Flexspline Bridge Circuit Layout for Accurate Torque Sensing
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Solution Overview
Problem
Conventional strain-wave gear assemblies in robotics face challenges in compact and lightweight design due to the need for space-consuming structures for torque sensing, which can compromise efficiency and accuracy.
Innovation Solution
The use of multiple bridge circuits strategically placed around the flexspline of a strain-wave gear assembly to measure strain and deformation, which enhances the accuracy and precision of torque sensing by canceling out ripples and reducing sampling errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional torque sensing structures are used in strain-wave gear assemblies, then torque sensing capability is achieved, but the actuator size and weight increase
Solution Approach 1:
The flexspline serves dual functions: as a structural component of the strain-wave gear mechanism and as a sensing element for torque measurement. By integrating strain gauges directly onto the flexspline, the same component performs both mechanical function and sensing function, eliminating the need for separate torque sensing structures and thereby reducing overall actuator weight.
Solution Approach 2:
The invention utilizes the flexible nature of the flexspline to embed strain gauges directly on its surface. This approach leverages the thin, flexible structure of the flexspline itself as the sensing substrate, avoiding the need for bulky rigid sensing structures and reducing the overall weight of the actuator while maintaining torque sensing capability.
2Measurement precision
If conventional torque sensing structures are used in strain-wave gear assemblies, then torque sensing capability is achieved, but the actuator volume increases
Solution Approach 1:
The flexspline serves dual functions: as a structural component of the strain-wave gear mechanism and as a sensing element for torque measurement. By integrating strain gauges directly onto the flexspline, the same component performs both mechanical function and sensing function, eliminating the need for separate torque sensing structures and thereby reducing overall actuator volume.
Solution Approach 2:
The strain gauges are embedded directly onto the surface of the flexspline, nesting the sensing function within the existing structural component. This nested arrangement eliminates the need for separate sensing structures and reduces the overall volume of the actuator while maintaining full torque sensing capability.
3Device complexity
If single bridge circuit is used for torque sensing, then device complexity is reduced, but measurement precision and reliability decrease
Solution Approach 1:
The torque sensing function is divided into multiple independent bridge circuits distributed around the flexspline. Each bridge circuit measures strain at a specific location, and the combined measurements provide more accurate and reliable torque data. This segmentation approach improves measurement precision while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
Different bridge circuits are positioned at different locations around the flexspline to capture local strain variations. This local measurement approach provides more comprehensive torque sensing data, improving overall measurement precision and reliability while allowing each individual bridge circuit to remain relatively simple in design.
4Measurement precision
If bridge circuits are placed circumferentially spaced apart on the flexspline, then torque measurement accuracy improves, but device complexity increases
Solution Approach 1:
The torque sensing function is divided into multiple independent bridge circuits distributed around the flexspline. Each bridge circuit measures strain at a specific location, and the combined measurements provide more accurate and reliable torque data. This segmentation approach improves measurement precision while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
Multiple bridge circuits are integrated onto a single flexspline component, combining multiple sensing functions into one unified structure. This merging approach improves torque measurement accuracy through multiple measurement points while avoiding the complexity of separate sensing structures, as all bridge circuits share the common flexspline substrate.
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 approach allows for more accurate and stable torque measurements, improves the robustness of the system by detecting malfunctions in individual bridge circuits, and maintains the compactness and lightweight nature of the actuator.
Implementation Method 1
a first sensor (e.g., a first bridge circuit) of the strain-wave gear assembly can be configured to measure strain and deformation via a first set of four portions of the flexspline
Data Source
AI summary
A strain-wave gear assembly in accordance with at least some embodiments of the present technology includes a circular spline, a flexspline, and a wave generator operably associated with one another. Relative rotation between the flexspline and the wave generator causes relative rotation between the circular spline and the flexspline about an axis. The strain-wave gear assembly further includes a first bridge circuit configured to generate a first electrical signal corresponding to strain at a first portion of flexspline. The strain-wave gear assembly also includes a second bridge circuit configured to generate a second electrical signal corresponding to strain at a second portion of flexspline circumferentially offset from the first portion of the flexspline about the axis. The first bridge circuit includes a first resistor at the first portion of the flexspline. Similarly, the second bridge circuit includes a second resistor at the second portion of the flexspline.