Pedal Force Sensor for Cyclist Power Estimation
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Solution Overview
Problem
Existing methods for estimating the useful power developed by a cyclist during pedaling require expensive angular sensors or significant energy resources for acceleration measurements, which can be imprecise.
Innovation Solution
A method that estimates average useful effort by measuring the pressing force on a pedal using a pressure sensor and applying a pre-established affine linear regression function, eliminating the need for angle measurements and extensive calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive angular sensors are used to measure crank position, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential measurement information (crank position) from the complex angular sensor system and replaces it with a simplified approach using only a force sensor on the pedal. The method calculates crank position indirectly from force measurements and timing, eliminating the need for dedicated angular position sensors while maintaining sufficient measurement precision for power calculation.
Solution Approach 2:
The patent replaces the mechanical/angular sensor system with a force-based measurement system. Instead of directly measuring angular position with encoders or accelerometers, the system uses a force sensor to measure pedal force, then derives position and velocity information from the force signal characteristics and timing, substituting a simpler mechanical sensing approach.
2Device complexity
If acceleration measurements are used to estimate angular position, then device complexity is reduced, but energy consumption increases and precision decreases
Solution Approach 1:
The patent extracts only the necessary information (force magnitude and timing) from the pedal force signal, avoiding the need to process complex acceleration data. By focusing on force measurements at specific crank positions rather than continuous acceleration analysis, the system reduces computational energy requirements while maintaining measurement simplicity.
3Device complexity
If force sensor measurements are used instead of angular sensors, then device complexity is reduced, but measurement precision may be affected
Solution Approach 1:
The patent implements a feedback mechanism where the force sensor measurements are continuously monitored and used to determine crank position and velocity. The system uses the measured force signal characteristics (magnitude, timing, waveform) to feedback-calculate the instantaneous power, ensuring that the simplified force-based measurement maintains sufficient precision for accurate power estimation.
Solution Approach 2:
The patent changes the measurement parameter from direct angular position to force magnitude. By measuring force at the pedal and using the relationship between force, crank position, and angular velocity to calculate power, the system achieves accurate useful effort estimation through parameter transformation rather than direct measurement, maintaining precision while reducing 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
This approach allows for simple and economical estimation of the average useful effort and power developed by a cyclist, providing accurate results with minimal energy consumption and without the need for expensive sensors.
Implementation Method 1
A pressure sensor arranged in or on the pedal measures the pressing force exerted on the pedal by the cyclist
Data Source
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AI summary
The method includes a step of measuring a support force (Fpn) on a pedal (1) of the crankset (4), distinct from the useful effort, exerted by the individual during a pedaling cycle, a step of determining a maximum (max(FPn)) of the support force measured during the pedaling cycle (CPj), and a step of estimating an average useful effort exerted by the individual during said pedaling cycle from the maximum of the support force determined and using a pre-established correlation function between a maximum of support force during a pedaling cycle and an average useful effort on said cycle.