4,872 research outputs found
Middleware platform for distributed applications incorporating robots, sensors and the cloud
Cyber-physical systems in the factory of the future
will consist of cloud-hosted software governing an agile
production process executed by autonomous mobile robots
and controlled by analyzing the data from a vast number of
sensors. CPSs thus operate on a distributed production floor
infrastructure and the set-up continuously changes with each
new manufacturing task. In this paper, we present our OSGibased
middleware that abstracts the deployment of servicebased
CPS software components on the underlying distributed
platform comprising robots, actuators, sensors and the cloud.
Moreover, our middleware provides specific support to develop
components based on artificial neural networks, a technique that
recently became very popular for sensor data analytics and robot
actuation. We demonstrate a system where a robot takes actions
based on the input from sensors in its vicinity
ML models for real-time hybrid systems
[Abstract] A correct system design can be systematically obtained from a specification model of a real-time system that integrates hybrid measurements In a realistic industrial environment, this has been carried out through complete Matlab / Simulink / Stateflow models. However, there is a widespread interest in carrying out that modeling resorting to Machine Learning models, which can be understood as Automated Machine Learning for Real-time systems that present some degree of hybridation. An AC motor controller which must be able to maintain a constant air flow through a filter is one of these systems. The article also discusses a practical application of the method for implementing a closed loop control system to show how the proposed procedure can be applied to derive complete hybrid system designs with ANN
Artificial Neuron-Based Model for a Hybrid Real-Time System: Induction Motor Case Study
Automatic Machine Learning (AML) methods are currently considered of great interest
for use in the development of cyber-physical systems. However, in practice, they present serious
application problems with respect to fitness computation, overfitting, lack of scalability, and the need
for an enormous amount of time for the computation of neural network hyperparameters. In this
work, we have experimentally investigated the impact of continuous updating and validation of
the hyperparameters, on the performance of a cyber-physical model, with four estimators based on
feedforward and narx ANNs, all with the gradient descent-based optimization technique. The main
objective is to demonstrate that the optimized values of the hyperparameters can be validated by
simulation with MATLAB/Simulink following a mixed approach based on interleaving the updates
of their values with a classical training of the ANNs without affecting their efficiency and automaticity
of the proposed method. For the two relevant variables of an Induction Motor (IM), two sets of
estimators have been trained from the input current and voltage data. In contrast, the training data
for the speed and output electromagnetic torque of the IM have been established with the help of a
new Simulink model developed entirely. The results have demonstrated the effectiveness of ANN
estimators obtained with the Deep Learning Toolbox (DLT) that we used to transform the trained
ANNs into blocks that can be directly used in cyber-physical models designed with Simulink.Junta de Andalucia B-TIC-42-UGR20European CommissionSpanish Science Ministry (Ministerio de Ciencia e Innovacion) PID2020-112495RB-C2
Synchronised firing patterns in a random network of adaptive exponential integrate-and-fire neuron model
Acknowledgements This study was possible by partial financial support from the following Brazilian government agencies: CNPq, CAPES, and FAPESP (2011/19296-1 and 2015/07311-7). We also wish thank Newton Fund and COFAP.Peer reviewedPostprin
Impact Assessment of Hypothesized Cyberattacks on Interconnected Bulk Power Systems
The first-ever Ukraine cyberattack on power grid has proven its devastation
by hacking into their critical cyber assets. With administrative privileges
accessing substation networks/local control centers, one intelligent way of
coordinated cyberattacks is to execute a series of disruptive switching
executions on multiple substations using compromised supervisory control and
data acquisition (SCADA) systems. These actions can cause significant impacts
to an interconnected power grid. Unlike the previous power blackouts, such
high-impact initiating events can aggravate operating conditions, initiating
instability that may lead to system-wide cascading failure. A systemic
evaluation of "nightmare" scenarios is highly desirable for asset owners to
manage and prioritize the maintenance and investment in protecting their
cyberinfrastructure. This survey paper is a conceptual expansion of real-time
monitoring, anomaly detection, impact analyses, and mitigation (RAIM) framework
that emphasizes on the resulting impacts, both on steady-state and dynamic
aspects of power system stability. Hypothetically, we associate the
combinatorial analyses of steady state on substations/components outages and
dynamics of the sequential switching orders as part of the permutation. The
expanded framework includes (1) critical/noncritical combination verification,
(2) cascade confirmation, and (3) combination re-evaluation. This paper ends
with a discussion of the open issues for metrics and future design pertaining
the impact quantification of cyber-related contingencies
Metastability, Criticality and Phase Transitions in brain and its Models
This essay extends the previously deposited paper "Oscillations, Metastability and Phase Transitions" to incorporate the theory of Self-organizing Criticality. The twin concepts of Scaling and Universality of the theory of nonequilibrium phase transitions is applied to the role of reentrant activity in neural circuits of cerebral cortex and subcortical neural structures
Designing Neural Networks for Real-Time Systems
Artificial Neural Networks (ANNs) are increasingly being used within
safety-critical Cyber-Physical Systems (CPSs). They are often co-located with
traditional embedded software, and may perform advisory or control-based roles.
