Vehicle Braking System Dynamic Pedal Feedback Control
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Solution Overview
Problem
Conventional vehicle braking systems fail to provide effective feedback to users during irregularities such as pressure leakage, brake fade, or over-boost conditions, as the pedal feel simulator maintains a fixed force-stroke relationship, unaware of system inefficiencies or abnormalities.
Innovation Solution
A vehicle braking system with a primary and secondary electronically controlled pressure generating unit, where the secondary unit modifies the force-stroke relationship by receiving fluid from the master cylinder, diverging from the predetermined feedback, and using a pedal feel simulator to provide adjustable feedback to the user through the brake pedal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pedal feel simulator maintains a fixed force-stroke relationship, then the braking system structure is simple, but the user cannot be aware of braking system irregularities such as pressure leakage or brake fade
Solution Approach 1:
The pedal feel simulator is transformed from a static fixed force-stroke relationship to a dynamic adjustable one. The controller modifies the force-stroke relationship in real-time based on feedback from pressure sensors that detect system irregularities. When abnormalities such as pressure leakage or brake fade are detected, the controller adjusts the simulator's characteristics to provide distinctive feedback to the user, enabling awareness of system conditions while maintaining a relatively simple overall structure.
2Ease of operation
If the secondary braking unit receives fluid from the master cylinder to modify the force-stroke relationship, then user feedback is improved, but the braking system complexity increases
Solution Approach 1:
The secondary braking unit with the second pressure generating unit serves multiple functions: it can modify the force-stroke relationship of the brake pedal to provide enhanced feedback to the user, and it can also independently generate braking force at the wheel cylinder. This multi-functionality allows the system to improve ease of operation through better user feedback while managing device complexity by having a single secondary unit perform both feedback modification and braking functions.
Solution Approach 2:
The pedal feel simulator acts as an intermediary between the master cylinder and the user. It receives fluid from the master cylinder and uses this fluid to generate a modified force-stroke relationship that provides enhanced feedback to the user about system conditions. This intermediary approach allows improved user feedback without requiring direct modification of the main braking path, thereby managing system complexity.
3Reliability
If the pedal feel simulator provides fixed feedback, then the system is easier to control, but it cannot provide noticeable feedback under abnormal conditions
Solution Approach 1:
The system implements a feedback mechanism where pressure sensors continuously monitor the braking system for irregularities such as pressure leakage or brake fade. When abnormalities are detected, the controller receives this feedback information and dynamically adjusts the pedal feel simulator's force-stroke relationship to provide distinctive, noticeable feedback to the user. This feedback loop enables the system to adapt to abnormal conditions and provide appropriate user awareness while maintaining relatively simple control logic.
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 user awareness of braking system irregularities by modifying the brake pedal's force-stroke relationship, providing noticeable feedback and maintaining braking efficiency even under abnormal conditions, such as pressure leakage or brake fade.
Implementation Method 1
a pedal feel simulator operable to provide feedback to the brake pedal according to a fixed characteristic of the pedal feel simulator defining a predetermined force-stroke relationship
Implementation Method 2
a master cylinder, a brake pedal operable to transmit a user input force to the master cylinder
Implementation Method 3
a primary braking unit including a first electronically controlled pressure generating unit distinct from the master cylinder and operable to generate a braking force at the wheel cylinder
Data Source
AI summary
A vehicle braking system includes a wheel cylinder, a master cylinder, a brake pedal operable to transmit a user input force to the master cylinder, a primary braking unit including a first electronically controlled pressure generating unit distinct from the master cylinder and operable to generate a braking force at the wheel cylinder in a first mode of operation, a secondary braking unit including a second electronically controlled pressure generating unit distinct from the master cylinder and operable to generate a braking force at the wheel cylinder in a second mode of operation and a pedal feel simulator operable to provide feedback to the brake pedal according to a fixed characteristic of the pedal feel simulator defining a predetermined force-stroke relationship relating a travel distance of the brake pedal to the user input force. In the first mode of operation, the secondary braking unit is operable to receive fluid from the master cylinder to diverge from the predetermined force-stroke relationship at the brake pedal.