About

Gregory Buckner is a professor in the Department of Mechanical and Aerospace Engineering at NC State University. His research interests include modeling, analysis, and control of dynamic systems, electromechanical systems, manufacturing automation, intelligent control, and mechatronics. He is engaged in developing technologies that address human health needs, balancing mechanical and electrical systems design, with a focus on hands-on research, technology transfer, and commercialization. Dr. Buckner teaches courses such as Design of Electromechanical Systems, Engineering Dynamics, and Principles of Automatic Control, integrating fundamental theory with computational tools and industry-sponsored projects. His research and teaching emphasize the power of control systems, often illustrated through videos and practical applications, and his students are characterized as independent, motivated, and creative.

Research topics

• Computer Science
• Engineering
• Structural engineering
• Physics
• Radiology
• Aeronautics
• Aerospace engineering
• Acoustics
• Surgery
• Medicine
• Automotive engineering
• Biomedical engineering
• Materials science
• Nuclear medicine
• Mechanical engineering

Selected publications

• Portable and Versatile Catheter Robot for Image-Guided Cardiovascular Interventions

  IEEE/ASME Transactions on Mechatronics · 2025-04-30 · 2 citations

  article

  Cardiovascular disease remains the primary cause of death worldwide, necessitating the development of advanced endovascular instruments and procedures. These interventional procedures typically involve the use of guide catheters and guidewires, which are navigated through the vasculature under X-ray guidance. However, these procedures expose clinicians to prolonged radiation, posing potential health risks. Recent advances in endovascular catheter robots can mitigate the aforementioned risks by allowing teleoperation, but procedural efficacy has been hindered by their bulky designs that require designated facilities. In addition, these robots have limited compatibility with a wide range of instrument types and diameters, restricting their applicability to specific clinical interventions. To address these unmet needs, we have designed, fabricated, and experimentally validated a portable and versatile 4 degree-of-freedom catheter robot that can manipulate commercially available cardiovascular instruments with diameters ranging from 1 to 9 F. Furthermore, we analytically modeled the drive mechanism of the catheter robot and evaluated its tracking and insertion force and torque performance through experiments. Our portable robot (250 mm × 350 mm × 250 mm) is approximately 90% smaller than most state-of-the-art systems, e.g., Siemens Corindus system (1780 mm × 690 mm × 1170 mm), thanks to our highly integrated direct drive motors, mechatronics design, and modular instrument routing. Experimental evaluations confirm that the robot can actuate guidewires and guide catheters at clinically relevant force and torque amplitudes, speeds, and bandwidths without risking damage to delicate vascular tissues. The clinical potential of our catheter robot is demonstrated by performing a simulated percutaneous coronary intervention using a 3-D-printed model of the human heart. The portability and versatility of this catheter robot make it applicable to a wide range of cardiovascular procedures to potentially facilitate effective treatments.

  PublisherDOI

• Image-guided embolization using Ta@Ca-Alg microspheres with optimized mechanical performance

  Biomaterials Science · 2025-01-01 · 4 citations

  article

  hemocompatibility, sterility, and cytotoxicity studies confirmed excellent biocompatibility. These findings suggest that Ta@Ca-Alg MSs are a promising radiopaque embolic agent with optimized radiopacity, density, and mechanical properties, offering excellent potential for TAE procedures.

  PublisherDOI

• Design Optimization and Tradeoff Analysis of an Actuated Continuum Probe for Pulmonary Nodule Localization and Resection

