A path generation algorithm of an Automatic Guided Vehicle using sensor scanning method

In this paper, a path generation algorithm that uses sensor scannings is described. A scanning algorithm for recognizing the ambient environment of the Automatic Guided Vehicle (AGV) that uses the information from the sensor platform is proposed. An algorithm for computing the real path and obstacle length is developed by using a scanning method that controls rotating of the sensors on the platform. The AGV can recognize the given path by adopting this algorithm. As the AGV with two-wheel drive constitute a nonholonomic system, a linearized kinematic model is applied to the AGV motor control, An optimal controller is designed for tracking the reference path which is generated by recognizing the path pattern. Based on experimental results, the proposed algorithm that uses scanning with a sensor platform employing only a small number of sensors and a low cost controller for the AGV is shown to be adequate for path generation.     

重载AGV液压转向模糊PID控制

重载AGV在满载工况转向时,转向阻力明显增大,给转向控制系统敏捷、精确控制造成困难。为此,提出一种基于模糊PID的控制方法,以实时、动态的修正转向系统控制参数。根据AGV转向系统结构建立了控制模型,搭建了模糊PID控制器,制定了隶属度函数及模糊规则,并根据转角偏差及偏差变化率更新控制器的参数,使液压调整量根据需要进行动态修正,保证车轮在高转向阻力时快速、准确的偏转。仿真及试验结果表明,模糊自适应PID算法可有效降低系统超调量、振荡幅度,加快系统响应速度,提高了重载AGV液压转向系统的控制精度和反应速度。     

On a new sectionalized motion control strategy for automated guided vehicles: modeling and simulation validation

As key equipment in logistics system of modern manufacturing factories, the automated guided vehicle (AGV) plays an increasingly important role. Although many strategies for AGV motion control are available, in most cases, only a single control method is utilized during the entire process, which inevitably leads to the lack of flexibility in dealing with problems encountered in various stages of the AGV motion. In this paper, a new approach called sectionalized motion control (SMC) was proposed in order to achieve superb comprehensive performance (i.e., high precision, low energy consumption, and good stability) for the entire AGV tracking process. In this method, considering AGV’s various characteristics in different motion stages (early, middle, and terminal), the neural dynamics-based tracking, energy-efficient tracking, and model predictive control technologies were adopted. Furthermore, a simulation using Matlab software was performed in order to verify the proposed approach. The simulated results showed that the SMC is capable of providing smooth, energy-efficient, robust, and globally stable control for the AGV system.     

Immune algorithm based active PID control for structure systems

An immune algorithm is a kind of evolutional computation strategies, which is developed in the basis of a real immune mechanism in the human body. Recently, scientific or engineering applications using this scheme are remarkably increased due to its significant ability in terms of adaptation and robustness for external disturbances. Particularly, this algorithm is efficient to search optimal parameters against complicated dynamic systems with uncertainty and perturbation. In this paper, we investigate an immune algorithm embedded Proportional Integral Derivate (called I-PID) control, in which an optimal parameter vector of the controller is determined offline by using a cell-mediated immune response of the immunized mechanism. For evaluation, we apply the proposed control to mitigation of vibrations for nonlinear structural systems, cased by external environment load such as winds and earthquakes. Comparing to traditional controls under same simulation scenarios, we demonstrate the innovation control is superior especially in robustness aspect.     

Multi-loop control of UPS inverter with a plug-in odd-harmonic repetitive controller

This paper proposes an improved multi-loop control scheme for the single-phase uninterruptible power supply (UPS) inverter by using a plug-in odd-harmonic repetitive controller to regulate the output voltage. In the suggested control method, the output voltage and the filter capacitor current are used as the outer and inner loop feedback signals, respectively and the instantaneous value of the reference voltage feedforwarded to the output of the controller. Instead of conventional linear (proportional-integral/-resonant) and conventional repetitive controllers, a plug-in odd-harmonic repetitive controller is employed in the outer loop to regulate the output voltage, which occupies less memory space and offers faster tracking performance compared to the conventional one. Also, a simple proportional controller is used in the inner loop for active damping of possible resonances and improving the transient performance. The feedforward of the converter reference voltage enhances the robust performance of the system and simplifies the system modelling and the controller design. A step-by-step design procedure is presented for the proposed controller, which guarantees stability of the system under worst-case scenarios. Simulation and experimental results validate the excellent steady-state and transient performance of the proposed control scheme and provide the exact comparison of the proposed method with the conventional multi-loop control method.     

