Front-Wheel Steering Angle Estimation During SbW Failure
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Solution Overview
Problem
In vehicles equipped with a Steer-by-Wire (SbW) system, failures lead to a free-rolling state of the front wheels, making it difficult to measure the front-wheel steering angle in real time, which complicates vehicle control.
Innovation Solution
A vehicle control device and method that estimates the front-wheel steering angle using rear-wheel steering angle information, partial braking pressure information, and driving speed information, employing a coefficient extraction and estimation function to generate control signals for vehicle operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rear-wheel steering or partial braking is performed in SbW system failure, then vehicle control is possible, but front-wheel steering angle becomes difficult to identify and measure
Solution Approach 1:
The patent introduces an estimation function as an intermediary mechanism that calculates the front-wheel steering angle based on measurable parameters (rear-wheel steering angle, braking force, vehicle speed) when direct measurement is unavailable. This mediator bridges the gap between the unmeasurable front-wheel angle and the controllable vehicle state.
Solution Approach 2:
The patent replaces the mechanical measurement system (physical sensors on front wheels) with a computational estimation system that uses mathematical models and available sensor data to derive the front-wheel steering angle, eliminating the need for direct mechanical measurement in failure modes.
2Measurement precision
If physical front-wheel steering angle measurement is attempted in free-rolling state, then measurement may be obtained, but real-time measurement capability is limited
Solution Approach 1:
The patent pre-establishes an estimation function with predetermined coefficients that can immediately calculate the front-wheel steering angle from available data without requiring time-consuming sensor installation or calibration on the front wheels, enabling instant estimation when needed.
Solution Approach 2:
The patent creates a virtual copy of the front-wheel steering angle through mathematical estimation based on the relationship between rear-wheel steering and front-wheel steering in free-rolling conditions, providing a sufficient substitute for direct measurement that responds in real-time.
3Measurement precision
If SbW system is used, then steering control precision is improved, but system complexity increases and failure risk increases
Solution Approach 1:
The patent makes the estimation function serve multiple purposes: it provides front-wheel steering angle information during normal operation as a backup, and becomes the primary measurement method during SbW failure, thus one component serves multiple critical functions across different operational states.
Solution Approach 2:
The system uses its own existing sensors (rear-wheel steering angle sensors, braking force sensors, speed sensors) to generate the front-wheel steering angle information during failure, making the system self-sufficient without requiring additional external measurement devices.
Data Source
AI summary
The present embodiments relate to a vehicle control device and method capable of controlling a vehicle by estimating a front wheel steering angle. A vehicle control device may receive rear wheel steering angle information, partial braking pressure information, and driving speed information of a vehicle, may extract a coefficient of a front wheel steering angle variable, by using at least one of the rear wheel steering angle information, the partial braking pressure information, and the driving speed information, may estimate a front wheel steering angle of the vehicle by inputting the coefficient of the front wheel steering angle variable, the rear wheel steering angle information, and the partial braking pressure information into a steering angle estimation function, and may generate a control signal for controlling an operation of the vehicle, by using an estimated front wheel steering angle.