  UNC Libraries · 2024-05-04

  articleOpen access1st authorCorresponding

  Pulmonary nodules are abnormal tissue masses in the lungs, typically less than 3.0 cm in diameter, commonly detected during imaging of the chest and lungs. While most pulmonary nodules are not cancerous, surgical resection may be required if growth is detected between scans. This resection is typically performed without the benefit of intraoperative imaging, making it difficult for surgeons to confidently provide appropriate margins. To enhance the efficacy of wedge resection, researchers have developed a modified ultrasound imaging approach that utilizes both multiple scattering (MS) and single scattering (SS) to enhance the accuracy of margin delineation. Clinical deployment of this novel ultrasound technology requires a highly maneuverable ultrasound probe, ideally one that could be deployed and actuated with minimal invasiveness. This study details the design optimization and tradeoff analysis of an actuated continuum probe for pulmonary nodule localization and resection. This device, deployed through intercostal ports, would enable the intraoperative imaging and precise mapping of nodules for improved margin delineation and patient outcomes. To achieve this objective, multiple objective genetic algorithms (MOGAs) and a design of experiments (DOE) study are used to explore the design space and quantify key dimensional relationships and their effects on probe actuation.

  PublisherDOI

• Soft pneumatic actuators for pushing fingers into extension

  Journal of NeuroEngineering and Rehabilitation · 2024-08-30 · 8 citations

  articleOpen access

  BACKGROUND: Compliant pneumatic actuators possess many characteristics that are desirable for wearable robotic systems. These actuators can be lightweight, integrated with clothing, and accommodate uncontrolled degrees of freedom. These attributes are especially desirable for hand exoskeletons, where the soft actuator can conform to the highly variable digit shape. In particular, locating the pneumatic actuator on the palmar side of the digit may have benefits for assisting finger extension and resisting unwanted finger flexion, but this configuration requires suppleness to allow digit flexion while retaining sufficient stiffness to assist extension. METHODS: To meet these needs, we designed an actuator consisting of a hollow chamber long enough to span the joints of each digit while sufficiently narrow not to inhibit finger adduction. We explored the geometrical design parameter space for this chamber in terms of shape, dimensions, and wall thickness. After fabricating an elastomer-based prototype for each actuator design, we measured active extension force and passive resistance to bending for each chamber using a mechanical jig. We also created a finite element model for each chamber to enable estimation of the impact of chamber deformation, caused by joint rotation, on airflow through the chamber. Finally, we created a prototype hand exoskeleton with the chamber parameters yielding the best outcomes. RESULTS: A rectangular cross-sectional area was preferable to a semi-obround shape for the chamber; wall thickness also impacted performance. Extension joint torque reached 0.33 N-m at a low chamber pressure of 48.3 kPa. The finite element model confirmed that airflow for the rectangular chamber remained high despite deformation resulting from joint rotation. The hand exoskeleton created with the rectangular chambers enabled rapid movement, with a cycle time of 1.1 s for voluntary flexion followed by actuated extension. CONCLUSIONS: The developed soft actuators are feasible for use in promoting finger extension from the palmar side of the hand. This placement utilizes pushing rather than pulling for digit extension, which is more comfortable and safer. The small chamber volumes allow rapid filling and evacuation to facilitate relatively high frequency finger movements.

  PublisherOA PDFDOI

• Design Optimization and Tradeoff Analysis of an Actuated Continuum Probe for Pulmonary Nodule Localization and Resection

  Bioengineering · 2024-04-24 · 1 citations

  articleOpen accessSenior authorCorresponding

  Pulmonary nodules are abnormal tissue masses in the lungs, typically less than 3.0 cm in diameter, commonly detected during imaging of the chest and lungs. While most pulmonary nodules are not cancerous, surgical resection may be required if growth is detected between scans. This resection is typically performed without the benefit of intraoperative imaging, making it difficult for surgeons to confidently provide appropriate margins. To enhance the efficacy of wedge resection, researchers have developed a modified ultrasound imaging approach that utilizes both multiple scattering (MS) and single scattering (SS) to enhance the accuracy of margin delineation. Clinical deployment of this novel ultrasound technology requires a highly maneuverable ultrasound probe, ideally one that could be deployed and actuated with minimal invasiveness. This study details the design optimization and tradeoff analysis of an actuated continuum probe for pulmonary nodule localization and resection. This device, deployed through intercostal ports, would enable the intraoperative imaging and precise mapping of nodules for improved margin delineation and patient outcomes. To achieve this objective, multiple objective genetic algorithms (MOGAs) and a design of experiments (DOE) study are used to explore the design space and quantify key dimensional relationships and their effects on probe actuation.

