Redundant Vehicle Brake Control Using Parking Brake Takeover
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional brake systems for commercial vehicles lack redundancy in electronic control circuits, making them unsuitable for highly automated or autonomous driving scenarios where a driver is not present, as they do not have a backup mechanism to substitute driver-controlled brake functions in case of electronic control failures.
Innovation Solution
A redundant brake system is implemented, where the electronic parking brake controller takes over service brake functions in case of malfunction, providing both electrical and pneumatic redundancy by configuring the system with an electro-pneumatic service brake subsystem and an electro-pneumatic parking brake subsystem, allowing the electronic parking brake controller to control pressure modulators and spring brake cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-circuit electronic control system is used in conventional brake systems, then the system structure remains simple and easy to operate, but the reliability is insufficient for autonomous driving as there is no backup mechanism when electronic control fails
Solution Approach 1:
The electronic parking brake controller is designed to perform dual functions: normally it controls parking brake operations, but it can also take over and control service brake functions when the primary electronic brake control system fails. This multi-functionality provides redundancy without requiring a completely separate backup system, thus improving reliability while limiting complexity increase.
Solution Approach 2:
The system pre-configures the electronic parking brake controller and pneumatic components to be ready for takeover before any failure occurs. The pneumatic circuitry and control logic are established in advance so that when electronic control failure is detected, the parking brake controller can immediately assume service brake control without requiring complex real-time reconfiguration or additional backup hardware.
2Reliability
If additional redundancy components are added to provide backup brake control, then the reliability improves, but the device complexity and component count increase
Solution Approach 1:
The electronic parking brake controller serves dual purposes: its primary function for parking brake control and its secondary function as a backup service brake controller. By making the existing parking brake controller multi-functional, the system achieves redundancy without adding a separate backup controller, thus avoiding increased device complexity while improving reliability.
Solution Approach 2:
The system merges the backup control function into the existing electronic parking brake controller rather than creating a separate redundant control unit. The pneumatic components are also integrated into the existing brake system architecture. This consolidation provides the necessary redundancy while minimizing the increase in system complexity and component count.
3Reliability
If the electronic parking brake controller takes over service brake functions, then electric redundancy is provided, but pneumatic control pathways must be established
Solution Approach 1:
The pneumatic control pathways are pre-configured and physically installed before any failure occurs, connecting the electronic parking brake controller to the service brake chambers through the existing pneumatic circuitry. This preliminary setup ensures that when electronic takeover is needed, the pneumatic pathways are already in place and functional, eliminating the need for complex real-time pneumatic reconfiguration.
Solution Approach 2:
The existing pneumatic system components act as intermediaries that facilitate control signal transmission from the electronic parking brake controller to the service brake chambers. The pneumatic circuitry serves as a mediator that enables the electronic controller to actuate the mechanical brake components, bridging the gap between electrical control signals and pneumatic brake actuation without requiring direct electrical-pneumatic coupling.
Data Source
AI summary
A brake system, for a vehicle, includes a first electric-power-supply-unit (EPSU), and an electronic-brake-control-unit (EBCU) connected to the first EPSU. Furthermore, the brake system includes a first axle-pressure-modulator (APM) for service-brake-chambers associated with a first vehicle-axle. The first APM is connected to the EBCU. The brake system includes a second APM for spring-brake-cylinders associated with a second vehicle-axle. The second APM is connected to the EBCU. The brake system further includes a second EPSU, and an electronic-parking-brake-controller (EPBC). The EPBC is connected to the second EPSU. The EPBC is fluidically connected to the spring-brake-cylinders. The brake system includes a pressure modulator unit (PMU) fluidically connected to the first APM. The PMU is connected to the EPBC, which issues a control-signal for controlling the PMU. The PMU commands pneumatic-control-pressure for the first APM depending on the control-signal from the EPBC.