Smart actuation and sensing for meso-scale surgical robotic systems

This dissertation presents the development of meso-scale surgical robotics based on smart actuation and sensing for minimally invasive surgery (MIS). By replacing conventional straight tools by steerable surgical robots, surgical outcomes can potentially be improved due to more precise, stable, and flexible manipulation. Since bending and torsion are the two fundamental motion forms required by surgical tools to complete general surgical procedures, compact torsion and bending modules, both integrated with intrinsic sensors for motion feedback, have been developed based on shape memory alloy (SMA). The developed actuation and sensing techniques have been applied on a robot for neurosurgical intracerebral hemorrhage evacuation (NICHE) and a steerable catheter for atrial fibrillation (AFib) treatment. The NICHE robot consists of a straight stem, an SMA torsion module, and an SMA bending module as a distal bending tip. By synchronizing the motion of the stem, the bending module, and the torsion module, the robot is capable of tip articulation within the brain to remove hemorrhage effectively through suction and electrocauterization. In addition, a skull-mounted robotic headframe has been developed based on a Stewart platform to manipulate the NICHE robot. The robotic catheter is developed by integrating multiple SMA bending modules with flexible braid reinforced tubing. Polymer 3D-printing is used to fabricate all the structural components due to its relatively low cost, short fabrication period, and capability of fabricating complicated structures with high accuracy. The developed surgical robotic systems have been thoroughly evaluated using phantom or cadaver models under computed tomography (CT) and/or magnetic resonance imaging (MRI) guidance. The imaging-guided experimental studies showed that the developed robotic systems consisting of smart actuation and sensing were compatible with CT and MR imaging.Ph.D

Designing a robotic port system for laparo-endoscopic single-site surgery

Current research and development in the field of surgical interventions aim to reduce the invasiveness by using few incisions or natural orifices in the body to access the surgical site. Considering surgeries in the abdominal cavity, the Laparo-Endoscopic Single-site Surgery (LESS) can be performed through a single incision in the navel, reducing blood loss, post-operative trauma, and improving the cosmetic outcome. However, LESS results in less intuitive instrument control, impaired ergonomic, loss of depth and haptic perception, and restriction of instrument positioning by a single incision. Robot-assisted surgery addresses these shortcomings, by introducing highly articulated, flexible robotic instruments, ergonomic control consoles with 3D visualization, and intuitive instrument control algorithms. The flexible robotic instruments are usually introduced into the abdomen via a rigid straight port, such that the positioning of the tools and therefore the accessibility of anatomical structures is still constrained by the incision location. To address this limitation, articulated ports for LESS are proposed by recent research works. However, they focus on only a few aspects, which are relevant to the surgery, such that a design considering all requirements for LESS has not been proposed yet. This partially originates in the lack of anatomical data of specific applications. Further, no general design guidelines exist and only a few evaluation metrics are proposed. To target these challenges, this thesis focuses on the design of an articulated robotic port for LESS partial nephrectomy. A novel approach is introduced, acquiring the available abdominal workspace, integrated into the surgical workflow. Based on several generated patient datasets and developed metrics, design parameter optimization is conducted. Analyzing the surgical procedure, a comprehensive requirement list is established and applied to design a robotic system, proposing a tendon-driven continuum robot as the articulated port structure. Especially, the aspects of stiffening and sterile design are addressed. In various experimental evaluations, the reachability, the stiffness, and the overall design are evaluated. The findings identify layer jamming as the superior stiffening method. Further, the articulated port is proven to enhance the accessibility of anatomical structures and offer a patient and incision location independent design

