Wheel Brake Control for Front-Rear Efficacy Factor Estimation
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Solution Overview
Problem
Existing braking control systems do not account for the difference in the relationship between the magnitude of pressing force and braking force applied to the front and rear wheels, leading to inconsistent braking effectiveness.
Innovation Solution
A control device that adjusts braking forces applied to the front and rear wheels separately, using a braking control unit and an estimation unit to estimate an efficacy factor based on the deviation between generated drive power and actual drive power, allowing for micro-braking control to estimate the efficacy factor for each wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If micro-braking control is executed to estimate the efficacy factor, then the braking effectiveness can be accurately estimated, but the vehicle stability and occupant comfort deteriorate due to pitching motion and discomfort
Solution Approach 1:
The system executes micro-braking control only under predetermined conditions (when drive power is increased and wheel speed is within a specific range), preparing the system state in advance to ensure that efficacy factor estimation can be performed without causing vehicle instability or occupant discomfort. This preliminary condition checking prevents adverse effects before they occur.
2Device complexity
If the braking control device uniformly estimates the braking effectiveness for all wheels, then the estimation process is simplified, but the accuracy deteriorates because the difference between front and rear wheel braking characteristics is not considered
Solution Approach 1:
The braking control device is divided into separate braking control units for front wheels and rear wheels, allowing independent control and estimation of efficacy factors for each wheel type. This segmentation enables the system to account for the different braking characteristics of front and rear wheels, improving estimation accuracy while maintaining manageable system complexity through modular design.
Solution Approach 2:
The efficacy factor estimation is performed separately for front wheels and rear wheels, with each wheel type having its own local estimation process tailored to its specific braking characteristics. This local quality approach ensures that the braking effectiveness estimation accurately reflects the actual performance of each wheel type rather than using a uniform average.
3Measurement precision
If braking force is applied to estimate the efficacy factor, then the relationship between pressing force and braking force can be determined, but the productivity deteriorates due to the time required for micro-braking control execution
Solution Approach 1:
The micro-braking control for efficacy factor estimation is executed periodically under predetermined conditions rather than continuously, allowing the system to gather necessary data at appropriate intervals without constantly applying braking force. This periodic execution maintains productivity by minimizing the time spent in micro-braking mode while still achieving accurate efficacy factor determination when conditions are favorable.
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
Accurately estimates the efficacy factor for front and rear wheels, reducing the impact of braking force generation on vehicle comfort and stability, and ensuring precise control of braking forces.
Implementation Method 1
a friction braking system that applies a braking force to a wheel according to a pressing force to press a friction member against a rotary body integrally rotating with the wheel
Data Source
AI summary
In the case where drive power of a vehicle is increased, a control device starts micro-braking control for generating a braking force on at least one wheel of a front wheel and a rear wheel. During execution of the micro-braking control, the control device estimates an efficacy factor that is a factor indicating a relationship of a magnitude of the braking force to a magnitude of a pressing force generated by a friction braking system. The control device estimates the efficacy factor for the wheel, to which the braking force is applied by the micro-braking control, on the basis of a deviation between generated drive power, which is based on a required value for a power source, and actual drive power actually acting on the vehicle, and the pressing force corresponding to the wheel, to which the braking force is applied by the micro-braking control.