An actuator arrangement for applying a torque to a shaft of a machine for the damping of rotational vibrations of the shaft, the shaft being a crank shaft of a reciprocating piston machine, having at least the following features: a) at least one actuator device for applying the torque to the shaft , b) at least one rotatable seismic mass coupled to the shaft , c) the at least one actuator device being designed to apply the torque between the seismic mass and the shaft and the at least one actuator device forming a coupling between the seismic mass and the shaft, d) the actuator arrangement having at least one electrical machine for the provision of drive energy for the at least one actuator device , e) the actuator arrangement having at least one transmission by means of which the at least one actuator device is coupled to the at least one electrical machine in order to drive it , f) the at least one electrical machine being designed as an electric motor having a stator and a rotor , the stator being mounted in a fixed manner on a frame and the rotor being coupled to the at least one actuator device either indirectly via the transmission or indirectly, g) the at least one transmission and the at least one actuator device being arranged on the at least one seismic mass , h) the actuator arrangement having at least one controller for controlling the electrical machine , i) the actuator arrangement having at least one measuring device for gathering rotary vibration data relating to the shaft , and j) the controller being designed to control the electrical machine on the basis of the gathered rotary vibration data relating to the shaft in order to apply the torque to damp rotary vibrations of the shaft . a) at least one actuator device for applying the torque to the shaft , b) at least one rotatable seismic mass coupled to the shaft , c) the at least one actuator device being designed to apply the torque between the seismic mass and the shaft and the at least one actuator device forming a coupling between the seismic mass and the shaft, d) the actuator arrangement having at least one electrical machine for the provision of drive energy for the at least one actuator device , e) the actuator arrangement having at least one transmission by means of which the at least one actuator device is coupled to the at least one electrical machine in order to drive it , f) the at least one electrical machine being designed as an electric motor having a stator and a rotor , the stator being mounted in a fixed manner on a frame and the rotor being coupled to the at least one actuator device either indirectly via the transmission or indirectly, g) the at least one transmission and the at least one actuator device being arranged on the at least one seismic mass , h) the actuator arrangement having at least one controller for controlling the electrical machine , i) the actuator arrangement having at least one measuring device for gathering rotary vibration data relating to the shaft , and j) the controller being designed to control the electrical machine on the basis of the gathered rotary vibration data relating to the shaft in order to apply the torque to damp rotary vibrations of the shaft . <EOS>