US 12,120,211 B2
Time synchronization of local device
Tatsuo Soeda, Fukuoka (JP); and Kazutoshi Kobayashi, Fukuoka (JP)
Filed by KABUSHIKI KAISHA YASKAWA DENKI, Kitakyushu (JP)
Filed on Feb. 17, 2022, as Appl. No. 17/673,802.
Claims priority of application No. 2021-030227 (JP), filed on Feb. 26, 2021.
Prior Publication US 2022/0278820 A1, Sep. 1, 2022
Int. Cl. H04L 7/00 (2006.01)
CPC H04L 7/0016 (2013.01) 20 Claims
OG exemplary drawing
 
1. A controller comprising circuitry configured to:
receive global time data indicating a global time associated with an external global clock;
determine a time difference between the global clock and an internal controller clock of the controller based on the global time data;
compare an amount of time change corresponding to the time difference to a given threshold;
divide the amount of time change over a plurality of communication cycles of periodic communication to set an amount of correction, in response to determining that the amount of time change exceeds the given threshold;
correct the internal controller clock based on the amount of correction;
synchronize the corrected controller clock of the controller with the global clock based on the global time;
set a controller time based on the synchronized controller clock; and
transmit controller time data indicating the controller time to at least one robot through the periodic communication.