Machines

6710 KiB

Open AccessArticle

Vibration Protection of a Famous Statue against Ambient and Earthquake Excitation Using A Tuned Inerter–Damper

by Ali Siami, Alfredo Cigada, Hamid Reza Karimi and Emanuele Zappa

Machines 2017, 5(4), 33; https://doi.org/10.3390/machines5040033 - 20 Dec 2017

Cited by 14 | Viewed by 5041

This paper deals with the performance analysis of a vibration-isolation system for Michelangelo Buonarroti’s famous Ronadanini Pietà statue based on the monitoring and analysis of vibration signals. A tuned mass-damper–inerter is introduced in order to increase the effectiveness of the isolator in the [...] Read more.

This paper deals with the performance analysis of a vibration-isolation system for Michelangelo Buonarroti’s famous Ronadanini Pietà statue based on the monitoring and analysis of vibration signals. A tuned mass-damper–inerter is introduced in order to increase the effectiveness of the isolator in the horizontal direction. Specifically, a multi-degree-of-freedom (MDOF) model for the system, including non-linear terms, is proposed. The monitoring data of the structure inside the museum were utilized to update the MDOF model of this structure. Then, the effect of different parameters was analysed, and some modifications proposed to enhance the efficiency of the isolation system in its working condition. A combination of tuned mass-dampers (TMD) with an inerter is proposed to attain a considerable increase in the performance of the isolation system based on the main feature of the tuned mass-damper–inerter (TMDI), which can apply high apparent mass to a system without adding considerable real mass to the original system. Various performance functions are used to illustrate the efficiency of the proposed TMDI. It is shown that a significant effect of this passive method is to reduce the level of vibration in the updated model of this sensitive and valuable object. Full article

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10300 KiB

Open AccessArticle

A Moving 3D Laser Scanner for Automated Underbridge Inspection

by Marco Tarabini, Hermes Giberti, Silvio Giancola, Matteo Sgrenzaroli, Remo Sala and Federico Cheli

Machines 2017, 5(4), 32; https://doi.org/10.3390/machines5040032 - 19 Dec 2017

Cited by 5 | Viewed by 4764

Abstract

Recent researches have proven that the underbridge geometry can be reconstructed by mounting a 3D laser scanner on a motorized cart travelling on a walkway located under the bridge. The walkway is moved by a truck and the accuracy of the bridge model [...] Read more.

Recent researches have proven that the underbridge geometry can be reconstructed by mounting a 3D laser scanner on a motorized cart travelling on a walkway located under the bridge. The walkway is moved by a truck and the accuracy of the bridge model depends on the accuracy of the trajectory of the scanning head with respect to a fixed reference system. In this paper, we describe a vision-based measurement system that can be used to identify the relative motion of the cart that moves the 3D laser scanner with respect to the walkway. The orientation of the walkway with respect to the bridge is determined using inclinometers and a camera that detect the position of a laser spot, while the position of the truck with respect to the bridge is measured using a conventional odometer. The accuracy of the proposed system was initially evaluated by numerical simulations and successively verified by experiments in laboratory conditions. The complete system has then been tested by comparing the geometry of buildings reconstructed using the proposed system with the geometry obtained with a static scan. Results showed that the error is less than 6 mm; given the satisfying quality of the point clouds obtained, it is also possible to detect small defects on the surface. Full article

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1459 KiB

Open AccessArticle

Equivalence Analysis of Mass and Inertia for Simulated Space Manipulator Based on Constant Mass

by Sihui Tian, Xiaoqiang Tang and Chengyuan Xiang

Machines 2017, 5(4), 31; https://doi.org/10.3390/machines5040031 - 7 Dec 2017

Cited by 3 | Viewed by 3647

Abstract

A simulated space manipulator is designed to verify the reliability of the zero-gravity simulation system, which can avoid the risks of experiments involving the space manipulator in this zero-gravity ground system. To achieve similarity between the simulated and actual space manipulators, the mass, [...] Read more.

