Proper Controller Research Articles

Dynamic response simulation and experiment for gamma-type Stirling engine

This study presents a dynamic model of a gamma-type Stirling engine and examines variations of the crank rotational speed against time (Dynamic response). Kinematic relations of the engine linkages were determined and Lagrange formulations were formed for rigid body dynamics. Working gas pressures on each surface of the rigid bodies were calculated over time using a third order thermodynamic analysis code. A test setup was established for measuring dynamic and thermodynamic state variables of ST500engine. First, experiment data was used to validate the thermodynamic code results. Then the dynamic formulations combined with the thermodynamic code were simultaneously solved and the result is compared to ST500 dynamic response. Finally, using the whole dynamic model, new aspects of Stirling engine behavior were investigated. The dynamic–thermodynamic combination of the model gives the opportunity to instantly calculate a precise open-loop response, which is the essential part of designing proper load controllers for inherently unstable Stirling engines.

A virtual laboratory for system simulation and control with undergraduate curriculum

ABSTRACTSystem modelling and simulation are essential in engineering especially in automatic control systems (ACS) engineering. At many universities, undergraduate curricula include systems and control courses with dynamic modelling and simulations in their syllabi. In order to design a controller for a physical system, one has to know the operational behaviors of that system very well so that a proper controller could be designed. Keeping this in mind, educational computer‐aided software with a user‐friendly visual interface was developed. The software provides an opportunity for students to simulate physical systems without and with the controllers they designed. Since it was developed to accompany undergraduate control system courses, the main purpose of this software was to create an interactive, practical, visual, and functional environment for the students who taking ACS courses. Therefore, it was called as virtual control laboratory (VCL). Basically, the students were able to design and simulate classical proportional‐integral‐derivative (PID) controllers and fuzzy logic controller (FLC). Besides, any other type of compensator with a transfer function or a state space model can be also combined with the physical system model for simulation and analysis. A laboratory type scope with two input channels was embedded in VCL in order to visually see and analyze the simulation results in the time domain. Responses from the students taking ACS course were also given to evaluate the proposed educational software from students' point of view. © 2015 Wiley Periodicals, Inc. Comput. Appl. Eng. Educ. 24:122–130, 2016; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae.21678

Development of an excretion care support robot with human cooperative characteristics.

To support care giving in an aging society with a shrinking population, various life support robots are being developed. In the authors' laboratory, an excretion care support robot (ECSR) with human cooperative characteristic has been developed to relieve the burden of caregivers and improve the quality of life for bedridden persons. This robot consists of a portable toilet with storage tank and a mobile robot which can run autonomously to conduct the cooperative work with others. Our research is focused on how to improve the motion accuracy and how the robot can cooperate with users. In this paper, to enable the ECSR could precisely move in the indoor environment, a proper controller is proposed considering the center of gravity shift and load changes. Then, to perform the cooperative task, two acceleration sensors are used to recognize the users' intended posture and position when moving from bed to toilet. The robot's target angle and position are determined by the user's posture. The effectiveness of the proposed method is verified by a pseudo excretion support experiment.

Reduced-order controller synthesis with regional pole constraint

ABSTRACTA reduced order output feedback controller is designed for a linear time invariant system, which guarantees that the closed-loop poles are placed within some pre-specified stability region in the complex plane. A convex approximation of the non-convex constraints is used to pose a sequence of semi-definite programs, which provide the lowest order proper controller satisfying the approximate constraints. The proposed method is demonstrated on two practical controller design applications.

Modeling and control of autonomous underwater vehicle (AUV) in heading and depth attitude via self-adaptive fuzzy PID controller

This paper focuses on design of a new self-adaptive fuzzy PID controller based on nonlinear MIMO structure for an AUV. Complexity and highly coupled dynamics, time-variance, and difficulty in hydrodynamic modeling and simulation, complicates the AUV modeling process and the design of proper and acceptable controller. In this work, the comprehensive nonlinear model of AUV is derived through kinematics and dynamic equations and then its treatment in open-loop is verified. In proposed controller, the PID parameters are adjusted by Mamdani fuzzy rules. Combined adaptive methods and dual PID controllers can improve solving of the uncertainty challenge in the PID parameters and AUV modeling uncertainty. The simulation results indicate that developed control system is stable, competent, and efficient enough to control the AUV in tracking the two channels of heading and depth with stabilized speed. Obtained results show that the proposed controller is not only robust, but also gives excellent dynamic, stunning steady-state characteristics and robust stability compared with a classically tuned PID controller.

