A system to optimize a drilling parameter of a drill string includes a drill string control subsystem. The system includes an optimization controller to coordinate operations of the drill string control subsystem during a drilling process at least in part by: determining a first optimized rate of penetration based on a drilling parameter model and a first drilling parameter estimate; providing a first set of commands to the drill string control subsystem based on the first optimized rate of penetration; determining a second drilling parameter estimate during the drilling process based, at least in part, on the drilling parameter model and feedback corresponding to the drill string control subsystem; determining a second optimized rate of penetration during the drilling process based on the second drilling parameter estimate; and providing a second set of commands to the drill string control subsystem based on the second optimized rate of penetration.