Active method to control the vibrations of any specific point located along the length of an articulated arm for pumping concrete consisting of a plurality of segments articulated with respect to each other by means of an electronic controller, each of these segments being associated to its own actuators, the method comprising the following steps: a) construction of a numerical modal model of said articulated arm, described by modal variables, which is based on a reference model written in the form of the modes of the structure of the arm and is obtained starting from experimental data or from structural models, wherein, in the modal model, state modal variables that describe the system represent the contribution of how much each mode of vibrating participates in the overall motion of the arm; b) assignation of gains of said electronic controller, wherein said gains are expressed as a function of the actual position assumed by the articulated arm during the broad motion, and according to the value of force actually transmitted to the arm by the operator; c) multiplication of said gains by the difference between the reference modal coordinates and those calculated through the modal model starting from directly measured quantities, in order to determine the control forces to be applied, by means of each of said relative actuators, to the arm or to at least part of the relative segments; d) evaluation of the modal coordinates by means of a states estimator; e) comparison, in an adder, between estimated measurements estimated using said modal coordinates and real measurements, and correction of the estimate, so that it converges on real values; wherein said correction is made by an estimator by multiplying the differences between the real measurements and the estimated measurements by a suitable set of gains; f) action on the arm, by means of a feedback force which is added to the command given by the operator for the movement of the whole arm, if he intervenes during a command, or determining a compensation force also with the arm stationary during a pumping operation which itself causes vibrations. a) construction of a numerical modal model of said articulated arm, described by modal variables, which is based on a reference model written in the form of the modes of the structure of the arm and is obtained starting from experimental data or from structural models, wherein, in the modal model, state modal variables that describe the system represent the contribution of how much each mode of vibrating participates in the overall motion of the arm; b) assignation of gains of said electronic controller, wherein said gains are expressed as a function of the actual position assumed by the articulated arm during the broad motion, and according to the value of force actually transmitted to the arm by the operator; c) multiplication of said gains by the difference between the reference modal coordinates and those calculated through the modal model starting from directly measured quantities, in order to determine the control forces to be applied, by means of each of said relative actuators, to the arm or to at least part of the relative segments; d) evaluation of the modal coordinates by means of a states estimator; e) comparison, in an adder, between estimated measurements estimated using said modal coordinates and real measurements, and correction of the estimate, so that it converges on real values; wherein said correction is made by an estimator by multiplying the differences between the real measurements and the estimated measurements by a suitable set of gains; f) action on the arm, by means of a feedback force which is added to the command given by the operator for the movement of the whole arm, if he intervenes during a command, or determining a compensation force also with the arm stationary during a pumping operation which itself causes vibrations.