Lab News

IROS Best Paper Award Finalist (September 2014)
Our paper, Simultaneously Powering and Controlling Many Actuators With a Clinical MRI Scanner, by A. Becker, O. Felfoul and P. Dupont was named a finalist for the Best Paper Award at IEEE/RSJ IROS 2014.

The 7th NCIGT and NIH Image Guided Therapy Workshop (September 2014)
Our abstract, MRI-Powered, imaged and controlled actuators for interventional robots, by O. Felfoul et al. has been accepted for oral presentation at the 7th Annual Image-Guided Therapy workshop sponsored by the National Center for Image Guided Therapy (NCIGT) and the NIH that will be held on September 18, 2014.
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IDEA Users Group Meeting (July 2014)
Our work on Closed-Loop Real-Time Commutation Control of an MRI-Powered Robot Actuator was presented July 20, 2014 at the North American IDEA Users Group Meeting hosted by the Athinoula A. Martinos Center for Biomedical Imaging.
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ICRA Best Medical Robotics Paper Finalist (June 2014)
Our paper, FBG-based Shape Sensing Tubes for Continuum Robots, by S. Ryu and P. Dupont was named a finalist for the Best Medical Robotics Paper Award at IEEE ICRA 2014.

ICRA 2014 Workshop (June 2014)
We co-organized a workshop at ICRA 2014 entitled Advances in Flexible Robots for Surgical Interventions.
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At Children’s Hospital, engineer is a key post (October 2013)
Our work on esophageal atresia is featured in the Boston Globe.
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IET Webinar on Robotics for Ultra-minimally Invasive Surgery(April 2013)
Dr. Dupont was featured in a recent webinar by the Institute of Engineering and Technology.
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ICRA Best Medical Robotics Paper Finalist (April 2013)
Our paper, Closed-Loop Commutation Control of an MRI-Powered Robot Actuator by C. Bergeles et al., was nominated a finalist for the Best Medical Robotics Paper Award at IEEE ICRA 2013.

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Kinematic Control of Flexible Robots

Description
Cartesian control and, in particular, impedance control of a snake-like flexible manipulator requires considering the effect of manipulator flexion on both the kinematic mapping and the force mapping between the Cartesian space and the joint space of the manipulator. This research introduces a model-based impedance controller that uses a force-deflection manipulator model to implement a desired impedance at the tip of the manipulator. The measured tip position of the manipulator is used to calculate the desired tip force for the desired impedance. The desired tip force is then mapped to the joint positions of the manipulator using the tip force-deflection model. The latter mapping is accomplished by computing the desired joint positions that deform the flexible part of the manipulator so as to generate the desired tip force. Then position-tracking controllers are used to obtain the actuator torques that create the desired joint positions. When tip force magnitudes or directions are such that manipulator deflection is of the same scale as tip position measurement noise, tip forces are instead directly mapped to the joint torques using an energy-based mapping that considers the effect of manipulator flexion. The proposed impedance controller is illustrated for a concentric tube robot constructed from a set of precurved superelastic tubes. The equilibrium special Cosserat rod model is used to obtain the force-deflection model of the robot in real time. Simulation results show that the impedance controller provides the desired impedance independent of robot flexibility. We are currently implementing the impedance controller for a concentric tube robot.

Modeling of Needle Cutting

Description
During needle-based procedures, transitions between tissue layers often involve rupture events that produce substantial deformation and tend to drive the needle off course. In this research, we analyze the mechanics of these rupture events during the insertion of a sharp needle into an inhomogeneous tissue. The force-deflection curve of the needle prior to a rupture event is modeled by a nonlinear viscoelastic Kelvin model and a stress analysis is used to predict the relationship between rupture force and needle velocity. The model predicts that the force-deflection response of the needle is steeper and the tissue absorbs less energy when the needle moves faster. The force of rupture also decreases for faster insertion under certain conditions. The observed properties are sufficient to show that maximizing needle velocity minimizes tissue deformation and damage, and consequently, results in less needle insertion position error. The model predicts that tissue deformation and absorbed energy is reduced up to a critical insertion velocity, which is inversely proportional to the relaxation time of the tissue.

Optimal Port Placement for Minimally Invasive Surgery

Description
A computer-based algorithm has been developed which uses preoperative images to provide a surgeon with a list of feasible port triplets ranked according to tool dexterity and endoscopic view quality at each surgical site involved in a procedure. A computer simulation allows the surgeon to select from among the proposed port locations. The procedure selected for the development of the system consists of a coronary artery bypass graft (CABG). In this procedure, the interior mammary artery (IMA) is mobilized from the interior chest wall, and one end is attached to the coronary arteries to provide a new blood supply for the heart. Approximately 10-20 cm is dissected free, using blunt dissection and a harmonic scalpel or electrocautery.

Robot Assisted Fetal Heart Surgery

Description
It is sometimes possible and preferable to intervene early in the development of a fetus to correct congenital malformations. New transuterine minimally invasive procedures are being developed to correct such abnormalities in the 2nd and 3rd trimester of pregnancy. Topics of this research include developing image-based navigational interfaces and modeling tissue-instrument interaction forces for increased precision, reproducibility, safety, and speed of the surgical tasks.

Graphical Displays for Image Guided Surgery

Description
Over the past few years, several important applications for laparoscopic ultrasound (lapUS) have emerged, such as improved staging of hepatic and pancreatic malignancies. Despite these advances, surgeons have been slow to adopt lapUS. The major obstacle facing surgeons learning to use lapUS is understanding how the ultrasound images are oriented relative to the patient. The basis of this problem is that the orientation techniques used by transabdominal ultrasonographers are difficult to apply with laparoscopic instruments. This project developed a system which provides orientation information by rendering the lapUS image plane relative to an aortagram in real time. This display is helpful because it provides physicians with important spatial cues that ultimately improve their ability to interpret the ultrasound images. In the system validation trials, physicians identified more landmarks correctly using the navigation system (69% vs. 25%, p=0.02).

Acoustic Diffuser for Use in Medical Instruments

Description
Over the past few years, several important applications for laparoscopic ultrasound (lapUS) have emerged, such as improved staging of hepatic and pancreatic malignancies. Despite these advances, surgeons have been slow to adopt lapUS. The major obstacle facing surgeons learning to use lapUS is understanding how the ultrasound images are oriented relative to the patient. The basis of this problem is that the orientation techniques used by transabdominal ultrasonographers are difficult to apply with laparoscopic instruments. This project developed a system which provides orientation information by rendering the lapUS image plane relative to an aortagram in real time. This display is helpful because it provides physicians with important spatial cues that ultimately improve their ability to interpret the ultrasound images. In the system validation trials, physicians identified more landmarks correctly using the navigation system (69% vs. 25%, p=0.02).