It is important to validate both the timing and functional correctness of these
systems. However, most approaches in the literature consider guaranteeing only
the functionality of ANN based controllers. This issue stems largely from the
implementation strategies used within common neural network frameworks -- their
underlying source code is often simply unsuitable for formal techniques such as
static timing analysis. As a result, developers of safety-critical CPS must
rely on informal techniques such as measurement based approaches to prove
correctness, techniques that provide weak guarantees at best. In this work we
address this challenge. We propose a design pipeline whereby neural networks
trained using the popular deep learning framework Keras are compiled to
functionally equivalent C code. This C code is restricted to simple constructs
that may be analysed by existing static timing analysis tools. As a result, if
compiled to a suitable time-predictable platform all execution bounds may be
statically derived. To demonstrate the benefits of our approach we execute an
ANN trained to drive an autonomous vehicle around a race track. We compile the
ANN to the Patmos time-predictable controller, and show that we can derive
worst case execution timings.Comment: 4 pages, 2 figures. IEEE Embedded Systems Letters, 202
Brain Dynamics across levels of Organization
After presenting evidence that the electrical activity recorded from the brain surface can reflect metastable state transitions of neuronal configurations at the mesoscopic level, I will suggest that their patterns may correspond to the distinctive spatio-temporal activity in the Dynamic Core (DC) and the Global Neuronal Workspace (GNW), respectively, in the models of the Edelman group on the one hand, and of Dehaene-Changeux, on the other. In both cases, the recursively reentrant activity flow in intra-cortical and cortical-subcortical neuron loops plays an essential and distinct role. Reasons will be given for viewing the temporal characteristics of this activity flow as signature of Self-Organized Criticality (SOC), notably in reference to the dynamics of neuronal avalanches. This point of view enables the use of statistical Physics approaches for exploring phase transitions, scaling and universality properties of DC and GNW, with relevance to the macroscopic electrical activity in EEG and EMG
IMPROVEMENT OF POWER QUALITY OF HYBRID GRID BY NON-LINEAR CONTROLLED DEVICE CONSIDERING TIME DELAYS AND CYBER-ATTACKS
Power Quality is defined as the ability of electrical grid to supply a clean and stable power supply. Steady-state disturbances such as harmonics, faults, voltage sags and swells, etc., deteriorate the power quality of the grid. To ensure constant voltage and frequency to consumers, power quality should be improved and maintained at a desired level. Although several methods are available to improve the power quality in traditional power grids, significant challenges exist in modern power grids, such as non-linearity, time delay and cyber-attacks issues, which need to be considered and solved. This dissertation proposes novel control methods to address the mentioned challenges and thus to improve the power quality of modern hybrid grids.In hybrid grids, the first issue is faults occurring at different points in the system. To overcome this issue, this dissertation proposes non-linear controlled methods like the Fuzzy Logic controlled Thyristor Switched Capacitor (TSC), Adaptive Neuro Fuzzy Inference System (ANFIS) controlled TSC, and Static Non-Linear controlled TSC. The next issue is the time delay introduced in the network due to its complexities and various computations required. This dissertation proposes two new methods such as the Fuzzy Logic Controller and Modified Predictor to minimize adverse effects of time delays on the power quality enhancement. The last and major issue is the cyber-security aspect of the hybrid grid. This research analyzes the effects of cyber-attacks on various components such as the Energy Storage System (ESS), the automatic voltage regulator (AVR) of the synchronous generator, the grid side converter (GSC) of the wind generator, and the voltage source converter (VSC) of Photovoltaic (PV) system, located in a hybrid power grid. Also, this dissertation proposes two new techniques such as a Non-Linear (NL) controller and a Proportional-Integral (PI) controller for mitigating the adverse effects of cyber-attacks on the mentioned devices, and a new detection and mitigation technique based on the voltage threshold for the Supercapacitor Energy System (SES). Simulation results obtained through the MATLAB/Simulink software show the effectiveness of the proposed new control methods for power quality improvement. Also, the proposed methods perform better than conventional methods
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