Electromechanical Wheel Brakes With Decentralized Fallback Control
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Solution Overview
Problem
In electromechanical brake systems, the mechanical feedthrough of a brake pedal to wheel brakes is decoupled, preventing direct muscle power application and control of braking torque, especially in fallback modes due to electrically controlled brake force booster failures, leading to potential loss of braking ability and safety hazards.
Innovation Solution
A brake system with a central brake control unit connected to local brake control units via data connections, allowing for redundant operation and independent determination of operating information, enabling continued braking functionality even in central control unit failures, with minimal redundant components to minimize additional costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If mechanical feedthrough from brake pedal to wheel brakes is decoupled in electromechanical brake systems, then automation and electrical control are improved, but reliability and safety are worsened due to loss of fallback braking capability
Solution Approach 1:
The brake control system is segmented into a central brake control unit and multiple local brake control units, each capable of independent operation. The wheel brakes are controlled independently by local units that can receive commands from either the central unit or directly from the brake operating unit, enabling decentralized fallback operation.
Solution Approach 2:
The system changes its operational parameters between normal mode (centralized control via first data connection) and fallback mode (decentralized control via second data connection). This parameter change allows the system to adapt its control architecture based on the operational state, maintaining reliability while enabling automation.
2Reliability
If redundant elements and data connections are added to ensure fallback operation, then reliability is improved, but device complexity and manufacturing costs are worsened
Solution Approach 1:
Local brake control units serve as intermediaries between the brake operating unit and the wheel brakes. These intermediaries can process brake demands locally using the second data connection, enabling fallback operation without requiring a fully redundant central control unit, thus reducing overall system complexity.
Solution Approach 2:
The system implements partial redundancy by providing fallback capability at the local brake control level rather than requiring complete system redundancy. This partial action approach ensures safety-critical functionality while minimizing the number of redundant components needed.
3Ease of operation
If direct connection between brake operating unit and local brake control units is established, then ease of operation in fallback mode is improved, but device complexity is worsened due to additional data connections
Solution Approach 1:
The data connection architecture is segmented into two separate channels: a first data connection for normal centralized operation and a second data connection for fallback decentralized operation. This segmentation allows each connection to be optimized for its specific purpose while maintaining overall system manageability.
Data Source
AI summary
A brake system for a motor vehicle has electromechanical wheel brakes, a brake operating unit and a central brake control unit. The wheel brakes each have a local brake control unit. The central brake control unit is connected to the brake operating unit and the local brake control units via a first data connection. The brake operating unit is connected to the local brake control unit of at least one wheel brake via a second data connection. In a normal operating mode the central brake control unit determines at least one brake demand from first operating information, received via the first data connection and transmits control signals corresponding to the brake demand to the local brake control units. In a fallback operating mode the local brake control units actuate the respective wheel brakes basis on second operating information, received via the second data connection.