Steering Control Apparatus for Yaw Moment Suppression on μ-Split Roads
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Solution Overview
Problem
Vehicles on μ-split road surfaces experience yaw moment due to differences in braking force between wheels on surfaces with varying friction coefficients, making it difficult to stabilize the vehicle's attitude, especially requiring skilled countersteering to counteract this effect.
Innovation Solution
A steering control apparatus and method that calculate and adjust the steering control amounts based on the braking force difference between wheels, incorporating a braking force difference control amount and vehicle state control amount to cancel yaw moment, using a combination of ECU systems and sensors to determine the necessary steering and torque adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antiskid control is executed on a μ-split road surface, then braking force is applied to prevent skidding, but yaw moment is generated due to left-and-right braking force difference causing vehicle deflection
Solution Approach 1:
The control system calculates the braking force difference between left and right wheels before it causes significant vehicle deflection, and applies countersteering control in advance to prevent the harmful yaw moment from developing fully. This proactive approach抵消es the yaw moment generated by asymmetric braking forces on μ-split surfaces.
Solution Approach 2:
The system converts the harmful yaw moment generated by braking force difference into useful information for control. By detecting the braking force difference and using it to calculate the appropriate countersteering angle, the previously harmful effect becomes the basis for maintaining vehicle stability during antiskid control.
2Object-generated harmful factors
If countersteering is used to suppress yaw moment, then vehicle deflection is reduced, but the control requires certain level of driver skill
Solution Approach 1:
The control system performs the countersteering operation automatically without requiring driver intervention or skill. The ECU calculates the braking force difference, determines the appropriate countersteering angle, and controls the steering mechanism autonomously, allowing ordinary drivers to benefit from yaw moment suppression during antiskid control on μ-split surfaces.
Solution Approach 2:
The system replaces the need for manual driver countersteering with an automated electronic control system. The mechanical steering system is controlled by an ECU that calculates and applies the appropriate steering corrections based on detected braking force differences, eliminating the need for driver skill in performing countersteering maneuvers.
3Object-generated harmful factors
If a system controls steering mechanism based on wheel rotation speed difference, then yaw moment is suppressed, but vehicle attitude stabilization becomes difficult when antiskid control causes varying rotation speeds and moments
Solution Approach 1:
The control system continuously monitors wheel rotation speeds, calculates braking force differences in real-time, and adjusts the countersteering control accordingly. This closed-loop feedback mechanism allows the system to adapt to varying antiskid control conditions and maintain reliable vehicle attitude stabilization even when rotation speeds and moments change dynamically during braking.
Solution Approach 2:
The system employs dynamic control by continuously adjusting the countersteering angle based on real-time braking force difference calculations. Rather than using fixed steering corrections, the control amount varies dynamically with the changing braking conditions, allowing effective vehicle attitude stabilization throughout the antiskid control process on μ-split surfaces.
Data Source
AI summary
A steering control apparatus obtains a steered amount by which a steered wheel is steered based on a left-and-right braking force difference control amount, a vehicle state control amount, and a steering control amount. The apparatus changes the magnitude of the braking force difference control amount and the magnitude of the vehicle state control amount according to a vehicle speed or to time elapsed from when braking started to be applied to the left and right wheels. Accordingly, the vehicle driving on a μ-split road is prevented from being deflected toward a side of higher friction coefficient due to the left-and-right braking force difference when the braking is applied.