A simulated space manipulator is designed to verify the reliability of the zero-gravity simulation system, which can avoid the risks of experiments involving the space manipulator in this zero-gravity ground system. To achieve similarity between the simulated and actual space manipulators, the mass, barycenter, and inertia must be considered. In this study, a counterweight component is designed and an optimization method is used to match the mass parameters of the simulated joints to those of the space joints. In addition, an equivalence method is used to establish the relationship between the torques of these two manipulators. Full article

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9269 KiB

Open AccessArticle

Iron Loss Prediction Using Modified IEM-Formula during the Field Weakening for Permanent Magnet Synchronous Machines

by Pedram Asef, Ramon Bargallo and Andrew Lapthorn

Machines 2017, 5(4), 30; https://doi.org/10.3390/machines5040030 - 5 Dec 2017

Cited by 7 | Viewed by 6058

Abstract

During field weakening operation time (FWOT), the total iron loss rises and affects the accuracy of loss prediction and efficiency, especially if a large range of FWOT exists due to a large voltage drop that was rooted from the resistance of the used [...] Read more.

During field weakening operation time (FWOT), the total iron loss rises and affects the accuracy of loss prediction and efficiency, especially if a large range of FWOT exists due to a large voltage drop that was rooted from the resistance of the used material. Iron loss prediction is widely employed in investigations for a fast electrical machine analysis using 2D finite element analysis (FEA). This paper proposes harmonic loss analytically by a steady-state equivalent circuit with a novel procedure. Consideration of skin effects and iron saturation are utilized in order to examine the accuracy through the relative error distribution in the frequency domain of each model from 50 to 700 Hz. Additionally, this comparative study presents a torque-frequency-field density calculation over each single term of the modified institute of electrical machines formula (IEM-Formula). The proposed analytical calculation is performed using 2D FEA for a classic and modified IEM-Formula along with experimental verifications on a surface-mounted permanent magnet synchronous generator (PMSG) for a wind generation application. Full article

(This article belongs to the Special Issue High Speed Motors and Drives: Design, Challenges and Applications)

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10503 KiB

Open AccessArticle

Mechatronic Design for an Extrusion-Based Additive Manufacturing Machine

by Hermes Giberti, Luca Sbaglia and Marco Silvestri

Machines 2017, 5(4), 29; https://doi.org/10.3390/machines5040029 - 29 Nov 2017

Cited by 30 | Viewed by 7134

Abstract

3D printers, especially in the implementation of innovative extrusion processes which do not have a long history of development, are often built by adapting mechanical designs, drives and controls previously developed for generic machine tools. This is done through a process of choice [...] Read more.

3D printers, especially in the implementation of innovative extrusion processes which do not have a long history of development, are often built by adapting mechanical designs, drives and controls previously developed for generic machine tools. This is done through a process of choice and integration which is based principally on empirical criteria and taking into account separately the different aspects and parameters. Hereafter, we present an integrated mechatronic approach which has been adopted to design from the scratch a machine to implement the innovative metal injection moulding (MIM) technology. Its extrusion rate involves the adaptation of the generated trajectories and consequently requires “ad hoc” designs, drives and numerical controls (NC) to enable non standard acceleration (and hence torque) setpoint curves. Overall, the project resulted in an acceptable workspace volume (depending on the number of degrees of freedom of the platform) and allows one to combine the extruder flow rate, the given accuracy and the required working speed (1 m/s). The system is currently used as a test bench for exploring and optimizing the parameter space of a new MIM process. Full article

(This article belongs to the Special Issue Process Innovation in Digital Manufacturing)

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2666 KiB

Open AccessArticle

Utilizing Sequential Action Control Method in GaN-Based High-Speed Drive for BLDC Motor

by Payam Niknejad, Tanushree Agarwal and M. R. Barzegaran

Machines 2017, 5(4), 28; https://doi.org/10.3390/machines5040028 - 21 Nov 2017

Cited by 5 | Viewed by 4792

Abstract

This paper presents a hybrid model–based control algorithm that combines Model Predictive Control (MPC) and Sequential Action Control (SAC) deployed in a high-speed drive for Brushless DC (BLDC) motor by using a DC-DC converter with Gallium Nitride (GaN) switches. GaN FETs are selected [...] Read more.

