Sliding mode control of piezoelectric valve regulated pneumatic actuator for MRI-compatible robotic intervention

This paper presents the design of a magnetic resonance imaging (MRI) compatible pneumatic actuator regulated by piezoelectric valve for image guided robotic intervention. After comparing pneumatic, hydraulic and piezoelectric MRI compatible actuation technologies, we present a piezoelectric valve regulated pneumatic actuation system consisted of PC, custom servo board driver, piezoelectric valves, sensors and pneumatic cylinder. The system was proposed to investigate the control schemes of a modular actuator, which offers fully MRI compatible actuation; the initial goal is to control our MRI compatible prostate biopsy robot, but the controller and system architecture are suited to a wide range of image guided surgical application. We present the mathematical modeling of the pressure regulating valve with time delay and the pneumatic cylinder. Three sliding mode control schemes are proposed to compare the system performance. Preliminary simulation results are presented to validate the control algorithm.