Time Calibration Method for Automatic Driving Systems
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Solution Overview
Problem
Automatic driving systems face inaccuracies in time synchronization due to frequency drift caused by crystal oscillators, which are affected by temperature and other factors, leading to significant system drift between GPS time updates.
Innovation Solution
A time calibration method that determines observation errors between reference and system time points at different moments, calculates the unit drift per second, and calibrates the system time based on this drift to maintain accurate synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS time synchronization is used based on PPS signal, then time synchronization is updated at integral second, but crystal oscillator frequency drift causes large system drift between synchronizations
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring the time difference between the reference time (from multiple time sources) and the local system time. The calculated drift per second is fed back to adjust the local time, creating a closed-loop control system that compensates for crystal oscillator drift in real-time, thereby resolving the contradiction between periodic synchronization and continuous drift accumulation.
Solution Approach 2:
The patent changes the parameter of time synchronization from periodic updates at integral seconds to continuous adjustment based on calculated drift. By computing the drift per second parameter and applying continuous correction, the system transforms the synchronization approach to maintain accuracy without being constrained by the periodic nature of GPS PPS signals.
2Adaptability or versatility
If crystal oscillator maintains system time between GPS updates, then system operates independently, but temperature and other factors cause frequency drift
Solution Approach 1:
The patent replaces the purely mechanical crystal oscillator timekeeping with a hybrid system that substitutes physical drift compensation with computational correction. By using algorithms to calculate and compensate for drift based on multiple time sources, the system maintains independent operation while achieving higher accuracy than the mechanical oscillator alone could provide.
Solution Approach 2:
The patent creates a composite timekeeping system that combines multiple time sources (GPS PPS signal, reference time server, and local crystal oscillator) into a unified time synchronization mechanism. This composite approach leverages the strengths of each component: the independence of the local oscillator with the accuracy of reference time sources, resolving the contradiction between autonomous operation and measurement precision.
Data Source
AI summary
The present disclosure provides a time calibration method, an electronic device, and a storage medium, and relates to the technical field of automatic driving. The method can include: determining a first observation error between first reference time point and first system time point; determining a second observation error between second reference time point and second system time point; determining a unit drift per second of the system to be calibrated based on the first system time point, the second system time point, the first observation error, and the second observation error; and calibrating the time of the system to be calibrated based on the unit drift per second.