Composite control of a gyro mirror line-of-sight stabilization platform--design and auto-tuning

In this paper, we propose a composite control scheme for a gyro mirror line-of-sight stabilization system. It comprises of an adaptive controller augmented with a variable structure (VS) to remain efficient in the face of modeling errors and extraneous disturbances. Under an adequate selection of control parameters, the control scheme guarantees an asymptotically stable closed-loop response. An automatic tuning method is developed for the proposed control scheme which explicitly uses inherent properties of the control structure for tuning purposes. Simulation and experimental results are provided to illustrate the operational principles of the proposed scheme and to demonstrate its viability in real practical applications.     

Multi-objective parameter space approach based controller and add-on disturbance observer design

The parameter space approach based robust PI control design methodology for DC motor speed control is proposed in this paper. The multi-objective design requirements like D-stability, phase margin and mixed sensitivity (frequency domain) bounds are mapped into the controller parameter space to determine PI controller coefficients which satisfies the desired user-defined specifications. Besides robust PI controller, an add-on disturbance observer is utilized to enhance the tracking performance and disturbance rejection of the control system. The proposed control scheme is validated by simulations and experiments. The results prove that the effectiveness of the proposed control system against uncertainties in the modeling and disturbances on the system response.

     

Object oriented modelling and development of a dispatching algorithm for automated guided vehicles

The main problem for an automated guided vehicle (AGV) dispatching system is to assign vehicles to transport demands which optimise some predetermined objectives of a manufacturing shop. This paper presents a framework for an AGV dispatching system based on an object oriented approach using the unified modelling language (UML), and the development of a dispatching algorithm to facilitate a human controller to dispatch efficiently a fleet of AGVs in response to calls from any shop floor (or machine) operator. The main reason for this work is to model an AGV dispatching system as well as to develop a dispatching algorithm which can record details of the AGV position and movement and ensure their allocation of new orders. The provision of both immediate and pre-booked orders for an AGV is also incorporated in the proposed AGVs dispatching system. The underlying AGV dispatching system and algorithm are capable of dispatching a vehicle automatically to handle a call at the required time. In order to overcome difficulties associated with tackling immediate orders, pre-booked orders, and processing of information related to AGVs, a comprehensive dispatching algorithm is developed which aims to minimise lateness, traveling time and distance of empty vehicles in a simulated job-shop scenario. The effectiveness of the proposed framework for an AGV dispatching system is shown through a test problem.     

Automatic performance estimation of conceptual temperature control system design for rapid development of real system

This paper presents an automatic performance estimation scheme of conceptual temperature control system with multi-heater configuration prior to constructing the physical system for achieving rapid validation of the conceptual design. An appropriate low-order discrete-time model, which will be used in the controller design, is constructed after determining several basic factors including the geometric shape of controlled object and heaters, material properties, heater arrangement, etc. The proposed temperature controller, which adopts the multivariable GPC (generalized predictive control) scheme with scale factors, is then constructed automatically based on the above model. The performance of the conceptual temperature control system is evaluated by using a FEM (finite element method) simulation combined with the controller.     

Robust and novel two degree of freedom fractional controller based on two-loop topology for inverted pendulum

A rotary single inverted pendulum (RSIP) typically represents a space booster rocket, Segway and similar systems with unstable equilibrium. This paper proposes a novel two degree of freedom (2-DOF) fractional control strategy based on 2-loop topology for RSIP system which can be extended to control the systems with unstable equilibrium. It comprises feedback and feed-forward paths. Primary controller relates the perturbation attenuation while the secondary controller is accountable for set point tracking. To tune the parameters of proposed fractional controller a simple graphical tuning method based on frequency response is used. The study will serve the outstanding experimental results for both, stabilization and trajectory tracking tasks. The study will also serve to present a comparison of the performance of the proposed controller with the 1-DOF FOPID controller and sliding mode controller (SMC) for the RSIP system. Further to confirm the usability of the proposed controller and to avoid the random perturbations sensitivity, robustness, and stability analysis through fractional root-locus and Bode-plot is investigated.     

