Time source recovery system for an autonomous driving vehicle

An apparatus to recovery a time source for an autonomous driving vehicle (ADV), the apparatus comprising:

• a processor;
• a memory coupled to the processor to store instructions, which when executed by the processor, cause the processor to perform operations, the operations comprising:
• determining a difference in time between first time obtained from a first time source and second time obtained from a global positioning system (GPS) time source, in response to determining that the GPS time source becomes available from unavailable, wherein the first time source is utilized to generate timestamps while the GPS time source is unavailable;
• determining that the difference between the first time and the second time is less than a predetermined max limit, and
• performing a smooth recovery of the time source by converging the first time source to the GPS time source within a predetermined max recovery time interval, wherein subsequent timestamps are generated based on the converged first time source to timestamp sensor data obtained from a plurality of sensors mounted on a plurality of locations of the ADV, and wherein the sensor data is utilized by a host system to perceive a driving environment surrounding the ADV and to autonomously drive the ADV based on perception data.

A sensor unit for an autonomous driving vehicle (ADV), the sensor unit comprising:

• a sensor interface to be coupled to a plurality of sensors mounted on a plurality of locations of the ADV;
• a time source recovery logic coupled to the sensor interface, the time source recovery logic including:
• a time difference determiner module to determine a difference in time between first time obtained from a first time source and second time obtained from a global positioning system (GPS) time source, in response to determining that the GPS time source becomes available from unavailable, wherein the first time source is utilized to generate timestamps while the GPS time source is unavailable, and
• a smoothing module coupled to the time difference determiner module configured to:
• determine that the difference between the first time and the second time is less than a predetermined max limit, and
• perform a smooth recovery of the time source by converging the first time source to the GPS time source within a predetermined max recovery time interval;
• and
• a timestamp generator to generate timestamps based on the converged first time source to timestamp sensor data obtained from the sensors, and wherein the sensor data is utilized by the host system to perceive a driving environment surrounding the ADV and to autonomously drive the ADV based on perception data.