Brake Pedal Haptic Feedback via Passive Spring and Pulsating Valves
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Solution Overview
Problem
Existing brake-by-wire systems in motor vehicles fail to provide effective haptic feedback to drivers about the operating state of the brake system without giving the impression of a defect, especially during normal braking and ABS control, as they lack a reliable method to generate pulsating brake pedal movements without altering the pedal's basic characteristic.
Innovation Solution
A method using a passive simulator spring to maintain a constant relationship between pedal force and travel, with electronically controlled isolating valves generating superimposed pedal return travel to provide haptic information, utilizing existing components of the brake system to avoid the impression of a defect and ensure safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a brake pedal characteristic is modified to provide haptic feedback about operating state, then driver awareness is improved, but the basic pedal characteristic is altered causing driver discomfort
Solution Approach 1:
The patent applies periodic action by generating pulsating brake pedal movements at frequencies between 1-10 Hz during ABS control operations. These periodic pulsations provide haptic feedback to the driver about the brake system's operating state without permanently altering the pedal's basic characteristic, thus maintaining driver comfort while improving information feedback.
Solution Approach 2:
The patent implements dynamics by making the brake pedal characteristic dynamically adjustable based on operating conditions. During normal braking, the pedal maintains its basic characteristic for comfort. During ABS control, the pedal dynamically superimposes pulsating movements to provide haptic feedback, then returns to its basic characteristic afterward.
2Loss of information
If additional actuation systems are added to generate pulsating brake pedal movements, then haptic feedback capability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by making the existing brake-by-wire actuator perform multiple functions: it provides both the primary brake activation force and the superimposed pulsating movements for haptic feedback. This eliminates the need for separate actuation systems while maintaining the ability to communicate brake system operating state to the driver.
Solution Approach 2:
The patent merges the haptic feedback function with the existing brake actuation system. The same actuator that applies brake force also generates pulsating movements by modulating its output, combining two functions into one system and reducing overall complexity.
3Loss of information
If the brake pedal characteristic is changed to provide haptic feedback, then driver awareness of operating state is improved, but the impression of system defect is created
Solution Approach 1:
The patent uses periodic action with carefully controlled frequencies (1-10 Hz) that are recognized by drivers as normal ABS operation rather than system defects. The rhythmic pulsations occur only during ABS control when expected, creating a reliable association between the haptic feedback and the actual operating state.
Solution Approach 2:
The patent implements feedback by providing haptic information only about actual brake system operating states. During ABS control, pulsating feedback confirms the expected operation mode, while during normal braking, no pulsations occur. This accurate feedback loop maintains driver trust by matching the haptic information with the actual system state.
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
This approach allows for effective haptic communication of the brake system's operating state to the driver without altering the pedal's basic characteristic, ensuring driver awareness and safety during normal and ABS braking conditions without requiring additional actuation systems, and can be implemented purely through software control.
Implementation Method 1
a passive simulator spring which assigns a pedal travel to a given pedal force in an unchangingly constant relationship
Implementation Method 2
electronically controlled isolating valves generating superimposed pedal return travel
Data Source
AI summary
The invention relates to a method for providing haptic information to the driver of a motor vehicle, equipped with a brake-by-wire brake system, about the operating state of the brake system, in which method the brake pedal characteristic is generated by a pedal travel simulator, in the form of a functional relationship between the brake pedal opposing force and the brake pedal travel, and is modified as a function of an operating state. In order to provide the driver with the haptic information channel via which electronically controlled information can be communicated to the driver during braking, without the impression of a defect arising, the invention proposes that a basic brake pedal characteristic is generated by a passive simulator spring which assigns pedal travel, on which pedal return travel transporting the haptic information is superimposed, to a given pedal force in an unchanging, constant relationship.