Redundant Autonomous Vehicle Braking With Command Arbitration
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Solution Overview
Problem
Current braking systems for autonomous vehicles, particularly Level 4 systems, lack the necessary robustness and redundancy to ensure safe operation in case of failures, which is critical for fully autonomous vehicles that operate without human intervention.
Innovation Solution
The implementation of a redundant braking system architecture with multiple vehicle control units and brake controllers configured in a master/slave architecture, providing multiple paths for braking commands and using arbitration logic to select the operational set of commands, ensuring fail-operational and safe vehicle control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single braking control system is used, then the device complexity is low, but the reliability is insufficient for autonomous vehicle safety requirements
Solution Approach 1:
The braking control system is segmented into multiple independent control units (primary VCU, secondary VCU, primary brake controller, secondary brake controller) that operate in parallel. Each unit can independently generate braking commands, and the arbitration logic selects from multiple command paths. This segmentation provides functional redundancy, ensuring that if one unit fails, others can maintain safe operation.
Solution Approach 2:
The system implements beforehand cushioning by pre-configuring multiple redundant control paths and arbitration logic before any failure occurs. The master/slave architecture with hot standby controllers ensures that backup systems are already in place and can immediately take over if the primary system fails, providing a safety buffer without requiring complex real-time reconfiguration.
2Reliability
If multiple redundant control paths are implemented, then the reliability improves, but the device complexity increases
Solution Approach 1:
The arbitration logic serves as an intermediary component that manages the complexity of multiple control paths. It receives braking commands from multiple sources (primary VCU, secondary VCU, primary brake controller, secondary brake controller) and systematically selects the appropriate command based on predefined arbitration rules. This intermediary layer abstracts the complexity from the rest of the system, providing a clean interface while maintaining high reliability through multiple redundant paths.
3Reliability
If redundant components are added, then the safety is improved, but the manufacturing cost increases
Solution Approach 1:
The system uses copying by implementing duplicate control units (primary and secondary VCUs, primary and secondary brake controllers) that are essentially identical in function and structure. This approach allows for standardized manufacturing of each controller type, reducing per-unit manufacturing complexity while achieving the safety benefits of redundancy. The modular copy-based architecture simplifies production compared to designing entirely unique backup systems.
Data Source
AI summary
Devices, systems, and methods for redundant braking systems and architectures are described. An example method for controlling a vehicle includes receiving, by a braking system, a first set of commands generated by a primary brake controller and a primary vehicle control unit (VCU) comprising multiple processors, receiving a second set of commands generated by the primary VCU and a secondary brake controller, receiving a third set of commands generated by a secondary VCU and the primary brake controller, receiving a fourth set of commands generated by the secondary VCU and the secondary brake controller, and selecting, based on an arbitration logic, exactly one of the first, second, third, and fourth sets of commands to operate the braking system, wherein the primary VCU and the secondary VCU are configured in a master/slave architecture.