Vehicle Integrated Control System for Split-Braking Yaw Compensation
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Solution Overview
Problem
Conventional anti-lock braking systems (ABS) face challenges in maintaining stable braking performance when the friction coefficients of the left and right road surfaces differ, leading to excessive chattering and deterioration of braking performance due to uneven braking forces.
Innovation Solution
An integrated control system that calculates the friction coefficients of both road surfaces and adjusts braking pressures using a feedforward control method, combined with rear wheel steering to compensate for yaw behavior, ensuring stable braking and improved vehicle control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ABS control is performed based on insufficient wheel slip rate information, then the control system is simple to operate, but excessive chattering phenomenon occurs in braking force and braking performance is limited
Solution Approach 1:
The system performs preliminary estimation of road surface friction coefficients before braking occurs or at the beginning of braking, using wheel acceleration and slip rate information. This preliminary action allows the feedforward control to provide appropriate braking pressure from the start, preventing excessive chattering without requiring complex real-time adjustments during braking
Solution Approach 2:
The system implements feedback by continuously monitoring wheel slip rates and wheel accelerations during braking, then using this information to adjust the estimated friction coefficients and refine braking pressure calculations. This closed-loop feedback mechanism improves braking performance while maintaining manageable system complexity through iterative refinement rather than complex upfront modeling
2Reliability
If ABS operates on the wheel of the low friction road surface in split braking situation, then the ABS function is activated, but unnecessary yaw behavior occurs due to difference between left and right braking forces
Solution Approach 1:
The system applies local quality by independently estimating friction coefficients for left and right road surfaces based on individual wheel performance characteristics. This allows each side of the vehicle to have customized braking pressure adjustments tailored to its specific road surface conditions, preventing yaw instability caused by asymmetric braking while maintaining ABS functionality on both sides
Solution Approach 2:
The system deliberately introduces asymmetry in the control approach by treating left and right wheels differently - each side's braking pressure is calculated based on its own friction coefficient estimation and wheel performance. This asymmetric control strategy compensates for the natural asymmetry in road surface friction, balancing the overall braking forces and eliminating unwanted yaw behavior
3Stability of the object's composition
If control for reducing wheel braking amount is performed on high friction road surface for yaw stabilization, then vehicle yaw behavior is stabilized, but braking performance deteriorates
Solution Approach 1:
The system applies the counterweight principle by using rear wheel steering to generate a compensating lateral force that opposes the yaw moment created by asymmetric braking. Instead of reducing braking force on the high-friction side, the system maintains optimal braking pressure while introducing an opposing steering moment, thus stabilizing yaw without sacrificing braking performance
Solution Approach 2:
The rear wheel steering system acts as an intermediary mechanism that mediates between the conflicting requirements of maintaining high braking force and stabilizing yaw behavior. By introducing this intermediate control element, the system can achieve both objectives simultaneously - the steering intervention provides the necessary yaw correction while the braking system operates at optimal performance levels
Data Source
AI summary
An integrated control system for a vehicle is provided. The system includes a friction coefficient calculation unit that calculates friction coefficients of left side and right side road surfaces, respectively, based on vehicle wheel state information and a predetermined setting information collected during ABS operation. A feedforward braking pressure calculation unit calculates a feedforward braking pressure of each vehicle wheel using the friction coefficients. An ABS braking pressure calculation unit calculates an ABS braking pressure of the each vehicle wheel based on the feedforward braking pressure and slip rate information. A rear wheel steering control amount calculation unit calculates a rear wheel steering control amount for yaw compensation using the ABS braking pressure of each vehicle wheel and a rear wheel steering controller executes a rear wheel steering control according to the rear wheel steering control amount.