Strain Wave Gear Torque Sensing Without Flexing Interference
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Solution Overview
Problem
Existing strain wave gearings used in robot joints face challenges in torque detection precision, sensor durability, ease of installation, integration of additional sensors, and monitoring of gear reducer conditions, particularly due to the flexing of externally toothed gears and exposure to grease/oil.
Innovation Solution
A unitized strain wave gearing with a wine-glass-shaped externally toothed gear and a torque sensor attached to a flange, along with sensors like temperature and acceleration sensors housed in a protected recess, allows precise torque detection and monitoring of gear conditions without flexing interference and exposure to contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the hollow diameter of the strain wave gearing is increased for robot joint applications, then adaptability improves, but device complexity increases due to integration of torque sensor
Solution Approach 1:
The torque sensor components (strain gauge, lead, protective structure) are merged into the existing boss structure of the externally toothed gear, utilizing available structural elements rather than adding separate components, thereby maintaining simplicity while enabling torque sensing
Solution Approach 2:
The boss structure serves multiple functions: structural support for the diaphragm, transmission path for torque, and mounting location for the strain gauge, eliminating the need for separate torque sensing components and reducing overall device complexity
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 enhances torque detection precision, improves sensor durability, facilitates easy installation, and enables effective monitoring of gear conditions, including temperature and vibration, thereby preventing damage and facilitating predictive maintenance.
Implementation Method 1
a strain gauge is affixed to a diaphragm of a flexible externally toothed gear of a strain wave gearing that is used as a gear reducer, and torque transmitted via the externally toothed gear is detected
Data Source
AI summary
A strain wave gearing (1) is configured to have a unitized structure having a main bearing (5) that supports an internally toothed gear (2) and an externally toothed gear (3) in a manner that allows relative rotation, and an output flange (6) that is linked to the externally toothed gear (3). The externally toothed gear (3) is formed in the shape of a wine glass and ensures a large hollow diameter, which is required in cases where the externally toothed gear (3) is incorporated into a robot joint part or the like. A strain gauge (101) of a torque sensor (100) is attached to an outward-facing end surface portion of the output flange (6) linked to the externally toothed gear (3). The torque sensor (100) is capable of precisely detecting rotational torque without being affected by flexing of the externally toothed gear (3), and elements such as the strain gauge (101) are not exposed to oil, grease, or the like.