Modular Servo Research Articles

Experimental Results on Actuator/Sensor Failures in Adaptive GPC Position Control

This work relates to the reliable generalized predictive control issues in the case when actuator or sensor failures take place. The experimental results that form the basis from which the conclusions are drawn from have been obtained in the position control of a servo drive task, and extend the results from the prior research of the author, dedicated to velocity control problems. On the basis of numerous experiments, it has been shown which configuration of prediction horizons is most advantageous from the control performance viewpoint in the adaptive generalized predictive control framework, to cope with the latter failures, and related to a minimum performance deterioration in comparison with the nominal, i.e., failure-free, case. This case study is the main novelty of the presented work, as the other papers available in the field rather focus on additional modifications of the predictive control framework, and not leaving possible room for optimization/alteration of prediction horizons’ values. The results are shown on the basis of the experiments conducted on the laboratory stand with the Modular Servo System of Inteco connected to a mechanical backlash module to cause actuator/sensor failure-like behavior, and with a magnetic brake module to show the performance in the case of an unexpected load.

Real-Time Implementation of Passive Fault-Tolerant Speed Control for Unloading MS150 DC Motor System

The failure of a DC motor in an electric car caused by an error in the actuator and sensor can endanger the driver and the surrounding environment. This research focuses on the design of a Passive Fault Tolerant Control (PFTC) system that can work when an actuator and sensor error occurs in the MS150 DC modular servo system speed control. The first step is to identify the MS150 DC modular servo system. The second step is to design a state feedback control system with an integrator. The third step is to design a simulation PFTC system and design a PFTC system to be implemented in realtime. To find out the performance of the designed PFTC system, a test is carried out with a bias error of about 0.1 V to 0.8 V. On the results of implementing the PFTC system in real-time on the simulation error, the maximum overshoot value is smaller than the system without PFTC, besides the application of AFTC causes the resulting settling time is smaller than the system without PFTC.

Dynamic anti‐windup compensator for fractional‐order system with time‐delay

AbstractThis paper describes the results of introducing an additional dynamic element to an anti‐windup compensator from control quality and stability area anslysis viewpoint. The analyzed system consists of a first‐order plant with time delay and a fractional‐order PI controller, to present the discussed approach. The controller is tuned based on Hermite‐Biehler and Pontryagin theorems. In the paper, the stability analysis and tracking performance are presented based on both simulation and experimental results. The experiments have been performed using Inteco Modular Servo System with performance evaluated on the basis of the selected performance criterion, namely the Integral of Absolute Error, to verify the applicability of the proposed method. The results have proven that use of the additional dynamic element provides a wider range of controller parameters to ensure stability of the closed‐loop system and better tracking performance in comparison to the system without anti‐windup compensation or system with a standard anti‐windup compensator. It is actually the first time that this type of analysis for dynamic element compensation in anti‐windup framework has been presented for fractional‐order systems. In addition, all the obtained results are referred to the experimental data.

Design and Validation of Fractional-Order Control Scheme for DC Servomotor via Internal Model Control Approach

ABSTRACTThis paper proposes a robust fractional-order controller for DC servomotor using internal model control and CRONE (Commande Robuste d'Ordre Non Entier) principle. The controller acquires a PID (proportional-integral-derivative) form followed by a fractional-order integrator. Unlike the conventional fractional-order PID controller which demands five tuning parameters, the proposed scheme has only two tuning parameters which can be obtained on the basis of desired gain crossover frequency and phase margin. For speed control problem, the performance of the proposed controller is studied on hardware set up called precision modular servo system. The proposed controller outperforms in terms of robustness and optimality when compared with controllers designed by integer-order technique. Furthermore, the proposed scheme is applied for position control problem and validated on QUBE-Servo 2 set up.

Virtual Reference Feedback Tuning of Model-Free Control Algorithms for Servo Systems

This paper proposes the combination of two data-driven techniques, namely virtual reference feedback tuning (VRFT) and model-Free Control (MFC) in terms of the VRFT of MFC algorithms dedicated to servo systems. VRFT ensures the automatic optimal computation of the parameters of three MFC algorithms represented by intelligent proportional (iP), intelligent proportional-integral (iPI), and intelligent proportional-integral-derivative (iPID) controllers. The combination of MFC and VRFT leads to a novel mixed MFC-VRFT approach. The approach is validated by experimental results related to the angular speed control of modular servo system laboratory equipment. The performance of the control systems with the MFC algorithms (iP, iPI, and iPID controllers) tuned by the mixed MFC-VRFT approach is compared with that of control systems with MFC algorithms tuned by a metaheuristics gravitational search algorithm (GSA) optimizer, and of control systems with I, PI and PID controllers optimally tuned by VRFT and GSA in the same optimization problem.

Internal model control based PID tuning using first-order filter

The selection of filter plays an important role in internal model control (IMC) based controller design. As per the rule, for a minimum-phase delay free plant, IMC based controller is obtained by augmenting a filter. We suggest the use of first-order filter for controller design, which is then parameterized to a conventional PID controller. The proposed scheme brings filter size reduction, closed-loop bandwidth enhancement, and easy formulation of the PID structure. The proposed scheme is applied to some class of linear and nonlinear processes. Further the hardware testing for velocity control of precision modular servo system which contains DC servomotor is carried out through this scheme. Quantitative comparison of servo, regulatory and optimal attributes of the proposed scheme with other popular IMC-PID control techniques depicts sharp reference tracking, good disturbance rejection and minimum integral error performance.

