Tracking Control of Multi-Agent Systems Using a Networked Predictive PID Tracking Scheme

With the rapid development of network technology and control technology,a networked multi-agent control system is a key direction of modern industrial control systems,such as industrial Internet systems.This paper studies the tracking control problem of networked multi-agent systems with communication constraints,where each agent has no information on the dynamics of other agents except their outputs.A networked predictive proportional integral derivative(PPID)tracking scheme is proposed to achieve the desired tracking performance,compensate actively for communication delays,and simplify implementation in a distributed manner.This scheme combines the past,present and predictive information of neighbour agents to form a tracking error signal for each agent,and applies the proportional,integral,and derivative of the agent tracking error signal to control each individual agent.The criteria of the stability and output tracking consensus of multi-agent systems with the networked PPID tracking scheme are derived through detailed analysis on the closed-loop systems.The effectiveness of the networked PPID tracking scheme is illustrated via an example.

State coordinated voltage control in an active distribution network with on-load tap changers and photovoltaic systems

Decreasing costs and favorable policies have resulted in increased penetration of solar photovoltaic(PV)power generation in distribution networks.As the PV systems penetration is likely to increase in the future,utilizing the reactive power capability of PV inverters to mitigate voltage deviations is being promoted.In recent years,droop control of inverter-based distributed energy resources has emerged as an essential tool for use in this study.The participation of PV systems in voltage regulation and its coordination with existing controllers,such as on-load tap changers,is paramount for controlling the voltage within specified limits.In this work,control strategies are presented that can be coordinated with the existing controls in a distributed manner.The effectiveness of the proposed method was demonstrated through simulation results on a distribution system.

Group Hybrid Coordination Control of Multi-Agent Systems With Time-Delays and Additive Noises

A new kind of group coordination control problemgroup hybrid coordination control is investigated in this paper.The group hybrid coordination control means that in a whole multi-agent system(MAS)that consists of two subgroups with communications between them,agents in the two subgroups achieve consensus and containment,respectively.For MASs with both time-delays and additive noises,two group control protocols are proposed to solve this problem for the containment-oriented case and consensus-oriented case,respectively.By developing a new analysis idea,some sufficient conditions and necessary conditions related to the communication intensity betw een the two subgroups are obtained for the following two types of group hybrid coordination behavior:1)Agents in one subgroup and in another subgroup achieve weak consensus and containment,respectively;2)Agents in one subgroup and in another subgroup achieve strong consensus and containment,respectively.It is revealed that the decay of the communication impact betw een the two subgroups is necessary for the consensus-oriented case.Finally,the validity of the group control results is verified by several simulation examples.

Novel ARC-Fuzzy Coordinated Automatic Tracking Control of Four-Wheeled Mobile Robot

Four-wheeled,individual-driven,nonholonomic structured mobile robots are widely used in industries for automated work,inspection and explora-tion purposes.The trajectory tracking control of the four-wheel individual-driven mobile robot is one of the most blooming research topics due to its nonholonomic structure.The wheel velocities are separately adjusted to follow the trajectory in the old-fashioned kinematic control of skid-steered mobile robots.However,there is no consideration for robot dynamics when using a kinematic controller that solely addresses the robot chassis’s motion.As a result,the mobile robot has lim-ited performance,such as chattering during curved movement.In this research work,a three-tiered adaptive robust control with fuzzy parameter estimation,including dynamic modeling,direct torque control and wheel slip control is pro-posed.Fuzzy logic-based parameter estimation is a valuable tool for adjusting adaptive robust controller(ARC)parameters and tracking the trajectories with less tracking error as well as high tracking accuracy.This research considers the O type and 8 type trajectories for performance analysis of the proposed novel control technique.Our suggested approach outperforms the existing control methods such as Fuzzy,proportional–integral–derivative(PID)and adaptive robust controller with discrete projection(ARC–DP).The experimental results show that the scheduled performance index decreases by 2.77%and 4.76%.All the experimen-tal simulations obviously proved that the proposed ARC-Fuzzy performed well in smooth groud surfaces compared to other approaches.

Control method on serial type pump-valve coordinated electro-hydraulic servo system

In order to compromise the conflicts between control accuracy and system efficiency of conventional electro-hydraulic servo systems,a novel pump-valve coordinated electro-hydraulic servo system was designed and a corresponding control strategy was proposed.The system was constituted of a pumpcontrolled part and a valve-controlled part,the pump controlled part is used to adjust the flow rate of oil source and the valve controlled part is used to complete the position tracking control of the hydraulic cylinder.Based on the system characteristics,a load flow grey prediction method was adopted in the pump controlled part to reduce the system overflow losses,and an adaptive robust control method was adopted in the valve controlled part to eliminate the effect of system nonlinearity and parametric uncertainties due to variable hydraulic parameters and system loads on the control precision.The experimental results validated that the adopted control strategy increased the system efficiency obviously with guaranteed high control accuracy.

