Electric Bicycle Motor Control Stabilizing Output Fluctuations
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Solution Overview
Problem
Conventional electrically assisted bicycle control methods result in unstable bicycle outputs due to periodic changes in pedal force, leading to reduced ride comfort and safety issues, especially under acceleration or on slopes with increased assist ratios.
Innovation Solution
A control method that measures and adjusts pedal force to calculate a virtual pedal force, which is then used to determine a motor output, stabilizing bicycle output by matching pedal and virtual pedal forces and applying coefficients to maintain a constant assist ratio, thereby reducing amplitude fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If electrical assistance is provided by multiplying pedal force by an assist ratio, then motor output is increased to enhance bicycle performance, but bicycle output becomes unstable due to periodic variations in pedal force
Solution Approach 1:
The control device performs preliminary detection of pedal force variations and preemptively adjusts the assist ratio to compensate for upcoming fluctuations in bicycle output. By detecting the periodic nature of pedal force variations and predicting future states, the system pre-adjusts motor output to counteract expected fluctuations, thereby stabilizing the overall bicycle output while maintaining enhanced power assistance.
2Power
If the assist ratio is increased to provide more motor assistance, then bicycle output is enhanced, but the amplitude of bicycle output fluctuations increases
Solution Approach 1:
The control device dynamically adjusts the assist ratio in real-time based on the detected pedal force characteristics and current bicycle operating conditions. Rather than using a fixed assist ratio, the system continuously modifies the multiplication factor to compensate for periodic pedal force variations, thereby maintaining stable bicycle output while providing adaptive motor assistance that responds to changing ride conditions.
Solution Approach 2:
The control device implements a feedback mechanism that continuously monitors bicycle output fluctuations caused by periodic pedal force variations. Based on this feedback, the system adjusts the assist ratio to counteract detected fluctuations, creating a closed-loop control system that stabilizes bicycle output while maintaining appropriate motor assistance levels throughout the pedal cycle.
Data Source
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AI summary
When a bicycle travels with a periodically changing pedal force T in the presence of electrical assistance, a control method for the motor of an electrically assisted bicycle according to the present invention can suppress a reduction in motor output and reduce the amplitude of a bicycle output by raising the minimum value of a virtual pedal force Tv used for calculating the motor output, even in a period during which the pedal force T decreases.