EPS Steering Compensation for Diagonal Brake Circuit Failure
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Solution Overview
Problem
In vehicle brake systems with a diagonal split layout, when one brake circuit is non-functional, the system tends to auto-steer towards the front wheel side with brake torque, increasing the likelihood of skidding and loss of vehicle control due to uneven braking distribution.
Innovation Solution
An electronic power steering system (EPS) and electronic brake system (EBS) collaboration, where sensors measure steering column motion and torque, and a processor calculates a yaw torque value to recommend and implement steering adjustments to counteract the steering deviation caused by a failed brake circuit, using a motor to assist in compensating for the steering deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If one brake circuit is non-functional in a diagonal split layout, then braking is available at two diagonally disposed wheels, but the vehicle auto-steers towards the front wheel side with brake torque
Solution Approach 1:
The system applies preliminary anti-action by calculating the yaw torque caused by the failed brake circuit and generating a compensating steering torque in advance. The EPS motor applies this counter-torque to the steering column before the driver completes the steering action, preventing the auto-steer effect from occurring rather than correcting it after the fact.
Solution Approach 2:
The electronic power steering system acts as an intermediary between the driver's steering input and the vehicle's actual steering response. When a brake circuit failure is detected, the EPS motor introduces a compensating torque through this intermediary mechanism, offsetting the uneven braking forces before they can cause unwanted vehicle deviation.
2Stability of the object's composition
If brake pressure is controlled to limit yaw-moment gradient, then vehicle stability is improved, but the system complexity increases
Solution Approach 1:
The patent replaces complex mechanical brake pressure control mechanisms with an electronic steering assistance system. Instead of modifying brake pressure distribution through complex valve and hydraulic control systems, the solution uses electronic sensors and an EPS motor to generate compensating steering torque, achieving vehicle stability through steering intervention rather than brake pressure modulation.
Solution Approach 2:
The system changes the control parameter from brake pressure modulation to steering torque application. By detecting the yaw torque caused by uneven braking and applying an equal and opposite steering torque through the EPS motor, the system maintains vehicle stability by altering the steering angle rather than the brake pressure distribution.
3Ease of operation
If steering correction is applied automatically, then vehicle control is maintained, but driver awareness and acceptance of the system reduces
Solution Approach 1:
The system implements feedback by continuously monitoring steering wheel angle and torque through sensors, detecting when a brake circuit failure has occurred, and providing real-time compensating torque through the EPS motor. The control unit adjusts the compensation dynamically based on actual steering conditions, ensuring the driver receives appropriate assistance while maintaining awareness of the system's intervention.
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
Effectively mitigates the auto-steer effect by providing driver recommendations and motor-assisted steering corrections, ensuring stable vehicle control even when one brake circuit is inoperable, thereby reducing the risk of skidding and maintaining vehicle stability during hard braking.
Implementation Method 1
a motor constructed and arranged to provide torque to the steering column
Implementation Method 2
sensors constructed and arranged to measure motion and torque of a steering column of the vehicle
Data Source
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AI summary
A method and system corrects steering of a vehicle upon a brake system malfunction. The brake system (10) has a diagonal split layout. An electronic brake system (BBS) (30) controls operation of the master cylinder (24). An electronic power steering system (EPS) (28) includes sensors to measure motion and torque of a steering column (41) of the vehicle and includes a motor to provide torque to the steering column (41). During driver braking when one of the brake circuits (12; 18) has failed, the system calculates a yaw torque value introduced by a driver braking with just one functioning brake circuit (18; 12). Based on a steer wheel angle and a steer wheel torque obtained from the sensors (35) of the EPS (28) and on the yaw torque value, a steer wheel torque request defining a steer wheel torque/angle needed to counter the yaw torque value is calculated and sent to the EPS (28) which operates the motor to compensate for the steering deviation.