Control of Networked Robotic Systems

With the infrastructure of ubiquitous networks around the world, the study of robotic systems over communication networks has attracted widespread attention. This area is denominated as networked robotic systems. By exploiting the fruitful technological developments in networking and computing, networked robotic systems are endowed with potential and capabilities for several applications. Robots within a network are capable of connecting with control stations, human operators, sensors, and other robots via digital communication over possibly noisy channels/media. The issues of time delays in communication and data losses have emerged as a pivotal issue that have stymied practical deployment. The aim of this dissertation is to develop control algorithms and architectures for networked robotic systems that guarantee stability with improved overall performance in the presence of time delays in communication. The first topic addressed in this dissertation is controlled synchronization that is utilized for networked robotic systems to achieve collective behaviors. Exploiting passivity property of individual robotic systems, the proposed control schemes and interconnections are shown to ensure stability and convergence of synchronizing errors. The robustness of the control algorithms to constant and time-varying communication delays is also studied. In addition to time delays, the number of communication links, which prevents scalability of networked robotic systems, is another challenging issue. Thus, a synchronizing control with practically feasible constraints of network topology is developed. The problem of networked robotic systems interacting with human operators is then studied subsequently. This research investigates a teleoperation system with heterogeneous robots under asymmetric and unknown communication delays. Sub-task controllers are proposed for redundant slave robot to autonomously achieve additional tasks, such as singularity avoidance, joint angle limits, and collision avoidance. The developed control algorithms can enhance the efficiency of teleoperation systems, thereby ameliorating the performance degradation due to cognitive limitations of human operator and incomplete information about the environment. Compared to traditional robotic systems, control of robotic manipulators over networks has significant advantages; for example, increased flexibility and ease of maintenance. With the utilization of scattering variables, this research demonstrates that transmitting scattering variables over delayed communications can stabilize an otherwise unstable system. An architecture utilizing delayed position feedback in conjunction with scattering variables is developed for the case of time-varying communication delays. The proposed control architecture improves tracking performance and stabilizes robotic manipulators with input-output communication delays. The aforementioned control algorithms and architectures for networked robotic systems are validated via numerical examples and experiments

Safe Haptics-enabled Patient-Robot Interaction for Robotic and Telerobotic Rehabilitation of Neuromuscular Disorders: Control Design and Analysis

Motivation: Current statistics show that the population of seniors and the incidence rate of age-related neuromuscular disorders are rapidly increasing worldwide. Improving medical care is likely to increase the survival rate but will result in even more patients in need of Assistive, Rehabilitation and Assessment (ARA) services for extended periods which will place a significant burden on the world\u27s healthcare systems. In many cases, the only alternative is limited and often delayed outpatient therapy. The situation will be worse for patients in remote areas. One potential solution is to develop technologies that provide efficient and safe means of in-hospital and in-home kinesthetic rehabilitation. In this regard, Haptics-enabled Interactive Robotic Neurorehabilitation (HIRN) systems have been developed. Existing Challenges: Although there are specific advantages with the use of HIRN technologies, there still exist several technical and control challenges, e.g., (a) absence of direct interactive physical interaction between therapists and patients; (b) questionable adaptability and flexibility considering the sensorimotor needs of patients; (c) limited accessibility in remote areas; and (d) guaranteeing patient-robot interaction safety while maximizing system transparency, especially when high control effort is needed for severely disabled patients, when the robot is to be used in a patient\u27s home or when the patient experiences involuntary movements. These challenges have provided the motivation for this research. Research Statement: In this project, a novel haptics-enabled telerobotic rehabilitation framework is designed, analyzed and implemented that can be used as a new paradigm for delivering motor therapy which gives therapists direct kinesthetic supervision over the robotic rehabilitation procedure. The system also allows for kinesthetic remote and ultimately in-home rehabilitation. To guarantee interaction safety while maximizing the performance of the system, a new framework for designing stabilizing controllers is developed initially based on small-gain theory and then completed using strong passivity theory. The proposed control framework takes into account knowledge about the variable biomechanical capabilities of the patient\u27s limb(s) in absorbing interaction forces and mechanical energy. The technique is generalized for use for classical rehabilitation robotic systems to realize patient-robot interaction safety while enhancing performance. In the next step, the proposed telerobotic system is studied as a modality of training for classical HIRN systems. The goal is to first model and then regenerate the prescribed kinesthetic supervision of an expert therapist. To broaden the population of patients who can use the technology and HIRN systems, a new control strategy is designed for patients experiencing involuntary movements. As the last step, the outcomes of the proposed theoretical and technological developments are translated to designing assistive mechatronic tools for patients with force and motion control deficits. This study shows that proper augmentation of haptic inputs can not only enhance the transparency and safety of robotic and telerobotic rehabilitation systems, but it can also assist patients with force and motion control deficiencies

