Comparison of MRI-Compatible Mechatronic Systems With Hydrodynamic and Pneumatic Actuation

Abstract

The strong magnetic fields and limited space make it challenging to design the actuation for mechatronic systems intended to work in MRI environments. Hydraulic and pneumatic actuators can be made MRI-compatible and are promising solutions to drive robotic devices inside MRI environments. In this paper, two comparable haptic interface devices, one with hydrodynamic and another with pneumatic actuation, were developed to control one-degree-of-freedom translational movements of a user performing functionalMRI(fMRI) tasks. The cylinders were made of MRI-compatible materials. Pressure sensors and control valves were placed far away from the end-effector in the scanner, connected via long transmission lines. It has been demonstrated that both manipulandum systems were MRI-compatible and yielded no artifacts to fMRI images in a 3-T scanner. Position and impedance controllers achieved passive as well as active subject movements. With the hydrodynamic system we have achieved smoother movements, higher position control accuracy, and improved robustness against force disturbances than with the pneumatic system. In contrast, the pneumatic system was back-drivable, showed faster dynamics with relatively low pressure, and allowed force control. Furthermore, it is easier to maintain and does not cause hygienic problems after leakages. In general, pneumatic actuation is more favorable for fast or force-controlled MRI-compatible applications, whereas hydrodynamic actuation is recommended for applications that require higher position accuracy, or slow and smooth movements. Abstract-The strong magnetic fields and limited space make it challenging to design the actuation for mechatronic systems intended to work in MRI environments. Hydraulic and pneumatic actuators can be made MRI-compatible and are promising solutions to drive robotic devices inside MRI environments. In this paper, two comparable haptic interface devices, one with hydrodynamic and another with pneumatic actuation, were developed to control one-degree-of-freedom translational movements of a user performing functional MRI (fMRI) tasks. The cylinders were made of MRI-compatible materials. Pressure sensors and control valves were placed far away from the end-effector in the scanner, connected via long transmission lines. It has been demonstrated that both manipulandum systems were MRI-compatible and yielded no artifacts to fMRI images in a 3-T scanner. Position and impedance controllers achieved passive as well as active subject movements. With the hydrodynamic system we have achieved smoother movements, higher position control accuracy, and improved robustness against force disturbances than with the pneumatic system. In contrast, the pneumatic system was back-drivable, showed faster dynamics with relatively low pressure, and allowed force control. Furthermore, it is easier to maintain and does not cause hygienic problems after leakages. In general, pneumatic actuation is more favorable for fast or force-controlled MRI-compatible applications, whereas hydrodynamic a...

S Teleoperation System Based on 1-DOF Pneumatic Maipulator

“…There are only couple of paper, rising problem of inverse modelling used in self-sensing control unit of bilateral teleoperators. This work and papers [25,32,40,[47][48][49][50], addresses this problem.…”

Control of a Master–Slave Pneumatic System for Teleoperated Needle Insertion in MRI

“…Impedance control is the natural choice for pneumatic actuators, which are back-drivable and compliant [11]. Here this approach consists of the TDC position control on the slave unit and of a force control on the master.…”

“…Instead, pneumatic actuation can be designed to only employ nonmetallic materials and can qualify as MRI-safe [2]. Pneumatic actuation is clean, safe, and well suited for force control, as discussed in [1], [11] and references therein. However, commercially available pneumatic cylinders typically have high friction which makes position control and force control particularly challenging.…”

Load Self-Sensing Control Scheme for Telemanipulation - Part 1: Theory

“…The paper presents an approach to design of a control scheme for a master-slave system with force-feedback. The difference between sensor methods thus far is that, in the case of the proposed control scheme, there are no sensors mediating between the manipulator body and the environment, relative to papers [6,19,34,35,42,43]. The same thing can be noticed in self-sensing and piezo-ceramic micromanipulators used for micromanipulation an in impedance control methods [7, 8, 23-25, 40, 41, 44].…”