Bicycle ABS Speed Estimation During Wheel Lock and Slip
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Solution Overview
Problem
Existing ABS systems on bicycles struggle to accurately determine vehicle speed when one or both wheels are locked or slipping, as reliable data sources are unreliable during significant deceleration, leading to potential skidding or locking risks.
Innovation Solution
A method and system using front and rear wheel speed sensors and brake pressure transducers to estimate vehicle speed through a finite state machine and electronic control unit, which selects the most reliable speed source based on threshold comparisons and transitions, and applies a discontinuity correction to smooth changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wheel speed sensors are used to detect vehicle speed, then speed measurement is simple and direct, but the measurement becomes unreliable when wheels are locked or slipping
Solution Approach 1:
The patent introduces brake circuit pressure as an intermediary parameter to assess the reliability of wheel speed measurements. By monitoring pressure levels, the system determines whether wheel speed data is trustworthy or if alternative estimation methods should be employed, thus resolving the contradiction between simple measurement and reliability during braking.
Solution Approach 2:
The system dynamically switches between different speed detection strategies based on real-time conditions. When brake pressure indicates normal operation, direct wheel speed measurement is used; when pressure indicates locking or slipping, the system transitions to alternative estimation methods, maintaining measurement accuracy across varying operational states.
2Reliability
If multiple speed estimation methods are implemented to handle different braking conditions, then speed estimation reliability improves, but system complexity increases
Solution Approach 1:
The patent segments the speed estimation problem into distinct operational modes based on brake pressure thresholds. Each mode has a dedicated estimation strategy, allowing the system to handle different braking conditions with appropriate methods while keeping the overall structure organized and manageable through clear segmentation of logic.
Solution Approach 2:
The system uses brake circuit pressure feedback to automatically select the appropriate speed estimation method. This feedback mechanism allows the control unit to adaptively switch between estimation strategies without requiring complex manual intervention or overly sophisticated decision-making logic, thereby improving reliability while controlling complexity.
3Reliability
If the system switches between different speed sources based on brake pressure, then speed data reliability improves during braking, but discontinuities and calculation errors may occur
Solution Approach 1:
The patent applies preliminary corrections to speed calculations based on expected deceleration patterns. By anticipating the relationship between brake pressure and wheel deceleration, the system pre-adjusts speed estimates to prevent discontinuities and calculation errors that would otherwise occur during transitions between different speed sources.
Solution Approach 2:
The system cushions against potential calculation errors by incorporating deceleration-based corrections before problems manifest. This prior cushioning approach ensures smooth transitions between speed sources and prevents the discontinuities that would otherwise compromise measurement precision during braking events.
Data Source
AI summary
A method for detecting the speed of a bicycle, where the bicycle is equipped with an ABS system on the front wheel, in which, if the rear wheel deceleration is less than a preset threshold value, then the speed of the bicycle is identified with the rear wheel speed. If the front brake circuit pressure is below a preset low pressure threshold, then the speed of the bicycle is identified with the front wheel speed. Otherwise the speed of the bicycle is an estimated speed based on the last known speed and likely deceleration.