Coordinated nonlinear robust control of TCSC and excitation for multi-machine systems

An advanced nonlinear robust control scheme is proposed for multi-machine power systems equipped with thyristor-controlled series compensation (TCSC). First, a decentralized nonlinear robust control approach based on the feedback linearization and H∞ theory is introduced to eliminate the nonlinearities and interconnections of the studied system, and to attenuate the exogenous disturbances that enter die system. Then, a system model is built up, which has considered all the generators’ and TCSC’s dynamics, and the effects of uncertainties such as disturbances. Next, a decentralized nonlinear robust coordinated control law is developed based on this model. Simulation results on a six-machine power system show that the transient stability of the power system is obviously improved and die power transfer capacity of long distance transmission lines is enhanced regardless of fault locations and system operation points. In addition, the control law has engineering practicality since all the variables in the expression of he control strategy can be measured locally.

Dual sliding mode coordinated control of manipulator grasping system with visual assistance

The operation efficiency of the manipulator is placed in the primary position in automatic production. This paper proposes a coordinated control strategy for joint servo and visual servo to enable timely transfer and accurate gripping in the working area. Aiming at the issues of chattering and slow convergence of traditional sliding mode controller, a fast variable power reaching rate on the basis of the non-singular fast terminal sliding mode controller is proposed, which can effectively reduce the convergence time and chattering. For the purpose of addressing the problem that the traditional visual servo control method is sensitive to the environment, a visual servo controller based on integral sliding mode is proposed, to ensure the favorable positioning accuracy of the manipulator. Based on the two proposed controllers mentioned above, a coordinated control strategy is used to implement the control of the manipulator. Finally, the upper computer software is developed using the C# programming language to monitor the workstation. The feasibility of the above-mentioned method is verified through multiple simulations and experiments.

Chassis Coordinated Control for Full X-by-Wire Vehicles-A Review

An X-by-wire chassis can improve the kinematic characteristics of human-vehicle closed-loop system and thus active safety especially under emergency scenarios via enabling chassis coordinated control.This paper aims to provide a complete and systematic survey on chassis coordinated control methods for full X-by-wire vehicles,with the primary goal of summarizing recent reserch advancements and stimulating innovative thoughts.Driving condition identification including driver’s operation intention,critical vehicle states and road adhesion condition and integrated control of X-by-wire chassis subsystems constitute the main framework of a chassis coordinated control scheme.Under steering and braking maneuvers,different driving condition identification methods are described in this paper.These are the trigger conditions and the basis for the implementation of chassis coordinated control.For the vehicles equipped with steering-by-wire,braking-by-wire and/or wire-controlled-suspension systems,state-of-the-art chassis coordinated control methods are reviewed including the coordination of any two or three chassis subsystems.Finally,the development trends are discussed.

Motion Planning Based Coordinated Control for Hydraulic Excavators

Hydraulic excavator is one type of the most widely applied construction equipment for various applications mainly because of its versatility and mobility. Among the tasks performed by a hydraulic excavator, repeatable level digging or flat surface finishing may take a large percentage. Using automated functions to perform such repeatable and tedious jobs will not only greatly increase the overall productivity but more importantly also improve the operation safety. For the purpose of investigating the technology without loss of generality, this research is conducted to create a coordinate control method for the boom, arm and bucket cylinders on a hydraulic excavator to perform accurate and effective works. On the basis of the kinematic analysis of the excavator linkage system, the tip trajectory of the end-effector can be determined in terms of three hydraulic cylinders coordinated motion with a visualized method. The coordination of those hydraulic cylinders is realized by controlling three electro-hydraulic proportional valves coordinately. Therefore, the complex control algorithm of a hydraulic excavator can be simplified into coordinated motion control of three individual systems. This coordinate control algorithm was validated on a wheeled hydraulic excavator, and the validation results indicated that this developed control method could satisfactorily accomplish the auto-digging function for level digging or flat surface finishing.

Adaptive coordinated control of engine speed and battery charging voltage

In this paper, the control problem of auxiliary power unit （APU） for hybrid electric vehicles is investigated. An adaptive controller is provided to achieve the coordinated control between the engine speed and the battery charging voltage. The proposed adaptive coordinated control laws for the throttle angle of the engine and the voltage of the power-converter can guarantee not only the asymptotic tracking performance of the engine speed and the regulation of the battery charging voltage, but also the robust stability of the closed loop system under external load changes. Simulation results are given to verify the performance of the proposed adaptive controller.

