Redundant Steering Angle Sensor for Fail-Operational Signal Availability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing steering angle sensors are 'fail safe' systems that shut down upon detection of a failure, which is inadequate for steer-by-wire systems lacking mechanical connections, necessitating a transition to 'fail operational' systems ensuring continuous signal availability.
Innovation Solution
A redundant steering angle sensor with two functional blocks and independent angle sensing devices connected via a galvanic insulation bridge, utilizing magnetic gears and inductive targets to detect and bypass failures, maintaining functionality and safety integrity levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a steering angle sensor is designed as a fail-safe system that shuts down upon detection of failure, then system safety is improved, but signal availability deteriorates
Solution Approach 1:
The sensor is divided into two functionally independent blocks (first functional block and second functional block), each capable of independently measuring the steering angle. This segmentation allows one block to take over if the other fails, maintaining signal availability while ensuring safety through redundancy.
Solution Approach 2:
The system changes its operational state based on failure detection: in normal operation, both functional blocks operate; upon detecting a failure in one block, the system transitions to using only the remaining functional block, thereby maintaining signal availability while preserving safety through the fail-operational capability.
2Loss of information
If redundant sensing elements are added to achieve fail-operational capability, then signal availability is improved, but device complexity increases
Solution Approach 1:
Two angle sensing devices are integrated within a single sensor housing, sharing common components such as the evaluation unit and galvanic insulation connection bridge. This merging approach provides redundancy for fail-operational capability while minimizing the increase in overall device complexity through resource sharing.
Solution Approach 2:
Both functional blocks use identical angle sensing devices and evaluation logic, allowing either block to perform the complete steering angle measurement function. This universality enables one functional block to replace the other in case of failure, maintaining full functionality without requiring specialized backup components.
3Reliability
If galvanic insulation connection bridge is used to connect functional blocks, then system reliability is improved, but manufacturing complexity increases
Solution Approach 1:
A galvanic insulation connection bridge is introduced as an intermediary component between the first and second functional blocks. This bridge provides galvanic isolation to prevent error propagation while maintaining electrical connectivity for signal transmission, thereby improving reliability without requiring direct connection between functional blocks.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures continuous signal availability and system integrity by detecting and correcting failures, allowing safe operation even in the event of component malfunctions, enabling steer-by-wire systems to function reliably.
Implementation Method 1
The two angle sensing devices are based on two magnetic gears (10, 20)... sensing element A and sensing element B... sensing element C and sensing element D
Implementation Method 2
a galvanic insulation connection bridge (80) between both processing unit A and processing unit B
Implementation Method 3
an inductive target composed of a printed circuit board with adapted coils, connected to functional block A, configured to provide a rotation angle F
Data Source
Figure 1~2
AI summary
The present invention describes a Steering Angle Sensor (SAS), equipped with a redundancy system to allow the bypass of any failing part, keeping all functionalities intact, while ensuring all the required safety integrity levels. The proposed fail operational redundant steering angle sensor (100) comprises two functional blocks (60, 70) responsible to determine the absolute angle between at least two angling sensing devices (10, 20), detecting systematic failures of said devices.