  PublisherOA PDFDOI

• Comparing Deposition Characteristics of Various Embolic Particles Using an In Vitro Prostate Microvasculature Model

  Journal of Vascular and Interventional Radiology · 2024-07-01 · 3 citations

  articleOpen accessSenior author

  PURPOSE: To compare spatial distributions of radiopaque glass (RG) microspheres, tris-acryl gelatin (TAG) microspheres, and polyvinyl alcohol (PVA) nonspherical foam particles within a planar in vitro microvascular model of the hyperplastic hemiprostate. MATERIALS AND METHODS: A microvascular model simulating hyperplastic hemiprostate was perfused with a water-glycerin mixture. A microcatheter was positioned distal to the model's prostatic artery origin, and embolic particles (RG, 50 μm, 100 μm, and 150 μm; TAG, 100-300 μm and 300-500 μm; and PVA, 90-180 μm and 180-300 μm) were administered using a syringe pump. Microscopic imaging and subsequent semantic segmentation were performed to quantify particle distributions within the models. Distal penetrations were quantified statistically via modal analysis of the particle distributions. RESULTS: Maximum distal penetration was observed for RG microspheres of 50 μm, followed by RG microspheres of 100 μm and then TAG microspheres of 100-300 μm and RG microspheres of 150 μm. TAG microspheres of 300-500 μm, PVA particles of 90-180 μm, and PVA particles of 180-300 μm exhibited the lowest distal penetrations. The distal penetration metrics between groups were significantly different (P < .05) except between TAG microspheres of 100-300 μm and RG microspheres of 150 μm and between PVA particles of 90-180 and 180-300 μm. CONCLUSIONS: Comparing the spatial distributions of embolic particles in an in vitro microvascular model simulating the hyperplastic hemiprostate revealed that noncompressible particles and those with narrower size calibrations and smaller relative diameters exhibited higher degrees of distal packing. The embolization front was less distinct for particles with wider size calibrations, which resulted in smaller, more distal emboli along with larger, more proximal emboli. Both PVA particles and TAG microspheres of 300-500 μm exhibited relatively low overall distal penetration.

  PublisherOA PDFDOI

• Saturation and duty cycle tolerant self-sensing for active magnetic dampers

  Mechanical Systems and Signal Processing · 2023-07-18 · 2 citations

  articleSenior authorCorresponding
  PublisherDOI

• Sensor Fusion with Deep Learning for Autonomous Classification and Management of Aquatic Invasive Plant Species

  Robotics · 2022-06-28 · 12 citations

  articleOpen accessSenior authorCorresponding

  Recent advances in deep learning, including the development of AlexNet, Residual Network (ResNet), and transfer learning, offer unprecedented classification accuracy in the field of machine vision. A developing application of deep learning is the automated identification and management of aquatic invasive plants. Classification of submersed aquatic vegetation (SAV) presents a unique challenge, namely, the lack of a single source of sensor data that can produce robust, interpretable images across a variable range of depth, turbidity, and lighting conditions. This paper focuses on the development of a multi-sensor (RGB and hydroacoustic) classification system for SAV that is robust to environmental conditions and combines the strengths of each sensing modality. The detection of invasive Hydrilla verticillata (hydrilla) is the primary goal. Over 5000 aerial RGB and hydroacoustic images were generated from two Florida lakes via an unmanned aerial vehicle and boat-mounted sonar unit, and tagged for neural network training and evaluation. Classes included “HYDR”, containing hydrilla; “NONE”, lacking SAV, and “OTHER”, containing SAV other than hydrilla. Using a transfer learning approach, deep neural networks with the ResNet architecture were individually trained on the RGB and hydroacoustic datasets. Multiple data fusion methodologies were evaluated to ensemble the outputs of these neural networks for optimal classification accuracy. A method incorporating logic and a Monte Carlo dropout approach yielded the best overall classification accuracy (84%), with recall and precision of 84.5% and 77.5%, respectively, for the hydrilla class. The training and ensembling approaches were repeated for a DenseNet model with identical training and testing datasets. The overall classification accuracy was similar between the ResNet and DenseNet models when averaged across all approaches (1.9% higher accuracy for the ResNet vs. the DenseNet).

