Bicycle Crank Arm Assembly Multi-Direction Force Detection
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Solution Overview
Problem
Existing bicycle crank arm assemblies lack accurate measurement capabilities for forces acting on the crank, particularly in detecting forces in multiple directions and moments, leading to inaccuracies, especially in asymmetric designs.
Innovation Solution
A bicycle crank arm assembly incorporating first to third detecting circuits with strategically positioned and angled strain sensors on a shared attachment surface, allowing for precise detection of forces in different directions and moments, including a pedal shaft joint part for rotational movement, and a sheet member for integrated sensor attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple strain sensors are mounted on the attachment surface to detect forces in different directions and moments, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The detection function is segmented into three independent detecting circuits, each responsible for a specific force component or moment. Each circuit uses strategically placed strain sensors oriented in specific directions to detect particular forces, allowing precise measurement while maintaining clear functional separation and simplifying the overall system architecture.
Solution Approach 2:
Different regions of the attachment surface are assigned different sensor configurations tailored to local measurement requirements. The first strain sensors detect forces in the first direction at specific locations, the second strain sensors detect forces in the second direction at other locations, and the third strain sensors detect moments at designated positions, optimizing each local area for its specific measurement function.
2Measurement precision
If strain sensors are positioned and angled to detect forces in multiple directions, then measurement precision is improved, but ease of manufacture decreases
Solution Approach 1:
The attachment surface is pre-divided into distinct regions with predetermined sensor placement positions and orientation angles during the design phase. This preliminary configuration allows for standardized manufacturing processes where sensors can be mounted according to fixed patterns, reducing on-site assembly complexity while maintaining precise multi-directional force detection capabilities.
3Device complexity
If a shared attachment surface is used for all detecting circuits, then device complexity is reduced, but measurement precision may worsen due to potential interference
Solution Approach 1:
The attachment surface is functionally segmented into distinct zones for each detecting circuit, with each zone dedicated to specific sensor types oriented in specific directions. This spatial segmentation prevents interference between different measurement functions while maintaining the overall simplicity of a single attachment surface structure.
Solution Approach 2:
Each region of the attachment surface is optimized for its specific measurement function, with strain sensors positioned and oriented to detect particular force components without interference from other circuits. The local quality of each sensor region is tailored to its specific detection requirements while all regions share the common attachment surface structure.
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
Enables accurate measurement of forces and moments acting on the bicycle crank, reducing errors and enhancing detection accuracy, particularly in asymmetric crank arm designs by optimizing sensor placement and configuration.
Implementation Method 1
The first detecting circuit includes at least one first strain sensor mounted to the attachment surface. The second detecting circuit includes at least one second strain sensor mounted to the attachment surface. The third detecting circuit includes at least one third strain sensor mounted to the attachment surface.
Data Source
AI summary
A bicycle crank arm assembly basically includes a bicycle crank arm and first to third detecting circuits. The first detecting circuit is configured to detect a force acting in a first direction. The second detecting circuit is configured to detect a force acting in a second direction. The third detecting circuit is configured to detect a moment. The first detecting circuit includes a first strain sensor that is mounted to an attachment surface. The second detecting circuit includes a second strain sensor that is mounted to the attachment surface. The third detecting circuit includes a third strain sensor that is mounted to the attachment surface.