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Machines, Volume 9, Issue 7 (July 2021) – 12 articles

Cover Story (view full-size image): Exotic materials offer superior characteristics that, paradoxically, make them hard to cut. As a solution, electric discharge machining (EDM) stands out as a process that is able to cut complex shapes from any conductive materials, delivering accuracy and surface quality. However, EDM is embodied in CNC machines, offering a limited axis and envelope, constraining design freedom. To overcome the CNC constraints, traditional machining using six-axis robots has become a hot research topic. However, the inherent lack of robot stiffness results in vibration jeopardizing accuracy and surface finishing. Since EDM cuts with no contact and nearly no vibration, we explored the advantages of a synergistic combination of robotic matching and EDM. This study investigates outcomes and amends technical problems by using the TRIZ algorithm to propose a robotic system for hard-to-cut materials allegedly [...] Read more.
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Article
A Low-Cost System for Remote Access and Control of Automation Equipment
Machines 2021, 9(7), 138; https://doi.org/10.3390/machines9070138 - 20 Jul 2021
Viewed by 276
Abstract
The shift towards remote access and control of equipment has become more prominent, especially due to COVID-19 lockdowns. Access to physical/real equipment for practical learning remains important for engineering studies. Thus, this paper presents an approach for remotely accessing and controlling automation equipment [...] Read more.
The shift towards remote access and control of equipment has become more prominent, especially due to COVID-19 lockdowns. Access to physical/real equipment for practical learning remains important for engineering studies. Thus, this paper presents an approach for remotely accessing and controlling automation equipment for engineering practical activities. Specifically, it addresses the issue of accessing and controlling machines for programmable logic controller (PLC) programming tasks. The combination of a scheduler, remote desktop access, graphical user interface, and a micro-controller allows students to work remotely on practical equipment. The lab computer can be accessed via a remote computer to select one of multiple equipment for practical activities. A prototype system was constructed as proof of concept. The prototype system functions as required. Full article
(This article belongs to the Special Issue Intelligent Machines and Control Systems)
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Article
Coil Number Impact on Performance of 4-Phase Low Speed Toothed Doubly Salient Permanent Magnet Motors
Machines 2021, 9(7), 137; https://doi.org/10.3390/machines9070137 - 16 Jul 2021
Viewed by 293
Abstract
The low speed toothed doubly salient permanent-magnet (TDSPM) machine is an interesting candidate motor for electric ship applications because, of its high torque output, maintenance-free operation and flexible working modes, which gives the opportunity to increase system’s reliability, and decrease the system size, [...] Read more.
The low speed toothed doubly salient permanent-magnet (TDSPM) machine is an interesting candidate motor for electric ship applications because, of its high torque output, maintenance-free operation and flexible working modes, which gives the opportunity to increase system’s reliability, and decrease the system size, weight and noise which are key features for naval applications. However, particularly in the 3-phase configuration, the stator and rotor saliency of these machines leads to a high level of torque ripple. To overcome these drawbacks, the use of polyphase machines (with a number of phases greater than three) can be a relevant solution. In this paper, an optimal design of two kind of novel 4-phase motors is performed in order to fulfil the specifications of a high power naval ship propulsion. The designs aim to maximize the torque to mass ratio. The motors’ performances are directly linked to their structural parameters, so, the impact of the coil number in terms of mean torque, torque ripple, energy ratio values, and efficiency is also presented and analysed. The design of these two electromagnetic structures, as well as the determination of their electromagnetic performances, are carried out using a particle swarm optimization algorithm (PSO) with taking into account thermal constraint. The performance of the proposed machine in terms of mean torque, torque ripple, energy ratio, and efficiency values is presented and analysed. The results obtained reveal that the TDSPM machines with four poles/phase are good candidates to meet the requirements of high power direct-drive ship propulsion system. Full article
(This article belongs to the Special Issue Synchronous Reluctance Motor-Drive Advancements)
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Article
Blaise Pascal’s Mechanical Calculator: Geometric Modelling and Virtual Reconstruction
Machines 2021, 9(7), 136; https://doi.org/10.3390/machines9070136 - 16 Jul 2021
Viewed by 275
Abstract
This article shows the three-dimensional (3D) modelling and virtual reconstruction of the first mechanical calculating machine used for accounting purposes designed by Blaise Pascal in 1642. To obtain the 3D CAD (computer-aided design) model and the geometric documentation of said invention, CATIA V5 [...] Read more.
