Brake Controller Torque Request Selection via Travel and Pressure Sensors

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Solution Overview

Problem

Existing brake-by-wire systems face challenges in providing proper feedback to the operator and accurately reflecting braking intent at the wheels, particularly in controlling the braking torque.

Innovation Solution

A braking system that utilizes a brake travel sensor and a brake pressure sensor to generate travel data and force data, which are then used by a brake controller to determine two torque requests. The controller selects the appropriate torque request based on a transition flag, ensuring accurate and smooth braking torque application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single sensor type is used to determine braking torque, then the system complexity is reduced, but the accuracy and reliability of braking torque determination deteriorates

Engineering Contradiction:

Improvesensor system complexityVSAvoidbraking torque determination accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent combines data from two different sensor types (brake pedal travel sensor and brake pressure sensor) to determine braking torque. The controller integrates both travel data and pressure data to calculate torque requests, merging multiple measurement approaches to achieve higher accuracy than either sensor could provide alone.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The brake controller acts as an intermediary that processes and reconciles data from both sensors. It uses the transition flag mechanism to mediate between the two measurement approaches, selecting or combining torque requests based on operating conditions to optimize accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If only brake pedal travel data is used to determine torque, then the measurement system is simpler, but the accuracy deteriorates at high braking forces

Engineering Contradiction:

Improvemeasurement system complexityVSAvoidtorque determination accuracy at high force

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system dynamically switches between using travel-based torque requests and pressure-based torque requests based on the transition flag condition. When pressure exceeds the transition threshold, the system transitions to using pressure data for torque determination, adapting the measurement approach to the current operating conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the primary measurement parameter based on operating conditions. At low braking forces, travel data is used; at high braking forces, pressure data becomes the primary parameter for torque determination, optimizing accuracy across the full operating range.

Inventive Principle:

Principle #35Parameter changes

3Speed

If only brake pressure data is used to determine torque, then the response to operator intent is faster, but the accuracy deteriorates at low braking forces

Engineering Contradiction:

Improveresponse speed to operator intentVSAvoidtorque determination accuracy at low force

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The system dynamically selects which sensor data to prioritize based on the transition flag. At low pressures below the transition threshold, travel data is used for accurate low-force measurement. When pressure exceeds the threshold, the system transitions to pressure-based torque determination for fast response to strong braking intent.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The primary measurement parameter changes based on the pressure level. Travel data serves as the primary parameter at low forces, while pressure becomes the primary parameter at high forces, optimizing both accuracy and response speed across different operating conditions.

Inventive Principle:

Principle #35Parameter changes

4Measurement precision

If the system uses a transition flag to switch between torque requests, then the accuracy across different braking conditions is improved, but the control complexity increases

Engineering Contradiction:

Improveoverall torque determination accuracyVSAvoidcontroller logic complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The controller logic is segmented into distinct operational modes based on the transition flag condition. One mode handles low-pressure operations using travel-based torque requests, while another mode handles high-pressure operations using pressure-based torque requests. This segmentation makes the complex control logic more manageable and implementable.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS7634345B2Method and system for determining braking torque in an electronic braking system

Publication Date: 2009.12.15 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A braking system includes a brake travel sensor configured to generate travel data indicative of the distance a brake pedal has been displaced and a brake pressure sensor configured to generate force data indicative of the amount of force applied to the brake pedal. The braking system also comprises a brake controller configured to determine a first torque request from the travel data and a second torque request from the force data. The brake controller is further configured to generate brake commands from the first torque request when the first torque request and the second torque request are below a transition flag.