Active Cardiac Stabilization using H∞ Control Methodology

Beating heart surgery is an important milestone in cardiac surgery. This technique is currently made possible thanks to the use of passive mechanical stabilizers. Nevertheless, the commercially available stabilizers exhibit significant residual motion, which is inherent to their geometry. Recently, a novel active stabilizer based on a compliant structure has been designed. High-speed visual feedback is used to compensate for the residual cardiac motion with a piezo actuator. In this paper three H∞ control strategies with different levels of a priori knowledge on the disturbance are tested and compared. First, a classical feedback strategy without any assumption on the disturbance is designed. Second, a feedback control law with a resonant filter centered at the cardiac fundamental frequency is synthetized. Finally, a 2 degrees-of-freedom controller fed with a prediction of the heart motion is proposed. The prediction is obtained with an original method provided in this article.