Isuru S. Godage

Magnetic resonance (MR)-guided interventional robots have recently been developed for a variety of surgeries, such as biopsy, ablation, and brachytherapy. The actuators and encoders that power and track such robots must be MR conditional. In this paper, we propose an MR-conditional pneumatic motor with an integrated and custom-built fiber-optical encoder that provides powerful and accurate actuation. The motor is coupled with a modular plastic gearbox that provides a variety of gear ratio options so that the motor can be adapted to application requirements. With a 100:1 gear reduction at 0.55 MPa, the motor achieves 460 mN:m stall torque and 370 r/min no-load speed, which leads to the peak output power of 6 W. The motor has the bandwidth of approximately 1.1 and 3.5 Hz when connected to 8 and 0.2 m air hoses, respectively. The motor was tested in a 3T magnetic resonance imaging (MRI) scanner. No image artifact was observed and maximum signal-to-noise ratio (SNR) variation was less than 5%. Different from most of the existing MR-conditional pneumatic actuators, the proposed motor shape is more like the traditional electric motors, which offers more flexibility in the MR-conditional robot design.

This letter presents a novel miniature robotic endoscope that is small enough to pass through the Eustachian tube and provides visualization of the middle ear (ME). The device features a miniature bending tip previously conceived of as a small-scale robotic wrist that has been adapted to carry and aim a small chip-tip camera and fiber-optic light sources. The motivation for trans-Eustachian tube ME inspection is to provide a natural-orifice-based route to the ME that does not require cutting or lifting the eardrum, as is currently required. In this letter, we first perform an analysis of the ME anatomy and use a computational design optimization platform to derive the kinematic requirements for endoscopic inspection of the ME through the Eustachian tube. Based on these requirements, we fabricate the proposed device and use it to demonstrate the feasibility of ME inspection in an anthropomorphic model, i.e., a 3-D printed ME phantom generated from patient image data. We show that our prototype provides > 74% visibility coverage of the sinus tympani, a region of the ME crucial for diagnosis, compared to an average of only 6.9% using a straight nonarticulated endoscope through the Eustachian tube.

To achieve their full potential, soft and compliant continuum robots must move faster and more accurately than they can today. To facilitate this, accurate and computationally efficient dynamic models are essential. While the integral Lagrangian approach can produce accurate models, it is complex and computationally intensive. In this article we propose a new dynamic model based on numerically stable modal kinematics that is both accurate and computationally efficient. The proposed model is a lumped parameter model, but one that is more accurate than prior lumped parameter models because mass locations and quantities are derived from a detailed description of the total energy in a continuum arm with continuously distributed mass. We experimentally validated the model using a pneumatic muscle-actuated continuum arm, and the proposed model successfully simulates the transient and steady-state dynamics of the prototype arm. Further, the model is also compared to the integral Lagrangian and a lumped parameter model to highlight its advantages in terms of computational efficiency and its accuracy.