Predictive Brake Control for Rear Wheel Lift Prevention
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Solution Overview
Problem
Existing two-wheeled motor vehicle brake control systems are unable to predict and prevent rear wheel lifting effectively, resulting in a temporal delay in brake control responses after the lifting has occurred.
Innovation Solution
A predictive brake control method and system that determines the potential for rear wheel lifting by monitoring a predetermined parameter, controlling brake force generation when the parameter exceeds a first threshold, and releasing control when it falls below a second threshold, using an electronic control unit to manage oil pressure and brake fluid distribution between the front and rear wheel cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional brake control systems detect rear wheel lifting based on vehicle deceleration and rear wheel velocity, then the detection accuracy is improved, but the response time is delayed until after actual lifting has occurred
Solution Approach 1:
The system performs preliminary action by predicting rear wheel lifting before it actually occurs. The prediction is based on detecting when the sum of absolute values of front and rear wheel accelerations exceeds a predetermined threshold, which indicates potential lifting conditions. By acting before the harmful effect occurs, the system eliminates the temporal delay inherent in conventional detection methods that only recognize lifting after it has happened.
Solution Approach 2:
The system applies preliminary anti-action by controlling brake force generation in advance when prediction of rear wheel lifting is made. When the prediction condition is met, the control unit adjusts brake forces to prevent the lifting from occurring in the first place, rather than reacting after lifting has occurred. This proactive approach resolves the contradiction by preventing the harmful effect before it can manifest.
2Reliability
If brake control is executed after determination of rear wheel lifting and detection signal is obtained, then the control reliability is improved, but the temporal delay cannot be avoided until the effect of control appears
Solution Approach 1:
The control unit executes preliminary action by adjusting brake force generation before rear wheel lifting actually occurs. The prediction mechanism identifies potential lifting conditions in advance, allowing the control system to act proactively. This eliminates the temporal delay that would otherwise exist between detection and control execution, while maintaining reliability through the predictive algorithm.
Solution Approach 2:
The system implements feedback by continuously monitoring wheel accelerations and comparing them against threshold values to predict lifting conditions. This closed-loop feedback mechanism allows the system to adaptively adjust brake forces based on real-time vehicle dynamics, ensuring reliable control while minimizing response delay through continuous prediction and adjustment.
3Productivity
If the ratio between the height of the center of gravity and the inter-axial distance is increased, then the vehicle performance is improved, but the ease of operation deteriorates due to easier occurrence of rear wheel lifting
Solution Approach 1:
The control unit continuously monitors wheel accelerations and provides feedback to adjust brake forces dynamically. This feedback mechanism compensates for the reduced stability caused by a high center of gravity to inter-axial distance ratio, allowing the vehicle to maintain both high performance and ease of operation through active control.
Solution Approach 2:
The system applies dynamics by dynamically adjusting brake forces based on real-time prediction of rear wheel lifting conditions. Rather than relying on static vehicle geometry, the control system adapts to changing vehicle states, enabling high-performance vehicles with unfavorable center of gravity ratios to maintain good controllability through active brake management.
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
Enables quick and accurate control of brake force to prevent rear wheel lifting, reducing the brake distance and enhancing safety and reliability by anticipating and mitigating the lifting event before it occurs.
Implementation Method 1
capable of transmitting oil pressure arising in a front brake master cylinder in response to operation of a first brake operator to a front wheel cylinder via an oil pressure system
Implementation Method 2
capable of transmitting oil pressure arising in a rear brake master cylinder in response to operation of a second brake operator to a rear wheel cylinder via an oil pressure system
Implementation Method 3
determine that the potential for lifting of the rear wheel is large when the value of the predetermined parameter exceeds the first predetermined value and control generation of brake force by the front wheel cylinder
Data Source
AI summary
To predictively determine the occurrence of rear wheel lifting before actual lifting of a rear wheel occurs and enable control of brake force.Vehicle body deceleration is computed on the basis of wheel velocities obtained by wheel velocity sensors 45 and 46 (S102), and when it is determined that that computed value exceeds a predetermined value K1 (S104), then the pressure of a front wheel cylinder 3 is reduced by a predetermined pressure and held at that reduced pressure (S106), and when it is determined that vehicle body deceleration has fallen below a value that is, for example, lower by a predetermined value α than the predetermined value K1 (S108), then the state of holding of the pressure of the front wheel cylinder 3 is released (S110) and brake control returns to normal brake control.