Real-Time Workshop Research Articles

Human control of an inverted pendulum: Is continuous control necessary? Is intermittent control effective? Is intermittent control physiological?

Human motor control is often explained in terms of engineering 'servo' theory. Recently, continuous, optimal control using internal models has emerged as a leading paradigm for voluntary movement. However, these engineering paradigms are designed for high band-width, inflexible, consistent systems whereas human control is low bandwidth and flexible using noisy sensors and actuators. By contrast, engineering intermittent control was designed for bandwidth-limited applications. Our general interest is whether intermittent rather than continuous control is generic to human motor control. Currently, it would be assumed that continuous control is the superior and physiologically natural choice for controlling unstable loads, for example as required for maintaining human balance. Using visuo-manual tracking of an unstable load, we show that control using gentle, intermittent taps is entirely natural and effective. The gentle tapping method resulted in slightly superior position control and velocity minimisation, a reduced feedback time delay, greater robustness to changing actuator gain and equal or greater linearity with respect to the external disturbance. Control was possible with a median contact rate of 0.8±0.3 s(-1). However, when optimising position or velocity regulation, a modal contact rate of 2 s(-1) was observed. This modal rate was consistent with insignificant disturbance-joystick coherence beyond 1-2 Hz in both tapping and continuous contact methods. For this load, these results demonstrate a motor control process of serial ballistic trajectories limited to an optimum rate of 2 s(-1). Consistent with theoretical reasoning, our results suggest that intermittent open loop action is a natural consequence of human physiology.

A DSP-Based Dual Loop Digital Controller Design and Implementation of a High Power Boost Converter for Hybrid Electric Vehicles Applications

This paper presents a DSP based direct digital control design and implementation for a high power boost converter. A single loop and dual loop voltage control are digitally implemented and compared. The real time workshop (RTW) is used for automatic real-time code generation. Experimental results of a 20 kW boost converter based on the TMS320F2808 DSP during reference voltage changes, input voltage changes, and load disturbances are presented. The results show that the dual loop control achieves better steady state and transient performance than the single loop control. In addition, the experimental results validate the effectiveness of using the RTW for automatic code generation to speed up the system implementation.

Real-time particle swarm optimization based parameter identification applied to permanent magnet synchronous machine

Particle swarm optimization (PSO) has been widely used in optimization problems. If an identification problem can be transformed into an optimization problem, PSO can be used to identify the unknown parameters in a nonlinear model that is used to describe a system. Currently, most PSO based identification or optimization solutions can only be implemented offline. The difficulties of online implementation mainly come from the unavoidable lengthy simulation time to evaluate a candidate solution. In this paper, a technique for faster than real-time simulation is introduced and implementation details of PSO based identification algorithm is presented. Performance of the proposed technique is demonstrated through application to parameters identification of permanent magnet synchronous machine control system. The algorithm is implemented in Matlab/Simulink with the most fundamental blocks and Embedded Matlab Functions. Thus the program can be compiled to C/C++ code through Real-time Workshop and be able to run on hardware controllers like dSPACE. The proposed techniques can also be applied to many other online identification and optimization problems.

Directions for Combustion Engine Aerosol Measurement in the 21st Century

The Coordinating Research Council convened two Real-Time PM Measurement Workshops in December 2008 and March 2009 to take an intensive look at the current status and future directions of combustion aerosol measurement. The purpose was to examine the implications of parallel rapid developments over the past decade in ambient aerosol science, engine aftertreatment technology, and aerosol measurement methodology, which provide benefits and challenges to the stakeholders in air quality management. The workshops were organized into sessions targeting key issues in ambient and source combustion particulate matter (PM). These include (1) metrics to characterize and quantify PM, (2) the need to reconcile ambient and source measurements, (3) the role of atmospheric transformations on modeling emissions and exposures, (4) the impact of sampling conditions on PM measurement, and (5) the potential benefits of novel PM instrumentation. This paper distills the material presented by subject experts and the insights derived from the in-depth discussions that formed the core of each session. The paper’s objectives are to identify areas of consensus that allow wider practical application of the past decade’s advances in combustion aerosol measurement to improve emissions and air quality modeling, develop emissions reduction strategies, and to recommend directions for progress on issues in which uncertainties remain.

