A set of semi-active actuators is arranged in an elevator system to compensate a vibration of an elevator car. The actuators are controlled in accordance with the control policy based on a measured signal including values of the parameter measured during the operation of the elevator system. The control policy is determined, based on a model of the elevator system, wherein the control policy includes a state function representing an operation of the elevator system and a function of displacement representing an operation of the set of semi-active actuators. The state function is approximated, using the model of the elevator system, as a first function of a parameter representing the vibration. The function of displacement is approximated, using the model of the elevator system, as a second function of the parameter.