E-Bike Shift Control for Smooth Motor-Assisted Gear Changes
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Solution Overview
Problem
Existing control systems for human-powered vehicles do not adequately address the need for comfortable and efficient shifting operations, particularly during transitions involving motor assistance.
Innovation Solution
A control system with sensors to detect vehicle state and a controller that selectively stops or continues motor driving based on sensor inputs during shift operations, allowing for smooth gear ratio changes and motor-assisted or manual shift operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor drives the chain during shift operation to assist gear changing, then the shifting speed and efficiency are improved, but the shifting smoothness and rider comfort deteriorate due to motor interference
Solution Approach 1:
The controller stops the motor before the shift operation begins and prevents motor driving during the shift process. This preliminary action of stopping the motor eliminates interference with the chain movement during shifting, ensuring smooth gear changes while maintaining efficient shifting speed through proper timing control.
2Ease of operation
If the motor is stopped during shift operation to ensure smooth shifting, then the shifting smoothness is improved, but the shifting efficiency and speed deteriorate
Solution Approach 1:
The motor is stopped in advance before the shift operation starts, ensuring smooth chain movement during gear changing. After the shift is completed, the motor resumes driving to maintain shifting efficiency. This timing-based control resolves the contradiction by stopping the motor only when necessary and resuming it promptly to preserve overall shifting efficiency.
Solution Approach 2:
The control system dynamically adjusts the motor driving state based on the shift operation phase. The controller monitors shift status and dynamically switches between stopping and driving the motor, optimizing both shifting smoothness during the shift process and shifting efficiency during normal operation phases.
3Speed
If the shifter operation is detected during motor-driven chain movement, then the gear ratio change responsiveness is improved, but the chain tension control and mechanical stress worsen due to simultaneous motor and manual forces
Solution Approach 1:
When the controller detects shifter operation, it preemptively stops the motor to prevent simultaneous motor and manual forces from acting on the chain. This preliminary anti-action eliminates the harmful combination of forces that would create excessive chain tension and mechanical stress, while still allowing rapid gear ratio changes by quickly resuming motor control after the shift.
Solution Approach 2:
The control system uses feedback from shift operation detection to dynamically control the motor state. When shifter operation is detected, the feedback signal triggers the controller to stop the motor, preventing excessive chain tension. This closed-loop control ensures responsive gear ratio changes while maintaining safe mechanical stress levels through real-time monitoring and adjustment.
Data Source
AI summary
A control system includes at least one sensor configured to detect detection information regarding a traveling state of a human-powered vehicle, and a controller configured to control a motor and at least one transmission. A shift operation by the at least one transmission includes a first shift operation involving driving of a chain by the motor. The controller is configured to selectively stop or continue driving of the motor in accordance with a first detection result of the at least one sensor in a case where a shifter is operated during the first shift operation.