  PublisherOA PDFDOI

• A Permanent Magnet Synchronous Spherical Motor for High-Mobility Servo-Actuation

  Machines · 2022-07-26 · 3 citations

  articleOpen accessSenior authorCorresponding

  The development of direct-drive spherical motors offers a potential solution to the limitations of conventional multiple degree-of-freedom (DOF) actuators, which typically utilize single-DOF joints (rotational and/or prismatic), arranged in series or parallel and powered by multiple single-DOF actuators. These configurations can be accompanied by kinematic singularities, backlash, limited power density and efficiency, and computationally expensive inverse kinematics. This paper details the design, fabrication and experimental testing of permanent magnet synchronous spherical motors (PMSSM) for multi-DOF servo-actuation. Its stator-pole arrangement is based on a Goldberg polyhedron, with each pole comprised of hexagonal or pentagonal inner and outer plates. The stator geometry and winding configurations are optimized using electromagnetic finite element analysis. A custom-made controller board includes a microcontroller, servo drivers, a wireless serial interface, and a USB PC interface. Angular orientation is sensed using an inertial measurement unit in wireless communication with the microcontroller. A PID controller is implemented and demonstrated for time-varying reference trajectories.

  PublisherOA PDFDOI

• Comparison of Bolus Versus Dual-Syringe Administration Systems on Glass Yttrium-90 Microsphere Deposition in an In Vitro Microvascular Hepatic Tumor Model

  Journal of Vascular and Interventional Radiology · 2022 · 16 citations

  Senior authorCorresponding
  • Medicine
  • Nuclear medicine
  • Biomedical engineering

  PURPOSE: To utilize an in vitro microvascular hepatic tumor model to compare the deposition characteristics of glass yttrium-90 microspheres using the dual-syringe (DS) and traditional bolus administration methods. MATERIALS AND METHODS: liver with a total hepatic flow of 160 mL/min and was dynamically perfused. A microcatheter was placed in a 2-mm artery feeding the tumor model and 2 additional nontarget arteries. Glass microspheres with a diameter of 20-30 μm were administered using 2 methods: (a) DS delivery at a concentration of 50 mg/mL in either a single, continuous 2-mL infusion or two 1-mL infusions and (b) bolus delivery (BD) of 100 mg of microspheres in a single 3-mL infusion. RESULTS: for the BD case). This resulted in significantly higher deposition uniformity within the tumor model (90% for the DS delivery case vs 80% for the BD case, α = 0.05). CONCLUSIONS: The use of this new in vitro microvascular hepatic tumor model demonstrated that the administration method can affect the deposition of yttrium-90 microspheres within a tumor, with greater distal deposition and more uniform tumor coverage when the microspheres are delivered at consistent concentrations using a DS delivery device. The BD administration method was associated with less favorable deposition characteristics of the microspheres.

  PublisherDOI

Recent grants

• NIH Grant R01HL075489

  NIH · $1.3M · 2009

Frequent coauthors

• W.M. Insko

  Merrill (United States)

  35 shared

• J. Holmes Martin

  McGill University

  21 shared

• Shaphan R. Jernigan

  North Carolina State University

  19 shared

• A. M. Peter

  University of Uyo

  17 shared

• Amanda Harms

  Arkansas Agricultural Experiment Station

  15 shared

• Amanda H. Henry

  Emory University

  13 shared

• John H. Crews

  North Carolina State University

  12 shared

• Gil Bolotin

  Rambam Health Care Campus

  11 shared

Labs

• Gregory Buckner LabPI

Education

• PhD, Mechanical Engineering

  The University of Texas at Austin

  1996

• MS, Mechanical Engineering

  Virginia Tech

  1987

• BS, Mechanical Engineering

  Louisiana State University

  1986