Sliding mode control of a differentially flat vibrational mechanical system: experimental results

In this paper the differential flatness property and a sliding mode controller are applied to a vibrating mechanical system in order to achieve asymptotic output tracking and disturbance attenuation. The mechanical system consists of two masses connected with springs. The output to be controlled is the position of the under-actuated mass, which is directly affected by an undesirable vibration (harmonic force with variable excitation frequency). The active vibration control scheme exploits the differential flatness property during the control design, employing only position measurements and approximate time differentiation, and is dynamically able to track an off-line planned trajectory in spite of small disturbances. The overall system performance is validated by some numerical simulations and experimental results in a physical platform