109 research outputs found
Assisted Magnetic Soft Continuum Robot Navigation via Rotating Magnetic Fields
Innovative robotic catheters that are soft, flexible, and controlled by magnets have the potential to revolutionize minimally invasive surgical procedures in critical areas such as the lungs, brain and pancreas, which currently pose significant safe access challenges using existing technology. These shape forming millimetre-scale magnetic soft continuum robots (MSCRs) can be designed to be highly dexterous in order to access regions of the anatomy otherwise deemed inaccessible. However, due to their soft and slender nature, MSCRs are prone to buckling under compressive loads during insertion. In this study we demonstrate buckling free insertion of high aspect ratio (80 mm long by 2 mm diameter) MSCRs into narrow, tortuous lumens enabled by coupling a specific lengthwise magnetic profile with exposure to a rotating magnetic field (RMF). We present design, finite element modelling (FEM) of the motion, fabrication and actuation of three different MSCRs. These robots are cast from NdFeB doped silicone polymer to obtain 2 mm and 3 mm diameter catheters. These are magnetized in a predefined profile such that when the catheters are placed in an RMF, a serpentine motion is generated. Experiments were conducted to quantify the behaviour of these soft catheters navigating through a soft phantom that mimicked narrow tortuous lumens such as the pancreas and bile ducts. Oscillating actuation increased the inserted depth reached by the MSCR in a tortuous channel and even enabled squeezing through a 1 mm diameter opening via shape morphing. The experiments showed that an RMF reduced the required insertion forces by almost 45% and increased the distance inserted in a fixed time frame by 3 times
Characterisation and State Estimation of Magnetic Soft Continuum Robots
Minimally invasive surgery has become more popular as it leads to less bleeding, scarring, pain, and shorter recovery time. However, this has come with counter-intuitive devices and steep surgeon learning curves. Magnetically actuated Soft Continuum Robots (SCR) have the potential to replace these devices, providing high dexterity together with the ability to conform to complex environments and safe human interactions without the cognitive burden for the clinician. Despite considerable progress in the past decade in their development, several challenges still plague SCR hindering their full realisation. This thesis aims at improving magnetically actuated SCR by addressing some of these challenges, such as material characterisation and modelling, and sensing feedback and localisation.
Material characterisation for SCR is essential for understanding their behaviour and designing effective modelling and simulation strategies. In this work, the material properties of commonly employed materials in magnetically actuated SCR, such as elastic modulus, hyper-elastic model parameters, and magnetic moment were determined. Additionally, the effect these parameters have on modelling and simulating these devices was investigated.
Due to the nature of magnetic actuation, localisation is of utmost importance to ensure accurate control and delivery of functionality. As such, two localisation strategies for magnetically actuated SCR were developed, one capable of estimating the full 6 degrees of freedom (DOFs) pose without any prior pose information, and another capable of accurately tracking the full 6-DOFs in real-time with positional errors lower than 4~mm. These will contribute to the development of autonomous navigation and closed-loop control of magnetically actuated SCR
Development of a Novel Ball-and-Socket Flexible Manipulator for Minimally Invasive Flexible Surgery
This work proposes a novel flexible manipulator consisting of a series of 2-DOF vertebrae based on a ball-andsocket joint that is connected by a ball-shaped surface and a cupshaped socket and constrained by pins for circumferential rotation. This manipulator can demonstrate outstanding torsional stiffness since the circumferential rotation between the vertebrae is constrained by four ball pins. The point contact between ball pins and guideways effectively reduces the friction between the vertebrae, thus allowing the designed manipulator to yield a smooth bending shape with constant curvature. This manipulator features high axial and torsional stiffness, excellent bending performance, sufficient loading capacity, and convenient integration with surgical instruments. Moreover, the excellent torsional stiffness enables this manipulator to efficiently transfer torque and be applied in in-situ torsional motion, effectively addressing the typical issue of limited dexterity for torsional motion. The kinematic modeling of the proposed manipulator under in-situ torsional motion has been derived, and its workspace has been analyzed. A robotic system has been assembled, and experiments have verified the proposed design and modeling validity. The results show that the maximum position errors in bending motion are 2.39% (horizontal direction) and 1.98% (vertical direction), and its torsional stiffness is 21.13N∙mm/deg, which is 46 times higher than that of a typical spherical flexible manipulator (SFM). Such merits support this manipulator excellently performing the in-situ torsional motion with a maximum average position error of 3.58%. Furthermore, a phantom test of the larynx has been performed to verify the potential of clinical feasibility
