Electrical Engineering

Over the last decade, manufacturing processes have undergone significant change. Most factory activities have been transformed through a set of features built into a smart manufacturing framework. The tools brought to bear by the fourth industrial revolution are critical enablers of such change and progress. This review article describes the series of industrial revolutions and explores traditional manufacturing before presenting various enabling technologies. Insights are offered regarding traditional manufacturing lines where some enabling technologies have been included. The manufacturing supply chain is envisaged as enhancing the enabling technologies of Industry 4.0 through their integration. A systematic literature review is undertaken to evaluate each enabling technology and the manufacturing supply chain and to provide some theoretical synthesis. Similarly, obstacles are listed that must be overcome before a complete shift to smart manufacturing is possible. A brief discussi...

The increasing popularity of electric vehicles (EVs) has been attributed to their low-carbon and environmentally friendly attributes. Extensive research has been undertaken in view of the depletion of fossil fuels, changes in climatic conditions due to air pollution, and the goal of developing EVs capable of matching or exceeding the performance of today’s internal combustion engines (ICEs). The transition from ICE vehicles to EVs can reduce greenhouse gases significantly over a vehicle’s lifetime. Across the different types of EVs, the widespread usage of batteries is due to their high power density and steady output voltage, making them an excellent energy storage device (ESD). The current downsides of battery-powered electric vehicles include long recharge times, the impact of additional strain on the grid, poor societal acceptance due to high initial costs, and a lack of adequate charging infrastructure. Even more problematic is their short driving range when compared to standar...

The essence of grounding in power systems is very essential. This paper presents the performance and characteristic of backfill material such as bentonite and conductive cement. The backfill materials pay a pivotal role in controlling ground impedance of the soil. Protective devices are normally used to divert an excessive current during lightning strikes through earth rode to avoid damages to the equipment. Swaziland has been experiencing a lot of power failures due to lightning especially during rainy season. Most of their transformers has been lost because of this problem. Most of Swaziland network is overhead which is exposed to lightning. It is thus important to design an effect earthing system that will be able to protect the equipment during fault conditions. In this study, it has been found that the behaviour of backfill material depends on the voltage applied. It was also found that the time to breakdown in comparison between bentonite and conductive cement. This paper highlights some of the aspects need to take into consideration for grounding for a country like Swaziland.

The design of a compliant, safe, and reliable substation earth grid is not a straightforward process; in most cases, it requires some additional measures to be taken due to various constraints that differ from environment to environment, such as soil resistivity, a high fault level, a limited surface area, construction budget, etc. The IEEE Std 80-2013 proposes various refinement methods that can be applied to address different situations. For this study, the current limiting method, current diversion method, and touch and step voltage increment method were applied using the Electrical Transient Analysis Program (ETAP). A power system was designed, where a fault current generated by the supply transformers and back-fed by the power system’s motors was exported to the earth grid. Using this fault current, various simulations were conducted to assess the performance of the earth grid. The analysis results show that the application of the current limiting method using neutral earthing ...

Transmission line silicon rubber insulators are frequently subjected to harsh environmental conditions that can change their surface characteristics and result in a transient or permanent loss of hydrophobicity. Algae, fungi, mould, and lichen are examples of biological growth that can compromise the power system's ability to operate safely by lowering the insulator's flashover voltage. We evaluated and identified the major microorganisms that could be responsible for the flashovers of insulators in South Africa. Due to the difficulty of accessing insulators currently in use within the electricity network, only two insulators, from two provinces in South Africa, were used in the study. Although algae were not found on the insulators, two major filamentous fungi identified as Curvularia sp. and Aspergillus sp. were isolated. The absence of algae could be attributed to the weather pattern of the two locations where the insulators were placed during their use as part of the network. According to previous studies worldwide, the high occurrence of these fungi could be linked to the reduction of flashover voltage of the composite insulators. Although a larger survey including more insulators from all provinces in South Africa should be conducted, the current study demonstrates the need for a cleaning programme for insulators using cost-effective eco-friendly antimicrobial agents. • Degradation and loss of hydrophobicity on the overhead line composite due to biological growth were found to be an impediment to the safe operation of high-voltage insulators. Fungi were found to be the main factor causing the degradation of overhead transmission lines. • With these data, a model can be developed to predict the rate of biological growth on a given insulator, to estimate the degradation of the surface conditions with time for the utility to know when to remove them from the line. Such a model could lead to a more reliable and efficient power system and reduce the engineer's workload.

h i g h l i g h t s • Computational burden of high order robotic control significantly reduced. • Computation of flat output for 6-DOF robotic manipulator presented. • Comparison between PID and Flatness based control of ABB IRB140 robot provided. • Tracking control of 6-DOF ABB IRB140 robot in Joint space and Task space presented.

