Vehicle Clock Adjustment Using Cumulative Flight-Time Disparity
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Solution Overview
Problem
Existing methods for adjusting vehicle clocks are inaccurate due to heat sensitivity of quartz-based clocks and insecure, inaccurate time information from GPS and servers, which are affected by variable and unknown flight times.
Innovation Solution
A method involving a data server transmitting a sequence of consecutive actual-time values with fixed intervals, calculating differences and cumulative disparities, and adjusting the vehicle clock based on the minimum cumulative disparity to ensure accurate and secure timekeeping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the vehicle clock is adjusted using GPS time information, then the time accuracy is improved, but the security is worsened because GPS time information can be hacked
Solution Approach 1:
The patent introduces a server as an intermediary between the vehicle and the time source. The server receives secure time information (from GPS or other sources) and relays it to the vehicle through encrypted wireless communication. This mediator architecture maintains security while providing accurate time synchronization, as the server can authenticate and validate time information before forwarding it to vehicles.
2Reliability
If the vehicle requests time update from server, then the security is improved because connection is secure and encrypted, but the accuracy is worsened due to unknown and variable flight times up to tens of seconds
Solution Approach 1:
The server performs preliminary action by maintaining a buffer of time information and preparing responses in advance. When a vehicle requests time synchronization, the server can provide pre-computed time data that has already accounted for transmission delays, or the server continuously pushes time updates to vehicles without waiting for requests, thereby reducing the impact of variable flight times on accuracy.
3Measurement precision
If the internal clock is adjusted to GPS time, then the time accuracy is improved, but the security is worsened as GPS information can be hacked
Solution Approach 1:
The server acts as a trusted intermediary that validates GPS time information before relaying it to vehicles. The server can cross-check GPS data with other time sources, authenticate the information, and only forward verified accurate time data to vehicles through secure encrypted channels, thereby maintaining both accuracy and security.
Data Source
AI summary
A method for adjusting a clock on board a motor vehicle, the clock providing an actual time for functions of the vehicle, the vehicle connected via wireless communication to a data server, the method including: the server transmitting a sequence of consecutive actual-time values, separated from one another by a fixed time interval; the vehicle receiving the actual-time values shifted by an unknown and variable time of flight between transmission and reception; for each received actual-time value: calculating a difference between an actual-time value received at a given instant and an actual-time value received at a previous instant; calculating a discrepancy between the calculated difference and the fixed time interval; calculating a cumulative disparity, consisting in summing the discrepancy calculated for a time value received at one instant and a time value received at the previous instant; determining the actual time for adjusting the on-board clock according to the disparity.