Stability control of permanent magnet and electromagnetic hybrid Halbach array electrodynamic suspension system

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Cheng Luo ◽  
Kunlun Zhang ◽  
Da Liang ◽  
Yongzhi Jing
Keyword(s):  
Levitation Force ◽  
External Disturbance ◽  
Stability Control ◽  
Suspension Stability ◽  
Content Type ◽  
Analytical Expression ◽  
The Poor ◽  
Halbach Array ◽  
Acceleration Feedback ◽  
Electrodynamic Suspension

Purpose The purpose of the paper is to study the stability control of permanent magnet (PM) and electromagnetic hybrid Halbach array electrodynamic suspension (EDS) system because of the poor suspension stability caused by the well-known under-damped nature of PM EDS system. The adjustment control is realized by PM and electromagnetic hybrid Halbach array, which is composed by winding active normal conductor coils on PM surface. Design/methodology/approach The three-dimensional (3-D) electromagnetic force analytical expression of PM and electromagnetic hybrid Halbach array EDS system for a nonmagnetic conductive plate is derived. And the accuracy of the derived equations is verified by a 3-D finite-element model (FEM). Basing on the 3-D levitation force expression, an acceleration feedback suspension controller is designed to suppress the vibration of PM EDS system, and the suspension stability of the system under the track and load disturbance was simulated and analyzed. Findings The 3-D electromagnetic force comparison of analytical model and FEM are in good agreement, which verifies the correctness of the analytical expression. The simulation results show that the acceleration feedback suspension controller can make the system have good suspension stability under the external disturbance. So it proved that the PM and electromagnetic hybrid Halbach array EDS system can overcome the poor suspension stability caused by the under-damped nature of PM EDS system through the designed acceleration feedback suspension controller. Originality/value This paper designed an acceleration feedback suspension controller to suppress the vibration of PM and electromagnetic hybrid Halbach array EDS system under external disturbance, basing on the derived levitation force analytical expression. And the simulation results show that the acceleration feedback suspension controller can make the system have good suspension stability under the external disturbance.

Visual servoing of dynamic wheeled mobile robots with anti-interference finite-time controllers

2018 ◽  
Vol 38 (5) ◽  
pp. 558-567 ◽  
Author(s):  
Hua Chen ◽  
Lei Chen ◽  
Qian Zhang ◽  
Fei Tong
Keyword(s):  
Mobile Robots ◽  
Finite Time ◽  
Visual Servoing ◽  
Control Method ◽  
External Disturbance ◽  
Nonholonomic Systems ◽  
Stability Control ◽  
Interference Control ◽  
Wheeled Mobile Robots ◽  
Content Type

Purpose The finite-time visual servoing control problem is considered for dynamic wheeled mobile robots (WMRs) with unknown control direction and external disturbance. Design/methodology/approach By using finite-time control method and switching design technique. Findings First, the visual servoing kinematic WMR model is developed, which can be converted to the dynamic chained-form systems by using a state and input feedback transformation. Then, for two decoupled subsystems of the chained-form systems, according to the finite-time stability control theory, a discontinuous three-step switching control strategy is proposed in the presence of uncertain control coefficients and external disturbance. Originality/value A class of discontinuous anti-interference control method has been presented for the dynamic nonholonomic systems.

Stability control for end effect of mobile manipulator in uneven terrain based on active disturbance rejection control

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Chuang Cheng ◽  
Hui Zhang ◽  
Hui Peng ◽  
Zhiqian Zhou ◽  
Bailiang Chen ◽  
...  
Keyword(s):  
Disturbance Rejection ◽  
Control Method ◽  
External Disturbance ◽  
Stability Control ◽  
Mobile Manipulator ◽  
Active Disturbance Rejection Control ◽  
End Effector ◽  
Content Type ◽  
Active Disturbance Rejection ◽  
Disturbance Rejection Control

