Adaptive ABS Braking Control via Road Friction Estimation
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Solution Overview
Problem
Conventional Anti-lock Braking Systems (ABS) fail to adaptively brake vehicles on different road environments due to fixed enhance-pressure and reduce-pressure control periods that are not adaptable to varying friction coefficients, leading to suboptimal performance on dry, wet, or muddy surfaces.
Innovation Solution
A braking control method that adjusts the time lengths of enhancement and reduction stages in the stepped pressure-increasing and decreasing phases based on real-time wheel speed and estimated vehicle deceleration, which reflects the friction coefficient of the road surface, allowing for adaptive braking across different road conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fixed enhance-pressure and reduce-pressure control periods are used in conventional ABS, then the system structure is simple, but the braking performance is suboptimal on different road surfaces
Solution Approach 1:
The patent applies dynamics by making the enhance-pressure control period and reduce-pressure control period variable rather than fixed. The control period is dynamically adjusted based on the friction coefficient of the road surface, which is calculated in real-time. This allows the ABS system to adapt its braking control parameters to different road conditions (dry, wet, icy), thereby improving braking performance while maintaining a relatively simple system structure that builds upon conventional ABS architecture.
2Productivity
If the braking pressure is increased rapidly to prevent wheel lockup, then the deceleration performance is improved, but the wheels may be locked up too rapidly causing vehicle slip
Solution Approach 1:
The patent implements feedback by continuously monitoring wheel speed and calculating the friction coefficient of the road surface in real-time. Based on this feedback, the system dynamically adjusts the enhance-pressure control period to optimize braking force application. When the friction coefficient is high (dry road), the enhance-pressure period is shortened to prevent excessive braking force. When the friction coefficient is low (wet or icy road), the enhance-pressure period is extended to maintain adequate braking force, thus balancing deceleration performance with vehicle control stability.
3Reliability
If the enhance-pressure control period is extended to maintain braking force on low-friction surfaces, then the braking effectiveness is improved, but the wheels remain locked longer causing loss of steering control
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the enhance-pressure control period based on the calculated friction coefficient of the road surface. On low-friction surfaces (wet or icy roads), the enhance-pressure control period is extended to maintain adequate braking force and prevent wheel lockup. On high-friction surfaces (dry roads), the enhance-pressure control period is shortened to allow wheels to maintain rotation and steering control. This parameter adaptation resolves the contradiction between braking effectiveness and steering control by optimizing the control period for current road conditions.
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 method effectively prevents wheels from being rapidly locked up, maintaining friction and ensuring proper deceleration by adjusting braking pressure phases according to the road's friction coefficient, thus enhancing braking performance on diverse road surfaces.
Implementation Method 1
a wheel speed sensor 51 electrically connected to the control module 50 for signal transmission
Implementation Method 2
regulate the hydraulic pressure of the braking system 60
Data Source
AI summary
A braking control method according to friction of road surface includes computing a real-time wheel speed according to a signal received from a wheel speed sensor; storing the real-time wheel speed as a wheel initial velocity when a braking event occurs; determining a relative-peak value according to the real-time wheel speed; estimating a vehicle deceleration according to the relative-peak value and the wheel initial velocity; computing an adjustment parameter according to the vehicle deceleration and a tire slip threshold, wherein the adjustment parameter reflects friction coefficient of road surface; and adjusting time length of an enhancement stage in an enhance-pressure control period of a stepped pressure-increasing phase according to the adjustment parameter; or adjusting time length of a reduction stage in a reduce-pressure control period of a stepped pressure-decreasing phase according to the adjustment parameter.