This paper presents an intelligent method of tuning a flat controller for trajectory tracking of a single link flexible manipulator. The tip position of the manipulator was determined as the flat output. Using the flat output, a feedback control law is designed to stabilize the tip of the end effector and track the reference trajectories. The gains obtained for the flat controller is optimized using particle swarm optimization. Results show fast response to system trajectories, good tracking performance with no overshoots.

Predicting congestion in a telephone network has become part of an efficient network planning operation. The excellent capability of neural network (NN) to learn complex nonlinear systems makes it suitable for identifying the relationship between traffic congestion and the variables responsible for its occurrence in a time-varying traffic situation. This paper presents an artificial NN model for predicting traffic congestion in a telephone network. The design strategy uses a multilayered feedforward NN with backpropagation algorithm to model the telephone traffic situation. Matlab was used as a platform for all simulations. Regression analysis between predicted traffic congestion volumes and corresponding actual volumes gave a correlation coefficient of 87% which clearly shows the utility and effectiveness of Neural Networks in traffic prediction and control.

ABSTRACT This paper discusses the application of differential flatness to tracking control of a robot manipulator in the presence of gravity and friction. Including these terms in the coupled nonlinear dynamics of the robot increases the complexity of the control. Tracking a robot trajectory under these conditions would require accurate mathematical modeling of the robot. This knowledge will help in generating nominal trajectories and executing accurate tracking. Differential flatness based control enables both possibilities. Flat inputs are designed to drive the robot along its trajectory while eliminating the effects of friction and gravity. The control design is applied to the trajectory tracking control of a two link robot manipulator.

ABSTRACT In this paper, a nonlinear feedback controller is proposed for a single link flexible joint manipulator based on the concept of differential flatness. The control design is approached from the perspective of using input state feedback linearization via the flatness property of the robot. It is shown that the nonlinear dynamics of the manipulator satisfies the controllability and involutivity conditions required for the selection of a flat output. With the flat output, trajectories of motion are generated. A feedback controller is then designed to track the trajectories. Tracking results show the effectiveness of the proposed flatness based control scheme.

This paper discusses the open loop control problem of a flexible joint robot that is oriented in the vertical plane. This orientation of the robot arm introduces gravity constraints and imposes undesirable nonlinear behavior. Friction is also added at the joints to increase the accuracy of the model. Including these dynamics to the robot arm amplifies the open loop control problem. Differential flatness is used to propose a feedforward control that compensates for these nonlinearities and is able to smoothly steer the robot from rest to rest positions. The proposed control is achieved without solving any differential equations which makes the approach computationally attractive. Simulations show the effectiveness of the open loop control design on a single link flexible joint robot arm. 174 Didam Markus E.. Flatness based Feed-forward Control of a Flexible Robot Arm under Gravity and Joint Friction.

h i g h l i g h t s • Flatness based coordination of multiple interconnected flexible robots presented. • Constraints of coupling dynamics are taken into account in the synchronization design. • Flexibility in the choice of synchronization parameters. • Synchronization of multiple robots is enhanced via trajectory design based on flatness.

 Climate change is a key global concern particularly in the field of agriculture. Farmers around the world mainly in developing countries are faced with the critical problem due to reduction of potential crop yields and a decrease in water availability for irrigation and increasing food demands to cover the population needs. As a result, water shortage and poor yield are being increasingly accepted as major limitations. Researchers have documented that magnetic treatment can conserve both the quantity and quality of water and crop yield. This paper presents an extensive survey of studies on the effects of the fields on plants over the past 20 years. Many aspects of plants growth, seed germination, yield, quality and water as affected by magnetic fields (MF) are investigated. The inconsistency and contradictory outcomes from the studies appear to indicate that the effects of MF on plants may be dependent on species and/or MF characteristics such as intensity and exposure time.

The stochastic nature of energy consumption patterns in a port varies daily and weekly. The port must manage their load to save electricity costs, plan future infrastructure development and consolidate the power utility's optimal power generation efforts. This requires accurate Short-Term Load Forecast (STLF) for quality, quantity and efficiency. Recently Artificial Neural Networks (ANNs) have been proposed for short-term load forecasting (STLF). Here we aim to create a more exact method of short-term load forecasting using the nonlinear, autoregressive, multi-variable exogenous input (NARX) ANNs. We propose a new network architecture: an open-loop training neural network with real load and weather information, followed by a closed-loop network to produce a prediction with the predicted load as its feedback data. The proposed method utilizes its own performance to improve precision, essentially implementing a load feedback loop that is less dependent on external data. In our proposed system, mean absolute percentage errors were reached in the forecast range of 1%: 30% better on the average error by feedforward ANNs. Our test used actual reticulation network load data from Transnet Port Terminal in East London and climate statistics to predict port terminal load for a week in advance.