Modeling and Control of Steerable Ablation Catheters

Catheters are long, flexible tubes that are extensively used in vascular and cardiac interventions, e.g., cardiac ablation, coronary angiography and mitral valve annuloplasty. Catheter-based cardiac ablation is a well-accepted treatment for atrial fibrillation, a common type of cardiac arrhythmia. During this procedure, a steerable ablation catheter is guided through the vasculature to the left atrium to correct the signal pathways inside the heart and restore normal heart rhythm. The outcome of the ablation procedure depends mainly on the correct positioning of the catheter tip at the target location inside the heart and also on maintaining a consistent contact between the catheter tip and cardiac tissue. In the presence of cardiac and respiratory motions, achieving these goals during the ablation procedure is very challenging without proper 3D visualization, dexterous control of the flexible catheter and an estimate of the catheter tip/tissue contact force. This research project provides the required basis for developing a robotics-assisted catheter manipulation system with contact force control for use in cardiac ablation procedures. The behavior of the catheter is studied in free space as well in contact with the environment to develop mathematical models of the catheter tip that are well suited for developing control systems. The validity of the proposed modeling approaches and the performance of the suggested control techniques are evaluated experimentally. As the first step, the static force-deflection relationship for ablation catheters is described with a large-deflection beam model and an optimized pseudo-rigid-body 3R model. The proposed static model is then used in developing a control system for controlling the contact force when the catheter tip is interacting with a static environment. Our studies also showed that it is possible to estimate the tip/tissue contact force by analyzing the shape of the catheter without installing a force sensor on the catheter. During cardiac ablation, the catheter tip is in contact with a relatively fast moving environment (cardiac tissue). Robotic manipulation of the catheter has the potential to improve the quality of contact between the catheter tip and cardiac tissue. To this end, the frequency response of the catheter is investigated and a control technique is proposed to compensate for the cardiac motion and to maintain a constant tip/tissue contact force. Our study on developing a motion compensated robotics-assisted catheter manipulation system suggests that redesigning the actuation mechanism of current ablation catheters would provide a major improvement in using these catheters in robotics-assisted cardiac ablation procedures

Robotic manipulators for in situ inspections of jet engines

Jet engines need to be inspected periodically and, in some instances, repaired. Currently, some of these maintenance operations require the engine to be removed from the wing and dismantled, which has a significant associated cost. The capability of performing some of these inspections and repairs while the engine is on-wing could lead to important cost savings. However, existing technology for on-wing operations is limited, and does not suffice to satisfy some of the needs. In this work, the problem of performing on-wing operations such as inspection and repair is analysed, and after an extensive literature review, a novel robotic system for the on-wing insertion and deployment of probes or other tools is proposed. The system consists of a fine-positioner, which is a miniature and dexterous robotic manipulator; a gross-positioner, which is a device to insert the fine-positioner to the engine region of interest; an end-effector, such as a probe; a deployment mechanism, which is a passive device to ensure correct contact between probe and component; and a feedback system that provides information about the robot state for control. The research and development work conducted to address the main challenges to create this robotic system is presented in this thesis. The work is focussed on the fine-positioner, as it is the most relevant and complex part of the system. After a literature review of relevant work, and as part of the exploration of potential robot concepts for the system, the kinematic capabilities of concentric tube robots (CTRs) are first investigated. The complete set of stable trajectories that can be traced in follow-the-leader motion is discovered. A case study involving simulations and an experiment is then presented to showcase and verify the work. The research findings indicate that CTRs are not suitable for the fine-positioner. However, they show that CTRs with non-annular cross section can be used for the gross-positioner. In addition, the new trajectories discovered show promise in minimally invasive surgery (MIS). Soft robotic manipulators with fluidic actuation are then selected as the most suitable concept for the fine-positioner. The design of soft robotic manipulators with fluidic actuation is investigated from a general perspective. A general framework for the design of these devices is proposed, and a set of design principles are derived. These principles are first applied in a MIS case study to illustrate and verify the work. Finite element (FE) simulations are then reported to perform design optimisation, and thus complete the case study. The design study is then applied to determine the most suitable design for the fine-positioner. An additional analytical derivation is developed, followed by FE simulations, which extend those of the case study. Eventually, this work yields a final design of the fine-positioner. The final design found is different from existing ones, and is shown to provide an important performance improvement with respect to existing soft robots in terms of wrenches it can support. The control of soft and continuum robots relevant to the fine-positioner is also studied. The full kinematics of continuum robots with constant curvature bending and extending capabilities are first investigated, which correspond to a preliminary design concept conceived for the fine-positioner. Closed-form solutions are derived, closing an open problem. These kinematics, however, do not exactly match the final fine-positioner design selected. Thus, an alternative control approach based on closed-loop control laws is then adopted. For this, a mechanical model is first developed. Closed-loop control laws are then derived based on this mechanical model for planar operation of a segment of the fine-positioner. The control laws obtained represent the foundation for the subsequent development of control laws for a full fine-positioner operating in 3D. Furthermore, work on path planning for nonholonomic systems is also reported, and a new algorithm is presented, which can be applied for the insertion of the overall robotic system. Solutions to the other parts of the robotic system for on-wing operations are also reported. A gross-positioner consisting of a non-annular CTR is proposed. Solutions for a deployment mechanism are also presented. Potential feedback systems are outlined. In addition, methods for the fabrication of the systems are reported, and the electronics and systems required for the assembly of the different parts are described. Finally, the use of the robotic system to perform on-wing inspections in a representative case study is studied to determine the viability. Inspection strategies are shortlisted, and simulations and experiments are used to study them. The results, however, indicate that inspection is not viable since the signal to noise ratio is excessively low. Nonetheless, the robotic system proposed, and the research conducted, are still expected to be useful to perform a range of on-wing operations that require the insertion and deployment of a probe or other end-effector. In addition, the trajectories discovered for CTRs, the design found for the fine-positioner, and the advances on control, also have significant potential in MIS, where there is an important need for miniature robotic manipulators and similar devices.Open Acces

