Adaptive Steering Torque Limiting via Correlation Analysis
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Solution Overview
Problem
Existing electrically assisted steering systems in motor vehicles often incorrectly limit steering torque, leading to restricted functionality and potential safety issues during high steering angle velocities, especially in dynamic maneuvers, due to inadequate error detection and scenario classification.
Innovation Solution
A method that determines the correlation between steering angle velocity and driver manual torque change, setting an error signal if they are not correlated, allowing for adaptive adjustment of steering torque limits to maintain safety and efficiency, and incorporating deadband and inactivity detection to reduce false infringement detections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the steering torque is limited to small values to prevent errors, then safety is improved, but the authority and functionality of driver assistance systems is restricted
Solution Approach 1:
The patent applies dynamics by making the steering torque limit adaptive rather than static. The control unit dynamically adjusts the maximum steering torque based on correlation analysis between steering angle velocity and driver manual torque. When correlation is detected (indicating genuine driver intent), higher torque limits are permitted; when no correlation exists (indicating potential errors), limits are reduced. This dynamic adaptation resolves the contradiction by allowing high authority when safe and ensuring safety when uncertain.
Solution Approach 2:
The patent implements feedback through continuous monitoring and correlation analysis of steering angle velocity and driver manual torque. The system uses this feedback to determine whether to permit or limit steering torque requests from driver assistance systems. This closed-loop feedback mechanism enables the system to distinguish between genuine driver intentions and potential errors, allowing high functionality when appropriate while maintaining safety through adaptive limiting.
2Reliability
If the steering torque is limited during high steering angle velocities, then false error detections are reduced, but the normal function and performance of driver assistance systems is negatively influenced
Solution Approach 1:
The patent replaces traditional mechanical threshold-based limiting with a correlation-based detection system. Instead of simply limiting torque when steering angle velocity exceeds a fixed threshold (which causes false detections), the system analyzes the correlation between steering angle velocity and driver manual torque. This substitution of the detection mechanism eliminates false infringements during dynamic maneuvers while preserving legitimate driver assistance functions, as genuine driver actions maintain correlation even at high velocities.
Solution Approach 2:
The patent changes the parameter used for error detection from a simple velocity threshold to a correlation parameter between steering angle velocity and driver manual torque. This parameter change allows the system to distinguish between high velocity caused by driver intent (correlated with manual torque) and high velocity caused by system errors or dynamic maneuvers (uncorrelated). The correlation parameter remains effective across varying operating conditions, maintaining productivity while reducing false detections.
3Ease of operation
If known limiting functions are parameterized to avoid infringement during special maneuvers, then false detections are reduced, but the actual safety function is no longer ensured in a sufficient form
Solution Approach 1:
The patent applies preliminary action by establishing a correlation-based detection framework before parameter tuning for specific maneuvers is needed. The system pre-defines the correlation relationship between steering angle velocity and driver manual torque as the basis for error detection. This preliminary framework works universally across all driving scenarios, including special maneuvers, without requiring subsequent parameter adjustments. The correlation principle inherently distinguishes between genuine driver actions and errors regardless of the specific maneuver being performed.
Solution Approach 2:
The patent implements universality by creating a single correlation-based detection mechanism that functions effectively across all driving conditions and maneuver types. Unlike maneuver-specific parameterizations, the correlation approach between steering angle velocity and driver manual torque provides a universal solution that maintains safety function while reducing false detections in all scenarios, including normal driving, dynamic maneuvers, and special conditions. This multi-functional approach eliminates the need for separate parameter sets for different maneuvers.
Data Source
AI summary
A motor vehicle has an electrically assisted steering system. A steering angle velocity of the motor vehicle, and a driver manual torque change applied by a driver of the motor vehicle are determined. At least the steering angle velocity and the driver manual torque change are analyzed to determine whether the driver manual torque change and the steering angle velocity are not correlated. An error signal is output if the driver manual torque change and the steering angle velocity are not correlated.