Grandmaster Clock Correction Across GNSS and Vehicle Time Domains
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Solution Overview
Problem
Current methods for synchronizing clocks across different domains, such as Vehicle, Edge, and Cloud Computing, in autonomous vehicles are imprecise due to clock drift, skew, and oscillator instability, posing safety risks due to ambiguity in time references.
Innovation Solution
A mobile Grandmaster Clock system with a Clock Correction Host and neural network-based dynamic adaptive clock selection, utilizing GNSS, Ethernet, and Wireless sources for accurate time synchronization, managing clock drift and power consumption, and enabling seamless transitions between time domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GNSS-based clock synchronization is used across multiple domains, then time reference accuracy is improved, but system complexity increases due to managing clock drift and transitions between multiple time domains
Solution Approach 1:
The patent introduces a time domain manager as an intermediary component that mediates between multiple time domains (GNSS, vehicle, edge, cloud). This manager handles clock drift compensation and domain transitions, isolating the complexity from the core synchronization function while maintaining high time reference accuracy across all domains.
Solution Approach 2:
The system dynamically adapts between different time domains based on operational conditions. The time domain manager continuously monitors clock drift and automatically transitions between GNSS-synchronized mode, vehicle-domain mode, and hybrid modes, making the system flexible without requiring permanent complex infrastructure in each domain.
2Reliability
If multiple clock sources (GNSS, Ethernet, Wireless) are used for synchronization, then reliability is improved, but energy consumption increases
Solution Approach 1:
The system dynamically selects and switches between multiple clock sources (GNSS, Ethernet, Wireless) based on availability, accuracy requirements, and power constraints. The time domain manager activates only the necessary synchronization sources at any given time, maintaining high reliability through source diversity while minimizing energy consumption by avoiding continuous operation of all sources simultaneously.
Solution Approach 2:
The system changes operational parameters of clock sources based on conditions - adjusting sampling rates, activation states, and correction frequencies of different synchronization sources. This allows the system to maintain reliability across varying conditions while optimizing power consumption by reducing activity of less critical sources when full accuracy is not required.
3Reliability
If precise time synchronization is implemented across all domains, then operational safety is improved, but device complexity increases due to need for continuous clock correction and domain management
Solution Approach 1:
The time domain manager serves as a specialized intermediary that handles all complex aspects of multi-domain synchronization, including clock drift compensation, domain transitions, and coordination between Vehicle, Edge, and Cloud domains. This concentrates complexity in a single managed component rather than distributing it across all system devices, improving safety while containing overall system complexity.
Data Source
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AI summary
A Grandmaster clock is presented. The Grandmaster clock has a GNSS interface receiving GNSS time sync data, a Real Time Clock (RTC) with a crystal oscillator, one or more communication interfaces exchanging data with clock correction sources, and a clock correction host. The clock correction host computes clock drift based on the GNSS time sync data and the data from clock correction sources, generating adjusted clock data, and writing the adjusted clock data to the RTC from different locations. The Grandmaster clock may be in a vehicle.