A master-slave generalized predictive synchronization control for preheating process of multi-cavity hot runner system

As a key component of injection molding,multi-cavity hot runner(MCHR)system faces the crucial problem of polymer melt filling imbalance among the cavities.The thermal imbalance in the system has been considered as the leading cause.Hence,the solution may rest with the synchronization of those heating processes in MCHR system.This paper proposes a’Master-Slave’generalized predictive synchronization control(MS-GPSC)method with’Mr.Slowest’strategy for preheating stage of MCHR system.The core of the proposed method is choosing the heating process with slowest dynamics as the’Master’to track the setpoint,while the other heating processes are treated as‘Slaves’tracking the output of’Master’.This proposed method is shown to have the good ability of temperature synchronization.The corresponding analysis is conducted on parameters tuning and stability,simulations and experiments show the strategy is effective.

Multi-circular formation control with reinforced transient profiles for nonholonomic vehicles:A path-following framework

This article investigates a multi-circular path-following formation control with reinforced transient profiles for nonholonomic vehicles connected by a digraph.A multi-circular formation controller endowed with the feature of spatial-temporal decoupling is devised for a group of vehicles guided by a virtual leader evolving along an implicit path,which allows for a circumnavigation on multiple circles with an anticipant angular spacing.In addition,notice that it typically imposes a stringent time constraint on time-sensitive enclosing scenarios,hence an improved prescribed performance control(IPPC)using novel tighter behavior boundaries is presented to enhance transient capabilities with an ensured appointed-time convergence free from any overshoots.The significant merits are that coordinated circumnavigation along different circles can be realized via executing geometric and dynamic assignments independently with modified transient profiles.Furthermore,all variables existing in the entire system are analyzed to be convergent.Simulation and experimental results are provided to validate the utility of suggested solution.

A Novel Prescribed-Performance Path-Following Problem for Non-Holonomic Vehicles

The issue of achieving prescribed-performance path following in robotics is addressed in this paper,where the aim is to ensure that a desired path within a specified region is accu-rately converged to by the controlled vehicle.In this context,a novel form of the prescribed performance guiding vector field is introduced,accompanied by a prescribed-time sliding mode con-trol approach.Furthermore,the interdependence among the pre-scribed parameters is discussed.To validate the effectiveness of the proposed method,numerical simulations are presented to demonstrate the efficacy of the approach.

Environmental Impact Assessment Follow-Up of Seismic Survey Offshore Activities in Brazil

Follow-up of environmental impacts is an integral part of the Environmental Impact Assessment (EIA) process, closely related to the effectiveness of the instrument. EIA follow-up has been receiving a lot of interest from scientists and practitioners, though it is recognized as one of the weakest points of EIA systems globally. Also, EIA follow-up is influenced by the context, mainly in terms of the types of projects or activities and their related impacts on the environment. Therefore, the present paper is focused on the investigation of the follow-up stage applied to the activity of seismic survey coupled with offshore oil & gas exploitation in Brazil. Research was based on a qualitative approach that included document analysis and semi-structured interviews with analysts involved in EIA processes, and sought to generate evidence of effectiveness of the EIA follow-up as conducted by the Federal Environment Agency (Ibama) in order to situate the practice of follow-up in the broader context of international best practice principles. Based on the findings, it was concluded that, due to the peculiarities of offshore seismic survey, it is necessary to promote adaptations in the procedures for monitoring impacts in order to ensure proper alignment with the principles and conceptual foundations that guide EIA practice. Specifically, the timing of the execution of the activity imposes challenges for its integration into the “conventional” cycle that has guided the monitoring of the impacts in the EIA of projects.

