measurement precision
If a thinned sensing area is introduced in the flange, then torque measurement sensitivity is improved, but structural strength may be reduced
Solution Approach 1:
The flange is designed with local quality by creating a thinned sensing area only in the specific region where torque measurement is needed, while maintaining full thickness in other areas for structural support. This localized thinning provides measurement sensitivity without compromising overall structural strength.
Solution Approach 2:
The patent effectively creates a composite structure by combining aluminum material with a specific geometric configuration (thinned sensing area). The geometric variation acts as a form of structural composite that provides both compliance for measurement and strength for load bearing, eliminating the need for expensive stainless steel while maintaining performance.
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 system enables reliable, cost-effective torque measurement in robot joints, unaffected by axial or radial loads, facilitating torque control in collaborative robots with reduced manufacturing costs and improved accuracy.
Implementation Method 1
The measurement transducers may, alternatively, be configured for sensing torque based on other measurement methods as, for example, magnetic or optical measurement methods
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
The present disclosure provides a system (200, 300, 400, 500) for sensing torque of an object, comprising a flange (210, 310, 410, 510), for example, made of or comprising an isotropic material such as aluminum or an aluminum alloy, configured to be connected to the object and having a first length along a main axis of a main surface of the flange (210, 310, 410, 510) and at least one torque sensor device (220, 230, 520, 530) formed over the main surface of the flange (210, 310, 410, 510). The torque sensor device (220, 230, 520, 530) comprises a) a sensing portion (340, 350) and b) a plurality of measurement transducers (360, 370) formed over the sensing membrane (340, 350) and has c) a second length parallel to the main surface of the flange (210, 310, 410, 510) and d) a third length parallel to the main surface of the flange (210, 310, 410, 510). The second and third lengths of the at least one torque sensor device (220, 230, 520, 530) are smaller than half of the first length of the flange (210, 310, 410, 510).