Purpose When the mobile manipulator is traveling on an unconstructed terrain, the external disturbance is generated. The load on the end of the mobile manipulator will be affected strictly by the disturbance. The purpose of this paper is to reject the disturbance and keep the end effector in a stable pose all the time, a control method is proposed for the onboard manipulator. Design/methodology/approach In this paper, the kinematics and dynamics models of the end pose stability control system for the tracked robot are built. Through the guidance of this model information, the control framework based on active disturbance rejection control (ADRC) is designed, which keeps the attitude of the end of the manipulator stable in the pitch, roll and yaw direction. Meanwhile, the control algorithm is operated with cloud computing because the research object, the rescue robot, aims to be lightweight and execute work with remote manipulation. Findings The challenging simulation experiments demonstrate that the methodology can achieve valid stability control performance in the challenging terrain road in terms of robustness and real-time. Originality/value This research facilitates the stable posture control of the end-effector of the mobile manipulator and maintains it in a suitable stable operating environment. The entire system can normally work even in dynamic disturbance scenarios and uncertain nonlinear modeling. Furthermore, an example is given to guide the parameter tuning of ADRC by using model information and estimate the unknown internal modeling uncertainty, which is difficult to be modeled or identified.

Study on the characteristics of superconducting electrodynamic suspension system based on dynamic circuit theory

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Daoyu Hu ◽  
Maochun Zhai
Keyword(s):  
Analytical Model ◽  
Levitation Force ◽  
Superconducting Magnet ◽  
Circuit Theory ◽  
Parameter Study ◽  
Three Dimension ◽  
3D Fem ◽  
Content Type ◽  
Fem Method ◽  
Electrodynamic Suspension

Purpose The purpose of this paper is to analyze the influence of different parameters on the characteristics of the superconducting electrodynamic suspension (EDS) system. Design/methodology/approach The authors used an analytical model based on the dynamic circuit theory to perform the analysis. The authors proposed an inductance criterion to improve the calculation accuracy. They also proposed a three-dimension finite element method (FEM) to verify the validity of the analytical model. Findings The levitation force and guiding force increase with the superconducting magnet (SCM) speed and show a saturated trend, while the drag force decreases with the SCM speed. The vibration characteristic is the inherent characteristic of the superconducting EDS. The frequency and amplitude are affected by the gap between adjacent null-flux coils. The levitation force first increases and subsequently decreases with the levitation height. The total levitation force of the SCM increases with the superconducting coil (SC) number, while the average levitation force of an SC decreases with the SC number. The total levitation force nonlinearly increases with the SC number. Originality/value The authors introduced an inductance criterion for better understanding and using the analytical model, and they also proposed a 3D FEM method. The 3D FEM method could be extended to simulate the other EDS systems with more complex structures which the numerical model is no longer applicable. The results of the parameter study could deepen people’s understanding of EDS.

scholarly journals A numerical approach for the modelling of forming limits in hot incremental forming of AZ31 magnesium alloy

2021 ◽  
Author(s):  
Davide Campanella ◽  
Gianluca Buffa ◽  
Ernesto Lo Valvo ◽  
Livan Fratini
Keyword(s):  
Room Temperature ◽  
Incremental Forming ◽  
Material Model ◽  
Numerical Approach ◽  
Forming Limit ◽  
Material Strength ◽  
Wall Angle ◽  
Analytical Expression ◽  
The Poor ◽  
Specific Material

AbstractMagnesium alloys, because of their good specific material strength, can be considered attractive by different industry fields, as the aerospace and the automotive one. However, their use is limited by the poor formability at room temperature. In this research, a numerical approach is proposed in order to determine an analytical expression of material formability in hot incremental forming processes. The numerical model was developed using the commercial software ABAQUS/Explicit. The Johnson-Cook material model was used, and the model was validated through experimental measurements carried out using the ARAMIS system. Different geometries were considered with temperature varying in a range of 25–400 °C and wall angle in a range of 35–60°. An analytical expression of the fracture forming limit, as a function of temperature, was established and finally tested with a different geometry in order to assess the validity.

