GNSS-Based Vehicle Controller for Absolute Time Sync on Ethernet and CAN
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Solution Overview
Problem
Current vehicle time synchronization methods, particularly in autonomous vehicles, face challenges with low accuracy due to uncontrollable transmission time and resource occupation by Ethernet nodes in calculating absolute time synchronization, leading to inefficiencies and increased complexity.
Innovation Solution
A vehicle-mounted controller and method utilizing a GNSS module and MCU to transmit pulse signals and recommended positioning information, allowing the MPU and MCU to calculate and broadcast absolute times to Ethernet and CAN bus networks respectively, thereby avoiding resource occupation and improving synchronization accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Ethernet nodes calculate absolute time synchronization, then time synchronization can be achieved, but resource occupation increases and calculation accuracy decreases
Solution Approach 1:
The patent extracts the absolute time calculation function from the Ethernet nodes and concentrates it in the MPU. The MPU receives timing signals from the GNSS module, calculates absolute time, and then distributes this time information to all Ethernet nodes. This extraction eliminates the resource occupation and accuracy problems caused by distributed calculation at each node.
Solution Approach 2:
The MPU acts as an intermediary between the GNSS module and the Ethernet nodes. It receives the timing signal from the GNSS module, processes the absolute time calculation, and then mediates the distribution of this time information to all Ethernet nodes, ensuring centralized and accurate time synchronization across the network.
2Reliability
If multiple vehicle-mounted devices perform absolute time calculation independently, then each device can synchronize its time, but the overall synchronization accuracy decreases due to uncontrollable transmission time
Solution Approach 1:
The patent merges the distributed time calculation operations into a single centralized calculation performed by the MPU. All Ethernet nodes receive the same absolute time value calculated by the MPU, ensuring consistent and reliable synchronization across the network while eliminating the variability introduced by independent calculations at each device.
Solution Approach 2:
The MPU performs the absolute time calculation in advance based on the timing signal from the GNSS module before distributing it to all Ethernet nodes. This preliminary calculation ensures that all devices receive a pre-computed, accurate time value, eliminating the uncertainty of transmission-time-based calculations at each node.
3Measurement precision
If a unified time management system is implemented, then synchronization accuracy improves, but system complexity increases
Solution Approach 1:
The MPU serves multiple functions: it manages the timing signal from the GNSS module, performs absolute time calculation, and distributes time information to all Ethernet nodes. This multi-functionality consolidates what could be separate complex components into a single universal time management unit, improving accuracy while managing system complexity.
Data Source
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AI summary
A vehicle-mounted controller (100) includes: a GNSS module (101), an MPU (102) and an MCU (103). The GNSS module (101) transmits a pulse signal to the MPU (102) via the rigid line and transmits recommended positioning information to the MPU (102) via the serial port line at the moment when a change occurs in high and low levels of the pulse signal; the MPU (102) 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 (113) for absolute time synchronization; the MCU (103) 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 (112) for absolute time synchronization.