Conclusions of the 14th international real-time Ada workshop

The last session of IRTAW-14 was devoted to concluding on the results of the workshop, with the goal of prioritizing and selecting Ada Issues (AIs) to be produced and sent to the ISO/IEC JTC1/SC22/WG9 Ada Rapporteur Group (ARG). It allowed time for closing some open issues. In this report, Sections 2 to 4 summarize the final discussion around some open issues. Section 5 reflects the list of AIs to be produced by the workshop. The plan for next meeting is considered in Section 6. There is a final consideration about concurrency vulnerabilities in Section 7. Finally, Section 8 concludes with the closing of IRTAW-14.

Session details: Proceedings of the 14th international real-time Ada workshop

Session details: Proceedings of the 14th international real-time Ada workshop

Remote Quanser Experiments

This paper describes the implementation and operation of remote control systems working on Quanser experiments implemented to University of Craiova. The experiments cover experiments based on either the rotary servo or on the linear motion. Design software is included with each experiment and is written in MATLAB, Turbo C and Turbo Assembler. For real-time implementation of the control algorithms the Real-Time Workshop, xPC – Target toolbox from Matlab/Simulink environment and Wincon software are used. A communications link connects the host and target computers. The user designs the application on the host computer and download the real-time application to the target PC. The same communications interface is used to pass commands and parameter changes to the target PC.

풍력 터빈 모의 실험을 위한 Matlab 기반 가변 토오크 시뮬레이터 개발

In this paper the principles and structure of a WTS (Wind Turbine Simulator) are described. The proposed WTS is a versatile system specially designed for the purpose of developing and testing new control strategies for wind energy conversion systems. The simulator includes two sub-systems; a torque controller which controls a 3-phase induction motor in order to simulate the wind turbine and wind speed generator which can simulate an actual wind speed. In order to make the proposed system working in real-time, two sub-systems are incorporated into one simulink block by using Real-time workshop. The performance of the proposed system is verified by considering various wind speeds.

A real-time control system for single-phase unified power flow controllers

This paper proposes a real-time control system for a single-phase unified power flow controller (UPFC) which is constructed as a pilot power-quality compensation equipment of an electrical railway, and shows simulation and experimental results. For simulation, the control system is modeled in the form of block diagrams by using the Simulink, where the main control effort is focused on the power flow control with the UPFC and the hysteresis current controller is adopted to control the single-phase inverters of the UPFC. And for a small-scale rapid prototyping of the UPFC-equipped control system, the simulation blocks are modified and a real-time control platform is developed by using the real-time workshop and multiple digital signal processors. Both simulation and experiment results have proved the effectiveness of the proposed control system.

Introducing a Virtualization Technology for the FTU Plasma Control System

The Feedback control system running at FTU has been recently improved by the adoption of an Object-Oriented model, obtaining many advantages regarding the software extensibility, re-usability and testing capabilities. This new structure has been ported into a virtual environment using the QEMU processor emulator, in order to simulate, as close as possible to the hardware level, the control system behavior during the real experiment. This new approach introduces the advantage of decreasing dramatically the risks related to coding errors and operating system bugs arising at runtime, whereas it still supports the real-time control features. Moreover, the Real Time Workshop fast controller prototyping interface eliminates the model-translation related problems thanks to its automatic C code generation tools. The entire project flow is now completed: using Simulink, it is possible to design the diagram implementing a new control law, then synthesize the controller library. At this point, we can transfer the new library to the virtual machine, simulate the plasma control experiment in an open-loop configuration, and finally compare the simulation results to those from the past experiments, for a consistency check. The proposed framework is remotely managed by a new Matlab interface. After a satisfying simulation/validation of the new control model, the module can be easily transferred to the control system andhooked up to the real experiment, where it can operate in closed-loop. In this paper, we illustrate the advantages of this new approach and report on some experimental tests where the actual experimental data is compared to the simulations provided by the above-mentioned virtual environment.

Implementation of Gas Control Algorithm in EASTPCS

In this paper, gas control on EAST in open and closed loop is discussed and its implementation into EASTPCS (plasma control system for the experimental advanced superconducting tokamak) is introduced. Using a model to describe the plasma density response to the gas puff command, a gas simulation server (simserver) using MATLAB® simulink tools and real time workshop was built up. Proper operation of the gas control algorithm was verified using this simserver. The simulation results suggested that the gas control can be applied in the next EAST campaign.