Surgical Subtask Automation for Intraluminal Procedures using Deep Reinforcement Learning
Intraluminal procedures have opened up a new sub-field of minimally invasive surgery that use flexible instruments to navigate through complex luminal structures of the body, resulting in reduced invasiveness and improved patient benefits. One of the major challenges in this field is the accurate and precise control of the instrument inside the human body. Robotics has emerged as a promising solution to this problem. However, to achieve successful robotic intraluminal interventions, the control of the instrument needs to be automated to a large extent. The thesis first examines the state-of-the-art in intraluminal surgical robotics and identifies the key challenges in this field, which include the need for safe and effective tool manipulation, and the ability to adapt to unexpected changes in the luminal environment. To address these challenges, the thesis proposes several levels of autonomy that enable the robotic system to perform individual subtasks autonomously, while still allowing the surgeon to retain overall control of the procedure. The approach facilitates the development of specialized algorithms such as Deep Reinforcement Learning (DRL) for subtasks like navigation and tissue manipulation to produce robust surgical gestures. Additionally, the thesis proposes a safety framework that provides formal guarantees to prevent risky actions. The presented approaches are evaluated through a series of experiments using simulation and robotic platforms. The experiments demonstrate that subtask automation can improve the accuracy and efficiency of tool positioning and tissue manipulation, while also reducing the cognitive load on the surgeon. The results of this research have the potential to improve the reliability and safety of intraluminal surgical interventions, ultimately leading to better outcomes for patients and surgeons
Separable Tendon-Driven Robotic Manipulator with a Long, Flexible, Passive Proximal Section
This work tackles practical issues which arise when using a tendon-driven
robotic manipulator (TDRM) with a long, flexible, passive proximal section in
medical applications. Tendon-driven devices are preferred in medicine for their
improved outcomes via minimally invasive procedures, but TDRMs come with unique
challenges such as sterilization and reuse, simultaneous control of tendons,
hysteresis in the tendon-sheath mechanism, and unmodeled effects of the
proximal section shape. A separable TDRM which overcomes difficulties in
actuation and sterilization is introduced, in which the body containing the
electronics is reusable and the remainder is disposable. An open-loop redundant
controller which resolves the redundancy in the kinematics is developed. Simple
linear hysteresis compensation and re-tension compensation based on the
physical properties of the device are proposed. The controller and compensation
methods are evaluated on a testbed for a straight proximal section, a curved
proximal section at various static angles, and a proximal section which
dynamically changes angles; and overall, distal tip error was reduced
Design, Actuation, and Functionalization of Untethered Soft Magnetic Robots with Life-Like Motions: A Review
Soft robots have demonstrated superior flexibility and functionality than
conventional rigid robots. These versatile devices can respond to a wide range
of external stimuli (including light, magnetic field, heat, electric field,
etc.), and can perform sophisticated tasks. Notably, soft magnetic robots
exhibit unparalleled advantages among numerous soft robots (such as untethered
control, rapid response, and high safety), and have made remarkable progress in
small-scale manipulation tasks and biomedical applications. Despite the
promising potential, soft magnetic robots are still in their infancy and
require significant advancements in terms of fabrication, design principles,
and functional development to be viable for real-world applications. Recent
progress shows that bionics can serve as an effective tool for developing soft
robots. In light of this, the review is presented with two main goals: (i)
