Steering Failsafe Torque Sensor Communication
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Solution Overview
Problem
In vehicle steering systems, especially with automated driving assist systems, there is a need for a failsafe communication method between electronic control units (ECUs) and sensors to ensure system redundancy and safety, as a failure in one sensor can adversely affect overall performance, leading to safety hazards.
Innovation Solution
A computer-implemented method and system where each ECU determines assist torque signals based on sensor signals from multiple torque sensors, allowing the system to generate assist torque even if one torque sensor fails, by using a dual ECU architecture and torque calculation modules that adjust calculations based on diagnostic signals from both sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single torque sensor is used in the steering system, then the device complexity is reduced, but the reliability deteriorates because a sensor failure leads to loss of steering assist function
Solution Approach 1:
The patent applies local quality by giving different functional roles to the two torque sensors. The first torque sensor (primary) provides torque signals directly to the first ECU for normal steering assist operation, while the second torque sensor (secondary) provides torque signals to both the first and second ECUs for redundancy. This differentiated local quality ensures that upon failure of one sensor, the system can seamlessly switch to using the other sensor without complete loss of function.
Solution Approach 2:
The patent implements beforehand cushioning by pre-configuring a redundant torque sensor and the associated diagnostic and switching logic before any failure occurs. The second torque sensor and second ECU are prepared in advance as backup components. The first ECU is pre-programmed with diagnostic capabilities to detect sensor failures and switch to using torque signals from the second torque sensor, ensuring continuous steering assist operation without interruption.
2Reliability
If redundant ECUs and sensors are deployed to achieve higher safety levels, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent applies merging by having the first ECU perform multiple functions: it processes torque signals from the primary torque sensor for normal operation, simultaneously monitors the operational status of both torque sensors through diagnostic routines, and dynamically switches to using torque signals from the secondary torque sensor when failure is detected. This consolidation of monitoring and switching functions within the first ECU reduces the need for completely independent redundant control paths, thereby managing complexity while maintaining reliability.
Solution Approach 2:
The patent implements universality by designing the second ECU to be capable of performing the same steering assist control functions as the first ECU. Both ECUs are configured with identical control algorithms and can independently generate steering assist torque commands based on torque sensor inputs. This multi-functionality ensures that either ECU can take over completely if the other fails, providing robust redundancy without requiring specialized backup systems.
3Reliability
If the system continuously monitors diagnostic signals from multiple sensors to ensure safety, then the reliability is improved, but the use of energy increases due to continuous processing
Solution Approach 1:
The patent applies periodic action by implementing diagnostic monitoring at specific intervals rather than continuously. The first ECU executes diagnostic routines at predetermined periods to check the operational status of the torque sensors. This periodic monitoring approach maintains reliable failure detection capability while significantly reducing the energy consumption associated with continuous signal processing and analysis.
Data Source
AI summary
Technical solutions are described for providing failsafe assist torque in steering systems. An example method includes determining, by a first controller, a first assist torque signal using a first set of torque sensor signals from a first sensor and a second set of torque sensor signals from a second sensor, the first sensor corresponding to the first controller, and the second sensor corresponding to a second controller. The method further includes determining, by the second controller, a second assist torque signal using the first and second sets of torque sensor signals. Further the method includes generating, by a motor, an assist torque using the first and second assist torque signals, and in response to the first controller receiving a diagnostic signal indicating a failure of the first torque sensor, determining by the first controller, the first assist torque signal using only the second set of torque sensor signals.