Intelligent coordinated control of power-plant main steam pressure and power output

An intelligent coordinated control strategy has been proposed and successfully applied to a 300MW boiler-turbine unit i. e. Unit 1 of Yuanbaoshan power plant in China. Load following operation of coal-fired boiler-turbine unit in the power plant leads to changes in operating points which result in nonlinear variations of the plant variables and parameters. For the variation of operating condition and slowly varying dynamics, an intelligent control scheme has been developed by combining fuzzy self-tuning with adaptive control and auto-tuning techniques. As there exist strong couplings between control loops of main steam pressure and power output in the unit, a new design for static decoupler aimed at decoupling for setpoints and unmeasured pulverized coal disturbance of the system at the same time is presented. Satisfactory industrial application results show that such a control system has enhanced adaptability and robustness to the complex process, and better control performance and high economic benefit have been obtained.

Coordinated Controller Tuning of a Boiler Turbine Unit with New Binary Particle Swarm Optimization Algorithm

Coordinated controller tuning of the boiler turbine unit is a challenging task due to the nonlinear and coupling characteristics of the system.In this paper,a new variant of binary particle swarm optimization （PSO） algorithm,called probability based binary PSO （PBPSO）,is presented to tune the parameters of a coordinated controller.The simulation results show that PBPSO can effectively optimize the control parameters and achieves better control performance than those based on standard discrete binary PSO,modified binary PSO,and standard continuous PSO.

Constrained Power Plant Coordinated Predictive Control Using Neurofuzzy Model

In unit steam-boiler generation, a coordinated control strategy is required to ensure a higher rate of load change without violating thermal constraints. The process is characterized by nonlinearity and uncertainty. While neural networks can model highly complex nonlinear dynamical systems, they produce black box models. This has led to significant interest in neuro-fuzzy networks (NFNs) to represent a nonlinear dynamical process by a set of locally valid and simpler submodels. Two alternative methods of exploiting the NFNs within a generalised predictive control (GPC) framework for nonlinear model predictive control are described. Coordinated control of steam-boiler generation using the two nonlinear GPC methods show excellent tracking and disturbance rejection results and improved performance compared with conventional linear GPC.

Novel hybrid method: pulse CO_2 laser-TIG hybrid welding by coordinated control

In continuous wave CO2 laser-TlG hybrid welding process, the laser energy is not fully utilized because of the absorption and defocusing by plasma in the arc space. Therefore, the optimal welding result can only be achieved in a limited energy range. In order to improve the welding performance further, a novel hybrid welding method--pulse CO2 laser-TIG arc hybrid welding by coordinated control is proposed and investigated. The experimental results indicate that, compared with continuous wave CO2 laser-TIG hybrid welding, the absorption and defocusing of laser energy by plasma are decreased further, and at the same time, the availability ratio of laser and arc energy can be increased when a coordinated frequency is controlled. As a result, the weld appearance is also improved as well as the weld depth is deepened. Furthermore, the effect of frequency and phase of pulse laser and TIG arc on the arc images and welding characteristics is also studied. However, the novel hybrid method has great potentials in the application of industrials from views of techniques and economy.

Research on SFLA-Based Bidirectional Coordinated Control Strategy for EV Battery Swapping Station

As a good measure to tackle the challenges from energy shortages and environmental pollution,Electric Vehicles(EVs)have entered a period of rapid growth.Battery swapping station is a very important way of energy supply to EVs,and it is urgently needed to explore a coordinated control strategy to effectively smooth the load fluctuation in order to adopt the large-scale EVs.Considering bidirectional power flow between the station and power grid,this paper proposed a SFLA-based control strategy to smooth the load profile.Finally,compared simulations were performed according to the related data.Compared to particle swarm optimization(PSO)method,the presented SFLA-based strategy can effectively lower the peak-valley difference with the faster convergence rate and higher convergence precision.It is important for the swapping station that energy exchanging mode can supply energy for large-scale EVs with a smoother load profile than one-way charging mode.

Disturbance observer based finite-time coordinated attitude tracking control for spacecraft on SO(3)

To solve the problem of attitude synchronization control for spacecraft formation flying(SFF)suffering from external disturbances under a directed communication topology,a sliding mode disturbance observer(SMDO)based on the finite-time control strategy is developed to observe the time-varying external disturbance via estimating the upper bound of its first derivative.Meanwhile,the rotation matrix is employed to describe the attitude of SFF for the purpose of the avoidance of singularity and unwinding phenomenon.As for the attitude synchronization and the tracking control architecture,a sliding mode surface(SMS)is given such that the control objective can be achieved.The effectiveness and the validity of the proposed method are elaborated via theoretical analysis and numerical simulations.

