Redundant Brake Actuator Decoupling Against Fault Currents
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Solution Overview
Problem
In autonomous driving systems, redundant control circuits for braking systems face issues with fault currents and ground offsets, leading to potential destruction of electronic control units and loss of redundancy due to unintended current flows between voltage supplies.
Innovation Solution
A decoupling protective device using current blocking devices, such as diodes, is implemented to prevent fault currents and unwanted currents between power supplies, ensuring that a fault in one control circuit does not affect another, by providing a common connection for electropneumatic actuators and dedicated connections for individual current supply, with switching devices controlled by electronic control units to manage current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If redundant control circuits share common ground connections, then device complexity is reduced, but fault currents can flow between independent voltage supplies causing destruction of electronic control units
Solution Approach 1:
The patent segments the common ground connection by inserting individual isolation elements (diodes or isolation amplifiers) between each electronic control unit and the common ground line. This segmentation maintains the appearance of a common ground while actually creating electrically isolated paths, preventing fault currents from propagating between redundant control circuits.
Solution Approach 2:
The patent introduces intermediary components (isolation elements) between the electronic control units and the common ground connection. These intermediaries block harmful fault currents while allowing normal operation, thus protecting the redundant control circuits from mutual interference through the common ground path.
2Ease of operation
If electropneumatic actuators are controlled by multiple control units through common connections, then ease of operation is improved, but unwanted current flows can occur between independently voltage-supplied control units
Solution Approach 1:
The patent segments the common control connections to actuators by inserting isolation elements in series with each control unit's output path. This allows multiple control units to operate the same actuator while preventing harmful current flows between them, as each control unit's electrical path is isolated from the others.
Solution Approach 2:
Isolation elements are introduced as intermediaries in the control signal paths between control units and actuators. These intermediaries enable safe sharing of actuators among multiple independently voltage-supplied control units by blocking unwanted current flows while transmitting control signals.
3Reliability
If current blocking devices are added to prevent fault currents, then reliability is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent applies isolation elements selectively at critical points where fault currents could propagate (between control units and common ground, and between control units and actuators), rather than throughout the entire system. This localized approach provides necessary protection while minimizing the overall number of additional components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents voltage or ground offsets from causing undesirable current flows, maintaining redundancy in the system even under fault conditions, and preventing the unintentional reactivation of faulty control units, thus ensuring safe and reliable operation of autonomous driving systems.
Implementation Method 1
The protective device (100) comprises a predetermined number of current blocking devices, which are connected in the positive and/or the ground path in the form of diodes and/or components or elements that are functionally equivalent to them
Data Source
AI summary
A device for decoupling and/or protecting against compensation currents when at least one electropneumatic actuator is used jointly by a plurality of independently voltage-supplied control unit devices in redundant systems for autonomous driving. The electropneumatic actuator has, in each case, a common connection, via which the electropneumatic actuator can be coupled and switched to a common connection of other electropneumatic actuators, and has at least one dedicated connection via which the at least one electropneumatic actuator can be individually supplied with current. Switching devices, corresponding to the common connection and the number of dedicated connections of all the electropneumatic actuators, are arranged to apply or not apply a switched current in the at least one electropneumatic actuator. Provided is at least one current flow blocking device to prevent an unwanted current flow to a non-active electronic control unit of the first and second control unit devices.