Redundant Brake-by-Wire Control for Pedal and Controller Failures
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Solution Overview
Problem
Electric vehicles equipped with a single brake-by-wire system face increased driving risks due to undetectable faults in components like the brake pedal or central controller, leading to potential brake failures and safety hazards.
Innovation Solution
Implementing a brake system with control redundancy, featuring a central controller and four wheel end brake apparatuses, each with a wheel end controller and brake actuator, utilizing dual channels of brake pedal travel and force sensors to ensure accurate detection and redundancy in sensor and controller operations, enabling independent control by wheel end controllers in case of failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single brake-by-wire system is equipped, then the device complexity is reduced, but the reliability deteriorates due to undetectable faults and potential brake failures
Solution Approach 1:
The brake system is segmented into two independent control channels: a primary channel with the central controller receiving signals from brake pedal sensors, and a secondary channel with the wheel end controller directly connected to the brake pedal travel sensor. This segmentation allows independent operation of each channel, so that if one channel fails, the other can still provide brake control functionality.
Solution Approach 2:
The patent implements beforehand cushioning by designing a redundant control path before any failure occurs. The wheel end controller is pre-configured with direct access to brake pedal travel sensor signals, creating a backup control pathway that can immediately take over if the central controller or its sensor connections fail, thus cushioning against potential brake failures.
2Reliability
If dual channels of sensors and controllers are implemented, then the reliability is improved through redundancy, but the device complexity increases
Solution Approach 1:
The control system is divided into two functional segments: the primary control path through the central controller and the secondary control path through the wheel end controller. Each segment has its own sensor connections and control logic, allowing them to operate independently. This segmentation enables reliability through redundancy while managing complexity by organizing the system into distinct, manageable modules.
Solution Approach 2:
The brake pedal travel sensor serves a dual function: it provides signals to both the central controller (primary channel) and the wheel end controller (secondary channel). This multi-functionality allows a single sensor to support both control paths, reducing the need for additional sensors and thereby limiting the increase in device complexity while still achieving reliability through redundancy.
3Reliability
If the wheel end controller directly receives sensor signals, then the reliability is improved through independent detection capability, but the device complexity increases
Solution Approach 1:
The controller architecture is segmented into hierarchical levels: the central controller handles high-level brake control decisions, while the wheel end controller handles low-level actuator control with direct sensor input capability. This segmentation allows the wheel end controller to have independent detection capability for safety-critical parameters while keeping the overall system complexity manageable through clear division of responsibilities.
Solution Approach 2:
The wheel end controller is designed with self-service capability by directly receiving brake pedal travel sensor signals, enabling it to independently detect brake pedal status and control brake actuators without relying on the central controller. This self-service ability improves reliability by providing autonomous operation capability, while the modular design keeps the complexity increase acceptable.
Data Source
AI summary
A brake system with control redundancy includes a central controller and four wheel end brake apparatuses. The central controller receives one channel of brake pedal travel signal and one channel of brake pedal force signal. A wheel end controller is configured to receive the other channel of brake pedal travel signal and the other channel of brake pedal force signal. One of the sensors fails, and the other sensor can still detect a motion state of a brake pedal, to improve operational reliability of the brake system with control redundancy. In addition, even when the central controller fails, the four wheel end brake apparatuses can be controlled, based on the other channel of brake pedal travel signal and the other channel of brake pedal force signal, to output brake forces.