Hydraulic Brake Friction Estimation Without Vehicle Weight
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Solution Overview
Problem
Existing methods for estimating the coefficient of friction in hydraulic brake systems of motor vehicles require knowledge of automotive parameters like vehicle weight, and existing methods for adjusting braking torque lack precision in achieving desired actual braking torque.
Innovation Solution
A system and method that utilize additional actuator systems with high precision, such as direct drive motors or single-wheel electric motors, in conjunction with sensors like wheel rpm or brake pressure sensors, to estimate the coefficient of friction and adjust the set braking torque without relying on vehicle weight, by measuring wheel deceleration and transmission ratios to calculate actual braking torque and friction coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vehicle weight and automotive parameters are used to estimate the coefficient of friction, then the estimation can be performed with basic sensor data, but the method requires additional parameter knowledge that complicates the system
Solution Approach 1:
The patent extracts and removes the dependency on vehicle weight and automotive parameters from the coefficient of friction estimation process. By using only brake pressure and wheel deceleration data that are already available in the braking system, the method eliminates the need for additional parameter inputs, thereby reducing system complexity while maintaining estimation accuracy
Solution Approach 2:
The estimation method uses data that the braking system generates and measures itself (brake pressure and wheel deceleration) rather than requiring external parameters like vehicle weight. The system serves its own estimation needs using its own operational data, eliminating the need for additional sensors or parameter inputs
2Measurement precision
If traditional braking torque adjustment methods are used, then the system operates with existing control mechanisms, but the actual braking torque deviates from the desired value
Solution Approach 1:
The patent implements a feedback mechanism where the estimated coefficient of friction is continuously used to adjust the braking torque control. The system measures actual wheel deceleration, estimates the friction coefficient, and uses this information to correct the braking torque application, ensuring the actual torque matches the desired torque and improving braking performance consistency
Solution Approach 2:
The braking torque adjustment is made dynamic by continuously updating the coefficient of friction estimate based on real-time wheel deceleration measurements. Rather than using a fixed or pre-determined friction value, the system adapts the friction coefficient dynamically to match current operating conditions, ensuring accurate torque control throughout the braking process
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
Enables accurate estimation of the coefficient of friction and precise adjustment of braking torque without requiring vehicle weight, ensuring a consistent and desired actual braking torque, thereby improving braking system performance.
Implementation Method 1
The coefficient of friction (also known as the Cp value) of a hydraulic brake system between the brake pad and brake disc determines the braking torque produced and is proportional to the brake pressure
Implementation Method 2
A sensor device arranged on the disc measures the displacement in the brake mount caused by the action of the braking force in a direction perpendicular to the axial direction of the brake disc
Data Source
AI summary
A system and a method for estimating the coefficient of friction of a hydraulic brake system in a motor vehicle. A system and a method for adjusting the braking torque of a hydraulic brake system in a motor vehicle in order to obtain a desired actual braking torque.