STATE-VARIABLE FEEDBACK CONTROL OF A MAGNETICALLY SUSPENDED CENTRIFUGAL BLOOD PUMP

by Selby, Normajean

An integral state-variable feedback controller was developed to regulate flow in a rotodynamic magnetically suspended centrifugal pump (MSCP). The controller specification was to maintain blood flow within 15% of 4 L/min against an open-loop load disturbance resulting in changes in pressure difference of ± 50 mmHg about nominal 100 mmHg occurring at 100 mmHg/min. For controller and observer design purposes, the nonlinear system was represented by a state-space model linearized about a nominal operating point with an output disturbance. A proportional integral (PI) observer was developed to estimate the unmeasurable states and disturbance. Matlab® was used for model identification and design and simulation of the controller and observer, which were then implemented using Labview®. In simulation and on the physical system, the controller maintained acceptable blood flow against an extreme unknown load disturbance occuring at a rate of approximately 200 mmHg/min.