Vehicle Path Planning for Steer-by-Brake Fallback Control
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Solution Overview
Problem
Existing vehicle steering systems, particularly in cases of actuator faults or steer-by-wire failures, lack effective redundancy and stability, leading to potential road departure risks due to reduced steering capability and inadequate torque application.
Innovation Solution
A computer-implemented method for providing control data to driver support and driving assistance systems, utilizing curvature planning and steering angle data to determine maximum speed and apply steer-by-torque or steer-by-brake vectoring to maintain vehicle path-following capability during system failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brakes or torque vectoring are applied as redundant steering actuators, then steering capability is provided during actuator fault, but steering capability is reduced due to limited actuator capability and vehicle stability constraints
Solution Approach 1:
The system dynamically adjusts vehicle speed as a parameter when operating in fallback mode. The curvature planning unit calculates a reduced maximum speed based on the limited steering capability available from brakes or torque vectoring, and the control system enforces this speed limit to ensure the vehicle can safely negotiate curves without sufficient steering assistance.
2Reliability
If brakes or torque vectoring are applied to turn front wheels, then steering function is restored during failure, but road departure risk increases due to bad combination of speed and curvature
Solution Approach 1:
The system performs preliminary curvature planning by calculating the maximum safe speed for upcoming curves before the vehicle reaches them. The curvature planning unit uses vehicle models and sensor data to predict future path requirements and determines speed limits in advance, allowing the vehicle to slow down proactively before entering high-curvature sections where limited steering capability would be dangerous.
Solution Approach 2:
The system continuously monitors vehicle state through sensors (speed, position, curvature) and uses this feedback to dynamically adjust the planned speed profile. The curvature planning unit recalculates maximum speed based on real-time vehicle state and predicted path curvature, creating a closed-loop control system that adapts to changing conditions to prevent road departure.
3Reliability
If driver applies more torque to steering wheel during EPAS failure, then steering control is maintained, but steering control is applied too late or not sufficiently
Solution Approach 1:
The system automatically detects steering actuator failures and switches to fallback mode without requiring driver intervention. The control unit monitors steering actuator status and autonomously activates the curvature planning and speed control systems, providing immediate response to failures without the delay associated with driver recognition and reaction.
4Measurement precision
If steer-by-wire technique is used for autonomous driving, then steering precision is improved, but steering redundancy is lost when mechanical connection is removed
Solution Approach 1:
The system enables friction brakes and torque vectoring actuators to serve dual functions: their primary function for vehicle deceleration/stability control and a secondary function as steering actuators in fallback mode. This multi-functionality provides redundancy for steer-by-wire systems, allowing the same components to perform steering when needed without requiring dedicated backup steering hardware.
Data Source
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AI summary
A computer-implemented method for providing control data for at least one driver support system of a vehicle and/or for at least one driving assistance system of a vehicle for supporting the driving of the vehicle on a desired path through a curvature planning and steering, comprising: obtaining suspension data (10) of the vehicle; obtaining vehicle data (20) of the vehicle; obtaining vehicle driving sensor data (30) of the vehicle; determining a steering angle data (40) based on the suspension data, the vehicle data, and the vehicle driving sensor data; and determining control data (50) for at least one driver support system and/or driving support system based on the steering angle data and a curvature vehicle model.