Composite Nonlinear Feedback for Vehicle Active Front Steering

2014 ◽  
Vol 663 ◽  
pp. 127-134 ◽  
Author(s):  
M.H. Che Hasan ◽  
Y.M. Sam ◽  
Ke Mao Peng ◽  
Muhamad Khairi Aripin ◽  
Muhamad Fahezal Ismail
Keyword(s):  
Control Method ◽  
Actuator Saturation ◽  
External Disturbance ◽  
Reference Signal ◽  
Stability Control ◽  
Nonlinear Feedback ◽  
Composite Nonlinear Feedback ◽  
Active Front Steering ◽  
Yaw Stability ◽  
Fast Settling

In this paper, Composite Nonlinear Feedback (CNF) is applied on Active Front Steering (AFS) system for vehicle yaw stability control in order to have an excellent transient response performance. The control method, which has linear and nonlinear parts that work concurrently capable to track reference signal very fast with minimum overshoot, fast settling time, and without exceed nature of actuator saturation limit. Beside, modelling of 7 degree of freedom for typical passenger car with magic formula to represent tyre nonlinearity behaviour is also presented to simulate controlled vehicle as close as possible with a real situation. An extensive computer simulation is performed with considering a various profile of cornering manoeuvres with external disturbance to evaluate its performance in different scenarios. The performance of the proposed controller is compared to conventional Proportional Integration and Derivative (PID) for effectiveness analysis.

Assessing the Livelihood Empowerment Against Poverty (LEAP) program as a conditional income transfer: a search for a conceptual framework

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alhassan Abdul-Wakeel Karakara ◽  
Ernest Amoabeng Ortsin
Keyword(s):  
Conceptual Framework ◽  
Poverty Reduction ◽  
Social Protection ◽  
Insurance Coverage ◽  
Implementation Strategies ◽  
Cash Transfer ◽  
Primary Data ◽  
Transfer Program ◽  
Content Type ◽  
The Poor

Purpose Ghana has implemented different kinds of pro-poor program and policies since its independence to reduce poverty. The Livelihood Empowerment Against Poverty (LEAP) is one of such program. LEAP is a social cash transfer program and its implementation has been under the auspices of the Ministry of Gender, Children and Social Protection since 2008. It provides direct cash and health insurance coverage for extremely poor households across the country to alleviate short-term poverty and encourage long-term human capital development. This paper examines the LEAP program in terms of how it has achieved its aim and the opportunities for improvement.Design/methodology/approach Primary data were obtained from interviews of 110 beneficiaries of the program. The study proposes a conceptual framework that links poverty reduction and social policies to assist researchers analyze pro-poor or social cash transfer program.Findings The findings show that the program is challenged with administrative bureaucracies, irregular inflow of funds, perceived political interferences, inconsistent implementation strategies and low value of the cash transfer (which results in little or no impact on consumption). However, the data also show that LEAP has positive impacts on nonconsumption spending like children's schooling. The program' exit strategy does not impact much on beneficiaries to allow them exit without the tendency of being poor.Practical implications This paper discussed the LEAP program as a social cash transfer to the poor in Ghana. The study constructed a conceptual framework to help researchers and practitioners analyze the implementation of pro-poor interventions. This conceptualization allows for cash transfer program to empower beneficiaries and exits them to allow for other beneficiaries to enroll, ensuring reduction in poverty over time. Generally, the beneficiaries have benefited from the LEAP in the areas of consumption, education and healthcare with few beneficiaries being able to accumulate some few assets. The LEAP program has no exit plan.Originality/value This study adds to literature by offering a conceptual framework to help researchers and policy makers in dealing with social assistance policies to the poor. The study also gave an insight into how pro-poor policy strategies could be crafted.

