Evolution of Prehension Ability in an Anthropomorphic Neurorobotic Arm

In this paper we show how a simulated anthropomorphic robotic arm controlled by an artificial neural network can develop effective reaching and grasping behaviour through a trial and error process in which the free parameters encode the control rules which regulate the fine-grained interaction between the robot and the environment and variations of the free parameters are retained or discarded on the basis of their effects at the level of the global behaviour exhibited by the robot situated in the environment. The obtained results demonstrate how the proposed methodology allows the robot to produce effective behaviours thanks to its ability to exploit the morphological properties of the robot’s body (i.e. its anthropomorphic shape, the elastic properties of its muscle-like actuators, and the compliance of its actuated joints) and the properties which arise from the physical interaction between the robot and the environment mediated by appropriate control rules

Evolution of Grasping Behaviour in Anthropomorphic Robotic Arms with Embodied Neural Controllers

The works reported in this thesis focus upon synthesising neural controllers for anthropomorphic robots that are able to manipulate objects through an automatic design process based on artificial evolution. The use of Evolutionary Robotics makes it possible to reduce the characteristics and parameters specified by the designer to a minimum, and the robot’s skills evolve as it interacts with the environment. The primary objective of these experiments is to investigate whether neural controllers that are regulating the state of the motors on the basis of the current and previously experienced sensors (i.e. without relying on an inverse model) can enable the robots to solve such complex tasks. Another objective of these experiments is to investigate whether the Evolutionary Robotics approach can be successfully applied to scenarios that are significantly more complex than those to which it is typically applied (in terms of the complexity of the robot’s morphology, the size of the neural controller, and the complexity of the task). The obtained results indicate that skills such as reaching, grasping, and discriminating among objects can be accomplished without the need to learn precise inverse internal models of the arm/hand structure. This would also support the hypothesis that the human central nervous system (cns) does necessarily have internal models of the limbs (not excluding the fact that it might possess such models for other purposes), but can act by shifting the equilibrium points/cycles of the underlying musculoskeletal system. Consequently, the resulting controllers of such fundamental skills would be less complex. Thus, the learning of more complex behaviours will be easier to design because the underlying controller of the arm/hand structure is less complex. Moreover, the obtained results also show how evolved robots exploit sensory-motor coordination in order to accomplish their tasks

West Africa

This is the author accepted manuscript. The final version is available from OUP via the ISBN in this recor

Evolution of Prehension Ability in an Anthropomorphic Neurorobotic Arm

In this paper, we show how a simulated anthropomorphic robotic arm controlled by an artificial neural network can develop effective reaching and grasping behaviour through a trial and error process in which the free parameters encode the control rules which regulate the fine-grained interaction between the robot and the environment and variations of the free parameters are retained or discarded on the basis of their effects at the level of the global behaviour exhibited by the robot situated in the environment. The obtained results demonstrate how the proposed methodology allows the robot to produce effective behaviours thanks to its ability to exploit the morphological properties of the robot's body (i.e. its anthropomorphic shape, the elastic properties of its muscle-like actuators and the compliance of its actuated joints) and the properties which arise from the physical interaction between the robot and the environment mediated by appropriate control rules

DEVELOPMENT AND IMPLEMENTATION OF A HOMOGENEOUS AND A HETEROGENEOUS ANTHROPOMORPHIC END TO END QUALITY ASSURANCE AUDIT SYSTEM PHANTOM FOR MAGNETIC RESONANCE GUIDED RADIOTHERAPY MODALITIES RANGING FROM 0.35 T TO 1.50 T

Introduction: Magnetic resonance (MR) guided radiation therapy (MRgRT) is an emerging field that integrates an MR imager with either a linear accelerator or three radioactive cobalt-60 sources. Before institutions participate in multi-institutional NCI-sponsored clinical trials, they are required to perform a credentialing test provided by IROC-Houston. During the credentialing test, end-to-end phantoms are used to evaluate the institution’s ability to perform consistent and accurate radiation treatments. IROC-Houston’s conventional anthropomorphic phantoms are not visible in MR, thus they are insufficient for MRgRT systems. The purpose of this work was to create an anthropomorphic thorax and a head and neck (H&N) phantom for MRgRT systems with magnetic fields ranging from 0.35T to 1.5T. Methods: Over 80 synthetic materials were examined as potential materials used to construct the MRgRT thorax and H&N phantoms. Materials were characterized by: 1) measuring Hounsfield units, 2) visualizing in MR and CT imagers and 3) evaluating their dosimetric characteristics. Once materials were selected for the MRgRT phantoms, radiochromic film and double-loaded TLDs were then characterized in a 1.5T and a 0.35T MR environment. Reproducibility measurements on double-loaded TLDs were performed by using an acrylic block and irradiating it in 0T/1.5T and 0T/0.35T configurations on the Unity system and the MRIdian Cobalt 60 system, respectively. Geometrical thorax and H&N phantom slabs were designed to mimic similar interface conditions seen in anthropomorphic phantoms, but were simplified to reduce manufacturing time. The geometrical phantoms were designed with a rectangular tumor centrally located around surrounding tissue. These two phantoms were used to characterize radiochromic EBT3 film and TLDs by comparing beam profiles and point dose measurements irradiated with and without magnetic fields, respectively. GEANT4 Monte Carlo simulations validated the detectors in both Unity 0T/1.5T and MRIdian 0T/0.35T configurations. Two MRgRT anthropomorphic (H&N and thorax) phantoms were designed, manufactured and evaluated. A reproducibility and feasibility study was conducted to evaluate the phantom’s performance on MRgRT systems. Results: This study found four materials which were tissue equivalent and visible on both MR and CT. Additionally, this study showed negligible difference in dose response between TLDs and radiochromic film when irradiated in 0.35T and 1.5T magnetic field environments. Two anthropomorphic phantoms were constructed and evaluated. The anthropomorphic thorax and H&N phantoms passed IROC-Houston’s 7%/5mm and 7%/4mm gamma passing criteria, respectively. Conclusions: An anthropomorphic thorax and an H&N phantom were tissue equivalent, compatible with MR and CT workflows and could be used as end-to-end QA tools for MRgRT systems with magnetic fields ranging from 0.35T to 1.5T

