Redundant Electric Steering Control via Front Rear Axle Segmentation
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Solution Overview
Problem
Existing electric steering systems for motor vehicles face high costs and complexity in achieving redundancy to maintain steerability in case of actuator failure, as they require numerous components to ensure emergency steering operation.
Innovation Solution
A method for controlling an electric steering system that distributes redundancy between front and rear axle actuators, allowing self-locking actuators on both axles to switch and compensate for faults, using torque vectoring and enhanced steering angles to maintain vehicle stability and lane control, thereby reducing the need for complete redundancy on a single axle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fully redundant actuator on the front axle is used to ensure emergency steering, then steerability in case of failure is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent divides the steering system into two separate axles (front and rear), each with its own actuator. This segmentation allows the failure of one actuator to be compensated by the other, distributing the redundancy requirement across multiple components rather than concentrating it in a single complex redundant actuator.
Solution Approach 2:
The front and rear actuators are designed to be functionally equivalent and interchangeable. Either actuator can perform the steering function independently, making the system multi-functional in terms of which component can fulfill the primary steering role when the other fails.
2Reliability
If numerous components are added to enable emergency steering, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The front and rear actuators use identical or similar designs, allowing for standardized manufacturing processes and component procurement. This universality reduces the overall manufacturing cost compared to developing and producing specialized redundant components with different functions.
Solution Approach 2:
The patent utilizes the vehicle's existing rear-axle steering capability, which may already be equipped with actuators for other purposes (such as torque vectoring or enhanced maneuverability). By repurposing these existing actuators for emergency steering, no additional components need to be manufactured.
3Adaptability or versatility
If the steering system uses separate actuators for each steered wheel with no mechanical connection, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent combines the front and rear axle actuators into a unified control architecture where both actuators are managed by a single control unit. This merging of control functions reduces the overall system complexity compared to having completely independent control systems for each actuator.
Solution Approach 2:
The actuators are designed to perform multiple functions: normal steering operation, emergency steering compensation, and potentially torque vectoring. This multi-functionality reduces the need for separate specialized components for each function.
Data Source
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AI summary
The invention relates to a method for controlling an electrical steering system of a motor vehicle, comprising front axle steering (2) having a self-limiting front axle steering controller (20), with which the two front wheels (FL, FR) can be linked in a coupled manner, and rear axle steering (3) having a self-limiting rear axle steering controller (30), with which the two rear wheels (RL, RR) can be linked in a coupled manner, wherein the following method steps are provided: determining that the one of the steering systems (2, 3) has an error; deactivating the defective steering (2, 3) and actuating the fault-free steering (2, 3), wherein the steering controller (20, 30) of the fault-free steering (2, 3) is actuated in such a way that a target movement of the motor vehicle derived from a steering movement introduced into the steering wheel is achieved or that a target movement of the motor vehicle predefined by an autonomous driving mode is achieved.