Fig. 1 Schematic diagram of LVAD, its automatic controlled drive unit and circulatory system Fig. 2 Interface between the proposed simulator and the d

Fig. 1 Schematic diagram of LVAD, its automatic controlled drive unit and circulatory system Fig. 2 Interface between the proposed simulator and the digital controller of the drive unit of LVAD

a) SYSTOLIC PERIODb) DIASTOLIC PERIOD Fig. 3 The electric circuit model of the systemic circulation driven by LVAD a) COUNTER-PULSATION Fig. 4 Pulsation patterns of the left ventricle and LVAD

a) LEFT VENTRICULAR PRESSURE Fig. 5 Decomposition of the left ventricular pressure and the drive pressure of LVAD

Table 1 Parameters in the model of the systemic circulation driven by LVAD Fig. 6 State equation pattern of the systemic circulation model Fig. 7 Composition of state equations for four periods

Fig. 8 An example of the simulation under a pathological condition (poor function of natural heart)

Fig. 9 Comparison of the simulation between COP and CP modes EGG: ECG of the goat, AOP: the aortic pressure, DRP: the drive pressure, LVP: the left ventricular pressure, AHF: the outflow from LVAD Fig. 10 Time series data obtained from the circulatory system of an adult goat

Fig. 11 An example of the simulation under the conditions of UP, CUP and shutdown of LVAD Fig. 12 Data obtained from the circulatory system of an adult goat under the conditions of CP, COP and shutdown of LVAD

a) FI CONTROL SYSTEM b) AOAFTIVE CONTROL SYSTEM Fig. 13 Block diagram of the automatic control system Fig. 14 Tracking characterics of the PI control system and the adaptive control system

1) V. V. Chalam: Adaptive control systems, Marcel Dekker (1987) 2) T. Kitamura & H. Akashi: A design of an adaptive control system for left ventricular assist, Proc. of 8th IFAC World Congress, 3767/3772 (1981) 3) B. C. Mclnnis, R. L. Everett, J. C. Wang, B. Vajapeyam & T. Akutu: A microcomputer based adaptive control system for the artificial heart, Proc. of IFAC 8th World Congress, XXI, 130/137 (1981) 4) T. Kitamura: Atrial pressure controller design for a portable artificial heart drive system, Proc. of 9th Annu. Conf. of IEEE/EMBS, 194/195 (1987) 5) H. Reul: Cardiovascular simulation models, Life Support Syst., 2, 77/98 (1984) 6) B. C. Mclnnis, Z. W. Guo, P. C. Lu & J. C. Wang: Adaptive control of left ventricular bypass assist device, IEEE Trans. Automat. Control, AC-30-4, 322/329 (1985) 7) P. F. Moller, W. K. R. Barnikol, D. Popovit, G. Thiele, E. Henning & E S. BUcherl: Evaluation of hemodynamic parameters for adaptive control of the artificial heart by simulation of the vascular system, Proc. of 9th World Congress of the Iternational Federation of Automatic Control, 52/57 (1984) 8) D. A. Spyker: Simulation in the analysis and control of a cardio-circulatory assist device, Simulation, 15-5, 196/ 205 (1970) 9) C. M. Anderson & J. W. Clark: Analog simulation of left ventricular bypass mode control, IEEE Trans. Biomed. Eng., BME-22-5, 384/392 (1975) 10) N. N. Pun, J. K-J. Li, S. Fich & W. Welkowitz: Control system for circulatory assist devices: Determination of suitable control variables, Trans. Am. Soc. Artif. Intern. Organs, 28, 127/132 (1982) 14) G. F. Franklin & J. D. Powell: Digital control of dynamic systems, Addison Wesley (1980) 15) G. C. Goodwin & K. S. Sin: Adaptive filtering, prediction and control, Prentice-Hall (1984)

Synthesis and Evaluation of the Adaptive Control System for the Ventricular Assist Device by Using the Circulatory System Simulator* Jin-Shan FENG,** Makoto YOSHIZAWA,** Hiroshi TAKEDA,** Makoto MIURA,*** An on-line digital simulator using microcomputer system was developed to mimic the hemodynamic behavior of the human circulatory system under ventricular assist device (VAD) pumping. This simulator could calculate the response to the variation of the cardiac function or the driving mode of VAD in the real-time fashion. This simulator was used as the mock controlled object to evaluate and improve the algorithm of an adaptive controller of the drive unit for VAD. The adaptive one-step ahead controller was introduced as the precompensator for the PI-controller, which decides the outflow volume from VAD in order to follow up the reference flow value by changing the systolic duration. It was confirmed that the proposed adaptive control system improved the response speed of the VAD driving system automatically according to the variation of the controlled object. *Received on April 5th 1988, Revised on Dec. 20th 1988 **Deptartment of Electrical Engineering, Faculty of Engineering, Tohoku University ***School of Medicine, Tohoku University