A global sliding mode controller design for an intra-aorta pump

Area of Science:

• Biomedical Engineering
• Control Systems
• Medical Devices

Background:

• Intra-aorta pump systems and circulation systems are inherently nonlinear, posing challenges for traditional control methods.
• Existing control strategies often struggle with external perturbations and internal uncertainties common in these physiological systems.
• The chattering effect in controllers can degrade performance and introduce undesirable oscillations.

Purpose of the Study:

• To develop and evaluate a robust global sliding mode controller (GSMC) for nonlinear intra-aorta pump systems.
• To mitigate the chattering effect and enhance the dynamic performance and stability of the pump system.
• To validate the controller's effectiveness through both simulation and experimental studies.

Main Methods:

• Implementation of a global sliding mode controller (GSMC) designed for nonlinear systems.
• Integration of a dynamic disturbance compensator to estimate and counteract system uncertainties.
• Extensive simulations to assess robustness, dynamic response, and disturbance rejection.
• Experimental validation to compare real-world performance against simulation results.

Main Results:

• Simulations demonstrated the elimination of the chattering effect, achieving a 0.08-second settling time for a 5 L/min flow rate step response without overshoot.
• The controller exhibited rapid disturbance rejection, with a 0.025-second settling time when subjected to a 0.4 Nm load torque disturbance.
• Experimental results showed a 0.26-second settling time and 0.1 L/min flow rate error, indicating controller effectiveness despite slower feedback frequencies.

Conclusions:

• The proposed global sliding mode controller (GSMC) offers a robust and effective solution for controlling nonlinear intra-aorta pump systems.
• The dynamic disturbance compensator successfully eliminated chattering and improved system response.
• While experimental performance slightly degraded due to feedback limitations, the GSMC demonstrated significant potential for clinical applications.