Robot controller and method of controlling robot

A controller for controlling a plurality of robots, each of the plurality of robots having a same default work load, such that a default combined work load of the plurality of robots is a combination of a plurality of the default work loads, the controller comprising:

• a failure predictor configured to predict a failure time for each of the robots if each of the robots were to operate at the default work load, such that a plurality of failure times are predicted for the plurality of robots, wherein the predicted failure time is an estimated time for each of the robots to fail to function, a first failure time is an earliest failure time among the plurality of failure times, and a last failure time is a latest failure time among the plurality of failure times;
• and
• a load adjuster configured to:
• determine whether a time period starting from the first failure time and ending at the last failure time falls within a predetermined period that includes a maintenance time determined in common to each of the robots, the predetermined period including a first sub-period before the maintenance time and a second sub-period after the maintenance time;
• and
• in response to determining that the time period starting from the first failure time and ending at the last failure time falls within the predetermined period, at least one of the plurality of robots has a predicted failure time that falls within the first sub-period, and at least one of the plurality of robots has a predicted failure time that falls within the second sub-period, perform adjustment of a work load of at least one robot among the plurality of robots according to each of the predicted failure times prior to the earliest failure time and before the predetermined period starts, so that each of the robots operates until the maintenance time, wherein an adjusted combined work load of the plurality of robots remains the same as the default combined work load, and the maintenance time remains the same.