This paper presents a hybrid model–based control algorithm that combines Model Predictive Control (MPC) and Sequential Action Control (SAC) deployed in a high-speed drive for Brushless DC (BLDC) motor by using a DC-DC converter with Gallium Nitride (GaN) switches. GaN FETs are selected because of their higher speed and lower power loss as compared with traditional Si switches. In the proposed framework, SAC processes the initial values of the control variables as well as their time of application and their duration in MPC loop. After receiving the underlying estimation of future contribution from SAC, MPC consolidates it with current input and predicts future control values by using the system state space model. This hybrid control conserves control effort and reduces sensitivity to initial conditions. In this way, converter’s output voltage is controlled to produce the reference speed at the motor output. National Instrument PXIe-6356 module is utilized as the interface between software and hardware that is a multi-function, LabVIEW-compatible data acquisition device. The viability of the proposed hybrid optimization for the high-speed drive is confirmed numerically by utilizing MATLAB/Simulink and approved experimentally using a Gallium Nitride (GaN) half-bridge DC-DC converter. Full article

(This article belongs to the Special Issue High Speed Motors and Drives: Design, Challenges and Applications)

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5268 KiB

Open AccessArticle

The Decision making System for Condition Monitoring of Induction Motors Based on Vector Control Model

by Abdullah Alwadie

Machines 2017, 5(4), 27; https://doi.org/10.3390/machines5040027 - 12 Nov 2017

Cited by 11 | Viewed by 4853

Abstract

Induction motors are mainly used for variable load applications and it is vital to have a condition monitoring system with capabilities to diagnose motor faults in variable load conditions. The environment noise varies has non-linear relation with motor load and it challenges the [...] Read more.

Induction motors are mainly used for variable load applications and it is vital to have a condition monitoring system with capabilities to diagnose motor faults in variable load conditions. The environment noise varies has non-linear relation with motor load and it challenges the decision making capability of the condition monitoring system. This paper addresses the issue of reliable decision making on the existence of bearing faults in variable load conditions. Two type of threshold schemes have been proposed to reliably diagnose bearing faults in Park vector modulus spectrum. The performance of the developed threshold based condition monitoring system has been analyzed theoretically and experimentally. Full article

(This article belongs to the Special Issue Machinery Condition Monitoring and Industrial Analytics)

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6329 KiB

Open AccessArticle

Modeling, Analysis, and Realization of Permanent Magnet Synchronous Motor Current Vector Control by MATLAB/Simulink and FPGA

by Chiu-Keng Lai, Yao-Ting Tsao and Chia-Che Tsai

Machines 2017, 5(4), 26; https://doi.org/10.3390/machines5040026 - 28 Oct 2017

Cited by 13 | Viewed by 11504

Abstract

In this paper, we present the modeling, analysis, and realization of current vector control for a permanent magnet synchronous motor (PMSM) drive using MATLAB/Simulink and a field programmable gate array (FPGA). In AC motor drive systems, most of the current vector controls are [...] Read more.

