Active Suspension Roll Torque Distribution for Vehicle Dynamics
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Solution Overview
Problem
Conventional roll stabilization systems in two-axle vehicles primarily focus on reducing roll angles and improving driving comfort but neglect the influence on lateral and longitudinal dynamics, leading to suboptimal self-steering behavior and driving stability, especially during cornering and braking.
Innovation Solution
The system adjusts the distribution of roll support torque between the front and rear axles based on braking conditions and load changes, using a combination of map-based control and longitudinal dynamic pilot control to optimize the vehicle's self-steering behavior and traction, while allowing for targeted roll angles to enhance driving stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If roll support torque is increased to reduce roll angle and improve driving comfort, then vertical dynamics and comfort are improved, but lateral dynamics and self-steering behavior deteriorate due to excessive understeer or oversteer
Solution Approach 1:
The system dynamically adjusts the distribution of roll support torque between front and rear axles based on driving conditions (braking status, load changes, cornering). By changing the parameter of torque distribution ratio, the system optimizes both vertical dynamics (comfort) and lateral dynamics (self-steering behavior) without compromising either aspect.
Solution Approach 2:
The invention implements a dynamic control system that continuously monitors braking conditions, wheel load differences, and vehicle state to adjust roll support torque distribution in real-time. This dynamic adaptation allows the system to maintain optimal performance across varying driving conditions, resolving the contradiction between comfort and stability.
2Ease of operation
If roll support torque is distributed equally between front and rear axles, then the system is simple to control, but the vehicle exhibits severe understeer and suboptimal self-steering behavior
Solution Approach 1:
The system applies different roll support torque distributions to different axles based on local conditions. During braking, more torque is applied to the front axle; during acceleration, more torque is applied to the rear axle. This localized adaptation optimizes self-steering behavior while maintaining manageable control complexity through rule-based adjustments.
3Shape
If wheel load difference on axles is increased during cornering, then roll angle is reduced, but cornering force decreases due to non-linear tire characteristics
Solution Approach 1:
The system dynamically adjusts the roll support torque distribution parameter based on wheel load difference and cornering conditions. By optimizing the torque split between axles, the system maintains adequate wheel load on both axles during cornering, preserving cornering force while still achieving roll angle reduction through coordinated anti-roll moments.
Data Source
Figure 1a~2
Figure 3~4
AI summary
The invention relates to a method for actuating an active suspension of a two-axle two-track motor vehicle, wherein forces directed opposite a roll of the vehicle superstructure either at the wheels of the rear axle or at the wheels of the front axis and oriented in the vertical direction can be directed into the wheel suspension between each wheel and the superstructure by means of at least one suitable actuator. Additionally, in order to achieve the goal of limiting the roll angle, a control with regard to the transverse dynamics is input into the actuation of the actuator, in addition to a servo-control with regard to the transverse dynamics of the vehicle. By suitably actuating the actuator as a function of the transverse acceleration currently acting on the vehicle in the sense of a transverse dynamic servo-control, a roll angle is preferably permitted or set, said angle optionally being derived substantially from a so-called friction-independent roll characteristic curve for neutral characteristic roll performance under consideration of an additional roll angle having a low magnitude and generating a slightly understeered driving performance, said angle providing the magnitude of a so-called neutral roll angle for each potential transverse acceleration, by means of which the vehicle performs neutrally, that is, neither oversteered nor significantly understeered.