Robotic Catheters for Beating Heart Surgery

Compliant and flexible cardiac catheters provide direct access to the inside of the heart via the vascular system without requiring clinicians to stop the heart or open the chest. However, the fast motion of the intracardiac structures makes it difficult to modify and repair the cardiac tissue in a controlled and safe manner. In addition, rigid robotic tools for beating heart surgery require the chest to be opened and the heart exposed, making the procedures highly invasive. The novel robotic catheter system presented here enables minimally invasive repair on the fast-moving structures inside the heart, like the mitral valve annulus, without the invasiveness or risks of stopped heart procedures. In this thesis, I investigate the development of 3D ultrasound-guided robotic catheters for beating heart surgery. First, the force and stiffness values of tissue structures in the left atrium are measured to develop design requirements for the system. This research shows that a catheter will experience contractile forces of 0.5 – 1.0 N and a mean tissue structure stiffness of approximately 0.1 N/mm while interacting with the mitral valve annulus. Next, this thesis presents the catheter system design, including force sensing, tissue resection, and ablation end effectors. In order to operate inside the beating heart, position and force control systems were developed to compensate for the catheter performance limitations of friction and deadzone backlash and evaluated with ex vivo and in vivo experiments. Through the addition of friction and deadzone compensation terms, the system is able to achieve position tracking with less than 1 mm RMS error and force tracking with 0.08 N RMS error under ultrasound image guidance. Finally, this thesis examines how the robotic catheter system enhances beating heart clinical procedures. Specifically, this system improves resection quality while reducing the forces experienced by the tissue by almost 80% and improves ablation performance by reducing contact resistance variations by 97% while applying a constant force on the moving tissue.Engineering and Applied Science

Proceedings of the NASA Conference on Space Telerobotics, volume 3

The theme of the Conference was man-machine collaboration in space. The Conference provided a forum for researchers and engineers to exchange ideas on the research and development required for application of telerobotics technology to the space systems planned for the 1990s and beyond. The Conference: (1) provided a view of current NASA telerobotic research and development; (2) stimulated technical exchange on man-machine systems, manipulator control, machine sensing, machine intelligence, concurrent computation, and system architectures; and (3) identified important unsolved problems of current interest which can be dealt with by future research

Development of Transformations between Designed and Built Structural Systems and Pipe Assemblies

Fabrication of steel assemblies is a challenging process using existing machines to perform the tasks involved such as cutting, drilling, and punching. Due to inaccuracies in the fabrication processes, imperfections will inevitably happen. In addition to the fabrication inaccuracies, errors may occur during transportation or due to the temperature changes on construction sites. These challenges become more important in the offsite construction as it requires sequenced fabrication, transportation and installation. Current approaches for quality inspection, in general, and discrepancy analysis, in particular, lack a sufficient level of automation and are prone to error due to the intensive manual work involved. Hence, a proactive framework is substantially required to systematically monitor the fabrication process and control the accuracy of assemblies in order to expedite the erection and installation processes. Additionally, finding defective assemblies is traditionally done through fitting trials on construction sites, which has always been a key challenge as it is associated with rework. Furthermore, realigning the defective assemblies is currently performed based on the workers’ experience and lacks automated planning. Therefore, detecting the defective parts in a timely manner and in a systematic way can expedite the erection process and avoids significant delays in construction projects and huge costs as a consequence. This research aims to improve the fabrication and installation processes by detecting the incurred inaccuracies automatically and plan for realignment of the defective components systematically. In summary, the required framework to achieve these objectives includes four primary steps: (1) Preprocessing and basic compliance checking, (2) Spatial discrepancy detection and characterization, (3) Calculation of the required alignments and adjustments, and (4) Generalization of the realignment planning and actuation strategy frameworks for parallel systems. The automated compliance checking and discrepancy analysis is performed employing advanced 3D imaging technologies which have recently opened up a wide range of solutions to acquire as-built status. Characterization of the detected discrepancies is performed by employing robotics forward kinematics concepts and combining with 3D imaging techniques. The required alignment is calculated accordingly using the robotic analogy and inverse kinematic concept. Although the proposed approach can be applied in any types of construction assembly, this thesis mainly focuses on industrial facilities such as steel pipe modules and pipe spools, in particular. Contributions of developing the described framework include: (1) Developing a proactive strategy for rework avoidance, (2) Algorithmic and programmable framework, (3) Efficiency and robustness of the functions and metrics developed, and (4) Time effectiveness of the framework

