Brake Fluid Pressure Control for Rollover Prevention
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Solution Overview
Problem
Existing brake fluid pressure control systems for vehicles are inadequate in detecting rollover tendencies early enough to initiate effective rollover prevention control, especially during abrupt steering maneuvers, and fail to sufficiently increase braking forces on outside wheels after a steering-back maneuver, leading to instability during sharp turns.
Innovation Solution
A brake fluid pressure control apparatus that calculates a composition roll angle by combining actual and earlier-phase roll angles with adjustable weight ratios to detect rollover tendencies earlier, and applies distinct braking forces to outside and inside wheels on the same axle to enhance stability and prevent rollover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rollover tendency is detected by comparing sensor measurements (lateral acceleration, roll angle) with predetermined threshold values, then the detection method is simple, but the rollover prevention control cannot act sufficiently when rollover tendency increases abruptly
Solution Approach 1:
The system calculates a composition roll angle that combines actual roll angle with predicted roll angle (derived from yaw rate and vehicle speed) to detect rollover tendency earlier. This preliminary detection allows the rollover prevention control to act before the actual roll angle reaches dangerous levels, especially during abrupt steering maneuvers where roll angle increases rapidly.
Solution Approach 2:
The weight assignment ratio between actual roll angle and predicted roll angle is dynamically adjusted based on vehicle conditions. During abrupt steering maneuvers or when rollover risk is higher, the predicted roll angle component is given higher weight to enable earlier detection. This dynamic adjustment optimizes both detection accuracy and timing without requiring complex additional sensors.
2Ease of operation
If rollover tendency is detected only when roll angle reaches predetermined threshold value, then the detection criterion is clear, but the control cannot effectively respond when roll angle increases rapidly
Solution Approach 1:
By incorporating predicted roll angle (calculated from yaw rate and vehicle speed) into the composition roll angle, the system detects rollover tendency before the actual roll angle reaches the threshold. This preliminary detection provides advance warning time, allowing the rollover prevention control to apply braking forces earlier and more effectively counteract rapid roll angle increases during abrupt steering maneuvers.
3Stability of the object's composition
If preparatory brake is applied to turning inside wheels after steering-back maneuver, then some stabilization is achieved, but braking forces on outside wheels do not increase sufficiently and vehicle speed reduction is limited
Solution Approach 1:
The system applies preparatory brake to the turning inside wheels before the steering-back maneuver is completed, based on detection of the steering-back maneuver itself. This timing allows the braking force to be already applied when the outside wheels become the new inside wheels after steering-back, ensuring sufficient braking force is available to prevent rollover. The compositional roll angle detection enables this earlier intervention.
Solution Approach 2:
The system dynamically adjusts braking force distribution based on detected steering maneuvers and composition roll angle. During steering-back maneuvers, the braking force on the inside wheels is increased more aggressively and for a longer duration to ensure sufficient vehicle speed reduction and rollover prevention, overcoming the limitation of fixed braking strategies.
Data Source
AI summary
A brake fluid pressure control apparatus for a vehicle includes a parameter calculation unit configured to calculate a rollover detection parameter; and a steering maneuver determination unit configured to determine whether an abrupt steering maneuver is made. The parameter calculation unit is configured to calculate a first composition roll angle as the rollover detection parameter, by combining at a predetermined weight assignment ratio a first roll angle equivalent to an actual roll angle with a second roll angle obtained using a parameter which changes with a phase earlier than the first roll angle, and to calculate the first composition roll angle by changing the weight assignment ratio such that a weight of the second roll angle is higher when the steering maneuver determination unit determines that an abrupt steering maneuver is made than when the steering maneuver determination unit determines that the abrupt steering maneuver is not made.