Major League Baseball is on track to expand its experiment with robot umpires to all 30 triple-A ballparks this season.

MLB used the Automatic Ball-Strike system at five triple-A stadiums for parts of last season and will go ahead with the wider use this year if owners approve of it next month. MLB's intent was first reported by ESPN.

MLB started the experiment in the independent Atlantic League in 2019. A challenge system was tried last year at Low-A in which a pitcher, batter or catcher had the right to appeal a human umpire's decision to the computer call.

Baseball commissioner Rob Manfred said he liked the challenge system but said the sport's competition committee was not going to consider the robot umpires for the major leagues for 2023.

"There are difficult issues surrounding the strike zone that affect outcomes on the field, and we need to make sure we understand those before we jump off that bridge," he said in June.