This article shows the three-dimensional (3D) modelling and virtual reconstruction of the first mechanical calculating machine used for accounting purposes designed by Blaise Pascal in 1642. To obtain the 3D CAD (computer-aided design) model and the geometric documentation of said invention, CATIA V5 R20 software has been used. The starting materials for this research, mainly the plans of this arithmetic machine, are collected in the volumes Oeuvres de Blaise Pascal published in 1779. Sketches of said machine are found therein that lack scale, are not dimensioned and certain details are absent; that is, they were not drawn with precision in terms of their measurements and proportions, but they do provide qualitative information on the shape and mechanism of the machine. Thanks to the three-dimensional modelling carried out; it has been possible to explain in detail both its operation and the final assembly of the invention, made from the assemblies of its different subsets. In this way, the reader of the manuscript is brought closer to the perfect understanding of the workings of a machine that constituted a major milestone in the technological development of the time. Full article
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Article
Development and Application of Fuzzy Proportional-Integral Control Scheme in Pitch Angle Compensation Loop for Wind Turbines
Machines 2021, 9(7), 135; https://doi.org/10.3390/machines9070135 - 16 Jul 2021
Viewed by 283
Abstract
Wind energy is regarded as one of the oldest energy sources and has played a significant role. As the nature of wind changes continuously, the generated power varies accordingly. Generation of the pitch angle of a wind turbine’s blades is controlled to prevent [...] Read more.
Wind energy is regarded as one of the oldest energy sources and has played a significant role. As the nature of wind changes continuously, the generated power varies accordingly. Generation of the pitch angle of a wind turbine’s blades is controlled to prevent damage during high wind speed. This paper presents the development and application of a fuzzy proportional integral control scheme combined with traditional proportional control in the dynamic behavior of pitch angle-regulated wind turbine blades. The combined control regulates rotor speed and output power, allowing control of the power while maintaining the desired rotor speed and avoiding equipment overloads. The studied model is a large-scale wind farm of 120 MW in the Gulf El-Zayt region, Red Sea, Egypt. The control system validity is substantiated by studying different cases of wind speed function: ramp, step, random, and extreme wind speed. The results are compared with the traditional combined control. The model is simulated using MATLAB/SIMULINK software. The simulation results proved the effectiveness of fuzzy tuned PI against traditional PI control. Full article
(This article belongs to the Section Turbomachinery)
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Article
PFC-Based Control of Friction-Induced Instabilities in Drive Systems
Machines 2021, 9(7), 134; https://doi.org/10.3390/machines9070134 - 16 Jul 2021
Viewed by 249
Abstract
This paper is concerned with control-based damping of friction-induced self-excited oscillations that appear in electromechanical systems with an elastic shaft. This approach does not demand additional oscillations measurements or an observer design. The control system provides the angular velocity and damping control via [...] Read more.
This paper is concerned with control-based damping of friction-induced self-excited oscillations that appear in electromechanical systems with an elastic shaft. This approach does not demand additional oscillations measurements or an observer design. The control system provides the angular velocity and damping control via the combination of a parallel feed-forward compensator (PFC) and adaptive λ-tracking feedback control. The PFC is designed to stabilize the zero dynamics of an augmented system and renders it almost strict positive real (ASPR). The proposed control approach is tested in simulations. Full article
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Article
VIAM-USV2000: An Unmanned Surface Vessel with Novel Autonomous Capabilities in Confined Riverine Environments
Machines 2021, 9(7), 133; https://doi.org/10.3390/machines9070133 - 15 Jul 2021
Viewed by 342
Abstract
Unmanned Surface Vessels (USVs) have witnessed an increasing growth in demand for development due to their compactness, mobility and maneuverability, which make them well-suited for environmental monitoring on narrow water in Vietnam in particular and in general at several similar tropical regions. However, [...] Read more.
Unmanned Surface Vessels (USVs) have witnessed an increasing growth in demand for development due to their compactness, mobility and maneuverability, which make them well-suited for environmental monitoring on narrow water in Vietnam in particular and in general at several similar tropical regions. However, current surface vessels are limited to operation on open water only. In this paper, we design a USV, namely, VIAM-USV2000, equipped with advanced autonomous capabilities to satisfactorily carry out missions in confined riverine environments. More specifically, our prototype is designed to follow a smooth B-Spline path that is self-planned to meet the limiting curvature and avoid static obstacles. Moreover, the vessel is capable of avoiding dynamic obstacles by an advanced Set-based Guidance mechanism. Simulated and experimental results at a local lake prove the effectiveness of the proposed capabilities, thereby paving the way for the extensive deployment of USVs in many real-world applications. Full article
(This article belongs to the Special Issue Dynamics and Motion Control of Unmanned Aerial/Underwater Vehicles)
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Article
Conceptual Design of a High-Speed Wire EDM Robotic End-Effector Based on a Systematic Review Followed by TRIZ
Machines 2021, 9(7), 132; https://doi.org/10.3390/machines9070132 - 07 Jul 2021
Viewed by 417
Abstract
Exotic materials such as titanium offer superior characteristics that, paradoxically, make them hard-to-cut by conventional machining. As a solution, electric discharge machining (EDM) stands out as a non-conventional process able to cut complex profiles from hard-to-cut materials, delivering dimensional accuracy and a superior [...] Read more.