Haptics: Science, Technology, Applications

This open access book constitutes the proceedings of the 12th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2020, held in Leiden, The Netherlands, in September 2020. The 60 papers presented in this volume were carefully reviewed and selected from 111 submissions. The were organized in topical sections on haptic science, haptic technology, and haptic applications. This year's focus is on accessibility

Controlled manipulation using autonomous aerial systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, February 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 134-135).The main focus of the thesis is to design and control Autonomous Aerial Systems, also referred to as Unmanned Aerial Vehicles (UAVs). UAVs are able to hover and navigate in space using the thrust forces generated by the propellers. One of the simplest such vehicles that is widely used is a Quadrotor. While UAVs have been predominantly used for "fly and sense" applications, very few investigations have focused on using them to perform manipulation by contact. The latter is challenging because of the dual goal of performing manipulation and maintaining stable flight. Because Quadrotors can quickly reach a location, their ability to manipulate can be impactful in many scenarios. While efficient flight control of Quadrotor has been an active research area, using Quadrotor to perform manipulation is novel and challenging. In this thesis, a range of Quadrotor designs and control strategies are proposed in order to carry out autonomous manipulation of objects. We first derive a dynamic model of the Quadrotor that accounts for the presence of contact, object dynamics and kinematics. To improve manipulation performance, a passive light-weight end-effector interface between the Quadrotor and the object is proposed. The complexity of the dynamics is systematically reduced by making certain assumptions. The resulting dynamic model is divided into nonlinear subsystems on the basis of their degrees of freedom, for each of which separate controllers are designed. An efficient docking approach is proposed that permits fast and aggressive docking, even at very high speeds. Because a single Quadrotor UAS is limited in manipulation capability, a multi Quadrotor cooperative manipulation scheme is proposed. Control strategies are proposed to deal with kinematic and parametric uncertainties. A manipulation scheme to open a door with unknown hinge location is proposed. A nonlinear adaptive controller is implemented to perform efficient tracking in the presence of parametric uncertainty. In order to improve robustness to accidental contacts, a novel flexible Quadrotor, denoted as ParaFlex, is designed. The advantages of ParaFlex over a rigid Quadrotor are demonstrated. A Simulation, Test and Validation Environment (STeVE) is developed to facilitate smooth and efficient transition from design process to simulation to experiments.by Manohar B. Srikanth.Ph.D

Enhancing tele-operation - Investigating the effect of sensory feedback on performance