Practical output tracking of switched nonlinear systems in p-normal form with unstable subsystems

This paper studies practical output tracking of switched nonlinear systems in p-normal form. No solvability of the practical output tracking problem for subsystems is required. A constructive scheme to solve the problem for a switched nonlinear system is set up by exploiting the single Lyapunov function method and the tool of adding a power integrator. Also, we design a proper switching law and construct state-feedback controllers of subsystems. A two inverted pendulums as a practical example, which cannot be handled by the existing approaches, illustrates our theoretical result.

LCL filter with passive damping for DSTATCOM using PI and HC regulators indq0current controller for load compensation

This paper presents a Distribution Static Compensator (DSTATCOM) with interface inductor–capacitor–inductor (LCL) filter controlled using dq0 current controller and Sinusoidal Pulse Width Modulation (SPWM) switching for compensation of unbalanced nonlinear load. Voltage Source Inverter (VSI) of DSTATCOM, connected at the point of common coupling (PCC) through interface filter, injects currents corresponding to load reactive and harmonic powers. These currents consist of switching frequency ripples. LCL filter has superior switching ripple attenuation capability compared to L filter. Moreover, this can be achieved with small value of overall LCL filter inductance than L filter. However, one major concern with LCL filter is its resonating frequency (determined from its L, C, L values), which can create resonance currents and results in improper load compensation. Therefore, in the present study, a proper design of LCL filter for high switching ripple attenuation along with passive damping and proper dq0 current controller are presented. The dq0 current controller is implemented in Synchronous Reference Frame (SRF) rotating at fundamental frequency and consists of Harmonic Compensation (HC) regulator (realized by sum of Sinusoidal Signal Integrators (SSI)) in parallel to Proportional Integrator (PI) regulator. SSI provides high gain to specified tuned harmonic frequency and helps in minimizing filter current tracking error for harmonic load current compensation. Neutral current compensation, which is required for compensating unbalance in load, is carried out through 0-axis controller. SPWM strategy generates constant frequency gating pulses for VSI switches. This will simplify the design of interface LCL filter, reduces stress on switches and switching noise. A Matlab/Simulink model of LCL filter DSTATCOM is developed and detailed simulation results of load compensation are presented. Experimental validation of proposed scheme is done on a three phase DSTATCOM prototype using dSPACE 1104 with Matlab Real Time Interface (RTI).

A Petri Net-Based Discrete-Event Control of Automated Manufacturing Systems With Assembly Operations

In the context of automated manufacturing systems (AMSs), Petri nets are widely adopted to solve the modeling, analysis, and control problems. So far, nearly all known approaches to liveness-enforcing supervisory control study AMSs with flexible routes, whereas little work investigates the ones with synchronization operations. Compared with flexibility, synchronization allows the disassembly and assembly operations that correspond to splitting to and merging from different subprocesses, respectively. Such structures bring difficulties to establish a liveness condition of the Petri net model of AMSs. In this paper, we propose a novel class of systems, which can well deal with these features so as to facilitate the investigation of such complex systems. Using structural analysis, we show that their liveness can be attributed to deadlock freeness, which is much easier to analyze, detect, and control by synthesizing a proper supervisory controller. Furthermore, a set of mathematical formulations is proposed to describe and extract the corresponding deadlocks. This facilitates the synthesis of liveness enforcing supervisors as it avoids the consideration of deadlock-free but nonlive scenarios. The effectiveness and efficiency of this new method is shown by AMS examples.

H∞ Control of Continuous-Time Linear Systems Using Dynamic and Static Output Controllers

The paper deals with the problem of the H ∞ control of continuous-time linear systems by proper dynamic output controllers of order equal to the plant model order and by static output controller. The design procedure is based on solution of the set of linear matrix inequalities and the matrix equality and ensures the closed-loop asymptotic stability using Lyapunov approach and the H ∞ performance, to guarantee the closed-loop system robustness to unknown disturbance. Numerical examples are given to illustrate the design procedures and the relevance of the method as well as to validate the performances of the proposed approach.