Teleoperation of MRI-Compatible Robots with Hybrid Actuation and Haptic Feedback

Image guided surgery (IGS), which has been developing fast recently, benefits significantly from the superior accuracy of robots and magnetic resonance imaging (MRI) which is a great soft tissue imaging modality. Teleoperation is especially desired in the MRI because of the highly constrained space inside the closed-bore MRI and the lack of haptic feedback with the fully autonomous robotic systems. It also very well maintains the human in the loop that significantly enhances safety. This dissertation describes the development of teleoperation approaches and implementation on an example system for MRI with details of different key components. The dissertation firstly describes the general teleoperation architecture with modular software and hardware components. The MRI-compatible robot controller, driving technology as well as the robot navigation and control software are introduced. As a crucial step to determine the robot location inside the MRI, two methods of registration and tracking are discussed. The first method utilizes the existing Z shaped fiducial frame design but with a newly developed multi-image registration method which has higher accuracy with a smaller fiducial frame. The second method is a new fiducial design with a cylindrical shaped frame which is especially suitable for registration and tracking for needles. Alongside, a single-image based algorithm is developed to not only reach higher accuracy but also run faster. In addition, performance enhanced fiducial frame is also studied by integrating self-resonant coils. A surgical master-slave teleoperation system for the application of percutaneous interventional procedures under continuous MRI guidance is presented. The slave robot is a piezoelectric-actuated needle insertion robot with fiber optic force sensor integrated. The master robot is a pneumatic-driven haptic device which not only controls the position of the slave robot, but also renders the force associated with needle placement interventions to the surgeon. Both of master and slave robots mechanical design, kinematics, force sensing and feedback technologies are discussed. Force and position tracking results of the master-slave robot are demonstrated to validate the tracking performance of the integrated system. MRI compatibility is evaluated extensively. Teleoperated needle steering is also demonstrated under live MR imaging. A control system of a clinical grade MRI-compatible parallel 4-DOF surgical manipulator for minimally invasive in-bore prostate percutaneous interventions through the patient’s perineum is discussed in the end. The proposed manipulator takes advantage of four sliders actuated by piezoelectric motors and incremental rotary encoders, which are compatible with the MRI environment. Two generations of optical limit switches are designed to provide better safety features for real clinical use. The performance of both generations of the limit switch is tested. MRI guided accuracy and MRI-compatibility of whole robotic system is also evaluated. Two clinical prostate biopsy cases have been conducted with this assistive robot