exploring how innovative bioinspired strategies can revolutionize the design
and actuation of soft magnetic robots to realize various life-like motions;
(ii) examining how these bionic systems could benefit practical applications in
small-scale solid/liquid manipulation and therapeutic/diagnostic-related
biomedical fields
A Novel Continuum Overtube with Improved Triangulation for Flexible Robotic Endoscopy
This paper presents a novel continuum overtube that consists of a notched tendon-driven 2-DOF continuum joint and a distal deployable structure driven by a flexible screw rod. A smooth bending shape with constant curvature is achieved by adopting an overlapped area between notches to generate uniform stress distribution. The distal deployable structure provides an extensive triangulation for bimanual operations. The presented design achieves high flexibility, sufficient loading and anti-twisting capacity, and an improved layout of functional channels for flexible robotic endoscopy. Design optimization is performed to optimize structural parameters for performance investigation and improvement. The proposed continuum joint achieves an average distal positioning error of 1.48% and 1.20% within -115∘, 115∘ in the two bending planes with minor hysteresis errors of less than 1.5%, indicating the outstanding constant bending curvature characteristics for kinematic modeling and control. The loading capacity achieves 4.27N and provides significant advantages in terms of sufficient rigidity over the commercial endoscope. The designed deployable structure has significantly improved operational triangulation, which can effectively support bimanual operations with two instruments for complex operations. Meanwhile, the torsional stiffness of the designed continuum joint reaches a considerable value of 8.73mNm/∘ and provides stable support for instruments during operations. Ex-vivo experiments of gastric tissue biopsy have been performed to verify the feasibility of the presented design in a practical scenario
経尿道的結石破砕術における精密レーザー照射のための形状記憶合金を用いた多方向屈曲デバイス
Tohoku University芳賀洋一課
Investigating Ultrasound-Guided Autonomous Assistance during Robotic Minimally Invasive Surgery
Despite it being over twenty years since the first introduction of robotic surgical systems in common surgical practice, they are still far from widespread across all healthcare systems, surgical disciplines and procedures. At the same time, the systems that are used act as mere tele-manipulators with motion scaling and have yet to make use of the immense potential of their sensory data in providing autonomous assistance during surgery or perform tasks themselves in a semi-autonomous fashion. Equivalently, the potential of using intracorporeal imaging, particularly Ultrasound (US) during surgery for improved tumour localisation remains largely unused. Aside from the cost factors, this also has to do with the necessity of adequate training for scan interpretation and the difficulty of handling an US probe near the surgical sight. Additionally, the potential for automation that is being explored in extracorporeal US using serial manipulators does not yet translate into ultrasound-enabled autonomous assistance in a surgical robotic setting.
Motivated by this research gap, this work explores means to enable autonomous intracorporeal ultrasound in a surgical robotic setting. Based around the the da Vinci Research Kit (dVRK), it first develops a surgical robotics platform that allows for precise evaluation of the robot’s performance using Infrared (IR) tracking technology. Based on this initial work, it then explores the possibility to provide autonomous ultrasound guidance during surgery. Therefore, it develops and assesses means to improve kinematic accuracy despite manipulator backlash as well as enabling adequate probe position with respect to the tissue surface and anatomy. Founded on the acquired anatomical information, this thesis explores the integration of a second robotic arm and its usage for autonomous assistance. Starting with an autonomously acquired tumor scan, the setup is extended and methods devised to enable the autonomous marking of margined tumor boundaries on the tissue surface both in a phantom as well as in an ex-vivo experiment on porcine liver. Moving towards increased autonomy, a novel minimally invasive High Intensity Focused Ultrasound (HIFUS) transducer is integrated into the robotic setup including a sensorised, water-filled membrane for sensing interaction forces with the tissue surface. For this purpose an extensive material characterisation is caried out, exploring different surface material pairings. Finally, the proposed system, including trajectory planning and a hybrid-force position control scheme are evaluated in a benchtop ultrasound phantom trial
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