Electro-Hydraulic Actuator System Control via Pole Assignment Controler and Minimum Variance Controller

Precise control is necessary in controlling electro-hydraulic actuator system (EHAS). However due to its nonlinearities and uncertainties, controlling hydraulic actuator system had become a challenging task that need to be solved. A proper controller can be designed when an accurate model of a system is defined. In this paper, the process to obtain an EHAS system’s model by using system identification approached is presented. System identification is chosen because this technique only requires input and output data from system in order to obtain system model. An ARX model is chosen as a model structure for EHAS. A pole assignment controller and minimum variance controller (MVC) is later been designed based on the obtained model. The simulation result shows that both controllers manage to regulate at the desired input signal. However MVC controller prove to provide a better output performance compared to pole assignment controller by minimizing the phase lagging and having a better rise time.

Synthesis of multiple model switching controllers using [formula omitted] theory for systems with large uncertainties

The switching based control is an effective way to handle systems with large and fast varying uncertainties. Many conventional methods, however, do not use robust controllers to stabilize each model, and thus need a large number of controllers to ensure the stability of systems with large uncertainties. Under the structure of supervisory control, this paper presents a robust multiple model switching control (RMMSC) method using H∞ control for MIMO linear systems with large parametric uncertainty. The proposed method uses H∞ controller to maximize the stability region of each model with uncertainties, and thus to significantly reduce the number of candidate controllers. The candidate controllers are designed by using linear matrix inequality (LMI), and an exponentially decaying switch index is proposed to select the proper controller by estimating the system norm of each model uncertainty. Using such switch index, the closed-loop control system is then equivalent to a switching system with smaller uncertainty whose system norm can be predefined by designers. The robust stability under arbitrary switching conditions is proven by the small gain theorem; and for slow switching conditions, the acceptable dwell time for stability is analyzed and presented. The effectiveness of this method is demonstrated with the second order inertial system with large model uncertainties.

Feedback Linearization for Input-saturation Nonlinear System Based on T-S Fuzzy Model

Considering input saturation problem of nonlinear system, a linearized model of multi-inputs nonlinear system is proposed in this paper. The final linear model has prescribed poles and has the same convergence nearby the designed equilibrium points. After this, the linear control theorem can be applied. During the calculation of linearization, T-S (Takagi Sugeno) fuzzy model and pole placement method were utilized. Pole placement just was applied only once for the final model comparing the traditional case where it was designed for every fuzzy rule. This means fewer LMIs (linear matrix inequality) will be needed and its solution will be guaranteed as much as possible. In this paper, nonlinear system will be transferred to T-S fuzzy model first. Note that the T-S fuzzy model is still nonlinear. Then, by employing a series of transfer matrix, nonlinear T-S fuzzy model will be transferred into a nearly linear form accompanied with only one nonlinear part. Finally, by designing a proper controller, linear pole placement method is used and the designed linearization controller gains can be calculated out with LMIs.

High-Order Sliding Mode-Based Synchronous Control of a Novel Stair-Climbing Wheelchair Robot

For the attitude control of a novel stair-climbing wheelchair with inertial uncertainties and external disturbance torques, a new synchronous control method is proposed via combing high-order sliding mode control techniques with cross-coupling techniques. For this purpose, a proper controller is designed, which can improve the performance of the system under conditions of uncertainties and torque perturbations and also can guarantee the synchronization of the system. Firstly, a robust high-order sliding mode control law is designed to track the desired position trajectories effectively. Secondly, considering the coordination of the multiple joints, a high-order sliding mode synchronization controller is designed to reduce the synchronization errors and tracking errors based on the controller designed previously. Stability of the closed-loop system is proved by Lyapunov theory. The simulation is performed by MATLAB to verify the effectiveness of the proposed controller. By comparing the simulation results of two controllers, it is obvious that the proposed scheme has better performance and stronger robustness.

