MRI-powered actuators for robotic interventions

Abstract

This paper presents a novel actuation technology for robotically assisted MRI-guided interventional procedures. Compact and wireless, the actuators are both powered and controlled by the MRI scanner. The design concept and performance limits are described and derived analytically. Simulation and experiments in a clinical MR scanner are used to validate the analysis and to demonstrate the capability of the approach for needle biopsies. The concepts of actuator locking mechanisms and multi-axis control are also introduced.

An MRI-powered and controlled actuator technology for tetherless robotic interventions

“…First, full advantage can be taken of the three independent coordinate-direction gradient inputs. In addition, multi-actuator control can be achieved through the use of locking mechanisms as described in [Vartholomeos et al, 2011] as well as through the techniques currently being developed for the independent control of magnetic milli-and micro-robots [Vartholomeos et al, 2012].…”

A survey on actuators-driven surgical robots

“…This type of actuator completely removes the transmission means. In surgical application using magnetic actuator as the main mode of transmission, the use of moving external permanent magnet/electromagnet to drive the internal magnet 71,218 or MRI gradients to induce motion to ferromagnetic components 131,132,204 is the basic working principles. In these systems, the power and torque are magnetically transmitted from the external units through the abdominal wall into the internal units as shown in Fig.…”

Achieving Commutation Control of an MRI-Powered Robot Actuator

“…To achieve real-time tracking, the proposed technique uses single-dimensional pulse sequences, as in [1], [9], [18], [19], and [25]. These sequences have short gradient durations and do not generate unwanted rotor motion.…”

“…Alternatively, MRI-powered actuators may be fabricated inexpensively from plastic parts and metal spheres and can be actuated, imaged, and controlled directly by the MRI scanner [18], [19]. This approach can be explained by analogy to an electric motor, as shown in Fig.…”

“…In our initial implementation of an MRI-powered actuator, commutation was performed in open loop using sinusoidal gradients commanded to rotate at the desired angular rate of the motor [18], [19]. While this approach enabled needle insertion using an outer position control loop, it possessed several limitations.…”