Exotic materials such as titanium offer superior characteristics that, paradoxically, make them hard-to-cut by conventional machining. As a solution, electric discharge machining (EDM) stands out as a non-conventional process able to cut complex profiles from hard-to-cut materials, delivering dimensional accuracy and a superior surface. However, EDM is embodied in CNC machines with a reduced axis and machining envelope, which constrains design freedom in terms of size and shape. To overcome these CNC constraints, traditional machining using six-axis industrial robots have become a prominent research field, and some applications have achieved cost efficiency, an improved envelope, and high flexibility. However, due to the lack of stiffness and strength of the robot arm, accuracy, material rate removal, and surface finishing are not comparable to CNC machining. Therefore, the present study investigates the design of a novel WEDM combined with six-axis robotic machining to overcome the limitations of traditional robotic machining and enhance EDM applications. This study extends the work of a conference paper to confirm potential outcomes, quantifying and ranking undesired interactions to map technical problems and applying the TRIZ approach to trigger solutions. Finally, an effective robotic end-effector design is proposed to free EDM from CNC and deliver robotic machining as a flexible and accurate machining system for exotic materials. Full article
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Article
Investigation of Characteristics of a Novel Torque Motor Based on an Annulus Air Gap
Machines 2021, 9(7), 131; https://doi.org/10.3390/machines9070131 - 07 Jul 2021
Viewed by 397
Abstract
Although a two-dimensional (2D) valve has excellent performance, the processing of its spiral groove has a high cost and is time-consuming. This paper proposes a novel torque motor based on an annulus air gap (TMAAG) to replace the negative feedback function of the [...] Read more.
Although a two-dimensional (2D) valve has excellent performance, the processing of its spiral groove has a high cost and is time-consuming. This paper proposes a novel torque motor based on an annulus air gap (TMAAG) to replace the negative feedback function of the spiral groove to reduce the machining difficulty. In order to study the torque change law of the TMAAG, the air gap permeance was analyzed, and then a qualitative analytical model was established. Orthogonal tests were carried out to initially select the crucial parameters, which were further optimized through a back propagation (BP) neural network and genetic algorithm. The prototype of TMAAG was machined, and a special experimental platform was built, and experiment results are similar to the simulation values, which verifies the accuracy of the air gap analysis and qualitative model. For torque-angle characteristics, the output torque increases with both current and rotation angle and reaches about 0.754 N·m with 2 A and 1.5°. While for torque-displacement characteristics, due to the negative feedback mechanism, the output torque decreases with increasing armature displacement, which is about 0.084 N·m with 2 A and 1 mm. The research validates the unique negative feedback mechanism of the TMAAG and indicates that it can be potentially used as an electro-mechanical converter of a 2D valve. Full article
(This article belongs to the Section Electrical Machines and Drives)
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Article
Real-Time Hybrid Deep Learning-Based Train Running Safety Prediction Framework of Railway Vehicle
Machines 2021, 9(7), 130; https://doi.org/10.3390/machines9070130 - 29 Jun 2021
Viewed by 404
Abstract
Train running safety is considered one of the key criteria for advanced highway trains and bogies. While a number of existing research studies have focused on its measurement and monitoring, this study proposes a new and effective train running a safety prediction framework. [...] Read more.
Train running safety is considered one of the key criteria for advanced highway trains and bogies. While a number of existing research studies have focused on its measurement and monitoring, this study proposes a new and effective train running a safety prediction framework. The wheel derail coefficient, wheel rate of load reduction, and wheel lateral pressure are considered the decision variables for the safety framework. Data for actual measured rail conditions and vibration-based signals are used as the input data. However, advanced trains and bogies are influenced more by their inertial structures and mechanisms than by railway conditions and external environments. In order to reflect their inertial influences, past data of output variables are used as recurrent data. The proposed framework shares advantages of a general deep neural network and a recurrent neural network. To prove the effectiveness of the proposed hybrid deep-learning framework, numerical analyses using an actual measured train-railway model and transit simulation are conducted and compared with the existing deep learning architectures. Full article
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Article
Stability Analysis of a Fractional-Order High-Speed Supercavitating Vehicle Model with Delay
Machines 2021, 9(7), 129; https://doi.org/10.3390/machines9070129 - 24 Jun 2021
Viewed by 438
Abstract
A novel fractional-order model (FOM) of a high-speed super-cavitating vehicle (HSSV) with the nature of memory is proposed and investigated in this paper. This FOM can describe the behavior of the HSSV superior to the integer-order model by the memory effects of fractional-order [...] Read more.
