Active Rear Steering Control for Lane Centering Stability
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Solution Overview
Problem
Existing vehicle systems lack the ability for an advanced driver assistance system (ADAS) to independently control the rear steering angle of an active rear steering (ARS) system, necessitating the rear steering angle to be set to zero during manual or automated driving, which compromises vehicle maneuverability and stability.
Innovation Solution
A computer-implemented method and system that determine a desired effective steering angle, measure front and rear road wheel angles, calculate an angle error, and generate a torque command to control the ARS system independently from the electronic power steering system, enabling selective control of the ARS based on vehicle velocity and rear wheel angle thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the rear steering angle is forced to zero during ADAS control, then the control system complexity is reduced, but the vehicle maneuverability and stability are compromised
Solution Approach 1:
The patent divides the steering control into two independent segments: front wheel steering controlled by electronic power steering system and rear wheel steering controlled by active rear steering system. Each system operates independently with its own control algorithms, allowing the rear steering angle to be non-zero during ADAS control while maintaining manageable system complexity through modular architecture
Solution Approach 2:
The patent implements dynamic control of rear steering angle based on vehicle operating conditions. The active rear steering system adjusts the rear wheel angle dynamically according to vehicle velocity, steering angle, and acceleration signals, enabling the system to adapt to different driving scenarios (high-speed stability, low-speed maneuverability, lane changing) rather than maintaining a fixed zero angle
2Device complexity
If the rear steering angle is forced to zero during ADAS control, then the control algorithm simplification is achieved, but the high-speed stability and lane changing smoothness are degraded
Solution Approach 1:
The patent implements feedback control in the active rear steering system by continuously monitoring vehicle velocity, front steering angle, and acceleration signals. The control algorithm processes these feedback signals to dynamically adjust the rear steering angle, providing stability at high speeds through active compensation rather than passive fixed-angle control
Solution Approach 2:
The patent changes the operating parameters of the rear steering system from a fixed zero angle to a dynamically variable angle based on vehicle velocity and steering conditions. The system adjusts rear steering angle magnitude and direction according to real-time parameters, enabling improved high-speed stability and lane changing performance without overwhelming computational complexity
3Device complexity
If the rear steering angle is forced to zero, then the system integration is simplified, but the turning radius and maneuverability are worsened
Solution Approach 1:
The patent merges the front wheel steering system and rear wheel steering system into a coordinated vehicle control architecture. Both systems work together to achieve superior maneuverability, with the active rear steering system enhancing the turning capability by allowing independent rear wheel rotation, thereby reducing the effective turning radius without requiring complex integration of a single unified steering mechanism
Data Source
AI summary
A computer-implemented method that, when executed by data processing hardware, causes the data processing hardware to perform operations comprising determining a desired effective steering angle based on a desired path, measuring a front road wheel angle and a rear road wheel angle, determining an actual effective steering angle, determining an effective steering angle error based on the desired effective steering angle and the actual effective steering angle, generating a torque command for an electronic power steering system based on the effective steering angle error, and controlling an active rear steering system independently from the electronic power steering system.