Steer-by-wire Brake Pull Mitigation via Load Separation
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Solution Overview
Problem
Steer-by-wire vehicles lack a natural means to differentiate desirable and undesirable loads, resulting in brake-induced steering pull, which affects the steering feel experienced by the operator.
Innovation Solution
A method and system that utilize sensors to measure brake pressure and vehicle characteristics, a controller processes data to identify and remove brake-induced steering load biases by generating a characterization table and transmitting a control signal to the steering system, thereby filtering out undesirable loads and providing a true cornering load signal to the operator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If steer-by-wire system uses measured tie rod loads to simulate road feedback, then steering feedback is provided to operator, but brake-induced steering pull is transmitted to operator
Solution Approach 1:
The patent extracts and removes the brake-induced load component from the total tie rod load signal. The controller identifies the portion of steering load caused by braking and separates it from the genuine road feedback signal, then transmits only the filtered signal to the operator, eliminating the harmful brake pull effect while preserving useful steering information.
Solution Approach 2:
The controller acts as an intermediary between the tie rod load sensor and the steering feedback mechanism. It processes the raw tie rod load signal by subtracting the brake-induced component (calculated from brake pressure sensor data) before transmitting the corrected signal to the steering actuator, thereby mediating to remove harmful effects while preserving useful information.
2Loss of information
If steer-by-wire system provides full tie rod load feedback, then complete road information is transmitted, but undesirable brake loads are included in feedback
Solution Approach 1:
The system extracts only the desirable road feedback information from the total tie rod load by removing the brake-induced component. The controller calculates the brake load portion using brake pressure data and subtracts it from the measured tie rod load, transmitting only the purified road information signal to the operator.
Solution Approach 2:
The system uses feedback from the brake pressure sensor to dynamically adjust the steering feedback signal. The brake pressure measurement provides information about the harmful load component, which is used to correct the tie rod load signal in real-time, ensuring accurate road feedback without brake interference.
Data Source
AI summary
An exemplary method for identifying and removing load biases correlated to a vehicle braking system includes providing a first vehicle sensor configured to measure a vehicle brake pressure of a vehicle brake assembly, providing a second vehicle sensor configured to measure one or more vehicle characteristics, providing a controller in communication with the first and second vehicle sensors, the vehicle brake assembly, and a vehicle steering system, receiving first sensor data indicative of the vehicle brake pressure and second sensor data indicative of the one or more vehicle characteristics, determining if a first condition is satisfied, and if the first condition is satisfied, generating a characterization table based on the first and second sensor data, and determining a brake-induced steering load from the first and second sensor data, wherein the characterization table includes data indicative of a relationship between the first and second sensor data.