Regenerative Braking Control for Wet Condition Wheel Bump
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Solution Overview
Problem
In vehicles equipped with both friction and regenerative braking systems, anti-lock braking events in wet conditions can lead to harsh driving experiences due to abrupt reduction of regenerative braking, which is misinterpreted as traction wheel skidding, causing undesirable wheel bump-activation.
Innovation Solution
Implementing a control strategy that adjusts regenerative braking force based on weather conditions detected by rain sensors and windshield wiper activity, using correction factors to modify service brake regeneration maps, thereby reducing regenerative braking force in wet conditions to prevent harsh wheel bump-activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If regenerative braking force is reduced during anti-lock control in wet conditions, then wheel bump-activation is prevented and driving harshness is reduced, but braking performance and energy recovery are compromised
Solution Approach 1:
The brake control system dynamically adjusts the regenerative braking force based on detected wheel slip conditions and weather information. During anti-lock control in wet conditions, the system modulates the regenerative braking force to prevent wheel bump-activation while maintaining optimal braking performance, transitioning from static to dynamic control based on real-time conditions
Solution Approach 2:
The system changes the regenerative braking force parameter based on weather conditions and wheel slip detection. In wet conditions during anti-lock control, the regenerative braking force is reduced or modulated to prevent harmful wheel bump-activation, while in dry conditions the full regenerative braking force is maintained for optimal energy recovery
2Loss of energy
If regenerative braking force is maintained at high level during anti-lock control, then energy recovery is maximized, but wheel bump-activation occurs causing harsh driving experience
Solution Approach 1:
The brake control system uses feedback from wheel speed sensors and weather information to continuously monitor wheel slip conditions. When wheel bump-activation is detected during anti-lock control in wet conditions, the system provides feedback to reduce the regenerative braking force, creating a closed-loop control system that prevents harmful effects while maximizing energy recovery when conditions permit
3Measurement precision
If weather-based correction factors are applied to service brake regeneration maps, then braking control accuracy is improved in wet conditions, but system complexity increases
Solution Approach 1:
The system pre-calculates and stores weather-based correction factors for different weather conditions (wet, dry, icy) in lookup tables. When weather information is received, the appropriate correction factor is selected and applied to the service brake regeneration map, avoiding complex real-time calculations and reducing computational complexity while maintaining high braking control accuracy
Data Source
AI summary
An automotive braking system includes a windshield wiper system, a traction wheel, and a non-friction brake system configured to apply a braking force to the traction wheel. The system also includes one or more controllers operatively connected with the windshield wiper system, and configured to, in response to a braking request, command the non-friction brake system to apply the braking force to the traction wheel. The braking force has a magnitude that depends on whether the windshield wiper system is active.