Bicycle Spindle Force Measurement With Drift-Compensated Load Cell
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Solution Overview
Problem
Existing external force measurement systems for bicycles lack precision and durability, particularly in measuring forces applied to spindles, and are prone to environmental influences and drift issues.
Innovation Solution
An external force measurement unit comprising a load cell with strain gauges on flaps, an evaluation unit for resistance measurement, and a motor housing for protection, along with a freewheel and angular encoder for improved accuracy and durability, and drift compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are arranged on flaps of a load cell to measure external forces, then measurement precision is improved, but the system becomes more sensitive to environmental influences and drift
Solution Approach 1:
The patent implements a feedback mechanism where the measurement system continuously monitors external forces and compensates for drift and environmental influences. The evaluation unit processes signals from multiple strain gauges and applies correction algorithms to maintain measurement accuracy over time, addressing the drift issue through active feedback control.
Solution Approach 2:
The patent changes the physical parameters of the measurement system by arranging strain gauges in specific patterns on the load cell flaps and using differential measurement techniques. This configuration allows the system to distinguish between actual force changes and environmental effects by analyzing parameter variations across multiple sensors.
2Reliability
If a comprehensive measurement system with multiple components (load cell, strain gauges, evaluation unit, angular encoder) is implemented, then measurement reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple measurement functions into a single integrated system. The load cell with flaps and strain gauges is combined with the angular encoder and evaluation unit to create a unified measurement system that simultaneously captures force magnitude and directional information, reducing the need for separate independent systems.
Solution Approach 2:
The evaluation unit serves multiple functions: it processes signals from strain gauges, compensates for drift, integrates angular encoder data for directional measurement, and outputs corrected force values. This multi-functionality reduces the need for separate dedicated components for each task.
3Measurement precision
If drift compensation mechanisms are added to the measurement system, then long-term measurement accuracy is improved, but ease of operation deteriorates
Solution Approach 1:
The measurement system implements self-service through automatic drift compensation. The evaluation unit continuously monitors measurement signals and applies correction algorithms without requiring manual calibration or intervention. The system automatically adjusts for drift based on real-time signal analysis, making the operation transparent to the user.
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 provides a precise, durable, and reliable measurement of external forces applied to bicycle spindles, enhancing the accuracy of torque calculation and reducing environmental impact, while maintaining system compactness and efficiency.
Implementation Method 1
a first strain gauge which is arranged on the first flap and a second strain gauge, which is arranged on the second flap, wherein depending on a change of length of the first flap or the second flap due to a material expand the first strain gauges and/or the second strain gauge is adapted to change their respective resistance
Data Source
AI summary
The invention relates to a harmonic pin ring drive with an outer gear ring toothing comprises a quantity of teeth which is greater by exact one than the quantity of teeth of an inner gear ring toothing. The invention further relates to a motor unit comprising such a harmonic pin ring drive and to an electrically assisted bicycle.