In this paper, we present the modeling, analysis, and realization of current vector control for a permanent magnet synchronous motor (PMSM) drive using MATLAB/Simulink and a field programmable gate array (FPGA). In AC motor drive systems, most of the current vector controls are realized by digital signal processors (DSPs) because of their complete and compact hardware functions. However, the performances of drive systems realized by low-cost DSP are limited by the hardware structure and computation capacity, which may lead to the difficulty of reaching a fast enough response, above all, for those motors with a small electrical time constant. Therefore, we use FPGA to speed up the calculation about the current vector control to attain a fast response. Simulations and practical experimental results are used to verify the correctness and performance of the designed full hardware system. Full article

(This article belongs to the Special Issue High Speed Motors and Drives: Design, Challenges and Applications)

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1864 KiB

Open AccessFeature PaperArticle

Virtual Reference Feedback Tuning of Model-Free Control Algorithms for Servo Systems

by Raul-Cristian Roman, Mircea-Bogdan Radac, Radu-Emil Precup and Emil M. Petriu

Machines 2017, 5(4), 25; https://doi.org/10.3390/machines5040025 - 24 Oct 2017

Cited by 28 | Viewed by 5592

Abstract

This paper proposes the combination of two data-driven techniques, namely virtual reference feedback tuning (VRFT) and model-Free Control (MFC) in terms of the VRFT of MFC algorithms dedicated to servo systems. VRFT ensures the automatic optimal computation of the parameters of three MFC [...] Read more.

This paper proposes the combination of two data-driven techniques, namely virtual reference feedback tuning (VRFT) and model-Free Control (MFC) in terms of the VRFT of MFC algorithms dedicated to servo systems. VRFT ensures the automatic optimal computation of the parameters of three MFC algorithms represented by intelligent proportional (iP), intelligent proportional-integral (iPI), and intelligent proportional-integral-derivative (iPID) controllers. The combination of MFC and VRFT leads to a novel mixed MFC-VRFT approach. The approach is validated by experimental results related to the angular speed control of modular servo system laboratory equipment. The performance of the control systems with the MFC algorithms (iP, iPI, and iPID controllers) tuned by the mixed MFC-VRFT approach is compared with that of control systems with MFC algorithms tuned by a metaheuristics gravitational search algorithm (GSA) optimizer, and of control systems with I, PI and PID controllers optimally tuned by VRFT and GSA in the same optimization problem. Full article

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1110 KiB

Open AccessReview

Rotating Electrical Machine Condition Monitoring Automation—A Review

by Mallikarjun Kande, Alf J. Isaksson, Rajeev Thottappillil and Nathaniel Taylor

Machines 2017, 5(4), 24; https://doi.org/10.3390/machines5040024 - 19 Oct 2017

Cited by 47 | Viewed by 11471

Abstract

We review existing machine condition monitoring techniques and industrial automation for plant-wide condition monitoring of rotating electrical machines. Cost and complexity of a condition monitoring system increase with the number of measurements, so extensive condition monitoring is currently mainly restricted to the situations [...] Read more.

We review existing machine condition monitoring techniques and industrial automation for plant-wide condition monitoring of rotating electrical machines. Cost and complexity of a condition monitoring system increase with the number of measurements, so extensive condition monitoring is currently mainly restricted to the situations where the consequences of poor availability, yield or quality are so severe that they clearly justify the investment in monitoring. There are challenges to obtaining plant-wide monitoring that includes even small machines and non-critical applications. One of the major inhibiting factors is the ratio of condition monitoring cost to equipment cost, which is crucial to the acceptance of using monitoring to guide maintenance for a large fleet of electrical machinery. Ongoing developments in sensing, communication and computation for industrial automation may greatly extend the set of machines for which extensive monitoring is viable. Full article

(This article belongs to the Special Issue Machinery Condition Monitoring and Industrial Analytics)

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6520 KiB

Open AccessArticle

Toilet Assistive System Designed for the Reduction of Accidental Falls in the Bathroom Using Admittance Controller

by Martin J.-D. Otis, Abid Adjelane, Eric Jomphe and Khaled Youssef

Machines 2017, 5(4), 23; https://doi.org/10.3390/machines5040023 - 13 Oct 2017

Cited by 3 | Viewed by 5412

Abstract

This paper suggests an assistive system for the toilet with the objective of measuring human activities and to provide intelligent mechanical assistance to help seating and standing. The project intends to develop a seating assistance as a technical aid in order to reduce [...] Read more.

