Bicycle Pedal Sensor Angular Velocity Detection
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Solution Overview
Problem
Traditional bicycle cadence sensors are complex, prone to component failure, and may not accurately report pedaling state, especially in suspension-equipped mountain bicycles, leading to poorly controlled suspensions due to inaccurate pedaling frequency detection.
Innovation Solution
A compact, wireless sensor system mounted to the drivetrain that detects angular velocity and position in less than a single revolution of the crank axle, using a processor to determine pedaling states and communicate with external components, such as suspension controllers, for real-time, accurate pedaling state analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional cadence sensors use multiple magnets mounted on the crank arm to increase reporting frequency, then the frequency of reporting is increased, but the system complexity increases and reliability decreases due to more components that can break, fall off, or become misaligned
Solution Approach 1:
The patent divides the sensing function into multiple independent magnetic sensors positioned at different angular locations around the crank arm's rotational path. Each sensor detects the passage of a single magnet, and the processor combines these detections to determine crank rotation frequency. This segmentation allows the system to achieve high reporting frequency without requiring multiple magnets on the crank arm, thereby maintaining reliability while improving speed of reporting.
Solution Approach 2:
The patent introduces a processor as an intermediary that receives signals from multiple sensors and synthesizes them to determine crank rotation frequency. The processor acts as a mediator that combines information from distributed sensors to achieve accurate frequency measurement without requiring physical attachment of multiple magnets to the rotating crank arm, thus resolving the contradiction between reporting frequency and component reliability.
2Speed
If traditional cadence sensors use multiple magnets mounted on the crank arm to increase reporting frequency, then the reporting frequency is increased, but the device complexity increases due to additional components and wiring
Solution Approach 1:
The system segments the detection function across multiple fixed sensors positioned around the crank arm's rotation path rather than attaching multiple magnets to the moving crank arm. This segmentation approach distributes the sensing function across stationary components, reducing mechanical complexity and eliminating the need for precise alignment of multiple rotating magnets.
Solution Approach 2:
The single magnet mounted on the crank arm serves multiple functions by passing sequentially past multiple fixed sensors during rotation. The magnet essentially 'services' all detection points automatically through its rotational motion, eliminating the need for multiple magnets and reducing system complexity while maintaining high reporting frequency.
3Device complexity
If traditional cadence sensors only report wheel turning for any reason, then the sensor system is simple, but the accuracy of pedaling state detection is poor
Solution Approach 1:
The system uses multiple sensors positioned at different angular locations to provide feedback about the crank arm's rotational characteristics. The processor analyzes the timing and pattern of signals from these sensors to distinguish between pedaling-induced rotation and rotation caused by other forces (such as gravity on steep climbs or wind resistance). This feedback mechanism enables accurate pedaling state detection while maintaining reasonable system simplicity.
Solution Approach 2:
The patent employs more sensors than the minimum single sensor would require, creating an 'excessive' sensing capability that provides redundant information about crank rotation. This partial redundancy allows the system to analyze rotational patterns in detail and accurately determine pedaling state, overcoming the limitation of simple sensors that cannot distinguish between different causes of crank rotation.
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
Provides accurate, real-time, and low-latency pedaling state detection, reducing component complexity and improving suspension control by accurately determining pedaling states without the need for multiple magnets or wires, enhancing the reliability and performance of bicycle suspension systems.
Implementation Method 1
a sensor mounted to and rotating with a portion of a drivetrain. The sensor is configured to detect the angular velocity and the position of a crank axle
Data Source
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AI summary
An apparatus for determining bicycle (100) pedaling may include a sensor (220) that detects the angular velocity and position of a drivetrain (114) or rear sprocket assembly (134) of the bicycle (100) and a processor (20) that is configured to compare the detected values against values indicative of at least one pedaling state. The apparatus may be configured to be housed within a component of the bicycle (100), such as within a hollow opening (142) of the spindle or crank axle (124). The apparatus also may include a wireless transmitter to communicate with another component, such as a suspension controller.