Vehicle Time Controller for GNSS-Based Ethernet and CAN Synchronization
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Solution Overview
Problem
Existing vehicle time synchronization systems face challenges in achieving accurate absolute time synchronization due to uncontrollable network transmission times, which occupy resources at Ethernet nodes and require each node to calculate absolute time.
Innovation Solution
A vehicle-mounted controller is provided, comprising a GNSS module, an MPU, and an MCU, which transmit and receive pulse signals and recommended positioning information to determine absolute time and broadcast it to Ethernet and CAN bus networks, respectively, thereby eliminating the need for individual node calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each Ethernet node calculates absolute time independently, then time synchronization capability is distributed, but network transmission time becomes uncontrollable and resources at Ethernet nodes are occupied
Solution Approach 1:
The patent introduces a dedicated time synchronization device as an intermediary that receives timing signals from the GNSS module and distributes absolute time to both Ethernet and CAN bus networks. This mediator handles the complex task of time calculation and distribution, freeing Ethernet nodes from performing these operations while ensuring controllable and accurate time synchronization across the network.
2Measurement precision
If network transmission time is used for absolute time calculation, then time synchronization is achieved, but resource occupation at Ethernet nodes increases
Solution Approach 1:
The patent extracts the time calculation function from Ethernet nodes and concentrates it in a dedicated time synchronization device. This device receives the timing signal from the GNSS module and pre-calculates absolute time, then distributes it to all network participants. This extraction eliminates the need for each Ethernet node to perform resource-intensive time calculations while maintaining synchronization accuracy.
3Adaptability or versatility
If multiple communication protocols are used for time distribution, then compatibility with different vehicle-mounted devices is improved, but system complexity increases
Solution Approach 1:
The time synchronization device is designed with multi-functionality to support multiple communication protocols simultaneously. It can distribute absolute time through both Ethernet network and CAN bus using appropriate protocols for each, enabling universal compatibility with different vehicle-mounted devices without requiring each device to implement complex time calculation logic.
Data Source
AI summary
A vehicle-mounted controller includes: a GNSS module, an MPU and an MCU. The GNSS module transmits a pulse signal to the MPU via the rigid line and transmits recommended positioning information to the MPU via the serial port line at the moment when a change occurs in high and low levels of the pulse signal; the MPU determines first absolute time according to first reception time when the pulse signal is received, second reception time when the recommended positioning information is received, and the recommended positioning information, and broadcasts the first absolute time to Ethernet network for absolute time synchronization; the MCU determines second absolute time according to time when the pulse signal is received, time when the first absolute time is received, and the recommended positioning information, and broadcasts the second absolute time to a CAN bus for absolute time synchronization.