Browsing by Author "Dr. Gregory Buckner, Committee Chair"

Filter results by typing the first few letters
Now showing 1 - 4 of 4
  • No Thumbnail Available
    Actuation and Control Strategies for Miniature Robotic Surgical Systems
    (2002-08-12) Stevens, Jason Michael; Dr. Edward Grant, Committee Member; Dr. Gregory Buckner, Committee Chair; Dr. M.K. Ramasubramanian, Committee Member
    Over the past 20 years, tremendous advancements have been made in the fields of minimally invasive surgery (MIS) and minimally invasive robotic assisted (MIRA) surgery. Benefits from MIS include reduced pain and trauma, reduced risks of post-operative complications, shorter recovery times, and more aesthetically pleasing results. MIRA approaches have extended the capabilities of MIS by introducing three-dimensional vision, eliminating tremors, and enabling the precise articulation of smaller instruments. These advancements come with their own drawbacks, however. Robotic systems used in MIRA procedures are large, costly, and do not offer the miniaturized articulation necessary to facilitate tremendous advancements in MIS. This research tests the hypothesis that miniature actuation can overcome some of the limitations of current robotic systems by demonstrating accurate, repeatable control of a small end-effector. A 10X model of a two link surgical manipulator is developed, using antagonistic shape memory alloy (SMA) wires as actuators, to simulate motions of a surgical end-effector. Artificial neural networks (ANNs) are used in conjunction with real-time visual feedback to "learn" the inverse system dynamics and control the manipulator endpoint trajectory. Experimental results are presented for indirect, on-line learning and control. Manipulator tip trajectories are shown to be accurate and repeatable to within 0.5 mm. These results confirm that SMAs can be effective actuators for miniature surgical robotic systems, and that intelligent control can be used to accurately control the trajectory of these systems.
  • No Thumbnail Available
    Electromechanical Actuator Development for Integrated Chatter Prediction on High Speed Machining Centers
    (2003-04-24) Caulfield, F. Donald; Dr. Gregory Buckner, Committee Chair; Dr. Larry Silverberg, Committee Member; Dr. Eddie Grant, Committee Member
    Machine tool chatter imposes limitations on the productivity and quality of modern high speed machining (HSM) operations. It has been shown that chatter prediction and avoidance strategies can lead to increased machining productivity if certain modal characteristics of the machine are known. The objectives of this research are to design and demonstrate an electromechanical actuator (EMA) to easily and accurately identify these characteristics. Design specifications for this actuator reflect a wide range of machine tools and operating conditions. A simulation-based design strategy is employed, based on traditional electromechanical analysis, finite element analysis (FEA), and computer simulations to ensure performance meets the design specifications. A prototype EMA system is built to validate the analytical results and demonstrate its capabilities as part of an automated chatter prediction and avoidance system. The EMA is shown to generate the required modal characteristics, namely frequency response functions (FRFs) and stability lobe diagrams (SLDs) quickly, accurately, and with fewer technical skill requirements than other vibration testing methods. Experimental machining tests demonstrate that the EMA can be an effective component of an integrated chatter prediction and avoidance system.
  • No Thumbnail Available
    Finite Element Modeling of the Left Atrium to Facilitate the Design of an Endoscopic Atrial Retractor
    (2006-04-17) Jernigan, Shaphan Rees; Dr. Denis Cormier, Committee Member; Dr. Jeffrey Eischen, Committee Member; Dr. Gregory Buckner, Committee Chair
    With the worldwide prevalence of cardiovascular diseases (CVDs), much attention has been focused on simulating the characteristics of the human heart to better understand and treat cardiac disorders. The purpose of this study is to build a finite element model of the left atrium that incorporates detailed anatomical features and realistic material characteristics to investigate the interaction of heart tissue and surgical instruments. This model is used to facilitate the design of an endoscopically deployable atrial retractor for use in minimally invasive, robotically assisted (MIRA) mitral valve repair. The left atrial geometry is imported directly from MRI data of an explanted porcine heart, and material properties are derived from experimental testing of cardiac tissues. Model accuracy is verified by comparing simulated cardiac wall deflections to those measured by MRI. Finite element analysis is shown to be an effective tool for analyzing instrument/tissue interactions and for designing surgical instruments.
  • No Thumbnail Available
    Intelligent Event Detection in Aircraft Engines
    (2008-05-19) Noel, Nana K.; Dr. Gregory Buckner, Committee Chair; Dr. M.K. Ramasubramanian, Committee Member; Dr. Paul Ro, Committee Member