変位出力を用いたプロパーなコントローラによる柔軟宇宙構造物のロバスト安定化

変位出力を用いたプロパーなコントローラによる柔軟宇宙構造物のロバスト安定化

Robust Observer-Based Feedback Control for Lipschitz Singularly Perturbed Systems

The observer-based feedback control for singularly perturbed systems (SPSs) with Lipschitz constraint is addressed. A sufficient condition, independent of the perturbation parameter, for a full-order observer is presented in terms of linear matrix inequality (LMI) such that observation error is exponentially stable for all sufficiently small perturbation parameters. Then, for observer-based feedback control, a proper controller is constructed to guarantee the input-to-state stability of the system with regard to the observation error. Considering the convergence of observation error, the stability of the system can be obtained based on the input-to-state stability property. It is shown that the proposed method is simple and easy to operate. Moreover, the upper bound of the small perturbation parameter for stability of systems can be explicitly estimated with a workable computation way. Finally, two numerical examples show the effectiveness of the proposed method.

Active damping method to reduce the output impedance of the DC–DC converters

In the cascaded power system, instability may occur because of the impedance interaction. The system can be stabilised by passive damping or control methods to reduce the output impedance of the source converter and improve the damping characteristics. This study focuses on the source converter in the cascaded system and presents a new active damping control to reduce the output impedance of the converter by a proper active damping controller. The method to compute the corresponding active damping controller is proposed in this study. By the application of the active damping method, a virtual resistor in parallel with the output of the converter's small signal model can be realised. Therefore the output impedance can be reduced. Because the virtual resistor exists only in the small signal model, the steady-state operating point is not affected and the value of the virtual resistor can be changed. The experiment results of a Buck converter with the active damping controller under different conditions are proposed to verify the effectiveness of the active damping control. Besides, an active damping controller is applied to an unstable cascaded system in simulation to stabilise the cascaded system so the effectiveness of this method is also verified.

Regenerative Cascaded Cell Inverter with Active Filter

In the medium voltage application it is very beneficial to use cascaded inverters. Traditionally, this type of inverter is based on diode front end and bulky phase shifting transformer. Due to the demand of 4 quadrant drives and more severe grid requirement, the cascaded inverters with active front end have been started to emerge in the market. This article introduces regenerative cascade inverter topologies. After a short summary about the topologies, single-phase cell solution with NPC is analyzed in detail. Since one of the most challenging problems is the elimination of low order grid harmonic at low motor speed, the article demonstrates the origin of this harmonics. After the clarification of the harmonic generation phenomenon, a novel harmonic elimination method is introduced. Apart from the description of the new elimination concept, the proper controller structure is described as well. Finally, the performance of the novel method is verified by Matlab simulation.

変位出力を用いたプロパーな局所コントローラによる大型柔軟宇宙構造物の分散ロバスト最適制御

This paper considers position and attitude control of large flexible space structures composed of a number of subsystems(substructures) which are interconnected by flexible links modeled by springs and dampers. It is assumed that sensors and actuators are collocated in each subsystem. The purpose of the paper is to propose a decentralized control method by local proper controllers using only displacement / angular displacement output, which makes both each closed-loop subsystem and an overall closed-loop system not only robustly stable against uncertainty of characteristic parameters such as mass, damping, and stiffness, but also optimal for a quadratic cost function.

Decentralized robust optimal control of large flexible space structures by local proper controllers using displacement output

Decentralized robust optimal control of large flexible space structures by local proper controllers using displacement output

Control of Plane Non-Holonomic Mobile Robot Based on Image Recognition

With intensive research on robot and wide application of machine vision and movement control in relevant field of robot, image recognition and movement control of robot have become the research focus gradually. This thesis sets the plane non-holonomic mobile robot as the research subject, mainly discusses the control of the plane non- holonomic mobile robot based on image recognition, it has put forward practical stabilization of plane non-holonomic mobile robot based on bounded input, proper controller has been designed aimed at (2,0) type robot and certified feasibil- ity of the controller in theory and simulation; then constructed a test platform for the plane non-holonomic mobile robot which is suitable for this system, introducing this test platform from hardware and software.