Parent-Reported Reasons for Loss-to-Follow Up in Patients Hospitalized at the Neonatology Unit at Laquintinie

Introduction: Despite the known benefits of newborn follow-up clinics, attendance has historically been difficult. Infants with reported follow-up difficulty have a greater incidence of severe sensorimotor and cognitive deficits and poorer access to early intervention programs. Our objective was to determine the parent-reported reasons for loss-to-follow up in patients hospitalised at the neonatology unit of Laquintinie Hospital. Methodology: We carried out a cross-sectional study through phone interviews with parents/caregivers of patients hospitalised at Laquintinie over a 2-year period from 1st January 2021 to 31st December 2022. A non-standardised structured interview guide was used for data collection. Loss-to-follow up referred to absence to at least one visit as recorded in the neonatal follow-up chart. All necessary administrative and ethical considerations were duly respected. Results: Most neonates were born through vaginal delivery (n = 313, 69.45%). The neonates were admitted at a median gestational age of 33 weeks (Q1-Q3;32 - 35) and the median duration of hospitalisation was 12 days (Q1 - Q3;8 - 18). A total of 23 neonates had died at the time of interview giving a mortality rate of 5.1%. The three most reported reasons for loss-to-follow-up was lack of money (n = 310, 68.13%), assumption that follow-up had ended (n = 37, 8.13%), and newborn that died (n = 23, 5.1%). Conclusion: This study highlights the significant impact of financial constraints and absence of a robust follow-up system on poor uptake of neonatal follow-up post-discharge in resource limited settings like Cameroon. Our results serve as advocacy for national health insurance especially in neonates.

缺乏位置信息的视觉移动机器人leader-following编队控制

针对视觉移动机器人编队在缺乏位置信息情况下的控制问题,提出一种基于视觉的leader-following编队反馈控制方法。该方法利用leader标志物特征点在follower摄像机像平面上的坐标信息设计了观测器,对leader与follower间的相对位置进行估计,基于相对位置估计量与它们速度的关系,设计出leader-following编队反馈控制器,通过Lyapunov理论证明了闭环系统的稳定性。仿真结果表明,该控制方法能有效解决缺乏位置信息情况下视觉移动机器人编队的控制问题。

FEA-Based Fatigue Life Assessment of Cycloidal Displacement Cam and Flat-Faced Follower Mechanism

Cam-followers provide reliable and controlled motions in various mechanical systems. Due to the highly fluctuating load between the cam and follower in operation, the cam-follower may be subjected to a high risk of contact fatigue failure. This paper assesses the fatigue life of a cycloidal displacement cam and a flat-faced follower under the defined loads and constraints. Computer-aided design (CAD) model of the cam-follower is developed in CATIA software and imported to ANSYS software for finite element analysis (FEA) of fatigue life. MATLAB programming is developed for determining the appropriate spring constant and pre-load force to always keep the cam and follower in contact. The fatigue life of the cam-follower has been estimated under the specified operating conditions. The analysis method can be applied to investigate the fatigue life of cams with other profiles, including the modified trapezoidal functions, polynomial functions, etc.

Master-Slave机器手协调控制选择行列式算法

提出了一种基于选择行列式的Master-Slave机器手的协调控制算法。通过选择行列式的导入,实现了对Master机器手和Slave机器手各个变量的协调控制。本方法应用于装有视觉传感器的机器手的追踪控制,经过实验证明了基于选择行列式的算法能够实现人类的某些技能赋予机器手,在支援机器手的同时还能够通过有效地协调遥控,完成机器手的自主控制。

GRACE与GRACE Follow-On重力卫星数据揭示出的黄河流域2002-2020年干旱特征

研究黄河流域干旱时空变化特征,对认知黄河流域水资源演化规律具有重要意义。本文充分利用GRACE(gravity recovery and climate experiment)与GRACE-FO(GRACE Follow-On)重力卫星在大尺度范围下监测水文信息变化中的优势,基于2002年4月至2020年7月GRACE和GRACE-FO RL06 Mascon数据,计算了黄河流域陆地水储量异常(terrestrial water storage anomaly,TWSA)及对应的水储量亏损赤字(water storage deficit index,WSDI),据此分析了黄河流域上游、中下游干旱事件及其严重性、干旱持续时间、平均与最大水储量赤字等干旱特征,并与其他4种常用干旱指数,标准降水蒸散发指数(standardized precipitation evaporation index,SPEI)、自矫正帕尔默干旱指数(self correct-Palmer drought severity index,sc-PDSI)、标准化降水指数(standardized precipitation index,SPI)和标准化径流指数(standardized runoff index,SRI)识别结果进行了对比分析。研究结果表明:在WSDI识别出的黄河流域上游、中下游分别发生的5期干旱事件及其对应的干旱等级中,存在其他传统干旱指数未识别现象;在黄河流域以往干旱事件识别中,WSDI也展现出了较其他4种传统干旱指数显著的识别优势。相比传统干旱指标多仅依赖于稀疏地表水文监测信息,基于重力卫星监测数据的WSDI干旱指标可在大尺度范围下有效识别出流域干旱特征。

