Open-loop system identification of an AC motor-driven arterial flow generation platform: vessel-specific models and a parsimonious common ARX model

Accurate reproduction of arterial flow waveforms is important for in vitro cardiovascular experiments and controlled biomedical flow platforms. This study characterizes the open-loop dynamics of an AC motor-inverter-centrifugal-pump platform using five experimentally recorded input-output datasets representing femoral, carotid, iliac, coronary, and aortic waveform conditions. The inverter command was the input, the magnetic flow-meter voltage was the output, and all original recordings were sampled at 100 Hz. Vessel-specific FIR, ARX, and ridge-regularized ARX models were screened separately. A common model was selected using nested chronological validation and assessed on untouched test segments using one-step prediction, recursive free-run simulation, and diagnostic analyses. Vessel-specific one-step validation fits ranged from 80.33% to 92.80%. The common ARX(5,4,80) model achieved mean one-step and free-run fits of 95.82% and 80.04%, respectively. All poles were inside the unit circle, but significant residual autocorrelation showed that the measured response was not fully explained. The common model provides a compact nominal representation of the tested platform. Its comparison with vessel-specific models is descriptive because it uses more training data, and cycle consistency within a recording does not establish between-session experimental reproducibility.