Motorcycle ABS Wheelie Detection and Speed Estimation
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Solution Overview
Problem
Existing anti-lock brake systems for motorcycles struggle to perform proper anti-lock control quickly after a wheelie, as they misconceive frequency jumps as noise, leading to delayed estimation of actual vehicle speed and subsequent anti-lock control.
Innovation Solution
An anti-lock brake apparatus that includes a wheelie end determining unit to assess conditions such as rear wheel speed exceeding estimated vehicle speed by a threshold and front wheel acceleration meeting a certain value, allowing the system to switch to calculating estimated vehicle speed based solely on the rear wheel speed, thereby enabling quicker anti-lock control post-wheelie.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the estimated vehicle speed is calculated based on the front wheel speed after wheelie landing, then the system response time is reduced, but the frequency jump is misconceived as noise leading to incorrect speed estimation
Solution Approach 1:
The patent dynamically switches the basis for estimating vehicle speed based on the operational state of the motorcycle. During wheelie conditions, it uses rear wheel speed; after wheelie ends, it transitions to front wheel speed. This dynamic adaptation allows the system to respond quickly after wheelie while maintaining accurate speed estimation by selecting the appropriate wheel speed source based on current conditions.
Solution Approach 2:
The patent changes the parameter used for speed estimation from front wheel speed to rear wheel speed during wheelie conditions, and vice versa after wheelie ends. This parameter switching resolves the contradiction by using rear wheel speed (which doesn't exhibit frequency jump) during wheelie to maintain accuracy, then switching to front wheel speed after wheelie to reduce response time.
2Reliability
If the front wheel speed is fixed to previous low speed when frequency jump is detected, then noise filtering is improved, but the anti-lock control becomes improper due to incorrect speed estimation
Solution Approach 1:
The patent performs preliminary identification of wheelie conditions by monitoring the relationship between front and rear wheel speeds before the frequency jump occurs. By detecting the wheelie state in advance (when rear wheel speed exceeds front wheel speed by a threshold), the system can prepare to switch to rear wheel speed for estimation, preventing the need to fix front wheel speed and avoiding improper anti-lock control.
Solution Approach 2:
The patent uses feedback from comparing front and rear wheel speeds to determine whether the motorcycle is in wheelie condition. This feedback mechanism allows the system to continuously monitor the speed difference and switch estimation sources appropriately, maintaining both noise filtering reliability and speed estimation accuracy through continuous adjustment based on actual conditions.
Data Source
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AI summary
The anti-lock brake apparatus 1 for a motorcycle has an estimated vehicle speed calculating unit 32C and an anti-lock control unit 32B performing anti-lock control on each wheel T based on the wheel speed and the estimated vehicle speed. The front wheel acceleration calculating unit 32A has a wheelie end determining unit 32D which determines that the wheelie has ended when the front wheel TF is in non anti-lock control, the wheel speed of the rear wheel is higher than the estimated vehicle speed by a speed threshold value α or more, and the wheel acceleration of the front wheel is equal to or higher than an acceleration threshold value. When the end of the wheelie is determined by the wheelie end determining unit 32D, the estimated vehicle speed is calculated based on only the wheel speed of the rear wheel for at least a predetermined time.