Controlling drill string rotation

An apparatus comprising:

• a control system operable to control a well construction system, wherein the control system comprises:
• a first tier of controllers each operable to control a corresponding actuator of the well construction system, wherein the first tier of controllers comprise a first controller operable to control rotation of a driver operable to rotate a drill string to form a wellbore extending into a subterranean formation;
• a second tier of controllers each communicatively connected with a corresponding instance of the first tier of controllers, wherein the second tier of controllers comprise a second controller communicatively connected with the first controller;
• and
• a third controller communicatively connected with each instance of the second tier of controllers, wherein the first, second, and/or third controller comprises a processor and a memory storing executable program code instructions comprising a stick-slip algorithm, wherein the first, second, and/or third controller is operable to receive input parameters of the stick-slip algorithm, and wherein during drilling operations the first, second, and/or third controller is operable to:
• execute the program code instructions to generate a rotational speed command based on the input parameters and on status information indicative of operational status of the drill string;
• and thereby
• cause the driver to vary rotational speed of the drill string based on the rotational speed command to reduce rotational waves traveling along the drill string.