Optimisation of CT protocols for cardiac imaging using three-dimensional printing technology

Objective: This thesis investigates the application of 3D-printing technology for optimising coronary CT angiography (CCTA) protocols using iterative reconstruction (IR) as a dose optimisation strategy. Methods: In phase one, a novel 3D-printed cardiac insert phantom for the Lungman phantom was developed. The attenuation values of the printed phantom were compared to CCTA patients and Catphan® 500 images. In phase two, the printed phantom was scanned at multiple dose levels, and the datasets were reconstructed using different IR strengths. The image quality characteristics were measured to determine the dose reduction potential. In phase three, the influence of IR strengths with low-tube voltage for dose optimisation studies was investigated. The printed phantom and the Catphan® 500 were scanned at different tube currents and voltages. The results were compared to the patient datasets to measure the agreement between the phantoms and patient datasets. Results: In phase one, the attenuation values were consistent between the printed phantom, patient and Catphan® 500 images. In phase two, the results showed that decreasing dose levels had significantly increased the image noise (p<0.001). The application of various IR strengths had yielded a stepwise improvement of noise image quality with a dose reduction potential of up to 40%. In phase three, the results showed a significant interaction between the effects of low-tube voltage and the IR strengths on image quality (all p<0.001) but not the attenuation values. The mean differences were small between the patient-phantom datasets. The optimised CT protocols allowed up to 57% dose reduction in CCTA protocols while maintaining the image quality. Conclusions: The 3D-printed cardiac insert phantom can be used to evaluate the effect of using IR on dose reduction and image quality. This thesis proposes and validates a new method of developing phantoms for CCTA dose optimisation studies

Real Loneliness and Artificial Companionship: Looking for Social Connections in Technology

Loneliness among older adults is a problem with severe consequences to individual health, quality of life, cognitive capacity, and life-expectancy. Although approaches towards improving the quality and quantity of social relationships are the prevailing model of therapy, older adults may not always be able to form these relationships due to either personality factors, decreased mobility, or isolation. Intelligent personal assistants (IPAs), virtual agents, and social robotics offer an opportunity for the development of technology that could potentially serve as social companions to older adults. The present study explored whether an IPA could potentially be used as a social companion to older adults feeling lonely. Additionally, the research explored whether the device has the potential to generate social presence among both young and older adults. Results indicate that while the devices do show some social presence, participants rate the device low on some components of social presence, such as emotional contagion. This adversely affects the possibility of a social relationship between an older adult and the device. Analysis reveals ways to improve social presence in these devices

Multimodal phantoms for clinical PET/MRI

Phantoms are commonly used throughout medical imaging and medical physics for a multitude of applications, the designs of which vary between modalities and clinical or research requirements. Within positron emission tomography (PET) and nuclear medicine, phantoms have a well-established role in the validation of imaging protocols so as to reduce the administration of radioisotope to volunteers. Similarly, phantoms are used within magnetic resonance imaging (MRI) to perform quality assurance on clinical scanners, and gel-based phantoms have a longstanding use within the MRI research community as tissue equivalent phantoms. In recent years, combined PET/MRI scanners for simultaneous acquisition have entered both research and clinical use. This review explores the designs and applications of phantom work within the field of simultaneous acquisition PET/MRI as published over the period of a decade. Common themes in the design, manufacture and materials used within phantoms are identified and the solutions they provided to research in PET/MRI are summarised. Finally, the challenges remaining in creating multimodal phantoms for use with simultaneous acquisition PET/MRI are discussed. No phantoms currently exist commercially that have been designed and optimised for simultaneous PET/MRI acquisition. Subsequently, commercially available PET and nuclear medicine phantoms are often utilised, with CT-based attenuation maps substituted for MR-based attenuation maps due to the lack of MR visibility in phantom housing. Tissue equivalent and anthropomorphic phantoms are often developed by research groups in-house and provide customisable alternatives to overcome barriers such as MR-based attenuation correction, or to address specific areas of study such as motion correction. Further work to characterise materials and manufacture methods used in phantom design would facilitate the ability to reproduce phantoms across sites