Design of adaptive control system for total artificial heart

Abstract

One of the most difficult problems which prevent us from successfully controlling the total artificial heart is that we have not yet established any methods of setting the value of cardiac output regarded as a reference input to the control system. 1/R control method may be valid for avoiding this problem because it aims at making the recipient's circulatory center decide the value of cardiac output via peripheral vascular resistance. However, this method has a deficiency which consists in deciding an unknown parameter included in its algorithm in a trial and error manner. To cope with this deficiency, the present study proposed a new design strategy for TAH control. First, the cardiovascular system driven by a TAH was modelled as a two-input two-output system whose inputs are drive rate and peripheral vascular resistance and whose outputs are aortic pressure and cardiac output. Next, a decoupling controller was designed for the modelled system on the basis of the adaptive control theory. Computer simulation demonstrated that the proposed design strategy enables us to avoid the trial and error problem for deciding the unknown parameter and it can yield an automatic controller which can adapt to variation in characteristics of the cardiovascular system with individual or with a very long time span.