Battery-Assisted Bicycle Motor Control for Stable Walking
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Solution Overview
Problem
Battery-assisted bicycles with electric motors experience abrupt changes in assist force when the user walks them without pedaling, making it difficult for the user to support the vehicle due to sudden motor stoppage.
Innovation Solution
Incorporating a vehicle speed calculator, a first state determiner, an operation unit for issuing stop signals, and a motor controller that maintains a prescribed vehicle speed for a set period before stopping the electric motor, ensuring a stable assist force transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the electric motor is operated to assist the movement of the battery-assisted bicycle when the user moves the vehicle with no pedal effort, then the user can move the heavy vehicle more easily, but the assist force changes abruptly when the switch is turned off, making it difficult for the user to support the vehicle
Solution Approach 1:
The control unit detects stop operation in advance and maintains the current driving state for a predetermined time period before actually stopping the electric motor. This preliminary action allows the user to stabilize their posture before the assist force is reduced, preventing abrupt changes that would make it difficult to support the vehicle.
2Speed
If the electric motor stops immediately when the stop signal is input, then the response time is short, but the assist force changes abruptly causing instability
Solution Approach 1:
The control unit detects stop operation in advance and maintains the current driving state for a predetermined time period before actually stopping the electric motor. This preliminary action allows the user to stabilize their posture before the assist force is reduced, preventing abrupt changes that would make it difficult to support the vehicle.
Data Source
Figure 1
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Figure 3
AI summary
A battery-assisted bicycle less prone to abrupt change in assist force as the assist by the electric motor is stopped while the battery-assisted bicycle moves by the assist with no pedal effort. The battery-assisted bicycle (1) includes an electric motor (61), a vehicle speed calculator (152) that calculates a vehicle speed of the battery-assisted bicycle (1), a first state determiner (150) that determines whether a first state is attained, an operation unit (190) capable of outputting a stop signal used to give instruction to stop the electric motor (61), a timing unit (157) that measures time from when a stop signal is input, and a motor controller (105) that controls driving of the electric motor (61) so that the vehicle speed attained when the time elapsed from the point of input of the stop signal reaches a prescribed first period is a first vehicle speed and stops the electric motor (61) after the first period, if the first state determiner (150) determines that the battery-assisted bicycle (1) is in the first state and the stop signal is input from the operation unit (190).