Control Of Mechanical Systems Research Articles

Robust tracking control of a differential drive wheeled mobile robot using fast nonsingular terminal sliding mode

Differential drive wheeled mobile robots (DDWMRs) have been widely used in various applications due to their maneuverability and energy-saving characteristics. Tracking control of such mechanical systems with nonholonomic constraints in the presence of uncertainties and disturbances has attracted much attention. In this paper, a robust control scheme is developed for trajectory tracking control of a DDWMR in the presence of parametric uncertainties and disturbances. To fulfill the controller design, an inner–outer loop control structure is adopted for the DDWMR. For the inner-loop controller, a fast nonsingular terminal sliding mode (FNTSM) control law is applied for robust disturbance rejection in a finite time. Based on the kinematic model of the DDWMR, the outer-loop controller is designed for accurate trajectory tracking control. Finally, experiments are carried out to validate that the proposed control scheme has more robust tracking accuracy and faster response than an existing robust method.

Vascular Changes and Hypoxia in Periodontal Disease as a Link to Systemic Complications.

The hypoxic microenvironment caused by oral pathogens is the most important cause of the disruption of dynamic hemostasis between the oral microbiome and the immune system. Periodontal infection exacerbates the inflammatory response with increased hypoxia and causes vascular changes. The chronicity of inflammation becomes systemic as a link between oral and systemic diseases. The vascular network plays a central role in controlling infection and regulating the immune response. In this review, we focus on the local and systemic vascular network change mechanisms of periodontal inflammation and the pathological processes of inflammatory diseases. Understanding how the vascular network influences the pathology of periodontal diseases and the systemic complication associated with this pathology is essential for the discovery of both local and systemic proactive control mechanisms.

기력발전 운영 환경 변화를 반영한 보일러 연소 최적화 기술의 소프트컴퓨팅적 접근 방법론 연구

In this paper, in order to evaluate the availability of the boiler combustion optimization of MPC technology for the current method of thermal power generation operation, two cases of experiment were implemented. Firstly, an experiment was performed using simulator linkage and actual process operation information. As a result, it was possible to obtain effects such as reducing overshooting when the target load was reached when linking the simulator. Secondly, an experiment was performed using actual operation information for optimizing combustion-related variables. However. the result of optimization by MPC solution was difficult to apply to actual process control. This is because the mechanical power generation control system is designed for the purpose of following the demand load, ① it is difficult to define a clear causal relationship between the process operation variables and nitrogen oxides and carbon monoxide, and ② data preprocessing techniques for handling disturbances and time delays. It could be confirmed that this was due to the inadequacy of the optimization technique among the multiple conflicting variables. To supplement this, soft-computing approaches including ① data linearization applying Bayesian optimization method, ② generalization of process situation prediction algorithm through application of multi-stage machine learning prediction structure and incremental data utilization, ③ global optimization method through combination of empirical-heuristic optimization algorithm are introduced to optimize the boiler combustion of thermal power plant.

Smooth second-order sliding mode controller for multivariable mechanical systems

This paper proposes a smooth second-order sliding mode controller for a class of multi-input multi-output mechanical systems with uncertain parameters and external disturbances. Since the control law is smooth, the chattering effect that can occur with non-smooth controllers is reduced. Lyapunov-based theorems are used to prove global and finite-time convergence of the sliding mode controller. Numerical simulations are presented to illustrate the performance of the proposed controller by applying it first to a variable-length pendulum and then to a two-link robotic manipulator. For the robotic manipulator, a detailed comparison is given of the finite-time convergence and chattering properties of the proposed controller, a super-twisting controller and a super-twisting like controller.Article HighlightsA new smooth second-order sliding mode controller is proposed for multivariablesystems with uncertain parameters and external disturbances.Global finite-time convergence of the controller is proved using Lyapunov theory.Numerical simulations are used to show the performance of the controller on thevariable-length pendulum and two-link robotic manipulator.