Construction and Implementation Approaches of Ecological Compensation Mechanism for Coordinated Control of Air Pollution in Beijing-Tianjin-Hebei Region

The spatial spillover of air pollution in Beijing-Tianjin-Hebei region makes the territorial governance model inefficient.At the same time,it is facing the contradiction between environmental governance and economic development.So far,there is still no regional long-term mechanism for coordinated governance of air pollution.Ecological compensation theory is becoming an effective guiding theory to coordinate economic and environmental benefits.There is relatively little research on ecological compensation mechanism in the coordinated control of regional air pollution.Ecological compensation mechanism is an effective tool to promote air pollution control.At the same time,regional cooperation can realize the efficient control of air pollution.Scientifically constructing the cross regional cooperative control model of Beijing,Tianjin and Hebei is a favorable way to implement comprehensive control of air pollution.This paper discusses the necessity of ecological compensation mechanism for regional coordinated control of air pollution.Referring to practical experience of provinces and cities that have implemented the ecological compensation mechanism for air pollution control,and the effective way to distribute the compensation amount,compensation subject and compensation standard determination method that can be implemented in Beijing-Tianjin-Hebei region are analyzed,further proposing an effective way to establish an ecological compensation mechanism for regional air pollution collaborative control according to its reality.

Coordinated voltage control of renewable energy power plants in weak sending-end power grid

The utilization of renewable energy in sending-end power grids is increasing rapidly,which brings difficulties to voltage control.This paper proposes a coordinated voltage control strategy based on model predictive control(MPC)for the renewable energy power plants of wind and solar power connected to a weak sending-end power grid(WSPG).Wind turbine generators(WTGs),photovoltaic arrays(PVAs),and a static synchronous compensator are coordinated to maintain voltage within a feasible range during operation.This results in the full use of the reactive power capability of WTGs and PVAs.In addition,the impact of the active power outputs of WTGs and PVAs on voltage control are considered because of the high R/X ratio of a collector system.An analytical method is used for calculating sensitivity coefficients to improve computation efficiency.A renewable energy power plant with 80 WTGs and 20 PVAs connected to a WSPG is used to verify the proposed voltage control strategy.Case studies show that the coordinated voltage control strategy can achieve good voltage control performance,which improves the voltage quality of the entire power plant.

Coordinated Control of Sliding Mode and Hamiltonian for PWM Rectifier

Aiming at the PWM rectifier control strategy of sliding mode control, steady state performance weak Hamiltonian control dynamic tracking performance is poor, the coordinated compound control is proposed, the feedback linearization controller and sliding mode controller Hamiltonian system is obtained, and the design of a coordinated control strategy. In order to verify the accuracy of this method, MATLAB/Simulink is used for simulation analysis. The simulation results show that the composite control can achieve the coordinated dynamic rapid tracking and constant DC output and unit power factor operation, and satisfy the control requirements of the rectifier, effectively reducing the disturbance effect on the system. Compared with Hamiltonian control, the proposed method combines the advantages of the two methods, which have the fast tracking performance and excellent steady-state characteristics, and the research prospect is broad.

Analysis of China’s PM_(2.5)and ozone coordinated control strategy based on the observation data from 2015 to 2020

The coordinated control of PM_(2.5)and ozone has become the strategic goal of national air pollution control.Considering the gradual decline in PM_(2.5)concentration and the aggravation of ozone pollution,a better understanding of the coordinated control of PM_(2.5)and ozone is urgently needed.Here,we collected and sorted air pollutant data for 337 cities from 2015 to 2020 to explore the characteristics of PM_(2.5)and ozone pollution based on China’s five major air pollution regions.The results show that it is necessary to continue to strengthen the emission reduction in PM_(2.5)and ozone precursors,and control NO_(x) and VOCs while promoting a dramatic emission reduction in PM_(2.5).The primary method of curbing ozone pollution is to strengthen the emission control of VOCs,with a long-term strategy of achieving substantial emission reductions in NO_(x),because VOCs and NO_(x) are also precursors to PM_(2.5);hence,their reductions also contribute to the reduction in PM_(2.5).Therefore,the implementation of a multipollutant emission reduction control strategy aimed at the prevention and control of PM_(2.5)and ozone pollution is the only means to realize the coordinated control of PM_(2.5)and ozone.