基于轨迹控制的AGV运动控制器设计研究

对基于计算机视觉的AGV路径跟踪技术进行了研究,提出了基于轨迹控制的AGV运动控制器设计新方法,重点解决AGV路径跟踪效果与高速运动稳定性问题。首先对AGV工作环境与计算机视觉的特点进行分析,设计了适合AGV路径跟踪的图像处理流程。然后在深入分析两轮差速驱动运动平台的基础上,提出了基于轨迹控制的AGV运动控制器设计新方法。该控制器以AGV相对路径所处的状态量为输入,输出AGV控制指令——两轮的速度差和运动时间,从而控制AGV按指定轨迹运动,实现轨迹控制即AGV路径跟踪的目标。试验结果表明,AGV路径跟踪技术对直线和弧线具有较好的跟踪效果且AGV运动平稳。     

An improved approach for robust control of dynamic voltage restorer and power quality enhancement using grasshopper optimization algorithm

This paper presents a novel contribution of a low complexity control scheme for voltage control of a dynamic voltage restorer (DVR). The scheme proposed utilizes an error-driven proportional–integral–derivative (PID) controller to guarantee better power quality performance in terms of voltage enhancement and stabilization of the buses, energy efficient utilization, and harmonic distortion reduction in a distribution network. This method maintains the load voltage close to or equal to the nominal value in terms of various voltage disturbances such as balanced and unbalanced sag/swell, voltage imbalance, notching, different fault conditions as well as power system harmonic distortion. A grasshopper optimization algorithm (GOA) is used to tune the gain values of the PID controller. In order to validate the effectiveness of the proposed DVR controller, first, a fractional order PID controller was presented and compared with the proposed one. Further, a comparative performance evaluation of four optimization techniques, namely Cuckoo search (CSA), GOA, Flower pollination (FBA), and Grey wolf optimizer (GWO), is presented to compare between the PID and FOPID performance in terms of fault conditions in order to achieve a global minimum error and fast dynamic response of the proposed controller. Second, a comparative analysis of simulation results obtained using the proposed controller and those obtained using an active disturbance rejection controller (ADRC) is presented, and it was found that the performance of the optimal PID is better than the performance of the conventional ADRC. Finally, the effectiveness of the presented DVR with the controller proposed has been assessed by time-domain simulations in the MATLAB/Simulink platform.     

Modeling and control of non-square MIMO system using relay feedback

This paper proposes a systematic approach for the modeling and control of non-square MIMO systems in time domain using relay feedback. Conventionally, modeling, selection of the control configuration and controller design of non-square MIMO systems are performed using input/output information of direct loop, while the output of undesired responses that bears valuable information on interaction among the loops are not considered. However, in this paper, the undesired response obtained from relay feedback test is also taken into consideration to extract the information about the interaction between the loops. The studies are performed on an Air Path Scheme of Turbocharged Diesel Engine (APSTDE) model, which is a typical non-square MIMO system, with input and output variables being 3 and 2 respectively. From the relay test response, the generalized analytical expressions are derived and these analytical expressions are used to estimate unknown system parameters and also to evaluate interaction measures. The interaction is analyzed by using Block Relative Gain (BRG) method. The model thus identified is later used to design appropriate controller to carry out closed loop studies. Closed loop simulation studies were performed for both servo and regulatory operations. Integral of Squared Error (ISE) performance criterion is employed to quantitatively evaluate performance of the proposed scheme. The usefulness of the proposed method is demonstrated on a lab-scale Two-Tank Cylindrical Interacting System (TTCIS), which is configured as a non-square system.     