Generic Real-Time Modeling of Solid Oxide Fuel Cell Hybrid Systems

Real-time (RT) modeling is a recognized approach to monitor advanced systems and to improve control capabilities. Applications of RT models are commonly used in the automotive and aerospace fields. Starting from existing components and models developed in TRANSEO[REF], a new approach, called the multipurpose RT approach, is developed for the solid oxide fuel cell hybrid system application. Original C-based models have been reprogrammed into embedded MATLAB functions for direct use within MATLAB-SIMULINK. Also, models in TRANSEO have been simplified to improve execution time. Using MATLAB’s Real-Time Workshop application, the system model is able to be translated into an autogenerated C-code, and run as an application specific RT executable.

Modeling and Simulation of Crush Natural Gas Turbo Engine

The development of Crush Natural Gas (CNG) Engine Control Unit (ECU) depends on expensive bench tests or traditional gasoline engine simulation software, which expand researching and developing period. A new approach is presented in this paper, in which a novelty CNG Turbo engine model based on Mean Value Model and Hardware In Loop (HIL) platform are included. The model acts as many roles e.g. simulation, embedded fault diagnosis and ECU test model which provide more accuracy and efficiency for development of ECU. The new HIL simulation policy is based on Matlab/Simulink, Real Time Workshop (RTW) and NI PXI board. The experiment results prove that it acquired quality Real-time response and accuracy, and economy budget.

A Fault Diagnosis Toolbox Applying Classification and Inference Method

This paper presents a MatLab/SIMULINK based toolbox for fault diagnosis. It has been witnessed that while the fault detection methods must be tailored specifically to the process that is to be supervised, the fault diagnosis methods on the other hand are very similar in most applications. Therefore, a MatLab/SIMULINK-based toolbox was developed by the authors which shall be presented in this paper and is available for download. The software is designed such that it can be used with the Real-Time Workshop and can thus be compiled and downloaded to a wide range of rapid control prototyping system. Depending on the type and availability of a-priori knowledge, one can either employ classification or inference methods. Both approaches are supported by development environment. Classification is used whenever there are experimental data available which describe the influence of the faults on the symptoms. The available implementations encompass the Bayes classifier, the k-nearest neighbor and the polynomial classifier. Inference methods are used, whenever rules or expert knowledge describing the influence of the fault on the symptoms are available. In the paper, a Fuzzy-Logic based inference engine is presented, where the symptoms are first fuzzified to account for the uncertainty in the reaction of residuals. Then, the individual symptoms are combined using Fuzzy-Logic AND and OR operators respectively. The mapping of the fuzzy outputs to the diagnosed fault is accomplished by determining the maximum fault possibility among all fault possibilities. The different diagnostic engines have already successfully been applied to a wide range of prototype fault management realizations at the institute and have proven very capable.

Design and Implementation of Web-Based Control Laboratory for Test Rigs in Geographically Diverse Locations

This paper compares current remote laboratories and describes the design and implementation of the Networked Control System Laboratory (NCSLab) in the University of Glamorgan on http://www/ncslab.net, which provides a unified and flexible Web-based interface to access test rigs located in different countries of the world. All the test rigs are connected and managed together by the NCSLab system. They are well cataloged by their characteristics, and their geographical locations are not necessarily known to the users. A three-layer structure, which consists of the main server, subservers, and test rigs, is adopted to organize the distributed facilities. All the control algorithms for the test rigs are generated by using the Matlab Real-time Workshop. Users can design and implement their own control algorithms for the test rigs. The Web interface is designed using Java JSP/Servlet technology which gives the users great flexibility, including remote tuning, remote monitoring (both data and videos), and remote control logics. In order to manage the massive information and support concurrent access, MySQL database is also integrated into the system.

