Biased Braking Steering Backup for Steer-by-Wire Failure
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Solution Overview
Problem
Existing steering systems with 'Steer-by-Wire' technology lack redundancy mechanisms, leading to potential loss of steering control and stability when a failure occurs, necessitating a solution to ensure stable emergency steering without additional mechanical devices.
Innovation Solution
A system and method utilizing biased braking power to control a vehicle's steering through an integrated control unit, braking actuator, and suspension control, converting a negative scrub radius to a positive scrub radius during failures, using a 3-degree of freedom transverse vehicle dynamic state spatial model to calculate required braking torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If biased braking power is applied with negative scrub radius to reduce yaw motion, then vehicle stability is improved, but emergency steering capability is lost
Solution Approach 1:
The scrub radius is made dynamically switchable between negative and positive values based on operational requirements. During normal operation, negative scrub radius maintains stability. Upon steering system failure detection, the system switches to positive scrub radius to enable emergency steering capability through biased braking power.
Solution Approach 2:
The invention changes the scrub radius parameter from a fixed negative value to a variable parameter that can switch between negative and positive values. This parameter change is achieved through dynamic adjustment of suspension geometry or steering axis position, allowing the system to optimize between stability and steering capability based on operational state.
2Ease of operation
If Steer-by-Wire technology is applied to eliminate mechanical connection, then ease of operation and safety are improved, but redundancy and reliability are worsened
Solution Approach 1:
The braking system serves as an intermediary backup mechanism when the primary Steer-by-Wire system fails. By utilizing the existing brake actuators and suspension system, the invention creates a secondary steering path that bypasses the failed electronic steering system, ensuring continued vehicle controllability.
Solution Approach 2:
The system uses its own existing components (brake actuators, suspension system, steering wheel) to provide backup steering functionality. The steering wheel's mechanical connection to the vehicle chassis and the brake system's inherent capability to generate asymmetric braking forces are leveraged to create emergency steering without requiring external or additional mechanical steering devices.
3Stability of the object's composition
If negative scrub radius is maintained for vehicle stability, then yaw motion is reduced, but target steering direction conformability is worsened
Solution Approach 1:
The scrub radius is dynamically adjusted based on the operational state. During normal steering operation, the system can use smaller negative or zero scrub radius to improve steering response and conformability. When steering system failure occurs, the system switches to positive scrub radius to enable emergency steering while maintaining acceptable stability through controlled yaw motion.
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 stable emergency steering by converting a negative scrub radius to a positive scrub radius, reducing yaw motion and ensuring vehicle stability during steering system failures without additional mechanical devices.
Implementation Method 1
biased braking power utilizing a brake system
Implementation Method 2
a suspension geometry is generally designed so that a wheel angle rotates in an opposite direction to a yaw motion
Data Source
AI summary
According to the present disclosure, there is an effect in that a braking control unit controls a braking actuator of a vehicle and biased-brakes the vehicle in order to satisfy a target biased braking torque by receiving a target biased braking torque value calculated by an integrated control unit, and when biased braking power is generated in a vehicle by the braking control unit, a suspension control unit receives a signal from the integrated control unit to control a height of a suspension to be increased in order to reduce a yaw motion of the vehicle.