Electromechanical Steering Drive Redundancy via Mutual Test Signals
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Solution Overview
Problem
Conventional electromechanical steering systems face reliability challenges, especially when autonomous driving functions are implemented, as they require high redundancy to ensure continued safe operation despite component failures, but increased component numbers increase the probability of additional failures.
Innovation Solution
A fault-tolerant steering drive system with two control apparatuses controlling separate winding circuits of a steering drive motor, where one control apparatus provides a test signal to ensure the other's functionality, and sensorless position detection is activated if the first control apparatus fails, maintaining system operation with minimal additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundancy is increased to ensure continued safe operation during component failures, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines the functions of two control apparatuses into a single integrated system where they share common components such as the winding circuits of the steering drive motor. This merging approach allows redundancy to be achieved while minimizing additional components, as the control apparatuses can failover to each other's resources.
Solution Approach 2:
Each control apparatus is designed to perform multiple functions: normal steering control and emergency takeover control. The control apparatuses are universally capable of operating the steering system independently, allowing one to compensate for the failure of the other without requiring dedicated backup components.
2Device complexity
If component numbers are reduced to decrease probability of additional failures, then device complexity is reduced, but reliability may be compromised
Solution Approach 1:
The patent implements preliminary monitoring actions where each control apparatus continuously monitors the operational status of the other through test signals. This preliminary detection of potential failures allows the system to switch to emergency mode before actual failure occurs, maintaining reliability without adding physical backup components.
Solution Approach 2:
The system employs feedback mechanisms where control apparatuses exchange status information and test signals. This feedback loop enables real-time assessment of system health and automatic switching between control apparatuses, ensuring reliability is maintained through information-based redundancy rather than component-based redundancy.
3Reliability
If test signal monitoring is implemented to detect control apparatus failures, then reliability is improved, but device complexity increases
Solution Approach 1:
The control apparatuses perform self-diagnosis and mutual monitoring using their existing computational resources and communication channels. Each control apparatus generates and monitors test signals from the other, utilizing their own processing capabilities to detect failures without requiring external monitoring equipment or additional dedicated test hardware.
Data Source
AI summary
A steering drive system for a steering system of a transportation vehicle having a first control unit for actuating a first winding circuit of a steering drive motor with a test circuit to make available a defined changing test signal and a second control unit for actuating a second winding circuit of the steering drive motor, wherein a test signal reception circuit of the second control unit receives the test signal, and wherein the second control unit actuates the steering drive motor based on the presence or absence of the test signal.