The decline in the number of healthcare service providers in comparison to the growing numbers of service users prompts the development of technologies to improve the efficiency of healthcare services. One such technology which could offer support are assistive robots, remotely tele-operated to provide assistive care and support for older adults with assistive care needs and people living with disabilities. Tele-operation makes it possible to provide human-in-the-loop robotic assistance while also addressing safety concerns in the use of autonomous robots around humans. Unlike many other applications of robot tele-operation, safety is particularly significant as the tele-operated assistive robots will be used in close proximity to vulnerable human users. It is therefore important to provide as much information about the robot (and the robot workspace) as possible to the tele-operators to ensure safety, as well as efficiency. Since robot tele-operation is relatively unexplored in the context of assisted living, this thesis explores different feedback modalities that may be employed to communicate sensor information to tele-operators. The thesis presents research as it transitioned from identifying and evaluating additional feedback modalities that may be used to supplement video feedback, to exploring different strategies for communicating the different feedback modalities. Due to the fact that some of the sensors and feedback needed are not readily available, different design iterations were carried out to develop the necessary hardware and software for the studies carried out. The first human study was carried out to investigate the effect of feedback on tele-operator performance. Performance was measured in terms of task completion time, ease of use of the system, number of robot joint movements, and success or failure of the task. The effect of verbal feedback between the tele-operator and service users was also investigated. Feedback modalities have differing effects on performance metrics and as a result, the choice of optimal feedback may vary from task to task. Results show that participants preferred scenarios with verbal feedback relative to scenarios without verbal feedback, which also reflects in their performance. Gaze metrics from the study also showed that it may be possible to understand how tele-operators interact with the system based on their areas of interest as they carry out tasks. This findings suggest that such studies can be used to improve the design of tele-operation systems.The need for social interaction between the tele-operator and service user suggests that visual and auditory feedback modalities will be engaged as tasks are carried out. This further reduces the number of available sensory modalities through which information can be communicated to tele-operators. A wrist-worn Wi-Fi enabled haptic feedback device was therefore developed and a study was carried out to investigate haptic sensitivities across the wrist. Results suggest that different locations on the wrist have varying sensitivities to haptic stimulation with and without video distraction, duration of haptic stimulation, and varying amplitudes of stimulation. This suggests that dynamic control of haptic feedback can be used to improve haptic perception across the wrist, and it may also be possible to display more than one type of sensor data to tele-operators during a task. The final study carried out was designed to investigate if participants can differentiate between different types of sensor data conveyed through different locations on the wrist via haptic feedback. The effect of increased number of attempts on performance was also investigated. Total task completion time decreased with task repetition. Participants with prior gaming and robot experience had a more significant reduction in total task completion time when compared to participants without prior gaming and robot experience. Reduction in task completion time was noticed for all stages of the task but participants with additional feedback had higher task completion time than participants without supplementary feedback. Reduction in task completion time varied for different stages of the task. Even though gripper trajectory reduced with task repetition, participants with supplementary feedback had longer gripper trajectories than participants without supplementary feedback, while participants with prior gaming experience had shorter gripper trajectories than participants without prior gaming experience. Perceived workload was also found to reduce with task repetition but perceived workload was higher for participants with feedback reported higher perceived workload than participants without feedback. However participants without feedback reported higher frustration than participants without feedback.Results show that the effect of feedback may not be significant where participants can get necessary information from video feedback. However, participants were fully dependent on feedback when video feedback could not provide requisite information needed.The findings presented in this thesis have potential applications in healthcare, and other applications of robot tele-operation and feedback. Findings can be used to improve feedback designs for tele-operation systems to ensure safe and efficient tele-operation. The thesis also provides ways visual feedback can be used with other feedback modalities. The haptic feedback designed in this research may also be used to provide situational awareness for the visually impaired

State of the art of cyber-physical systems security: An automatic control perspective

Cyber-physical systems are integrations of computation, networking, and physical processes. Due to the tight cyber-physical coupling and to the potentially disrupting consequences of failures, security here is one of the primary concerns. Our systematic mapping study sheds light on how security is actually addressed when dealing with cyber-physical systems from an automatic control perspective. The provided map of 138 selected studies is defined empirically and is based on, for instance, application fields, various system components, related algorithms and models, attacks characteristics and defense strategies. It presents a powerful comparison framework for existing and future research on this hot topic, important for both industry and academia

