Vehicle Dynamics Control Load Transfer Function
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Solution Overview
Problem
Existing vehicle dynamics control systems are not fully optimized to effectively manage understeer during cornering, particularly in reducing the understeering tendency and improving handling and stability.
Innovation Solution
A dynamic load change is achieved by abruptly shifting the vehicle's weight from the rear axle to the front axle through rapid deceleration using actuators like brakes, engine control, or an electric machine, increasing the wheel contact force at the front wheels and reducing it at the rear wheels, thereby enhancing the vehicle's cornering potential and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If braking interventions are performed at individual wheels to generate yawing moment, then understeer is counteracted and vehicle returns to controlled state, but the intervention may cause additional yaw moments that affect vehicle stability
Solution Approach 1:
The invention extracts the load transfer function from the conventional yaw moment control strategy. Instead of using individual wheel braking to generate yaw moments, the system separately implements a load transfer function that shifts weight between axles to optimize cornering capability while maintaining stability.
Solution Approach 2:
The control system is segmented into two independent functions: yaw moment control (for stability) and load transfer control (for cornering optimization). This separation allows each function to operate independently without interfering with the other, resolving the contradiction between stability and harmful yaw moments.
2Reliability
If vehicle speed is reduced to decrease lateral acceleration, then front wheels grip improves and understeer tendency reduces, but the response time is insufficient in critical situations
Solution Approach 1:
The load transfer function performs preliminary action by shifting weight to the front axle before the braking intervention takes full effect. This pre-positioning of weight ensures that the front wheels are already optimized for maximum grip when the braking forces are applied, improving the overall effectiveness and response time.
Solution Approach 2:
The system dynamically adjusts the load distribution between axles based on the critical driving situation. By making the load transfer dynamic and responsive, the system can quickly optimize front wheel grip without being constrained by gradual speed reduction alone.
3Duration of action of moving object
If a short pulsed braking intervention is performed to achieve load change, then the duration of brake engagement is minimized, but the pulsing action may cause additional vehicle oscillations
Solution Approach 1:
The load transfer function is extracted as a separate control mechanism from the continuous braking intervention. The pulsed braking is used solely for load transfer purposes, while yaw moment control is handled independently, preventing oscillations caused by combining both functions in a single continuous intervention.
4Force
If brake pressure is increased excessively at already applied wheel brakes, then the load change effect is enhanced, but the risk of wheel lockup increases
Solution Approach 1:
The load transfer function applies brake pressure selectively and locally to achieve weight transfer, while the yaw moment control handles the actual cornering correction. This local differentiation allows optimized pressure application that enhances load transfer without excessive pressure that would cause lockup.
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
This approach significantly reduces the understeering tendency by increasing the front wheels' ability to absorb lateral forces, maintaining better control during cornering and improving overall vehicle handling and stability.
Implementation Method 1
the vehicle brakes a short, pulse-shaped braking intervention is preferably performed
Implementation Method 2
an abrupt reduction of the engine torque also causes a high dynamic load shift from the rear wheels to the front wheels
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3c
AI summary
The method involves increasing the potential of a front-wheel (11) for the acceptance of side forces (F q), when an actuator is activated in a stepwise manner, to retard a vehicle (10) and to cause dynamic load displacement from a back wheel (12) to the front-wheel. An engine movement of an internal combustion engine is reduced to a value of null in stepwise manner by a driving dynamics controller. A short pulse-shaped brake intervention to a wheel brake is executed by the controller, where the duration of the intervention is less than 0.5 seconds. An independent claim is also included for a device for the execution of a method of stabilizing a vehicle.