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Preload-based Starling-like control of rotary blood pumps: An in-vitro evaluation
Fig 2
Block diagram of the control system.
CVS, cardiovascular system; VAD, ventricular assist device, LVAD, left VAD; u, mean pulse-width modulation drive signal to the LVAD; HCVS, differential pressure between the left ventricle and the aorta; CLn, Control line; S1, original state; S2 and S3, deviated states; QP, pump flow; 
, mean pump flow; 
, The reference (desired) mean pump flow; PLVEDm, mean left ventricular end diastolic pressure; ω, pump speed; 
, mean pump speed; 
, mean pump speed set-point; Grey circles, position of operating points after changes in states; Black circles, position of operating points upon arriving at the new steady state located at the intersection between the control line and the new system line. The controller drives the changes in the operating points along the path indicated by the arrows along the new system line; PLVEDm serves as the input to the preload controller (Eq 1); ∑, 1-second moving average filter.
doi: https://doi.org/10.1371/journal.pone.0172393.g002