Improving access to ultrasound imaging in northern, remote communities

Access to healthcare services—including access to medical imaging—is an important determinant of health outcomes. This thesis aims to improve understanding of and address gaps in access to ultrasound imaging for patients in northern, remote communities, and advance a novel ultrasound technology with the ultimate goal of improving patient care and health outcomes. This thesis first brings greater understanding of patients’ perceptions of access and factors which shape access to ultrasound imaging in northern, remote communities in Saskatchewan, Canada. A qualitative study was performed using interpretive description as a methodological approach and a multi-dimensional conceptualization of access to care as a theoretical framework. The study identified barriers which patients in northern, remote communities face in accessing ultrasound imaging, and demonstrated that geographic remoteness from imaging facilities was a central barrier. To determine whether disparities in access to ultrasound imaging resulted in disparities in utilization of ultrasound services, two population-based studies assessed the association between sociodemographic and geographic factors and obstetrical and non-obstetrical ultrasound utilization in Saskatchewan. In the first study investigating obstetrical ultrasound utilization, multivariate logistic regression analysis demonstrated that women living in rural areas, remote areas, and low income neighbourhoods, as well as status First Nations women, were less likely to have a second trimester ultrasound, an important aspect of prenatal care. In a second study investigating non-obstetrical ultrasound utilization across the entire provincial population, multivariate Poisson regression analysis similarly demonstrated lower rates of non-obstetrical ultrasound utilization among individuals living in rural and remote areas, individuals residing in low income neighbourhoods, and status First Nations persons. To address the barriers which patients in northern, remote communities face in accessing ultrasound imaging and to minimize disparities in ultrasound imaging utilization as identified in previous studies in this thesis, telerobotic ultrasound technology was investigated as a solution to improve access to ultrasound imaging. Using this technology, radiologists and sonographers could remotely manipulate an ultrasound probe via a robotic arm, thereby remotely performing an ultrasound exam while patients remained in their home community. A clinical trial comparing conventional and telerobotic ultrasound approaches was undertaken, validating this technology for obstetrical ultrasound imaging. To determine the feasibility of using telerobotic technology to establish an ultrasound service delivery model to remotely provide diagnostic ultrasound exams in underserved communities, pilot telerobotic ultrasound clinics were developed in three northern, remote communities. Telerobotic ultrasound exams were sufficient for diagnosis in the majority of cases, minimizing travel or reducing wait times for these patients. This technology was subsequently evaluated during a COVID-19 outbreak in northern Saskatchewan, demonstrating the potential of this technology to provide critical ultrasound services to an underserved northern population and minimize health inequities during the COVID-19 pandemic. An economic evaluation was performed to compare a service delivery model using telerobotic ultrasound technology to alternative service delivery models. Telerobotic ultrasound combined with an itinerant sonographer service was found to be the lowest cost option from both a publicly funded healthcare payer perspective and a societal perspective for many northern, remote communities. This thesis provides key insights for health system leaders seeking improved understanding and novel solutions to improve access to ultrasound imaging in northern, remote communities. Findings suggest that telerobotic ultrasound is a viable solution to improve access to ultrasound imaging and reduce costs associated with ultrasound service delivery. Evidence in this thesis may be used to help improve ultrasound services and health equity for patients in underserved northern, remote communities. Continued respectful collaboration with northern, remote, Indigenous peoples and communities will be a critical aspect to ensure that ultrasound services meet community needs

Molecular phylogeny of horseshoe crab using mitochondrial Cox1 gene as a benchmark sequence

An effort to assess the utility of 650 bp Cytochrome C oxidase subunit I (DNA barcode) gene in delineating the members horseshoe crabs (Family: xiphosura) with closely related sister taxa was made. A total of 33 sequences were extracted from National Center for Biotechnological Information (NCBI) which include horseshoe crabs, beetles, common crabs and scorpion sequences. Constructed phylogram showed beetles are closely related with horseshoe crabs than common crabs. Scorpion spp were distantly related to xiphosurans. Phylogram and observed genetic distance (GD) date were also revealed that Limulus polyphemus was closely related with Tachypleus tridentatus than with T.gigas. Carcinoscorpius rotundicauda was distantly related with L.polyphemus. The observed mean Genetic Distance (GD) value was higher in 3rd codon position in all the selected group of organisms. Among the horseshoe crabs high GC content was observed in L.polyphemus (38.32%) and lowest was observed in T.tridentatus (32.35%). We conclude that COI sequencing (barcoding) could be used in identifying and delineating evolutionary relatedness with closely related specie