A device for generating forces that are variable and controllable in amplitude, in direction, and in frequency, the device includes two unbalanced rotors (18, 20, 35 to 38) mounted coaxially in a casing (11). The device further includes electromagnetic drive elements for driving a first of the two rotors in rotation relative to the second of the two rotors, and brake elements (43 to 45) for braking the second rotor (20, 36, 38) relative to the casing.