Parking Brake Pushbutton Single-Wire Digital Control
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Solution Overview
Problem
The existing methods for operating a parking brake using buttons require a large number of lines for connection to a control unit, leading to high costs and weight in vehicle wiring harnesses, and often result in unclear error analysis between the button, wiring harness, and control unit, especially in analog systems.
Innovation Solution
A method utilizing a single-wire channel for transmitting encoded button states and check words generated by cyclic redundancy check, allowing for reduced line usage and error detection, with the option to implement the LIN protocol for message transmission and error handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a button with multiple functions is connected to a control unit using multiple lines, then the button can provide additional functions and states, but the number of lines increases leading to high costs and weight in the vehicle wiring harness
Solution Approach 1:
Multiple signal lines for button states and functions are merged into a single communication bus (CAN bus), allowing multiple data streams to be transmitted over one shared physical medium, thereby reducing wiring harness complexity and weight
Solution Approach 2:
The single communication bus serves multiple functions simultaneously - transmitting button state information, diagnostic data, and control signals - replacing what previously required separate dedicated lines for each function
2Reliability
If multiple lines are used to connect the button to the control unit, then the button state can be verified and additional functions can be implemented, but the complexity of the wiring harness increases
Solution Approach 1:
Verification signals and data lines are combined into a single bidirectional communication bus, maintaining the ability to verify button states while eliminating the need for separate verification and data transmission lines
Solution Approach 2:
The control unit sends request messages to the button and receives response messages, creating a feedback mechanism that verifies button states through software-based acknowledgment rather than dedicated hardware verification lines
3Device complexity
If an analog button evaluation is used, then the button can be simple in structure, but error analysis becomes unclear when errors occur, as it is difficult to determine whether the error originated from the button itself, the wiring harness or the control unit
Solution Approach 1:
A microcontroller unit embedded in the button assembly acts as an intermediary that reads the physical button state and communicates it digitally over the CAN bus, clearly separating the simple mechanical button from the complex evaluation logic and enabling precise error localization
Solution Approach 2:
The analog electrical connection system is replaced with a digital communication system where the button state is read by a microcontroller and transmitted as digital messages, substituting mechanical/electrical signal transmission with digital protocol-based communication that includes error detection and source identification
4Loss of information
If multiple lines are used for button connection, then comprehensive button state information can be transmitted, but the costs of the vehicle wiring harness increase
Solution Approach 1:
Multiple information channels (button state, diagnostic data, functional commands) are merged into a single CAN bus communication line, transmitting all data digitally in serialized form, thereby maintaining complete information transmission while eliminating parallel physical lines
Data Source
Figure 1~2
AI summary
The invention discloses a method for operating a parking brake by a driver of a vehicle, wherein the parking brake is operated with the aid of a pushbutton which is set up to adopt at least two and, in particular, three states, comprising: detecting the state of the pushbutton; coding the detected state; generating a check word for the coded state with the aid of a cyclic redundancy check; creating a message which is suitable for transmission via a single-wire channel and comprises the coded state and the check word; transmitting the message via a single-wire channel.