Medical Robotics

Optimal Port Placement for Minimally Invasive Surgery

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. At present, the port placement system is being evaluated in clinical trials.

Image guided Surgery

This project involves the development of systems, in which ultrasound images are used to guide robotic manipulators for minimally invasive surgery. In many cases, these surgical procedures involve the treatment of highly precise target locations within deformable tissues. While preoperative MRI and CT models can be used for surgical planning, they provide only coarse guidance during surgery due to their limited resolution and owing to tissue deformation. Ultrasound imaging, on the other hand, is a promising means of obtaining real-time intraoperative data for target localization that is particularly well suited to minimally invasive surgery due to its portability, speed, and safety.

Communicating Mobile Robotics

Contact Sensing

Modeling by Manipulation

At present, teleoperation is the only way that robots can perform sophisticated manipulation tasks in unstructured environments. In this control mode, the human operator performs all required sensing and planning, and generates all motion commands based on feedback from the remote environment. In practical teleoperation systems (e.g. undersea operations, tele-surgery, etc ), the sensory feedback is often limited to video images without force feedback, which greatly restricts dexterity and productivity. We have been working to alleviate this situation by using information from the remote robot arm's sensors to assist in teleoperated manipulation tasks . We have derived algorithms that identify first order geometric properties such as dimensions and orientations.

Structural Dynamics

Mechanical Realization

Before building main structures such as ship hulls and airplane fuselages on which equipments can survive, scaled mechanical models are often used to test structural design concepts. In this research, we want to study the design methods for mechanical emulators which preserve the driving-point behaviors of the active machineries (such as turbine generators, motors) and the passive equipments which are usually the most dynamically complex components in the dynamical system. For the passive equipment emulators, the following approaches will be used. First, by using model reduction methods, reduced-order models will be achieved based on modal analysis data. Second, the reduced-order models will be realized by different approaches such as optimization procedure, electrical network synthesis and state space techniques. For active mechanical emulators, shakers will be used to emulate the active components in the machineries.

MEMS Filter

High-Q Microelectromechanical (MEMS) resonators which are used for frequency selection can serve as on-chip replacements for off-chip crystal and SAW resonators. In this research, the concept of periodic structures has been used to design the MEMS resonators which have alternate stopbands and passbands. The dynamical responses of MEMS resonators are measured using Laser Doppler Vibrometer(LDV). Modal analysis and FEM techniques which have been widely used in macro mechanical structures are used to investigate dynamical properties of these MEMS resonators.

Control of Fluids

Friction Analysis

Friction Modeling

The nonlinear and dynamic behavior of friction is often a significant impediment to precision motion control in systems as diverse as disk drives and machine tools. There are three goals of this research. The first is to develop physically-based friction models for control and damping applications. The second is to derive techniques for on-line identification of friction parameters. The third goal is to derive control techniques which are robust with respect to variations in frictional dynamics.

Network Control Systems

Tactile Display

Multichannel Vibrotactile Display

Augmenting perception in man-machine systems consists of two parts. First, machine sensor data must be interpreted in a way appropriate to the task. Second, the task-specific information must be communicated to the operator in a format that addresses the limitations of human sensory information processing. For example, during teleoperated surgery, vocal communication between non-operator team members can interfere with an auditory display. Similarly, overlaying visual displays with an endoscope view during surgery can be costly and non-intuitive due to scene complexity and the wide range of viewpoints encountered. Within this context, a multichannel vibrotactile device was designed, developed and tested for sensory substitution during teleoperation.

Control of Mechanical Systems

This research has a number of applications components including motion planning and control of kinematically redundant manipulators, problems associated with anholonomy in planning motions for robots which have elastic joints and other components which store energy, the control theory of fluid structure interactions, the nonlinear control theory of microelectromechanism dynamics, adaptive optics, and network mediated control of large scale device arrays.
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