Brake Controller Deceleration Profiles for CAN Fault Response
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Solution Overview
Problem
Current brake controllers in vehicles operate in an open loop manner, leading to issues such as incomplete delivery of deceleration demands due to communication failures or congestion on the CAN bus, and inability to arbitrate between different deceleration levels from multiple XBR controlling devices.
Innovation Solution
A brake controller system that stores multiple deceleration profiles and safe state deceleration profiles in a local memory, allowing for automatic selection and execution based on signals from XBR controlling devices or vehicle operational parameters, and includes logic for determining faults and triggering safe state profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brake controllers operate in an open loop manner receiving XBR deceleration demands via CAN bus, then the system structure is simple and easy to implement, but communication failures or congestion may cause incomplete delivery of deceleration demands
Solution Approach 1:
The brake controller pre-stores multiple deceleration profiles (normal braking, emergency braking, ABS braking) in its memory before any braking event occurs. When a braking demand is received, the controller selects and executes the appropriate pre-stored profile, ensuring reliable deceleration delivery without needing complex real-time communication protocols or feedback mechanisms.
2Adaptability or versatility
If multiple XBR controlling devices send deceleration demand messages simultaneously, then the system allows flexible control from multiple sources, but the brake controller cannot arbitrate between different deceleration levels
Solution Approach 1:
The brake controller implements a feedback mechanism that monitors incoming XBR deceleration demand messages from multiple controlling devices. When multiple demands are received simultaneously, the controller compares the deceleration levels and provides feedback to determine which demand to execute, enabling arbitration while maintaining multi-device control flexibility.
3Reliability
If the brake controller waits for continuous communication commands, then the control system is simple to implement, but the system cannot respond automatically to communication network failures
Solution Approach 1:
The brake controller is equipped with fault detection logic that continuously monitors the communication network and vehicle systems. When a communication failure or system fault is detected, the controller automatically activates safe state deceleration profiles from its stored profiles without requiring external commands, enabling self-service fault response while maintaining system reliability.
4Speed
If deceleration commands are sent as individual messages, then the communication protocol is simple, but communication congestion may occur and delay deceleration response
Solution Approach 1:
Instead of sending multiple individual deceleration command messages, the system merges the deceleration demands into a single profile selection message. The brake controller receives one message containing a profile selection signal, retrieves the corresponding pre-stored deceleration profile, and executes the entire sequence, significantly reducing communication traffic and improving response speed.
Data Source
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AI summary
A brake controller in a vehicle determines braking profiles that may be exercised while operating the vehicle in autonomous or semi-autonomous conditions to decelerate the vehicle based on received commands or that may be exercised automatically in the event of a failure in a communication network of the vehicle or in other systems or components of the vehicle. The braking profiles decelerate the vehicle according to a deceleration profile. The execution of the deceleration profile may be initiated by a single command message received by the brake controller or it may be determined by the brake controller based on vehicle information. A safe state deceleration profile may be preselected by the controlling devices before the occurrence of a failure or an emergency situation, and then executed by the brake controller upon the occurrence of a failure or emergency.