Redundant Brake Control with Shared Wheel Speed Sensor Isolation
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Solution Overview
Problem
Existing solutions for autonomous driving systems, particularly from Level 3 onwards, face challenges in ensuring reliable wheel speed sensor data availability due to the electrical interface limitations, leading to increased costs and complexity with redundant sensor setups, which can compromise safety in case of component failures.
Innovation Solution
A standardizable hardware interface and behavior model that allows 4 standard wheel speed sensors to be connected to two control devices via a vehicle bus, with a sensor isolation circuit ensuring data integrity and fallback levels, and a test mode to verify system redundancy before activating automated driving functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If 8 wheel speed sensors are used (one per wheel and control unit), then data availability for both control units is ensured, but system complexity and cost increase significantly
Solution Approach 1:
The patent implements a universal sensor interface where 4 wheel speed sensors can serve both control units (primary and secondary) through a data bus communication system. The sensors transmit data via a standardized protocol that both control units can interpret, eliminating the need for dedicated sensors for each control unit while ensuring both have access to wheel speed information for braking control functions.
Solution Approach 2:
The patent introduces a data bus as an intermediary communication medium between the wheel speed sensors and the two control units. This mediator allows multiple control units to access sensor data without requiring direct dedicated connections to each sensor, thereby reducing the total sensor count while maintaining data availability for both primary and secondary braking systems.
2Reliability
If redundant wheel speed sensors are used, then safety is improved, but manufacturing cost increases due to low production quantities
Solution Approach 1:
The patent makes the 4 wheel speed sensors universal by implementing a communication protocol that allows both control units to access the same sensor data through a data bus. This eliminates the need for manufacturing 8 dedicated sensors or 4 redundant sensors with dual outputs, as the same 4 sensors serve both safety-critical control units, thereby reducing manufacturing costs while maintaining safety through data redundancy via the communication bus.
3Device complexity
If wheel speed sensors are connected via data bus, then system complexity is reduced, but data transmission reliability may be compromised
Solution Approach 1:
The patent implements a feedback mechanism where the control units continuously monitor the data bus communication for errors or disruptions. If data transmission reliability is compromised, the system can detect this through the feedback loop and switch to alternative data sources or activate diagnostic routines, thereby maintaining overall system reliability despite using a shared data bus connection.
Data Source
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AI summary
The invention relates to a device for controlling a safety-relevant process, such as the braking process in a motor vehicle (10). For highly automated driving (HAD), where the driver relinquishes control of the vehicle to the computer, special safety precautions are necessary. For this purpose, the braking system must be redundant. There is a primary braking system and, independently of it, a secondary braking system. Both can safely brake the vehicle and, in the event of a failure, take over the function of the other braking system. The control of the safety-relevant process is based on the evaluation of signals from at least one sensor (120), for the braking process, a wheel speed sensor. An improved hardware architecture and a test mode for this hardware architecture are proposed. A communication bus (140) is provided, which enables the exchange of data between the primary and secondary control units (110, 130).The hardware architecture is characterized in that the at least one sensor (120) can be connected to the primary control unit (110) and to the secondary control unit (130), wherein a sensor isolation circuit (116, 136) is assigned to the primary control unit (110) and the secondary control unit (130), which, when activated, isolates the associated primary or secondary control unit (110, 130) from the at least one sensor (120).