自主导航小车(AGV)轨迹跟踪的模糊预测控制

针对非完整约束的轮式移动机器人WMR轨迹跟踪问题,以差速驱动式轮式移动机器人XAUT.AGV100为研究对象,对WMR的运动控制问题作了进一步的研究。本文在分析现有移动机器人运动控制方法的基础上,充分利用模糊控制和预测控制的优点,将模糊控制的思想引入到预测控制中,设计了模糊预测控制算法,并采用此方法控制自主导航小车AGV以提高其轨迹跟踪的快速性和运动的平稳性。理论仿真分析和实验研究均证明,采用所设计的模糊预测方法控制AGV,可有效提高AGV轨迹跟踪的快速性和运动平衡性。     

Analytical design and analysis of mismatched Smith predictor

In this paper, an analytical design method is developed for the mismatched Smith predictor on the basis of the internal model control (IMC) method. Design formulas are given and design procedure is significantly simplified. One important merit of the proposed method is that the response of the closed loop system can be easily adjusted. The relation between the controller parameter and the system response is monotonous. In addition, necessary and sufficient condition for the robust stability of mismatched Smith predictor is also given. It is shown that the proposed method can provide good performance for perfectly matched system and a better response for mismatched system. Several numerical examples are given to illustrate the proposed method.     

基于ARM的弹道跟踪转镜控制器设计

弹道跟踪转镜已经成为一种跟踪拍摄弹丸飞行姿态的成熟可靠的方法.其中,伺服运动控制器是跟踪转镜的核心部件,其精度和实时性是决定系统整体性能的关键.基于advanced RISC machine(ARM)系统原理,提出了一种转镜伺服控制系统的设计方案,详细介绍了控制器的原理以及软硬件设计方案.分析结果表明:设计可以实现0....     

Controlling the navigation of automatic guided vehicle (AGV) using integrated fuzzy logic controller with programmable logic controller (IFLPLC)—stage 1

Material handling in manufacturing systems is becoming easier as the automated machine technology is improved. Nowadays, most of the research aims at increasing the flexibility and improving the performance of the automatic guided vehicle (AGV). In this paper, designed and made AGV in the Industrial Control Laboratory in Royce Lab at the University of Manchester Institute of Science and Technology will be presented. For controlling the navigation of the AGV, a newly developed controller integrated fuzzy logic with programmable logic controller will be used. By using integrated fuzzy logic controller with programmable logic controller (IFLPLC), the flexibility of AGV will be increased and we achieved great advantages, which can be used in future. Since this AGV uses programmable logic controller and fuzzy logic controllers together, then it will be useful for factories which implement flexible manufacturing system (FMS). Online maintenance and sending the commands to other machines from AGV and so on are the advantages that can be used in FMS. The aim of this paper is to propose the practical example of IFLPLC. The designed AGV is able to reach the target. Further researches are required for collision avoidance and selecting the best way in FMS     

Optimal solution,quantitative performance estimation,and robust tuning of the simplifying controller

Recently, a simplifying controller has been proposed based on the principal of simplification of the control system transfer functions, which offers improved control for processes with a large time delay. It is the purpose of this complementary paper to give a comprehensive analysis on the scheme. First, the relationship among the simplifying controller, the Smith predictor, and the internal model control are discussed. Second, an analytical design procedure is developed based on internal model control (IMC) and optimal solution is derived. Third, the problem of estimating the time domain performance of the closed loop system, quantitatively, is discussed. Fourth, a simple robust tuning procedure is presented. Numerical examples are provided to illustrate the proposed method.     

Robust internal model control of servo motor based on sliding mode control approach

This paper proposes a robust internal model control (IMC) based on sliding mode control (SMC) approach for high-performance motion control of a servo motor subject to uncertainties and/or disturbances. The proposed control strategy considers not only the simplicity and intuition of the IMC-based controller for a prescribed tracking performance but also the effectiveness of the SMC scheme to guarantee the robustness of the servo system. Since the performance of the IMC-based controller can be analyzed via a SMC structure, a robust control law based on the SMC technique is introduced into the IMC scheme to decrease the sensitivity to uncertainties and enhance the resistance to disturbances. Moreover, the 2-degree-of-freedom IMC integrating the robust SMC scheme is developed to further improve the control performance. The stability is analyzed based on Lyapunov theory, and the theoretical results show that a prescribed transient tracking performance and a final tracking accuracy of the servo system can be guaranteed. Comparative simulations and experiments are investigated to verify the high performance nature of the proposed control strategy.