A novel health indicator based on hysteresis loop for health prediction of flight control systems

For the high-demand operating safety and flight safety, the hysteresis dead-zone as a health indicator (HI) related to backlash abrasion is proposed for health monitoring and prediction of aircraft mechanical control systems (MCSs). First, a multi-backlash mass-damper-spring (MDS) model is built for MCSs degradation simulation to demonstrate the HI’s validity. Then, by comparing with Prandtl-Ishlinskii (PI), generalized PI (GPI), and Preisach model, the Backlash-like-PSO model gets the best results on criteria of correlation index (R2) and root mean square error (RMSE). The Backlash-like-PSO model is innovatively adopted for HI extraction. Finally, compared with several generally used approaches, the Gaussian process regression (GPR) approach is designated for the MCSs degradation prediction based on HI, depending on its better prediction accuracy and smoother degradation trend by performance estimation on RMSE, R2, etc. The effectiveness and feasibility of the proposed method are validated by the practical flight data.

Microclimate influence investigation on broilers industrial production intensification by information technology methods

The article contains regression mathematical models that describe the effect of mechanical and automatic microclimate control systems on the growth and development of Arbor Acres broiler chickens in Sayan broiler agro-industrial complex in conditions of on-ground keeping. The following microclimate parameters are considered: temperature, humidity, illumination. Cramer-Welch, Wilcoxon criteria are used to test the statistical hypothesis of homogeneity of the two considered samples. The Chow test is taken on the possibility of constructing two different mathematical models of the same type that describe the patterns of development of simulated indicators. Statistical estimates of the significance of the constructed models and factors included in the models are calculated. The Fisher criterion is checked to see the differences in the constructed models and choose a more acceptable one to describe the effect of the microclimate on the production of young birds. The results of regression analysis are interpreted in relation to the subject area under study. Graphical visualization of analysis of initial and output data of built models is performed. Factors are ranked by degree of their effect on the resulting index using elasticity coefficients and share of their influence. The main production indicators are calculated according to the results of population cultivation - average daily growth, absolute growth, relative growth rate, liveability. The article calculates the economic effect in one complete cycle of broiler chickens growing.

Mechanical system and dynamic control in photolithography for nanoscale fabrication: A critical review

AbstractAs one of the most advanced and precise equipment in the world, a photolithography scanner is able to fabricate nanometer‐scale devices on a chip. To realize such a small dimension, the optical system is the fundamental, but the mechanical system often becomes the bottleneck. In the photolithography, the exposure is a dynamic process. The accuracy and precision of the movement are determined by the mechanical system, which is even more difficult to control compared with the optical system. In the mechanical system, there are four crucial components: the reticle and wafer stages, the linear motor, the metrology system, and the control system. They work together to secure the reticle and substrate locating at the correct position, which determines the overlay and alignment performance in the lithography. In this paper, the principles of these components are reviewed, and the development history of the mechanical system is introduced.

Discontinuous dynamics of an asymmetric 2-DOF friction oscillator with elastic and rigid impacts

• An asymmetric 2 DOF oscillator with elastic and rigid impacts is investigated. • Negative feedback forces and nonlinear spring of cubic term are considered. • Switching conditions of motion at separation boundaries are explored. • Several typical motions are simulated numerically by MATLAB software. In this paper, by using flow switching theory of discontinuous dynamical systems , the discontinuous dynamic behavior of a 2-DOF (two-degree-of-freedom) friction oscillator with elastic impact and rigid impact on different sides is investigated. For the 2-DOF friction oscillator, when the direction of object’s velocity changes, the negative feedback works and the inequality of maximum static friction force and kinetic friction force leads to the existence of flow barriers. In addition, the elastic impact and rigid impact can change motion states of object, resulting in the discontinuity of this 2-DOF system. Considering the multiple motion states of object and better analyzing the equation of object’s motion, the phase space of each object is divided into different motion domains and boundaries in relative and absolute coordinates by means of the discontinuities resulted from the friction and impact. Moreover, because the elastic impact exists in a time period, there will be a variety of motion behaviors coexisting, such as elastic and rigid impacts occur simultaneously. With that in mind, in absolute coordinate system, the phase space of the system is divided in six cases according to whether there are stick motion and stuck motion. Based on flow switching theory, the switching conditions at discontinuous boundaries for all possible motions are given by using G-functions, and it should be noted that the vanishing conditions of the sliding motion become more complicated due to the existence of flow barriers at speed boundaries. Through defining the switching sets on separation boundaries, the mapping structures are further introduced to demonstrate the global dynamic behavior and periodic motions. For a better understanding of the object’s motion and the switching criteria at separation boundaries, the numerical simulation method is used to demonstrate several typical motions such as passable motion, sliding motion, grazing motion, stick motion (elastic impact), rigid impact and periodic motions etc. The results obtained have reference value for the optimization design and noise control of mechanical systems with gap couplings and negative feedbacks.