Control Education for Mechatronics: Robust State-Feedback Controller Design

The paper surveys selected state space robust control methods suitable for implementation in motion systems, and their implementation on a laboratory plant - the Modular Servosystem. Robust control theory is taught within control engineering courses in the MSc study program Applied Mechatronics, robust methods and algorithms are developed and verified in the control engineering laboratory during the solution of student and research projects. The project-based learning on suitable laboratory plants is a well-established method for control engineering education in mechatronics.

LQG/LTR based reference tracking for a modular servo

The paper presents an application of the LQG/LTR controller for a motion system – a laboratory modular servosystem. Basic results on LQ regulator and Kalman filter designs are briefly surveyed and tuning of their combination – the LQG controller is shown. Based on comparison of frequency properties of the LQR and LQG controllers, the LTR methodology is applied to fine-tune the LQG in order to improve its robustness. LQG/LTR speed controller for the modular servosystem plant was designed based on noisy measurements of the angular displacement. Simulation and experimental results illustrate implementation of the LQG controller.

Design of sensor and actuator multi model fault detection and isolation system using state space neural networks

This paper deals with the application of state space neural network model to design a Fault Detection and Isolation diagnostic system. The work describes approach based on multimodel solution where the SIMO process is decomposed into simple models (SISO and MISO). With such models it is possible to generate different residual signals which later can be evaluated with simple thresholding method into diagnostic signals. Further, such diagnostic signals with the application of Binary Diagnostic Table (BDT) can be used to fault isolation. All data used in experiments is obtain from the simulator of the real-time laboratory stand of Modular Servo under Matlab/Simulink environment.

Development of Computer-Aided EDM for Machining Micropits on Spherical Surface of Hip Implant

This study aims to develop dedicated computer-aided workpiece positioning system for biomedical application. The application is for machining micropits on spherical surface of hip implant using electrical discharge machining (EDM). New spherical positioning system has been designed and realized for further development. A computer is used as a main control unit to control the positioning system and modular servo motors with tuneable PID controller are utilized by the system. This paper explains the configuration of the implemented system and tuning process to optimize the system performance.

Superiority of fractional order controllers in limit cycle suppression

In this paper, we report an interesting advantage of fractional order controllers over integer order ones. It is found that the three-parameter-fractional-controllers such as PIa and [PI]a outperform integer PID in limit cycle suppression when designed to meet Wang et al. specifications. An elementary servo plant having separable static backlash non-linearity in its model is considered for the tuning purpose. For this plant, designed PIa and [PI]a produce significantly reduced limit cycles in the closed loop non-linear simulation response as compared to PID. The results are further verified with describing function method. Also, the results exhibiting such a ‘fractional superiority’ for a real time application of precision modular servo experimental set-up are included for the better illustration.

Performance Comparison Between PID and Fuzzy Logic Controller In Position Control System Of DC Servomotor

Objektif kertas kerja ini adalah untuk menyiasat dan membandingkan prestasi spesifikasi masa diantara pengawal konvensional dan pengawal suatu perisian interaktif komputer akan direka dengan menggunakan Microsoft Visual Basic 6.0 yang berupaya mengawal kedudukan shaft motor dalam sistem motor servo. Skop projek ini adalah untuk menggunakan teknik kawalan terus digital dalam mengawal kedudukan shaft motor servo. Pengawal PID dan logik kabur akan digunakan untuk mengawal isyarat keluaran motor servo. Projek ini terbahagi kepada dua bahagian iaitu perkakasan dan perisian. Bahagian perkakasan terdiri daripada membina hubungan antaramuka antara MS150 Modular servo sistem dengan kad perantaramukaan dan komputer peribadi. Bahagian perisian pula adalah lebih kepada mereka bentuk perisian untuk pengawal PID dan logik kabur dengan menggunakan Microsoft Visual Basic 6.0. Kata kunci: virtual instrumentation, PID, logik kabur, kedudukan sistem kawalan, motor servo, kawalan terus digital The objective of this paper is to compare the time specification performance between conventional controller and artificial intelligence controller in position control system of a DC motor. This will include design and development of a GUI software using Microsoft Visual Basic 6.0 for position control system experiment. The scope of this research is to apply direct digital control technique in position control system. Two types of controller namely PID and fuzzy logic controller will be used to control the output response. An interactive software will be developed to visualize and analyze the system. This project consists of hardware equipment and software design. The hardware parts involve in interfacing MS150 Modular servo System and Data Acquisition System with a personal computer. The software part includes programming real–time software using Microsoft Visual Basic 6.0. Finally, the software will be integrated with hardware to produce a GUI position control system. Key words: virtual instrumentation, PID, fuzzy logic, position control system, servomotor, direct digital control, graphic user interface

Modelling of dynamical systems based on almost orthogonal polynomials

A new class of the almost orthogonal filters is described in this article. These filters are a generalization of the classical orthogonal filters commonly used in the circuit theory, control system theory, signal processing, and process identification. Almost orthogonal filters generate the series of almost orthogonal Legendre functions over the interval (0, ∞). It is well known that all real systems suffer from some imperfections, so the models of these systems should reflect this fact. A new method for obtaining an imperfect system model is proposed. This method uses an almost orthogonal filter, which is based on almost orthogonal functions. Experiments with modular servo drive were performed to validate theoretical results and demonstrate that the method described in the article is suitable for modelling of imperfect systems.