Vehicle Turning Behavior Control via Inner Wheel Braking
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Solution Overview
Problem
Existing vehicle trajectory control systems fail to effectively correct understeer states when the turning radius of the actual vehicle trajectory differs significantly from the target trajectory, particularly due to insufficient lateral force generation by the turning inner front wheel, especially when the ground contact load is reduced.
Innovation Solution
A turning behavior control apparatus that applies a controlled braking force to the turning inner driving wheel when the deviation between the standard and actual yaw rates exceeds a threshold, increasing the ground contact load and lateral force, thereby reducing the understeer state. This apparatus includes a control unit that calculates and applies a target braking force based on the time change rate of the yaw rate deviation, limiting the braking force to prevent stability issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the steered wheels are steered in the turn-increasing direction to correct understeer state, then the steered angle is increased, but the lateral force does not increase enough due to reduced ground contact load
Solution Approach 1:
The patent changes the ground contact load parameter of the turning inner front wheel by applying a braking force to the turning inner rear wheel. This braking force creates a load transfer that increases the vertical load on the turning inner front wheel, thereby enabling the wheel to generate sufficient lateral force when steered in the turn-increasing direction to correct understeer state.
2Force
If a braking force is applied to the turning inner driving wheel, then the ground contact load increases, but vehicle stability may be compromised
Solution Approach 1:
The patent applies the braking force locally and selectively only to the turning inner rear wheel, not to all wheels or the turning inner front wheel. This localized application increases the ground contact load of the turning inner front wheel without creating excessive or unbalanced braking forces that would compromise overall vehicle stability. The control unit monitors and adjusts the braking force magnitude to maintain stability.
3Length of moving object
If the steered angle is increased to correct large deviation from target trajectory, then the turning radius decreases, but the actual trajectory cannot be effectively brought close to the target trajectory due to insufficient lateral force
Solution Approach 1:
The patent applies a preliminary action by increasing the ground contact load of the turning inner front wheel through braking force applied to the turning inner rear wheel, before the steered wheels are steered to correct the trajectory deviation. This preliminary load increase ensures that when the steered wheels are turned, the turning inner front wheel has sufficient lateral force generation capability to effectively reduce the turning radius and bring the actual trajectory close to the target trajectory.
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
The controlled application of braking force to the turning inner wheel increases the lateral force and yaw moment, effectively reducing the degree of understeer and maintaining vehicle stability by adjusting the braking force in real-time based on yaw rate deviation and time change rate.
Implementation Method 1
a load movement from the turning outer front wheel to the turning inner front wheel occurs
Implementation Method 2
a lateral force generated by the turning inner front wheel being steered in the turn-increasing direction is increased
Implementation Method 3
a turning yaw moment applied to the vehicle increases
Data Source
AI summary
A turning behavior control apparatus that is applied to a vehicle includes front wheel suspensions and rear wheel suspensions having anti-dive and anti-lift geometries, respectively, and left and right front wheels are steered wheels. The turning behavior control apparatus includes a control unit for controlling the braking device, and the control unit is configured to control the braking device to apply a braking force to a turning inner driving wheel when a deviation between a standard yaw rate of the vehicle and an actual yaw rate exceeds a deviation reference value and a time change rate of the deviation exceeds a start reference value in a situation where the vehicle is turning without braking.