Optimization of Neural Network-Based Self-Tuning PID Controllers for Second Order Mechanical Systems

The feasibility of a neural network method was discussed in terms of a self-tuning proportional–integral–derivative (PID) controller. The proposed method was configured with two neural networks to dramatically reduce the number of tuning attempts with a practically achievable small amount of data acquisition. The first network identified the target system from response data, previous PID parameters, and response characteristics. The second network recommended PID parameters based on the results of the first network. The results showed that it could recommend PID parameters within 2 s of observing responses. When the number of trained data was as low as 1000, the performance efficiency of these methods was 92.9%, and the tuning was completed in an average of 2.94 attempts. Additionally, the robustness of these methods was determined by considering a system with noise or a situation when the target position was modified. These methods are also applicable for traditional PID controllers, thus enabling conservative industries to continue using PID controllers.

Enhanced intelligent control with adaptive system for electrically assisted bicycle

This paper presents an enhanced fuzzy logic control strategy considering the human-bike interaction. A new transmission mechanism and intelligent control system for an electric bicycle are designed and validated through simulations and experimental setup. A load cell-based mini-sensor system is developed to measure the pedal torque. The transfer function of the system is obtained with data-based system identification and the control algorithms are first tested on this model and transferred to the real environment. Since the cycle interval time is important in the success of the control algorithm, the Fuzzy logic rule bases are operated by using the Hash Table method. The PI, PID, Fuzzy PID, and Hybrid Fuzzy algorithms are compared. Fuzzy PID and Hybrid Fuzzy methods are close to each other in terms of time analysis parameters and performance criteria, but more successful than other control strategies. The simulation and experimental results show that the proposed approach is satisfactory in terms of response time and speed control and provides driving comfort and safety.

Adaptive Coordinated Control Strategy of Multi Manipulator System based on Multi-Agent

With people's increasing awareness of life and the increasing complexity of exploration in unknown environment, a single robot can not meet the increasing demand, including the price, flexibility and efficiency of robots. As a common mechanical control system in industrial production instead of human production, multi manipulator system can be applied in complex environment, multi task and other conditions. In order to settle the coordinated control fault of multi manipulator system, we study adaptive coordinated control strategy with the help of multi-agent research method in this paper, which can simplify the complexity of the problem and design an efficient and feasible system control protocol. The complex items in the multi manipulator system are treated as non affine systems. Using the design idea of non affine algorithm, combined with implicit function theorem and median theorem, the non affine system is transformed into affine systems, the controller is separated, and a distributed adaptive control strategy is designed. The results indicate that manipulator systems can effectively track the active manipulator system in finite time and the significance of the algorithm is proven by MATLAB simulation analysis.

Optimal control of high-rise building mechanical ventilation system for achieving low risk of COVID-19 transmission and ventilative cooling.

As suggested by many guidelines, a high ventilation rate is required to dilute the indoor virus particles and reduce the airborne transmission risk, i.e., dilution ventilation (DV). However, high ventilation rates may result in high energy costs. Ventilative cooling (VC), which requires high ventilation rates like DV, is an option to reduce the cooling energy consumption. By combining DV and VC, this paper investigated the operation of the mechanical ventilation system in high-rise buildings during the COVID-19 pandemic, aiming to minimizing the cooling related energy consumption and reducing COVID-19 transmission. First, a modified Wells-Riley model was proposed to calculate DV rates. The ventilation rate required to achieve VC was also introduced. Then, a new ventilation control strategy was proposed for achieving DV and VC. Finally, a case study was conducted on a real high-rise building, where the required DV rate and the impact of the settings of the mechanical ventilation on the energy savings were evaluated. The results indicate that the required ventilation rates vary from 36 m3/s to 3306 m3/s depending on the protective measures. When the occupants follow the protective measures, the proper settings of the mechanical ventilation system can reduce energy consumption by around 40%.

