Bicycle Shift Timing Control Using Cadence and Torque Feedback
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Solution Overview
Problem
Human-powered vehicles, such as bicycles, often experience shift shock due to improper gear shifting timing, which can cause discomfort for riders, especially those without advanced skills to time their shifts effectively.
Innovation Solution
A shifting system that includes a controller receiving cadence and driving torque data from sensors to control a shift mechanism, allowing gear shifts only within a permitted cadence range and timing interval, thereby preventing shift shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If gear shift is performed without cadence control, then shifting operation is simple and responsive, but shift shock occurs causing rider discomfort
Solution Approach 1:
The control unit receives cadence information from a cadence sensor and uses this feedback to determine whether to execute the gear shift command. The system continuously monitors cadence during the shifting process and compares it against predetermined thresholds, executing the shift only when cadence remains within the acceptable range, thereby preventing shift shock while maintaining simple rider input
Solution Approach 2:
The system determines in advance whether the current cadence is within the permissible range before executing the gear shift. By pre-assessing the cadence condition and only permitting shifts when conditions are favorable, the system prevents harmful shift shock from occurring in the first place, rather than correcting it after the fact
2Device complexity
If gear shift timing is left to rider judgment, then shifting system is simple, but experienced riders only can avoid shift shock
Solution Approach 1:
The shifting system performs self-monitoring and self-control by automatically detecting cadence through the sensor and autonomously determining whether to execute the shift command. The control unit acts independently to assess shifting conditions and execute or cancel shifts based on predetermined criteria, eliminating the need for riders to possess specialized timing skills while ensuring consistent, reliable shift performance for all users
3Speed
If gear shift is executed immediately upon command, then shifting response is fast, but shift may occur at poor timing causing shock
Solution Approach 1:
The control unit continuously monitors cadence at regular intervals during the gear shift process, comparing cadence measurements against predetermined thresholds. This periodic checking ensures that the shift only proceeds when cadence remains within the acceptable range throughout the entire shifting duration, maintaining fast response while preventing shift shock through continuous verification
Data Source
AI summary
A shifting system for a human-powered vehicle comprises a controller. The controller is configured to receive a driving torque and a cadence of the human-powered vehicle from at least one sensor. The controller is configured to determine a permitted shift timing based on the driving torque and the cadence. The controller is further configured to control a shift mechanism to perform a gear shift during the permitted shift timing in accordance with a permitted cadence range and a first threshold of the driving torque.