Bicycle Transmission Control Device Using Dual Sensor Segmentation
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Solution Overview
Problem
Conventional bicycle transmission control devices often change gear ratios at inappropriate times due to reliance on single input signals from cadence or vehicle speed sensors, leading to inefficiencies and inappropriate gear shifts.
Innovation Solution
A bicycle transmission control device that switches between control states based on signals from both a crank rotation detector and a wheel rotation detector, incorporating a drive force sensor to adjust gear shifts according to rotational speeds and manual input, ensuring appropriate gear changes based on dynamic riding conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the transmission is controlled based only on signals from a single detector (cadence sensor or vehicle speed sensor), then the control system is simple, but the gear ratio may be changed at inappropriate times
Solution Approach 1:
The control system is segmented into multiple independent detection channels: a first detector for detecting actual crank rotational speed and a second detector for detecting maximum crank rotational speed based on vehicle speed. Each detector operates independently and provides data to the controller, which selects the appropriate signal based on current riding conditions. This segmentation allows the system to maintain simplicity while improving reliability by using multiple specialized sensors rather than one complex sensor.
Solution Approach 2:
The controller is designed with multi-functionality to handle both types of detection signals. It can operate in two control modes: first control state using actual rotational speed from the cadence sensor, and second control state using maximum rotational speed from the vehicle speed sensor. The controller automatically switches between these modes based on the relationship between actual and maximum rotational speeds, making the system adaptable to different riding scenarios without requiring separate control systems.
2Reliability
If the transmission controller uses multiple input signals and switches between control states, then the gear shifting accuracy is improved, but the device complexity increases
Solution Approach 1:
The control system dynamically adapts its operation mode based on real-time conditions. The controller continuously monitors the relationship between actual crank rotational speed (from the first detector) and maximum crank rotational speed (from the second detector). When these speeds match, the system operates in the first control state using actual speed data. When they diverge, indicating the rider is not maintaining optimal cadence, the system switches to the second control state using maximum speed data. This dynamic switching optimizes gear shifting accuracy while managing system complexity through adaptive behavior.
Solution Approach 2:
The system implements feedback by continuously comparing the actual crank rotational speed with the maximum crank rotational speed. This comparison provides feedback to the controller about the rider's pedaling efficiency and current riding state. Based on this feedback, the controller determines which control state to activate, ensuring that gear shifts occur at appropriate times. The feedback mechanism allows the system to self-regulate and maintain high shifting accuracy without requiring overly complex external control logic.
Data Source
AI summary
A bicycle transmission control device is basically provided with a transmission controller that is programmed to switch between a first control state and a second control state. The bicycle transmission control device operates in accordance with the first control state for controlling a transmission based on a first signal that is input from a first detector, which detects a rotation of a crank. The bicycle transmission control device operates in accordance with the second control state for controlling the transmission based on a second signal that is input from a second detector, which detects a value reflecting a bicycle speed.