Adaptive neural-based finite-time attitude synchronization and tracking control of multiple rigid bodies under actuator faults and saturation

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Amin Mihankhah ◽  
Ali Doustmohammadi
Keyword(s):  
Finite Time ◽  
Tracking Control ◽  
Estimation Error ◽  
External Disturbance ◽  
Upper Bounds ◽  
Rigid Bodies ◽  
Sliding Surface ◽  
Actuator Faults ◽  
Content Type ◽  
Attitude Synchronization

Purpose The purpose of this paper, is to solve the problem of finite-time fault-tolerant attitude synchronization and tracking control of multiple rigid bodies in presence of model uncertainty, external disturbances, actuator faults and saturation. It is assumed that the rigid bodies in the formation may encounter loss of effectiveness and/or bias actuator faults. Design/methodology/approach For the purpose, adaptive terminal sliding mode control and neural network structure are used, and a new sliding surface is proposed to guarantee known finite-time convergence not only at the reaching phase but also on the sliding surface. The sliding surface is then modified using a proposed auxiliary system to maintain stability under actuator saturation. Findings Assuming that the communication topology between the rigid bodies is governed by an undirected connected graph and the upper bounds on the actuators’ faults, estimation error of model uncertainty and external disturbance are unknown, not only the attitudes of the rigid bodies in the formation are synchronized but also they track the time-varying attitude of a virtual leader. Using Lyapunov stability approach, finite-time stability of the proposed control algorithms demonstrated on the sliding phase as well as the reaching phase. The effectiveness of the proposed algorithm is also validated by simulation. Originality/value The proposed controller has the advantage that the need for any fault detection and diagnosis mechanism and the upper bounds information on estimation error and external disturbance is eliminated.

Control-oriented modeling for the electrodynamic levitation with permanent magnet Halbach array

2021 ◽  
pp. 1-19
Author(s):  
Yongpan Hu ◽  
Zhiqiang Long ◽  
Yunsong Xu ◽  
Zhiqiang Wang
Keyword(s):  
Permanent Magnet ◽  
Controller Design ◽  
Levitation Force ◽  
Model Based ◽  
Halbach Array ◽  
Validation Experiment ◽  
Electromagnetic Models ◽  
Two Stages ◽  
Poor Stability ◽  
Maximum Minimum

Poor stability of the permanent magnet electrodynamic levitation hinders its application in the maglev field. Therefore, building a control-oriented model to improve its stability is most challenging. However, intractable electromagnetic models leading to an implicit relationship between levitation force and gap, yields a barrier for model-based controller design. To solve the above-mentioned problem, this paper develops a control-oriented model by two stages. Specifically, the first stage is to show an explicit formula of the levitation force with regard to the levitation gap by neglecting end effect; meanwhile the “maximum–minimum rectification” method is put forward to evaluating an accurate levitation force. The second stage is to bring forth the control-oriented model on basis of the estimated levitation force. Although the paper focus mainly on the development of the control-oriented model, an example of PD controller is provided to verify its validation. Experiment results demonstrate the estimated levitation force is highly consistent with the real one. Simulation results show that the control-oriented model is sufficiently reliable. The research bridges the gap between the physical model and the model-based controller for the electrodynamic levitation with permanent magnet Halbach array.

COVID-19 pandemic and the poor in the urban spaces of India with special reference to Mumbai

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sujayita Bhattacharjee ◽  
Sanjukta Sattar
Keyword(s):  
Special Reference ◽  
Urban Poor ◽  
Secondary Data ◽  
Urban Spaces ◽  
Right To The City ◽  
Content Type ◽  
The Poor ◽  
The Social ◽  
Socioeconomic Crisis ◽  
The City

