Steer-By-Wire Rollover Control With Staged Steering Limits
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Solution Overview
Problem
Existing motor vehicle stabilization methods, particularly for steer-by-wire systems, fail to provide safe and dynamic driving behavior by relying solely on braking interventions, leading to abrupt handling changes and compromised safety.
Innovation Solution
A method utilizing a predefined cascade of automatic control interventions, including steering and braking adjustments, tailored for steer-by-wire systems, to prevent tipping over by sequentially escalating interventions from gentle to aggressive based on predefined criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If braking interventions are used to prevent tipping, then vehicle stability is improved, but handling abruptness and driver comfort deteriorate
Solution Approach 1:
The control intervention is segmented into multiple stages with increasing intensity. The first stage applies gentle steering limitations, the second stage applies moderate steering limitations, and the third stage applies strong steering limitations. This segmentation allows the system to progressively increase intervention strength only when necessary, maintaining handling smoothness while ensuring vehicle stability.
Solution Approach 2:
The control system dynamically adjusts the steering angle limitation based on the current driving situation and risk level. The system transitions between different limitation stages (first, second, third) depending on whether the tipping risk criterion is met, allowing the intervention strength to adapt dynamically rather than applying fixed abrupt braking.
2Stability of the object's composition
If steering angle is limited to prevent tipping, then vehicle stability is improved, but driving dynamics deteriorate
Solution Approach 1:
The system dynamically adjusts steering angle limitations based on real-time assessment of tipping risk. Rather than applying constant limitations, the system only imposes steering angle restrictions when the tipping risk criterion is met, and releases them when the risk subsides. This dynamic approach maintains driving dynamics during normal operation while ensuring stability when needed.
Solution Approach 2:
The system changes the steering angle parameter limits based on the current operational stage. In the first stage, a moderate limitation is applied; in the second stage, a stricter limitation is applied; and in the third stage, the most stringent limitation is applied. This parameter adaptation allows the system to balance stability requirements with driving dynamics based on the actual risk level.
3Reliability
If aggressive braking interventions are applied, then tipping prevention is improved, but vehicle control smoothness deteriorates
Solution Approach 1:
The system applies preliminary gentle steering limitations in the first stage before the situation escalates to require stronger interventions. By acting early with mild limitations, the system prevents many tipping scenarios from developing, avoiding the need for aggressive braking interventions and maintaining control smoothness throughout the process.
Solution Approach 2:
The control system cushions against abrupt interventions by first applying gentler steering limitations that gradually escalate in strength. This cushioning approach prevents sudden aggressive braking by progressively increasing intervention intensity only as the tipping risk criterion continues to be met, thereby maintaining control smoothness while ensuring reliable tipping prevention.
Data Source
Figure 1
AI summary
The invention relates to a method and a control device (10) for preventing a motor vehicle (1) from tipping over, as well as to such a motor vehicle (1) with an electric power steering system (3, 4). In the method, the current driving situation of the motor vehicle (1) is monitored and analyzed for a risk of tipping over. If a risk of tipping over is detected, a predetermined, staged cascade of several different automatic control interventions to influence the driving situation is executed sequentially, escalating from stage to stage of the cascade, until the risk of tipping over is eliminated. The cascade includes, in a first stage, a limitation of the steering speed, in a second stage, a limitation of the steering angle, and in a third stage, a further limitation of the steering angle as well as active braking intervention.