Steer-by-Wire Rack Position Control for Smooth Mode Transitions
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Solution Overview
Problem
In vehicles equipped with a steer-by-wire (SBW) system, sudden changes in vehicle behavior occur during mode transitions due to variable gear ratios, leading to discomfort for the driver.
Innovation Solution
A vehicle control method and device that determines a mode change intention based on sensor information, sets a rack position control value, and adjusts it using a control limit value to minimize sudden changes in rack position, thereby reducing driver discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the rack position control value is changed suddenly during mode transition in an SBW system, then the vehicle behavior changes quickly to adapt to the new mode, but the driver experiences discomfort due to the abrupt change
Solution Approach 1:
The patent applies dynamics by making the rack position control value adjustable and transitionable between different modes (comfort mode and sport mode) based on driver selection. The system dynamically adapts the rack position control characteristics to match the selected driving mode, allowing the vehicle to transition smoothly between different operational states while maintaining driver comfort through controlled adjustment rates.
2Ease of operation
If the rack position control value is adjusted smoothly during mode transition, then driver comfort is improved, but the vehicle behavior changes slowly and may not respond quickly enough to the mode change
Solution Approach 1:
The patent implements periodic action by controlling the rack position adjustment in discrete time intervals during mode transitions. The control value is adjusted incrementally over multiple control cycles rather than instantaneously, allowing the system to achieve both smooth transitions for driver comfort and eventual attainment of the target mode characteristics. The adjustment continues periodically until the new mode is fully established.
3Device complexity
If a fixed rack position control value is used during mode transition, then the control system is simple, but the vehicle cannot adapt to different driving modes effectively
Solution Approach 1:
The system transitions from a fixed control value approach to a dynamic, mode-dependent control value system. The rack position control value is no longer fixed but varies according to the selected driving mode (comfort or sport mode). This dynamic adjustment enables the vehicle to adapt to different driving conditions and driver preferences while maintaining relatively simple control logic through predefined mode characteristics.
Data Source
AI summary
The present embodiments relate to a vehicle control method and device capable of receiving sensed information generated by one or more sensors, determining a mode change intention of a driver for changing a mode for driving a vehicle based on the sensed information of the one or more sensors, setting a rack position control value for controlling a rack position using the sensed information of the one or more sensors in response to the mode change intention of the driver, determining a control limit value by comparing a difference between the rack position control value set using the sensed information and a rack position value expected in the changed mode with a threshold value, and changing the rack position control value based on the control limit value.