EG-ICE 2021 Workshop on Intelligent Computing in Engineering

The 28th EG-ICE International Workshop 2021 brings together international experts working at the interface between advanced computing and modern engineering challenges. Many engineering tasks require open-world resolutions to support multi-actor collaboration, coping with approximate models, providing effective engineer-computer interaction, search in multi-dimensional solution spaces, accommodating uncertainty, including specialist domain knowledge, performing sensor-data interpretation and dealing with incomplete knowledge. While results from computer science provide much initial support for resolution, adaptation is unavoidable and most importantly, feedback from addressing engineering challenges drives fundamental computer-science research. Competence and knowledge transfer goes both ways

EG-ICE 2021 Workshop on Intelligent Computing in Engineering

The 28th EG-ICE International Workshop 2021 brings together international experts working at the interface between advanced computing and modern engineering challenges. Many engineering tasks require open-world resolutions to support multi-actor collaboration, coping with approximate models, providing effective engineer-computer interaction, search in multi-dimensional solution spaces, accommodating uncertainty, including specialist domain knowledge, performing sensor-data interpretation and dealing with incomplete knowledge. While results from computer science provide much initial support for resolution, adaptation is unavoidable and most importantly, feedback from addressing engineering challenges drives fundamental computer-science research. Competence and knowledge transfer goes both ways

Kinky structures

Rotational springs are not widely used in structural engineering other than within undergraduate texts to aid with the understanding of strut buckling or other similar theoretical exercises.The inclusion of rotational springs can significantly alter the behaviour of a structure, bringing several potential benefits if inserted strategically. For instance, allowing a frame to be delivered to site as a single deployable piece, where the rotational springs introduce an element of temporary stability during erection; by ensuring hinges form in specific locations during extreme loading events, creating reliable load paths whilst retaining structural integrity; or by limiting the axial force in specific elements, forcing an element to buckle at specific loads. Currently, there is a significant gap in the existing research with regards the analysis and behaviour of structures that have springs distributed through the frame. The inclusion of springs within structural frames will typically encourage gross, yet controlled and predictable displacements that are challenging to analyse. Equally, deployable structures require an element of instability to deploy. With most research focusing on the packed and deployed states of these structures, there is still considerable research to be done on the structural performance of the intermediate stages of deployment. Several forms of deployable structure, such as cable-chain arches for example, are vulnerable and unstable during their intermediate deployment phase and it is proposed that the integration of rotational springs in these types of structure could help control the deployment and maintain stability from a packed shape into the final in-service form as well as preventing phenomenon such as snap-through buckling under large loads. Original work within this thesis creates several repeatable and reliable methods for undertaking buckling analysis of sprung chains to determine an initial balanced equilibrium form to which in-service loadings can then be applied as well as determining the post-buckled behaviour for sprung structures. The application of numerical analysis methods is demonstrated as giving reliable results for single and multiple degrees of freedom systems, but due to the potential for incompatibilities between the stiffnesses of the rotational springs and beam elements there are issues associated with ill-conditioning and methods have been established to identify and mitigate these effects.Alternative structural forms, beyond simple arches, have also been developed through seeking inspiration from the higher buckling modes. Shapes resembling these higher modes have been generated through the careful manipulation of spring stiffnesses (mobilising linear and non-linear springs) combined with the introduction of initial geometrical imperfections allowing the structures to adopt alternative stable states in direct response to specific loading conditions.The analysis methods contained within this thesis are currently more advanced than the manufacturing techniques required to realise these designs in the real world. Although, flexible springs are already being cut into stiff plywood panels using living hinges and multi-material 3D printing is commonplace within the maker community, but these techniques have not yet progressed through to the scale and consistency needed to fabricate a large structural element.However, as these manufacturing techniques mature, the work presented within this thesis will provide a solid base from which the effective analysis of multi-stiffness structures will be possible