Bicycle Motor Control System Crank Angle Threshold
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Solution Overview
Problem
Bicycle motor control systems fail to optimally manage the timing and force of drive motor assistance, leading to discomfort and decreased riding experience when the rider suddenly stops pedaling, especially with coaster brakes, as the drive motor may not immediately stop during backpedaling.
Innovation Solution
A bicycle motor control system that uses a controller to detect manual drive force and torque thresholds to selectively stop the drive motor through regenerative braking, dynamic braking, or power interruption, ensuring smooth stops without sudden interruptions and avoiding coaster brake actuation during backpedaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drive motor continues running during backpedaling, then the rider can maintain momentum, but the rider experiences discomfort and the coaster brake may be unintentionally actuated
Solution Approach 1:
The controller continuously monitors the direction of crankshaft rotation and manually applied force through sensors. When backpedaling is detected (rearward rotation or negative torque), the controller provides feedback to stop the drive motor, preventing discomfort and unintended brake actuation while maintaining safety.
Solution Approach 2:
The system dynamically adjusts the drive motor operation based on real-time detection of pedaling direction. The motor runs during forward pedaling to assist momentum, and stops during backpedaling to prevent harmful effects, creating a dynamic response to rider input.
2Object-affected harmful factors
If the drive motor stops immediately when backpedaling is detected, then rider comfort is improved, but the stopping may be abrupt and unpleasant
Solution Approach 1:
The controller detects backpedaling conditions in advance and prepares to stop the motor smoothly. By anticipating the need to stop and using progressive braking methods, the system cushions the transition to avoid abrupt stops and unpleasant rider experiences.
3Productivity
If the force threshold is set to zero, then the motor stops responsive to any force change, but the motor stops inconsistently at top and bottom dead center angles
Solution Approach 1:
The system applies different force threshold values at different crankshaft positions. By setting higher thresholds at top and bottom dead center angles where torque naturally fluctuates, the system maintains consistent motor operation during normal pedaling while still stopping responsive to intentional backpedaling actions.
4Loss of time
If the drive motor stops at high bicycle speeds, then the rider can stop the motor quickly, but the system may unintentionally actuate the coaster brake
Solution Approach 1:
The controller uses feedback from rotation direction sensors to distinguish between intentional backpedaling (which should stop the motor) and situations where the motor should continue running. This feedback mechanism prevents unintended coaster brake actuation while maintaining quick stopping capability when appropriate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system allows users to easily stop the drive motor by ceasing manual force application, preventing discomfort and damage, and enhancing the riding experience by avoiding unintentional coaster brake actuation and ensuring consistent stopping at ideal crank angles.
Implementation Method 1
a torque sensor, and a crank rotation sensor that are provided in a sensory apparatus positioned in proximity to the crankshaft
Implementation Method 2
The controller is configured to cause the drive motor to stop by at least one of a regenerative braking operation, dynamic braking operation, and power interruption to the drive motor
Implementation Method 3
The controller is configured to cause the drive motor to stop by at least one of a regenerative braking operation, dynamic braking operation, and power interruption to the drive motor
Data Source
AI summary
A bicycle motor control system, configured to control a drive motor that is provided on a bicycle, comprises a controller configured to control a drive motor that is configured to selectively output driving force in accordance with a manual drive force, and cause the drive motor to stop when a detected manual drive force, sensed by a manual drive force sensor, falls below a predetermined force threshold value, which is set in accordance with a crank angle of a crankshaft.