CAN Repeater for Articulated Vehicle Braking Control
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Solution Overview
Problem
In articulated vehicles with extendable trailers exceeding 50m in length, the existing electronic braking systems face delays in applying trailer brakes due to the limitations of CAN bus length, necessitating a pneumatic backup system which introduces significant delays in brake application.
Innovation Solution
The implementation of a CAN repeater at the trailer connector allows for the extension of the CAN bus beyond the 18m limit, enabling rapid electrical braking control by converting pneumatic signals to electrical using a headboard pressure sensor, thereby eliminating delays in brake application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the CAN bus length is extended to accommodate trailers exceeding 50m in length, then the braking control can be maintained over longer distances, but the signal transmission delay increases and system reliability deteriorates
Solution Approach 1:
The CAN bus system is segmented into multiple sections with repeaters placed at strategic points (trailer connector and intermediate points). Each segment maintains acceptable signal integrity and transmission speed, while the overall system covers extended distances. The repeater at the trailer connector divides the bus into manageable sections, preventing signal degradation over the entire length.
Solution Approach 2:
CAN repeaters are introduced as intermediary devices that receive, regenerate, and retransmit braking control signals. These repeaters act as signal boosters and regenerators, maintaining signal quality over extended distances without requiring direct end-to-end communication between the tractor ECU and trailer ECU.
2Adaptability or versatility
If a pneumatic backup system is used for trailers exceeding CAN bus length limits, then the braking system can operate without additional wiring, but significant delays occur in brake application
Solution Approach 1:
The pneumatic backup system is replaced with an extended electrical CAN bus system using repeaters. The mechanical/pneumatic signal transmission is substituted with electrical signals that travel faster and can be regenerated by repeaters, eliminating the delays inherent in pneumatic transmission through long trailer lengths.
Solution Approach 2:
The repeaters are pre-positioned at the trailer connector and intermediate points to ensure they are ready to immediately regenerate and forward braking signals. This preliminary placement ensures that when braking is required, the signals are instantly amplified and transmitted without the delays associated with pneumatic system activation.
3Adaptability or versatility
If the CAN bus is disconnected between the trailer connector and trailer ECU to accommodate extended trailers, then the system can work with trailers of any length, but the electronic braking control is lost and pneumatic backup must be used
Solution Approach 1:
CAN repeaters serve as intermediaries that maintain the electrical connection between the tractor ECU and trailer ECU over extended distances. Instead of disconnecting the electronic system, the repeaters bridge the gap, allowing electronic braking control to function seamlessly with trailers of any length while maintaining full automation.
Solution Approach 2:
The extended CAN bus system with repeaters provides universal compatibility with trailers of varying lengths. The same electronic braking control system works whether the trailer is 20m or 100m in length, eliminating the need for different system configurations or fallback to pneumatic controls.
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
This configuration ensures timely and efficient braking control for extended trailers by maintaining electrical control over the braking system without additional wiring, reducing the delay associated with pneumatic signal transmission.
Implementation Method 1
converting pneumatic signals to electrical using a headboard pressure sensor
Data Source
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AI summary
An articulated vehicle comprising a tractor (12), a first trailer (42) and a second trailer (14), wherein the tractor (12) is provided with a braking demand signal generating device (33) which is operable by a driver of the vehicle to generate an electrical braking demand signal, and each trailer (14,42) is provided with an electrical braking control unit (18,48), wherein the first trailer (92) is provided with an electrical connector (44), and means are provided to transmit the electrical braking demand signal from the tractor (12) to the electrical connector (44), the electrical braking unit (18) of the second trailer (14) being connected to the electrical connector (44) so that the electrical braking demand signal may be transmitted from the electrical connector (44) to the electrical braking control unit (18) of the second trailer (14), wherein the electrical braking control unit (48) of the first trailer (42) is also connected to the electrical connector (44), power being supplied to the electrical braking control unit (48) of the first trailer (42) via the connection to the electrical connector (44).