Wheel Brake Drive Force Control Device
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Solution Overview
Problem
Conventional braking-driving-force control apparatuses for vehicles struggle to achieve the required braking-driving force and yaw moment, especially when there are differences in the maximum braking forces that can be generated by front and rear wheels, leading to instability and inefficiency in vehicle control.
Innovation Solution
A control apparatus that includes means for detecting driving operations, calculating target braking-driving forces and yaw moments, and adjusting these forces between front and rear wheels to maximize achievable values within their respective limits, ensuring the vehicle attains the necessary braking-driving force and yaw moment by optimizing the distribution of braking forces across wheels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the braking-driving force control apparatus controls braking forces of individual wheels to achieve target braking-driving force and yaw moment, then the traveling stability of the vehicle is improved, but when the required braking-driving force or yaw moment exceeds the capability of individual wheels, the control effectiveness deteriorates
Solution Approach 1:
The patent divides the vehicle's wheel group into a first wheel group (front or rear wheels) and a second wheel group (the other wheels). This segmentation allows independent control and optimization of braking forces for each group, enabling the system to achieve better overall braking performance and yaw moment control by coordinating between groups rather than treating all wheels uniformly.
Solution Approach 2:
The control apparatus dynamically adjusts the target braking forces for the first and second wheel groups based on real-time vehicle state and road conditions. The system calculates optimal braking force distribution that adapts to changing conditions, ensuring maximum utilization of available braking capability while maintaining stability control effectiveness.
2Manufacturing precision
If the braking-driving forces of individual wheels are controlled to achieve target values, then the vehicle control precision is improved, but when road surface friction varies between front and rear wheels, the achievable braking force and yaw moment are limited
Solution Approach 1:
The patent applies different control strategies to the first wheel group and second wheel group based on their specific road surface conditions and braking capabilities. Each wheel group receives customized target braking forces calculated according to local conditions, allowing the system to optimize performance for each group's specific friction characteristics rather than applying uniform control.
Solution Approach 2:
The control system intentionally creates asymmetric braking force distribution between the first and second wheel groups when road surface conditions differ. By allowing different braking force levels and control parameters for front versus rear wheels based on actual friction conditions, the system achieves better overall vehicle control than symmetric approaches.
3Speed
If the target braking-driving force and yaw moment are calculated based on driver operation, then the vehicle responsiveness is improved, but when individual wheel limitations are exceeded, the control accuracy deteriorates
Solution Approach 1:
The control apparatus calculates target braking forces for the first wheel group that may exceed individual wheel capabilities in certain conditions, then uses the second wheel group to compensate for the shortfall. This partial action approach allows the system to aim for aggressive target values while ensuring achievable performance through coordinated control of both wheel groups.
Data Source
AI summary
A target braking-driving force Fvn and a target yaw moment Mvn of the entire vehicle are calculated, and when the target braking-driving force Fvn and the target yaw moment Mvn cannot be achieved by the braking-driving forces of the front wheels, a target braking-driving force Fvft and a target yaw moment Mvft of the front wheels are adjusted such that the magnitudes of the braking-driving force and yaw moment of the vehicle produced by the braking-driving forces of the front wheels become the maximum at a ratio between Fvn and Mvn. A target braking-driving force Fvrt and a target yaw moment Mvrt of the rear wheels are calculated on the basis of Fvn, Mvn, Fvft, and Mvft, and similar adjustment is performed for them when necessarily.