Electrically Assisted Bicycle Motor Control Mode Switching
Solution Overview
Problem
Existing electrically assisted bicycles have limited output characteristics, which can affect riding comfort and convenience, as they do not provide a wide range of motor torque responses to match varying rider preferences and situations.
Innovation Solution
An electrically assisted bicycle with a control unit that switches between two control modes: a first control and a second control, where the second control provides quicker and greater changes in assisting torque in response to pedal torque changes, allowing for a wider range of motor output characteristics, enhancing user convenience and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single control calculation equation is used to determine assisting torque, then the control system is simple, but the output characteristics are limited and cannot match varying rider preferences and situations
Solution Approach 1:
The control system is segmented into multiple control calculation equations (first control equation and second control equation), each designed to provide different assisting torque characteristics. The control unit switches between these segmented control modes based on operating conditions, enabling diverse output characteristics while maintaining manageable complexity through modular control strategies.
Solution Approach 2:
The control system dynamically switches between different control calculation equations based on real-time operating conditions such as pedal torque, crank speed, and rider preferences. This dynamic adaptation allows the system to provide appropriate assisting torque characteristics for different situations, enhancing versatility without requiring a completely redesign of the control architecture.
2Speed
If the assisting torque changes slowly to meet pedal torque changes, then the riding comfort is enhanced, but the response speed is insufficient for quick acceleration or hill climbing
Solution Approach 1:
The control system dynamically adjusts the response characteristics by switching between control equations. The first control equation provides gradual torque changes for comfort during steady-state riding, while the second control equation enables rapid torque response for acceleration or hill climbing. The control unit selects the appropriate control mode based on real-time conditions, achieving both comfort and responsiveness.
Solution Approach 2:
Different control calculation equations use different parameters and weighting factors to determine assisting torque. The first control equation may use smoother transitions and longer time constants for comfort, while the second control equation uses faster response parameters and higher gain factors for quick acceleration. By changing these parameters based on operating mode, the system achieves both comfort and speed.
Data Source
Figure 1
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AI summary
There is provided an electrically assisted bicycle 1 having a motor control module 95 which calculates a command value which determines on the magnitude of assisting torque based on at least an output of the pedal torque detection unit 57. The motor control module 95 is configured so as to do the switching between: a first control; and a second control in which a time required for the assisting torque to change to meet a change in the pedal torque is shorter and the amount of change in the assisting torque to meet a change in the pedal torque is greater than in the first control.