Human-Powered Vehicle Motor Control for Smoother Gear Shifts
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Solution Overview
Problem
Existing control devices for human-powered vehicles with travel assist electric motors and transmissions do not optimally manage motor output during transmission ratio shifts, leading to noticeable changes in propulsion assistance that can disrupt the riding experience.
Innovation Solution
An electronic controller adjusts the upper limit value of the motor's output during up-shift and down-shift operations, ensuring smoother transitions by varying the motor output based on transmission ratio changes and human driving force, while maintaining assist force consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the motor output is maintained at a high upper limit value during transmission ratio shifts, then the propulsion assistance remains strong, but the shifting operation is hindered and the riding experience is disrupted
Solution Approach 1:
The electronic controller decreases the upper limit value of motor output in advance before the transmission ratio shift occurs, and restores it after the shift is complete. This preliminary action ensures the motor output does not interfere with the shifting operation, while quickly restoring propulsion assistance to maintain a natural riding experience.
2Ease of operation
If the upper limit value of motor output is decreased during shifting, then the shifting operation is facilitated, but the propulsion assistance noticeably decreases disrupting the riding experience
Solution Approach 1:
The electronic controller implements periodic adjustment of the motor output upper limit value - decreasing it during the shifting period and restoring it after shifting completes. This periodic action temporarily reduces power during the brief shifting interval while maintaining normal propulsion assistance before and after, ensuring smooth shifting without noticeable disruption to the overall riding experience.
3Productivity
If different upper limit values are used for up-shift and down-shift operations, then the motor output is optimized for each shift direction, but the control system complexity increases
Solution Approach 1:
The electronic controller applies different upper limit value adjustments specifically tailored to up-shift and down-shift operations. During up-shifts, the controller decreases the upper limit value to facilitate chain movement to higher ratio sprockets, while during down-shifts, it applies a different adjustment pattern suitable for moving to lower ratio sprockets. This localized quality approach optimizes shifting efficiency for each direction without requiring complex additional hardware.
Data Source
AI summary
A control device for a human-powered vehicle includes an electronic controller. The human-powered vehicle includes a motor that applies a propulsion force to the human-powered vehicle and a transmission that shifts a transmission ratio of the human-powered vehicle between a plurality of shift stages. The electronic controller is configured to control the motor. The electronic controller is configured to decrease an upper limit value of an output of the motor in an up-shift operation. The electronic controller is configured to decrease the upper limit value in a down-shift operation. The electronic controller is configured to control the motor so that the upper limit value in the up-shift operation performed between two predetermined ones of the shift stages that differ in the transmission ratio by one stage differs from the upper limit value in the down-shift operation performed between the two predetermined ones of the shift stages.