Vehicle Braking Force Control Apparatus Slip Rate Thresholds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle braking force control systems cause drivers to feel uneasy due to unexpected changes in braking force during anti-lock control and slip rate reduction, as the threshold settings for these controls do not align with the driver's expectations, leading to inconsistent slip rate management near the peak friction coefficient.
Innovation Solution
A vehicle braking force control apparatus with an electronic control unit that employs two slip rate thresholds: a first threshold for normal acceleration-and-deceleration and steering controls, set above the peak slip rate to maintain driver expectations, and a second threshold for driving assist controls, set near the peak slip rate to ensure smooth slip rate reduction without driver intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the predetermined slip rate threshold is set to a value slightly smaller than the peak slip rate to minimize vehicle braking distance, then the average slip rate can be maintained near the peak slip rate, but the braking force changes differently from what the driver expects, causing driver unease
Solution Approach 1:
The patent applies parameter changes by switching between two different slip rate threshold values based on the control mode. In normal braking control, a first slip rate threshold (greater than peak slip rate) is used to match driver expectations. In driving assist control, a second slip rate threshold (smaller than peak slip rate) is used to optimize braking distance. This dynamic parameter adjustment resolves the contradiction by adapting the threshold to the specific operational context.
Solution Approach 2:
The patent implements dynamics by making the slip rate threshold value changeable based on the type of control being executed. The electronic control unit dynamically selects between the first threshold (for normal control) and the second threshold (for driving assist control), allowing the system to adapt its behavior to different operational requirements rather than using a fixed threshold value.
2Ease of operation
If the predetermined slip rate threshold is set to a value greater than the peak slip rate to maintain driver expectations, then driver unease is reduced, but the average slip rate cannot be maintained near the peak slip rate, reducing braking efficiency
Solution Approach 1:
The patent resolves this contradiction by changing the threshold parameter based on control mode. When driving assist control is active, the second threshold (smaller than peak slip rate) is applied to optimize braking distance. When normal braking control is active, the first threshold (greater than peak slip rate) is applied to maintain driver expectations. This contextual parameter switching allows both objectives to be achieved in their respective operating conditions.
3Device complexity
If a single slip rate threshold is used for both normal control and driving assist control, then the control logic is simplified, but the system cannot simultaneously optimize braking distance and maintain driver expectations
Solution Approach 1:
The patent applies segmentation by dividing the control system into two distinct threshold regimes: a first slip rate threshold for normal braking control and a second slip rate threshold for driving assist control. This segmentation allows each control mode to have its own optimized threshold value, improving overall system reliability and performance consistency across different operating conditions.
Data Source
AI summary
A vehicle braking force control apparatus of the disclosure executes a slip rate reduction control to reduce a slip rate of any of wheels of a vehicle becoming equal to or greater than a predetermined slip rate threshold by automatically changing braking force applied to one or more of the wheels. The apparatus uses a first slip rate threshold as the predetermined slip rate threshold during a normal acceleration-and-deceleration control and a normal steering control. The apparatus uses a second slip rate threshold during a driving assist control. The second slip rate is set to a value smaller than the first slip rate threshold and near and smaller than the slip rate, at which a friction coefficient between the wheel and a surface of a road on which the vehicle moves is maximum.