자동변속기용 임베디드 시스템 성능 시험을 위한 Hardware-in-the Loop 시뮬레이터 구축

Drivers are becoming more fatigued and uncomfortable with increase in traffic density, and this condition can lead to slower reaction time. Consequently, they may face the danger of traffic accidents due to their inability to cope with frequent gear shifting. To reduce this risk, some drivers prefer automatic transmission (AT) over manual transmission (MT). The AT offers more superior drivability and less shifting shock than the MT; therefore, the AT market share has been increasing. The AT is controlled by an electronic control unit (ECU), which provides better shifting performance. The transmission control unit (TCU) is a higher-value-added product, so the companies that have advanced technologies end to evade technology transfer. With more cars gradually using the ECU, the TCU is expected to be faster and more efficient for organic communication and arithmetic processing between the control systems than the l6-bit controller. In this paper, the model of an automatic transmission vehicle using MATLAB/Simulink is developed for the Hardware in-the-Loop (HIL) simulation with a 32-bit embedded system, and also the AT control logic for shifting is developed by using MATLAB/Simulink. The developed AT control logic, transformed automatically by real time workshop toolbox, is loaded to a 32-bit embedded system platform based on Freescale's MPC565. With both vehicle model and 32-bit embedded system platform, we make the HIL simulation system and HIL simulation of AT based on real time operating system (RTOS) is performed. According to the simulation results, the developed HIL simulator will be used for the performance test of embedded system for AT with low cost and effort.

Real-Time Implementation of a Discrete Nonlinearity Compensating Multiloops Control Technique for a 1.5-kW Three-Phase/Switch/Level Vienna Converter

This paper presents and analyzes experimental results of a new discrete multiloop nonlinear control scheme, applied to a 1.5-kW laboratory prototype of a three-phase/level/switch boost-type Vienna rectifier. As for most split dc-bus voltage switched-mode rectifiers, the proposed control technique aims to ensure ac line currents shaping, output dc-bus voltage regulation and dc load unbalance compensation. The proposed technique is based on the dq nonlinear averaged model of the converter. To cancel the inherent nonlinearity of the converter, an input- to-output transform is applied to both inner and outer loops, thus linearizing the system and allowing the application of conventional linear pole placement method for controller tuning. The rectifier performance, during both nominal and severe operating conditions, are then evaluated in real-time using the dSPACE DS 1104 controller board, supported by a Matlab/Simulink real-time workshop environment.

Simulation and experimental tools for fractional order control education

The paper presents the simulation toolkit in MATLAB/Simulink® for the fractional order discrete, state-space system education. The toolkit has been written as a set of C-MEX S-functions which simulate several fractional order blocks - e.g. fractional order difference, fractional order discrete state-space representation, fractional order Kalman filter. This way the C code generation capability (using Real Time Workshop) has been provided. This allowed to easily implement the control algorithms in the experimental setup. For analysis of fractional order systems the ultracapacitor has been chosen. It represents the real-life system which is inherently of fractional order. Altogether the simulation toolkit and the experimental testbed form the basis for the advanced fractional order control lab at Institute of Control and Industrial Electronics, Warsaw University of Technology.

Robust Real-Time Control of a Two-Rotor Aerodynamic System

Abstract This paper presents the design and experimental evaluation of a two-degree-of-freedom discrete-time µ-controller for a laboratory two-rotor aerodynamic system with ten uncertain parameters. The controller implemented is of 24th order and ensures robust stability and robust performance of the closed-loop sampled-data system. This controller is realized on a PC by using the Real Time Workshop of MATLAB® with a sampling frequency of 100 Hz. The experimental results are close to the results predicted by using the linearized model of the system and highlight many of the difficulties associated with the practical implementation of robust control laws.

Tackling feedback design complexity

Feedback control dealt with the application of cheap commercial off-the-shelf (COTS) hardware to control problems. What does not come cheap, however, is the design, in terms of software and people skills. Engineering design was mostly based on hand calculations 30 years ago, and scientific calculators from the likes of Hewlett Packard and Texas Instruments were all the rage with designers. The feedback loop was expressed as an equation G = A/(1-AB), which still forms the basis of most simulation and design software today, where G is the gain of the system, with A representing the feed-forward element, typically an amplifier, and B representing the feedback element. The minus sign indicates negative feedback. The input to the equation is typically by means of a matrix, which is the foundation of several of today's leading software packages, including, amongst others, Math Works Matlab (matrix laboratory) and Simulink, and National Instruments (NI) MatrixX and Lab View. Both companies are working relentlessly to complete the design cycle from design and simulation through to testing and commissioning in hardware, and even in silicon. The Math Works has recently launched Embedded Matlab, which allows users to generate embeddable C code directly from Matlab programs, avoiding the common, time-consuming and error-prone process of rewriting Matlab algorithms in C. Embedded Matlab supports many high-level Matlab language features, such as multidimensional arrays, real and complex numbers, structures, flow control and subscripting. The conversion to C code is performed by Real-Time Workshop 7. If Simulink is used, synthesisable Verilog and VHDL can also be generated.