Leader-following多自主体系统时变编队跟踪控制

考虑时变时延,研究了高阶leader-following多自主体系统的分布式时变编队跟踪控制问题.针对连续高阶多自主体系统,设计了基于观测器的时变编队跟踪控制协议,通过状态变换,将系统的时变编队跟踪控制问题,转变为误差系统的稳定性问题.然后利用图论及李雅普诺夫稳定定理,研究了系统实现时变编队跟踪控制的充分条件,并且指出时变编队参考函数与时变时延无关.最后,数据仿真结果证明了所设计的协议能使follower自主体实现时变编队,并且跟踪leader自主体的轨迹.

Achievement of chaotic synchronization trajectories of master-slave manipulators with feedback control strategy

This paper addresses a master-slave synchro- nization strategy for complex dynamic systems based on feedback control. This strategy is applied to 3-DOF pla- nar manipulators in order to obtain synchronization in such complicated as chaotic motions of end-effectors. A chaotic curve is selected from Duffing equation as the trajectory of master end-effector and a piecewise approximation method is proposed to accurately represent this chaotic trajectory of end-effectors. The dynamical equations of master-slave manipulators with synchronization controller are derived, and the Lyapunov stability theory is used to determine the stability of this controlled synchronization system. In numer- ical experiments, the synchronous motions of end-effectors as well as three joint angles and torques of master-slave manipulators are studied under the control of the proposed synchronization strategy. It is found that the positive gain matrix affects the implementation of synchronization con- trol strategy. This synchronization control strategy proves the synchronization＇s feasibility and controllability for com- plicated motions generated by master-slave manipulators.

Exponential networked synchronization of master-slave chaotic systems with timevarying communication topologies

The networked synchronization problem of a class of master-slave chaotic systems with time-varying communication topologies is investigated in this paper. Based on algebraic graph theory and matrix theory, a simple linear state feedback controller is designed to synchronize the master chaotic system and the slave chaotic systems with a time- varying communication topology connection. The exponential stability of the closed-loop networked synchronization error system is guaranteed by applying Lyapunov stability theory. The derived novel criteria are in the form of linear matrix inequalities （LMIs）, which are easy to examine and tremendously reduce the computation burden from the feedback matrices. This paper provides an alternative networked secure communication scheme which can be extended conveniently. An illustrative example is given to demonstrate the effectiveness of the proposed networked synchronization method.

Finite-Time Sideslip Differentiator-Based LOS Guidance for Robust Path Following of Snake Robots

This paper presents a finite-time sideslip differentiator-based line-of-sight(LOS)guidance method for robust path following of snake robots.Firstly,finite-time stable sideslip differentiator and adaptive LOS guidance method are proposed to counteract sideslip drift caused by cross-track velocity.The proposed differentiator can accurately observe the cross-track error and sideslip angle for snake robots to avoid errors caused by calculating sideslip angle approximately.In our method,the designed piecewise auxiliary function guarantees the finite-time stability of position errors.Secondly,for the case of external disturbances and state constraints,a Barrier Lyapunov functionbased backstepping adaptive path following controller is presented to improve the robot’s robustness.The uniform ultimate boundedness of the closed-loop system is proved by analyzing stability.Additionally,a gait frequency adjustment-based virtual velocity control input is derived to achieve the exponential convergence of the tangential velocity.At last,the availability and superiority of this work are shown through simulation and experiment results.

Research on Master-slave Telerobot Force Telepresence Technology

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Adaptive H_∞ Synchronization of Master-slave Systems with Mixed Time-varying Delays and Nonlinear Perturbations: An LMI Approach

This paper proposes an adaptive synchronization problem for the master and slave structure of linear systems with nonlinear perturbations and mixed time-varying delays comprising different discrete and distributed time delays. Using an appropriate Lyapunov-Krasovskii functional, some delay-dependent sufficient conditions and an adaptation law including the master-slave parame- ters are established for designing a delayed synchronization law in terms of linear matrix inequalities（LMIs）. The time-varying controller guarantees the H ∞ synchronization of the two coupled master and slave systems regardless of their initial states. Particularly, it is shown that the synchronization speed can be controlled by adjusting the updated gain of the synchronization signal. Two numerical examples are given to demonstrate the effectiveness of the method.