Symplectic discrete-time energy-based control for nonlinear mechanical systems

We present a novel approach for discrete-time state feedback control implementation which reduces the deteriorating effects of sampling on stability and performance in digitally controlled nonlinear mechanical systems. We translate the argument of energy shaping to discrete time by using the symplectic implicit midpoint rule. The method is motivated by recent results for linear systems, where feedback imposes closed-loop behavior that exactly represents the symplectic discretization of a desired target system. For the nonlinear case, the sampled system and the target dynamics are approximated with second order accuracy using the implicit midpoint rule. The implicit nature of the resulting state feedback requires the numerical solution of an in general nonlinear system of algebraic equations in every sampling interval. For an implementation with pure position feedback, the velocities/momenta have to be approximated in the sampling instants, which gives a clear interpretation of our approach in terms of the Störmer–Verlet integration scheme on a staggered grid. Both the Hamiltonian and the Lagrangian perspective are adopted. We present discrete-time versions of impedance or energy shaping plus damping injection control as well as computed torque tracking control in the simulation examples to illustrate the performance and stability gain compared to the quasi-continuous implementation. We discuss computational aspects and show the structural advantages of the implicit midpoint rule compared to other integration schemes in the appendix.

An investigation of a novel LuGre-based friction force model

The LuGre friction force models are amongst the most popular and powerful approaches to treat frictional contact in modeling, simulation and control of mechanical systems. However, these friction force models have some numerical difficulties related to physical inconstancies, when the systems under analysis include frictional contacts with significant variations in the normal loads. The LuGre friction force models can exhibit some problems resulting in the ratio between the friction and normal contact forces exceeding the friction coefficients. Another limitation deals with the drift problem which might occur during sticking periods. Thus, this work is aimed at presenting a new investigation based on the LuGre friction foundation capable of overcoming those limitations. In a simple manner, the new solution for the LuGre friction force model includes a stiffness coefficient to adjust and accommodate the variations of the normal contact forces in dynamical systems. In this study, two LuGre friction force models are revisited to facilitate the description of the proposed solution. Finally, several numerical application examples regarding a block of mass on a horizontal plane are presented to compare and examine the advantages and potentials of the original, amended and proposed models.

Design and Application of Mechanical Control System Based on Computer

With the development of computer technology, computer technology has been applied to all walks of life in industry, especially in traditional industrial system. With the application of information technology, computer control system has been applied to the field of machinery, which can also help people better control various equipment. Through computer technology, we can better manage, maintain and control the mechanical system, which can realize various functions of the system. The computer control system can obtain a series of data through various sensors. Through the process of collection, storage, processing and transmission, the computer can classify, calculate and organize the data. Finally, through the control system, we can realize the automation of mechanical equipment, which will avoid the uncertainty of manual operation. Therefore, the computer improves the efficiency of the mechanical control system, which also improves the safety of the control process. First of all, this paper analyzes the current situation of mechanical control system of computer. Then, this paper takes the automobile as an example to analyze the application of the module in the mechanical control system.

A speed regulator for a force-driven cart-pole system

In this paper, we present a speed regulator for a force-driven cart-pole system. The proposed controller allows bringing the pole towards its upright position, while the cart moves asymptotically at desired constant speed, recovering the position regulation when we assign a desired constant position of the cart. The main motivation for addressing speed regulation is to broaden the scope of control of underactuated mechanical systems, because so far, the control of this class of mechanical systems has been focused primarily on position regulation; and therefore, there is few information and results available on broader control objectives, such as speed regulation. In particular, we design a speed regulator for the cart-pole system, as this system is one of the more representative test benches of underactuated mechanical system found in many automatic control research laboratories. Another novelty is the introduction of an alternative energy shaping approach for the velocity control design of a class of underactuated mechanical systems. A complete asymptotic stability analysis based on the Lyapunov theory and the Barbashin–Krasovskii theorem is presented. Local asymptotic stability is concluded. Simulation results upon a force-driven cart-pole model illustrate the performance of the proposed controller.

