The twin rotor damper (TRD) is a newly developed active mass damper. It is presented here along with respective closed-loop control algorithms. The greatest advantage of the device is its low power demand when operated in a preferred mode of operation, the continuous rotation mode. In this mode, two eccentric masses rotate in opposite directions about two parallel axes with a mostly constant angular velocity. The resultant force is harmonic and can be used for the control of structural vibrations. To study the effect of the TRD on a single degree-of-freedom (SDOF) oscillator, various state variables are introduced and a feedback control algorithm is developed for the continuous rotation mode of operation. For reaching and leaving the continuous rotation mode, ramp-up and ramp-down trajectories are developed. These trajectories are designed such that the power and energy demand as well as the mechanical wear on the device are minimized. The feedback control algorithm is validated on a test setup. The damping effectiveness and the low power and energy demands encourage further investigation of the device under stochastic loading and comparisons with other active mass dampers.