Tremor suppression in master-slave robot remote welding system

Welding seam tracking precision was decreased due to human hand tremor during the master-slave welding teleoperation. To solve this problem, a master-slave robot remote welding system was built, the system consisted of a master manipulator with six degree of freedom （ DOF ） , an industrial computer control system and a slave Motoman HP3 J robot, and human hand tremor and digital filtering were discussed. An optimal digital filter was designed to clean human tremor signal for improving the welding seam tracking precision. The experimental results show that the digital filter suppresses the operator＇ s tremor signal.

Constrained Moving Path Following Control for UAV With Robust Control Barrier Function

This paper studies the moving path following(MPF)problem for fixed-wing unmanned aerial vehicle(UAV)under output constraints and wind disturbances.The vehicle is required to converge to a reference path moving with respect to the inertial frame,while the path following error is not expected to violate the predefined boundaries.Differently from existing moving path following guidance laws,the proposed method removes complex geometric transformation by formulating the moving path following problem into a second-order time-varying control problem.A nominal moving path following guidance law is designed with disturbances and their derivatives estimated by high-order disturbance observers.To guarantee that the path following error will not exceed the prescribed bounds,a robust control barrier function is developed and incorporated into controller design with quadratic program based framework.The proposed method does not require the initial position of the UAV to be within predefined boundaries.And the safety margin concept makes error-constraint be respected even if in a noisy environment.The proposed guidance law is validated through numerical simulations of shipboard landing and hardware-in-theloop(HIL)experiments.

Hierarchical hybrid control network design based on LON and master-slave RS-422/485 protocol

Aiming at the weaknesses of LON bus, combining the coexistence of fieldbus and DCS (Distribu ted Control Systems) in control networks, the authors introduce a hierarchical hybrid control network design based on LON and master slave RS 422/485 protocol. This design adopts LON as the trunk, master slave RS 422/485 control networks are connected to LON as special subnets by dedicated gateways. It is an implementation method for isomerous control network integration. Data management is ranked according to real time requirements for different network data. The core components, such as control network nodes, router and gateway, are detailed in the paper. The design utilizes both communication advantage of LonWorks technology and the more powerful control ability of universal MCUs or PLCs, thus it greatly increases system response speed and performance cost ratio.

LSTM-DPPO based deep reinforcement learning controller for path following optimization of unmanned surface vehicle

To solve the path following control problem for unmanned surface vehicles(USVs),a control method based on deep reinforcement learning(DRL)with long short-term memory(LSTM)networks is proposed.A distributed proximal policy opti-mization(DPPO)algorithm,which is a modified actor-critic-based type of reinforcement learning algorithm,is adapted to improve the controller performance in repeated trials.The LSTM network structure is introduced to solve the strong temporal cor-relation USV control problem.In addition,a specially designed path dataset,including straight and curved paths,is established to simulate various sailing scenarios so that the reinforcement learning controller can obtain as much handling experience as possible.Extensive numerical simulation results demonstrate that the proposed method has better control performance under missions involving complex maneuvers than trained with limited scenarios and can potentially be applied in practice.

Distributed Generation Islanding Effect on Distribution Networks and End User Loads Using the Master-Slave Islanding Method

This study aims to address the feasibility of planned islanding operation and to investigate the effect of unplanned islanding using the master-slave islanding method for controlling the distributed generation units during grid-connected and islanding operation. Neplan desktop power simulation tool was used for the modelling and simulation of a realistic MV network with four different distributed generation technologies (diesel, gas, hydro and wind) along with their excitation and governor control systems, while an exponential model was used to represent the loads in the network. The dynamic and steady state behavior of the four distributed generation technologies were investigated during grid-connected operation and two transition modes to the islanding situation, planned and unplanned. The obtained results that validated through various case studies have shown that a suitable planned islanding transition could provide support to critical loads at the event of electricity utility outages.