This paper presents a review on techniques used to monitor rolling stock equipment in order to predict the maintenance needs and activities before failure could actually occur. There is limited number of research on this study which has focused majorly on the infrastructure, and very little has covered the topic on maintenance or the rolling stock maintenance. This paper explores the available current source and findings about three maintenance strategies, two which are currently the most commonly practiced in South Africa and one which is taking the focus on this research. The review also revealed that artificial intelligence techniques are rarely used in monitoring of railway equipment. Part of the discussion in this paper is about the use of these AI techniques in maintenance. A discussion of a proposed maintenance strategy that uses the application of AI techniques is included and the whole review is closed off by outlining the possible challenges and future considerations relating to the predictive maintenance of Electric Trains.

Offshore oil production facilities exhibit nonlinear dynamic characteristics. With the existence of many flow regulating valves, these dynamics require to be linearized in order to achieve the performance criteria necessary for production of hydrocarbons. Consequently, the dynamic nature of these valves affect their production performance as regular tuning of process controllers are required due to changes in reservoir fluid flow and future constraints. To address this phenomenon, this paper proposes an MPC-PID control system strategy for offshore oil production platform. This strategy includes the use of model predictive controller providing the most economic and efficient set point for distributed PID controllers in the respective loops. The model predictive controller employs a strategy based on the process model to solve the optimal control problem. The proposed approach is further developed using a dynamic engineering design tools available in MATLAB/Simulink and implemented on Gas-Liquid Cylindrical Cyclone (GLCC) compact separator. The system is subjected to set point variation and process disturbances. The results indicate stable controller design and prove the ability of MPC controller to handle constraints and reject disturbances while reducing the energy required and hence overall reduction in production cost with maximum performance.

Studies has shown that medical diagnosis of patients in most developing countries and especially in rural areas are adversely affected by lack of proper healthcare structures, poor patient to doctor ratio and substandard educational systems. More so, these services are not accessible due non-affordability and poor human resource allocation in public facilities. In an attempt to bridge this gap, medical Robotic assistive systems were recently introduced to enhance general healthcare access and to carry out early diagnosis of common ailments. The rapid expansion of wireless communication networks has enabled these developments. Such intelligence systems consist of wireless monitoring systems, sensor networks, medical devices, wireless communication, middleware software and software applications that help advance improvements in healthcare. This paper attempts to review the use of Medical Robotic assistive systems for early diagnosis of common ailments. Furthermore, the literature review exposes the gap in early diagnosis and some part of opportunity that have not been explored for early diagnosis of common ailments in rural areas. The study concludes that robotic systems will in fact be an important part of future interventions, but more research and clinical trials are needed. 1  Index Term-early diagnostics, wireless medical devices, sensor networks, Medical Robotic Assistive System (MRA), health tracking

1-Multiple mobile robotic systems have been applied in many scenarios. This is because they have obvious advantages compared to single mobile robotic systems. However, their control could be challenging and is still an open problem in robotic research. This paper presents a survey of the current state of affairs on formation control of multiple mobile robotic systems. The main contribution of this paper is to comprehensively analyse different cooperative multiple mobile robotic control techniques used in various literature. Different techniques were analysed, their strengths and weaknesses identified. However, differential flatness approach of cooperative multiple mobile robots control has not gained much popularity; thus a gap of future work was determined.

A new approach to tracking control of industrial robot manipulators is presented in this paper. The highly coupled nonlinear dynamics of a six degrees of freedom (6-DOF) serial robot is decoupled by expressing its variables as a function of a flat output and its derivatives. Hence the derivation of the flat output for the 6-DOF robot is presented. With the flat output, trajectories for each of the generalised coordinates are easily designed and open loop control is made possible. Using MATLAB/Simulink S-functions combined with the differential flatness property of the robot, trajectory tracking is carried out in closed loop by using a linear flat controller. The merit of this approach reduces the computational complexity of the robot dynamics by allowing online computation of a high order system at a lower computational cost. Using the same processor, the run time for tracking arbitrary trajectories is reduced significantly to about 10 seconds as compared to 30 minutes in the origin...