This paper suggests an assistive system for the toilet with the objective of measuring human activities and to provide intelligent mechanical assistance to help seating and standing. The project intends to develop a seating assistance as a technical aid in order to reduce accidents and falls in the bathroom. The preferred technique is human-robot physical interaction algorithms known in collaborative robotics (cobot) and adapting it to a personalized assistance technology installed on a smart toilet. First, the design of the mechanical assistance is presented. Then, an admittance controller is designed and implemented in order to help the user in a similar way as a cobot could be used. This technique could be used to assist the user and improve balance with adequate training and an adequate configuration of the admittance controller. Full article

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4653 KiB

Open AccessArticle

Quantification of a Low-Cost Stretchable Conductive Sensor Using an Expansion/Contraction Simulator Machine: A Step towards Validation of a Noninvasive Cardiac and Respiration Monitoring Prototype

by Elham Shabani Varaki, Paul P. Breen and Gaetano D. Gargiulo

Machines 2017, 5(4), 22; https://doi.org/10.3390/machines5040022 - 6 Oct 2017

Cited by 16 | Viewed by 4072

Abstract

The use of wearable sensors in health monitoring is increasing dramatically, largely due to their convenience and low-cost. Understanding the accuracy of any given sensor is paramount to avoid potential misdiagnosis. Commercially available electro-resistive band (ERB) sensors have been integrated into several newly [...] Read more.

The use of wearable sensors in health monitoring is increasing dramatically, largely due to their convenience and low-cost. Understanding the accuracy of any given sensor is paramount to avoid potential misdiagnosis. Commercially available electro-resistive band (ERB) sensors have been integrated into several newly developed wearable devices with a view to using these sensors to monitor a range of respiratory and cardiovascular metrics. Quantification of the ERBs is a necessary to step towards validation of these prototypes, as it provides valuable information, which could be exploited for compensation and ultimately, for improvement of their performance. Here, we present an analysis of the ERB sensors using an expansion/contraction simulator machine. Using the developed rig, the characteristics of four ERBs were compared with a linear displacement sensor (string potentiometer) during continuous use over the course of four-and-a-half days to investigate the error and nonlinearity of the ERBs. The analysis of the recorded data includes calculation and comparison of the total harmonic distortions of the two sensors to quantify ERB nonlinearity. Moreover, comparisons between the peak-to-peak voltages and signal-to-noise ratios of the ERB and string potentiometer demonstrate the effect nonlinearity on these factors. This paper demonstrates the nonlinearity of ERBs and highlights the implications for their use in practice. Full article

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5781 KiB

Open AccessReview

A Review of Feature Extraction Methods in Vibration-Based Condition Monitoring and Its Application for Degradation Trend Estimation of Low-Speed Slew Bearing

by Wahyu Caesarendra and Tegoeh Tjahjowidodo

Machines 2017, 5(4), 21; https://doi.org/10.3390/machines5040021 - 27 Sep 2017

Cited by 350 | Viewed by 17602

Abstract

This paper presents an empirical study of feature extraction methods for the application of low-speed slew bearing condition monitoring. The aim of the study is to find the proper features that represent the degradation condition of slew bearing rotating at very low speed [...] Read more.

This paper presents an empirical study of feature extraction methods for the application of low-speed slew bearing condition monitoring. The aim of the study is to find the proper features that represent the degradation condition of slew bearing rotating at very low speed (≈ 1 r/min) with naturally defect. The literature study of existing research, related to feature extraction methods or algorithms in a wide range of applications such as vibration analysis, time series analysis and bio-medical signal processing, is discussed. Some features are applied in vibration slew bearing data acquired from laboratory tests. The selected features such as impulse factor, margin factor, approximate entropy and largest Lyapunov exponent (LLE) show obvious changes in bearing condition from normal condition to final failure. Full article

(This article belongs to the Special Issue Machinery Condition Monitoring and Industrial Analytics)

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Machines, Volume 5, Issue 4 (December 2017) – 13 articles

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