PurposeThe lives of the poor in the urban spaces of India are filled with hardships. They live amidst poverty and struggle to survive within other problems such as insecure jobs, lack of proper housing, unsanitary conditions and low levels of health immunity. This vulnerable section of the population has been rendered furthermore vulnerable by the outbreak of the COVID-19 pandemic in ways that were never imagined before. Taking this into consideration, the purpose of this article is to examine the vulnerability of the poor in the urban settings of India with special reference to Mumbai in the context of the COVID-19 pandemic.Design/methodology/approachThe methodology adopted in the study is based on the analysis of secondary data and content analysis of the existing literature. In addition to this, the study also makes use of certain narratives of the urban poor in Mumbai that have been captured by various articles, reports and blogs.FindingsThe findings of the study reveal how the urban poor of India, with special reference to Mumbai, the financial capital of India, has emerged as the worst sufferers of the socioeconomic crisis caused by the social distancing and lockdown measures imposed for combating the pandemic.Originality/valueThe study tries to explore the reality of the urban poor's right to the city in the wake of the pandemic.

Stakeholders and opportunities of debt settlement as a values-based banking activity in Hungary

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Zsuzsanna Győri ◽  
Borbála Benedek
Keyword(s):  
Research Question ◽  
Good Practice ◽  
Banking System ◽  
Financial Inclusion ◽  
Stressful Situation ◽  
Content Type ◽  
Main Research ◽  
The Poor ◽  
Lessons Learnt

Purpose The purpose of this paper is to discuss the stakeholders of debt settlement programmes in general and some lessons learnt from the most significant debt settlement programmes of recent years in Hungary. The study also presents a planned debt settlement programme in Hungary. The paper explores and details behaviours and motivations of different stakeholders in debt settlement in general and also with reference to a specific case study. As for its main research question, the paper seeks to identify the preconditions of a successful debt settlement programme with specially emphasis on the poor. Design/methodology/approach Data from semi-structured in-depth expert interviews, documents and former research papers were collected for identifying previous Hungarian debt settlement programmes and potential lessons learnt. After a general discussion, based on primary and secondary sources, a case study is presented to obtain a more comprehensive understanding of opportunities and challenges of debt settlement. Findings Six preconditions of successful debt settlement targeting the poor are identified. In the case study, the existence and relevance of these preconditions are tested: the main finding is that they all are important for solving the situations, so a partial solution is not sufficient. In the scope of the case study, more precisely within the planned innovative banking solution, the motivations of the bank and the coordinator NGO are identified. On the part of the bank, motivations for solving social problems (both as far as business and moral issues are concerned) are relevant, while – as for the other party – the situation of the debtor is important to understand so that opportunities of cooperation can be identified. In addition, as other stakeholders also influence the potentials of the programme, their cooperative attitude is also needed. Research limitations/implications Limitations consist in generalisation: the study presents some cases from one single country and finally it focuses only on one specific case in one specific social and economic context in Hungary. Having recognized this risk, the author opted for basing research questions on theory, documented the process in detail, and also used triangulation through applying a multiple data collection (interview, content analysis, literature review) method. Practical implications Besides presenting an academic understanding of the phenomena, the goal of the study is to contextualize and interpret the case, to help the realization of currently frozen initiatives and to promote similar future ones. Social implications Indebtedness is a stressful situation affecting families, smaller communities and broader society as well. The planned cooperation of BAGázs and MagNet tries to help people excluded from the banking system. So that a deeper debt trap can be avoided, the goal of this programme is to purchase, partially discharge and reschedule pre-accumulated debts of carefully selected people who have regular income and are willing to undertake bearable repayment. The idea is very innovative with literally no good practice to follow. The research seeks to clarify the pitfalls and opportunities to help the realization of the project and similar future ones. Originality/value A certain form of values-based banking concerns the financial inclusion of the poor, e.g. debt settlement. Nevertheless, over-indebtedness and the settlement of existing debts as well as the relevance of such issues to the financial inclusion are not emphasized enough in the literature or in practice. Besides presenting an academic understanding of the phenomena, the goal of the study is to contextualize and interpret the case, to help the realization of currently frozen initiatives and to promote similar future ones.

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