Steer-by-Wire Steering With Separate Redundant Sensor Links
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing steer-by-wire steering systems face challenges in meeting functional safety requirements due to the complexity and cost of redundant control unit designs, necessitating an improved, cost-effective signal processing architecture.
Innovation Solution
A steer-by-wire steering system with redundant steering wheel angle sensors connected separately to a steering unit, utilizing separate communication connections and power supplies to ensure plausibility checks meet ASIL D safety standards, allowing the steering wheel unit to be designed simply with ASIL B compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant control unit designs are implemented to meet functional safety requirements, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The system separates the steering angle sensing function from the control unit by implementing standalone sensors that directly communicate with the actuator. This segmentation eliminates the need for redundant control unit designs while maintaining functional safety, as the sensors operate independently and provide direct feedback to the steering actuator.
Solution Approach 2:
The control unit is designed to perform multiple functions: it processes steering angle information from sensors, generates control signals for the steering actuator, and provides haptic feedback to the driver. This multi-functionality reduces the need for separate redundant control units while meeting safety requirements through integrated monitoring and control.
2Reliability
If redundant steering angle sensors are connected separately to ensure plausibility checks, then reliability is improved, but communication complexity increases
Solution Approach 1:
Multiple steering angle sensors are combined into a single communication interface with the control unit. The sensors are electrically connected in parallel to the control unit, allowing multiple sensors to transmit their signals through a unified communication channel, thereby reducing communication complexity while maintaining redundant sensing capability.
3Ease of manufacture
If the steering wheel unit is designed with simple architecture, then ease of manufacture is improved, but functional safety requirements may not be met
Solution Approach 1:
The system replaces complex mechanical redundancy with electronic sensing and communication. Instead of using multiple mechanical control units with physical redundancy, the invention uses electronic sensors and digital communication to achieve the same safety objectives, simplifying the steering wheel unit design while meeting functional safety requirements.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a steer-by-wire steering system (1) for steering a motor vehicle, comprising: - a steering wheel unit (2) comprising: ∘ a steering handle (21); ∘ several steering wheel angle sensors (22, 23) for redundant acquisition of steering wheel angle information; ∘ a feedback unit (25) configured to exert haptic feedback or a feedback torque on the steering handle (21); ∘ a control unit (28) which communicates with a steering unit (3) via a first or a private data bus system (CAN A, privateCAN) to obtain information about the haptic feedback or the feedback torque and to control the feedback unit (25) so that it exerts the haptic feedback or the feedback torque on the steering handle (21);- the steering unit (3) comprising: ∘ a steering actuator (33) which is connected to steered wheels (9) via a steering mechanism (34) to adjust the steering angle of the steered wheels (9); ∘ a steering control unit (31) which is configured to receive multiple steering wheel angle information from the multiple steering wheel angle sensors (22, 23), to validate this information, and to control the steering actuator (33) depending on the validated and secured steering wheel angle; wherein the steering wheel angle sensors (22, 23) transmit the respective steering wheel angle information to the steering unit (3) via separate communication links (7).