Device for servo-controlling a vibrator to a force setpoint signal (COEF) having an amplitude and a frequency that vary over time, the vibrator comprising a first pair of unbalanced rotors (10, 11) and a second pair of unbalanced rotors (12, 13), the servo-control device comprising a first electric motor and a second electric motor, the servo-control device comprising: - a first angular position sensor, - a second angular position sensor, - a first control means arranged to control the first motor, and - a second control means arranged to control the second motor, - the first pair of unbalanced rotors (10, 11) and the second pair of unbalanced rotors (12, 13) are driven in rotation by the first electric motor, the second electric motor being arranged to drive a phase shifter mechanism and to adjust mechanically the phase shift between the pairs (A, B) of rotors of the vibrator, the servo-control device comprising: - the first sensor which is sensitive to the angular position of a rotor of the first pair of unbalanced rotors, - the second sensor which is sensitive to the angular position of a rotor of the second pair of unbalanced rotors or to the position of the phase shifter mechanism, characterized in that - the first control means which is sensitive to the force setpoint signal and to the signals delivered by the first sensor and by the second sensor, said first control means being arranged to control the first motor as a function of the phase and the frequency of the force setpoint signal and also as a function of the signals delivered by the first and second sensors (C1, C2), - the second control means which is sensitive to the force setpoint signal and to the signals delivered by the first sensor and by the second sensor (C1, C2), said second control means being arranged to control the second motor as a function of the phase, the frequency and the amplitude of the force setpoint signal and also as a function of the signals delivered by the first and second sensors. - a first angular position sensor, - a second angular position sensor, - a first control means arranged to control the first motor, and - a second control means arranged to control the second motor, - the first pair of unbalanced rotors (10, 11) and the second pair of unbalanced rotors (12, 13) are driven in rotation by the first electric motor, the second electric motor being arranged to drive a phase shifter mechanism and to adjust mechanically the phase shift between the pairs (A, B) of rotors of the vibrator, the servo-control device comprising: - the first sensor which is sensitive to the angular position of a rotor of the first pair of unbalanced rotors, - the second sensor which is sensitive to the angular position of a rotor of the second pair of unbalanced rotors or to the position of the phase shifter mechanism, characterized in that - the first control means which is sensitive to the force setpoint signal and to the signals delivered by the first sensor and by the second sensor, said first control means being arranged to control the first motor as a function of the phase and the frequency of the force setpoint signal and also as a function of the signals delivered by the first and second sensors (C1, C2), - the second control means which is sensitive to the force setpoint signal and to the signals delivered by the first sensor and by the second sensor (C1, C2), said second control means being arranged to control the second motor as a function of the phase, the frequency and the amplitude of the force setpoint signal and also as a function of the signals delivered by the first and second sensors.