Data-driven robust tracking control of underactuated mechanical systems using identified flat output and active disturbance rejection control

This paper presents a data-driven control design framework to achieve robust tracking without exploiting mathematical model of nonlinear underactuated mechanical systems (UMS). The method leverages differential flatness property of linearised systems, online estimation and compensation of disturbances by active disturbance rejection control. The differentially flat output is derived directly from measured data with unknown dynamics and parameters by the flat output identification algorithm. A reduced nominal model of UMS is proposed to simplify the process of finding flat output and trajectory planning. Technique of sparse regression is applied to identify relationships between flat output and system states, which reduce the order of the well-known extended state observer (ESO) and thereby make the ESO more effective for trajectory planning and tracking in terms of the flat output. The proposed control is validated by experimental studies of a rotary crane system in which a rest-to-rest tracking control is implemented.

Design of Decentralized Adaptive Integral Terminal Sliding Mode Controller for Linear Interconnected Mechanical Systems in the Presence of External Disturbance

Design of Decentralized Adaptive Integral Terminal Sliding Mode Controller for Linear Interconnected Mechanical Systems in the Presence of External Disturbance

Preface

IFEMMT is an annual conference of Manufacturing Technology and Engineering Materials for all researchers from home and abroad, we have the strong organization team, dependable reputation and wide sponsors all around the world. The 2021 7th International Forum on Manufacturing Technology and Engineering Materials (IFEMMT 2021) was successfully held on June 18-20, 2021 in Dali, China.IFEMMT 2021 is to bring together innovative academics and industrial experts in the field of Manufacturing Technology and Engineering Materials to a common forum. The primary goal of the conference is to promote research and developmental activities in Manufacturing Technology and Engineering Materials and another goal is to promote scientific information interchange between researchers, developers, engineers, students, and practitioners working all around the world. The conference will be held every year to make it an ideal platform for people to share views and experiences in Manufacturing Technology and Engineering Materials and related areas.The conference brings together about 110 leading researchers, engineers and scientists in the domain of interest from different countries. The conference model was divided into two sessions, including oral presentations and keynote speeches. In the first part, some scholars, whose submissions were selected as the excellent papers, were given 15 minutes to perform their oral presentations one by one. Then in the second part, keynote speakers were each allocated 30-45 minutes to hold their speeches.In the keynote speech part, we were greatly honor to have invited four distinguished experts as our keynote speakers. Prof. Changsi Peng, Soochow University, China was the first one to perform a thought-provoking speech. His research interests are Semiconductor quantum dots and Nano Bionic. Prof. Yajun Liu, from South China University of Technology, China as our second keynote speakers. His research area: Mechanical system signal testing, analysis, characterization, control and performance optimization. And then we had Prof. Yun Wang, from Jiangsu University, China. He had outstanding research in High-precision material micro-forming method, quality control and other related areas. Prof. Weiwei Zhao, our finale keynote speakers, from Wuhan University of Technology, China. He devoted to Characterization of mechanical and mechanical properties of polymer hydrogels, research and development of biomimetic electroactive hydrogels, and applications of polymer materials in microfluidic devices and biomedicine research area.The proceedings of IFEMMT 2021 span over 3 topical tracks, that include: Advanced Design Technology, Manufacturing Systems and Automation, New Materials and Advanced Materials and other related fields. All the papers have been through rigorous review and process to meet the requirements of International publication standard.We would like to express our gratitude to everyone involved. Without this dedicated cooperation, it would be impossible to hold the conference at such a high level and prepare the IFEMMT 2021 proceedings.List of Committee member are available in this pdf.

Trajectory planning and low-chattering fixed-time nonsingular terminal sliding mode control for a dual-arm free-floating space robot

AbstractThis paper addresses fixed-time trajectory tracking for a dual-arm free-floating space robot (FFSR) with the large initial errors and bounded uncertainty. A wrist-based trajectory planning method is improved by fixed-time stability to fast eliminate the error caused by singularity. Then, a novel low-chattering and global-nonsingular fixed-time terminal sliding mode control strategy is studied by state approaching angle and switching sliding mode; the practical fixed-reachable Lyapunov stability analysis is presented for a mechanical control system. In the end, the proposed trajectory planning method and controller are combined to improve the tracking accuracy of end-effector to the nanoscale. Simulation results validate the effectiveness of the proposed methodologies.