A novel fractional-order model (FOM) of a high-speed super-cavitating vehicle (HSSV) with the nature of memory is proposed and investigated in this paper. This FOM can describe the behavior of the HSSV superior to the integer-order model by the memory effects of fractional-order derivatives. The fractional order plays the role of the advection delay, which is ignored in most of the prior studies. This new model takes into account the effect of advection delay while preserving the nonlinearity of the mathematical equations. It allows the analysis of nonlinear equations describing the vehicle with ease when eliminating the delay term in its equations. By using the fractional order to avoid the approximation of the delay term, the proposed FOM can also preserve the nature of the time delay. The numerical simulations have been carried out to study the behavior of the proposed model through the transient responses and bifurcation diagrams concerning the fractional-order and vehicle speed. The bifurcation diagrams provide useful information for a better control and design of new supper super-cavitating vehicles. The similar behaviors between the proposed model and prior ones validate the FOM while some discrepancies suggest that more appropriate controllers should be designed based on this new model. Full article
(This article belongs to the Special Issue Dynamics and Motion Control of Unmanned Aerial/Underwater Vehicles)
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Article
Research on the Volumetric Efficiency of a Novel Stacked Roller 2D Piston Pump
Machines 2021, 9(7), 128; https://doi.org/10.3390/machines9070128 - 24 Jun 2021
Cited by 1 | Viewed by 336
Abstract
In order to improve the volumetric efficiency of the axial piston pump, this paper proposes a novel stacked roller 2D piston pump. It utilizes the alternate communication between the distribution cylinder and the oil intake and discharge ports of the housing to realize [...] Read more.
In order to improve the volumetric efficiency of the axial piston pump, this paper proposes a novel stacked roller 2D piston pump. It utilizes the alternate communication between the distribution cylinder and the oil intake and discharge ports of the housing to realize the flow distribution. While removing the independent flow distribution mechanism of the traditional piston pump, the leakage loss at the distribution friction pair can be reduced to improve the volumetric efficiency. Based on the flow distribution principle, an analytical model of the volumetric efficiency of the stacked roller 2D piston pump was established. Then, a co-simulation model of the whole pump was built using both the Simulink and AMESim software. The variation curve of output flow and leakage flow under different load pressures and rotational speeds was obtained, as well as the influence of backflow, axial leakage, and circumferential leakage on the volumetric efficiency. On this basis, a prototype of the stacked roller 2D pump was designed and manufactured in order to measure the output flow under different load pressures and rotational speeds, and a dedicated test bench was established. The experimental results are consistent with the simulation results; when the rotational speed is 6000 rpm and the load pressure is 5 MPa, the volumetric efficiency of the prototype pump can reach 98.6%. The research work validates that the novel stacked roller 2D piston pump has high volumetric efficiency. Full article
(This article belongs to the Section Machine Design and Theory)
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Article
Finding the Best Programmable PWM Pattern for Three-Level Active Front-Ends at 18-Pulse Connection
Machines 2021, 9(7), 127; https://doi.org/10.3390/machines9070127 - 23 Jun 2021
Viewed by 387
Abstract
The existing publications on the analysis of power quality indicators in modern electric power supply systems are void of a comprehensive approach to improving these indicators in power systems by implementing multipulse connections. To the authors’ knowledge, this paper is the first to [...] Read more.
The existing publications on the analysis of power quality indicators in modern electric power supply systems are void of a comprehensive approach to improving these indicators in power systems by implementing multipulse connections. To the authors’ knowledge, this paper is the first to analyze current harmonic distortions in an 18-pulse connection of three-level active front-ends (AFE) featuring a programmed PWM. Raw data were obtained from, and current quality was analyzed for the power circuit of the main electric drive actuating the rolls in the rolling stand of a plate mill. The key feature of such circuitry is that the synchronous motor of each work roll is connected to the grid with an 18-pulse connection that uses three phase-shift transformers, where the phase shifts are 0° (delta/delta), 20° (delta/polygon) and −20° (delta/polygon). The circuitry connects three frequency converters (FC) with the AFEs in parallel. Phase-shift transformers were found to periodically overheat in the process. When overheating occurred, a programmed PWM voltage waveform was applied where harmonics 17 and 19 were eliminated. The goal and objectives were to analyze why the transformer would overheat and to find out how the issue could be addressed. The authors developed a simulation model of the research object in order to assess power quality parameters. Simulation results obtained in Matlab/Simulink were used to estimate the total harmonic distortions (THD) and individual harmonic factors for up to the 50th secondary transformer winding and grid harmonic with four different programmed AFE PWM voltage waveforms. The results helped find the best such waveform to prevent phase-shift transformers from overheating; one with harmonics 5, 7, 17 and 19 eliminated. The experimental and mathematical modeling results in the paper were confirmed by positive effects after industrial implementation of the system. Research performed directly on the operating equipment has been classified by the company and is not publicly available. These results are highly versatile and could be used in similar research on other circuitries to ensure the electromagnetic compatibility of nonlinear power-consuming devices. Full article
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