Strain Wave Gear Assembly With Integrated Encoder Positioning
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Solution Overview
Problem
Existing strain wave gears for robot arms are costly, require many parts for assembly, and lack the necessary rigidity and precision, especially in encoder positioning, which can lead to inaccuracies and increased complexity.
Innovation Solution
A strain wave gear design that integrates an outer ring, an inner ring with an internally toothed gear, a flexible spline with external teeth, and a wave generator, where the inner ring and output flange are formed as a single unit, reducing parts and assembly complexity, and incorporates an encoder directly on the gear for precise positioning without manual adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate components (output bearing part, circular spline part, output flange part) are used in strain wave gear assembly, then adaptability to different applications is improved, but device complexity and assembly difficulty increase
Solution Approach 1:
The patent combines the output bearing part and circular spline part into a single integrated component. The output bearing is directly formed on the circular spline part, eliminating the need for separate output flange part and multiple fastening screws. This merging reduces assembly complexity while maintaining adaptability through design variations in the integrated component.
2Adaptability or versatility
If multiple separate parts are assembled together, then adaptability is improved, but manufacturing precision and rigidity deteriorate due to interface accuracy requirements
Solution Approach 1:
By integrating the output bearing and circular spline into one piece, the patent eliminates multiple interfaces between separate components. This removes the accumulation of interface tolerance errors, ensuring high manufacturing precision and rigidity. The integrated design maintains adaptability through varying the geometry and features of the unified component across different applications.
3Ease of operation
If encoder read head is placed externally on housing or gear geometry, then ease of assembly is improved, but measurement precision deteriorates due to positioning adjustment requirements
Solution Approach 1:
The patent nests the encoder read head within the internal cavity of the circular spline part. This nested arrangement provides a built-in, precisely positioned mounting location for the encoder, eliminating the need for external adjustment. The encoder is automatically positioned at the correct distance and orientation relative to the read track, achieving high measurement precision while simplifying assembly.
4Measurement precision
If platform/bearing setup with flexible mechanism is used for encoder, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the encoder mounting function directly into the circular spline part by providing an integrated cavity and positioning features. This eliminates the need for separate platform, bearing, and flexible mechanism components. The high measurement precision is achieved through the precision-machined integrated features of the circular spline itself, reducing device complexity and cost.
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
This design results in a more cost-effective, rigid, and precise strain wave gear capable of handling higher loads with reduced assembly complexity and improved encoder accuracy, enhancing the reliability and precision of robot joints.
Implementation Method 1
a wave generator configured to flex the flexible part in a radial direction to partly mesh the external toothed gear with the internally toothed gear causing rotation of the inner ring in relation to the outer ring
Data Source
AI summary
A strain wave gear comprising an outer ring and an inner ring rotatably arranged in the outer ring. The inner ring comprises an internally toothed gear and a flex spline is arranged in the inner ring and comprise a flexible part comprising an external toothed gear. A wave generator is rotatable in relation to the flex spline and is configured to flex the flexible part in a radial direction to partly mesh the external toothed gear with the internally toothed gear causing rotation of the inner ring in relation to the outer ring. A part of said inner ring extends out of said outer ring and comprises an outwardly protruding output flange. An encoder reader can be disposed on the outer ring and an encoder track can disposed on the inner ring. A robot joint comprising the strain wave gear is also disclosed.