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Real-time hardware-in-the-loop simulation of electrical machine systems using FPGAs

This study focuses on the development an integrated software and hardware platform that is capable of performing real-time simulation of dynamic systems, including electrical machinery, for the purpose of hardware-in-the-loop simulation (HILS). The system to be controlled is first defined using a block diagram editor. The defined model is then compiled and downloaded onto an FPGA (“Field Programmable Gate Array”) based hardware platform, which is to interface with the controller under test and carry out the simulation in real-time. The full paper will elaborate the characteristics of this novel HILS platform.

Global urban localization of outdoor mobile robots using satellite images

Localization is one of the major research fields in mobile robotics. With the utilization of satellite images and Monte Carlo localization technique, the global localization of an outdoor mobile robot is studied in this paper. The proposed method employs satellite images downloaded from the Internet to localize the robot iteratively. To accomplish this, the proposed method matches the local laser scanner data with the segmented satellite images. Initial test results conducted on the METU campus are found to be quite promising. Further improvement of this approach has the potential of cutting down not only the operational costs but also the preparation period of the mobile robot enabling researchers to operate their robots in diverse outdoor settings.

Discrete parameter-nonlinear constrained optimisation of a gear train using genetic algorithms

This paper investigates the optimal design of a four-stage gear train using genetic algorithms. Five different genetic encoding schemes, which incorporate various heuristic search techniques, are proposed to deal with the most critical constraints of the problem. The fitness criterion used by all genetic algorithms includes a merit function for minimising the size of the gearbox. The results show improvement in the design merit over previous approaches without reliance on the designers interaction to avoid geometric constraint violations and facilitate the convergence.

A Cutting Force Estimator for CNC Machining Centers

Abstract This study presents a cutting force estimator topology for feed drives of CNC vertical machining centers to compute the machining forces accurately. The estimator employs recursive discrete Fourier transform to not only estimate inertial forces on the system but also to filter effectively the noise components in the measurements. The accuracy of the estimator is compared to that of a Luenberger observer while the overall performance of the estimator is evaluated through an experimental study. The paper also discusses its inherent limitations.

General Methodologies for Neural Network Programming

This paper presents a general methodology for designing neural networks by using a priori information on the process under study. The approach is especially useful in developing efficient neural networks for the applications where full-scale models are available but too complicated to implement on conventional computer systems. Traditional neural network development techniques are known to have considerable disadvantages, including a tedious (trial-and-error-based) design process and a long training phase for most real world problems. The presented network design paradigm overcomes these well-known shortcomings. The paper also illustrates the methods application to a real-world problem on the estimation of milling forces in an ideal machining process.

A new hardware-in-the-loop simulator for control engineering education

As a part of a “lab-at-home” education paradigm for control engineering courses, this paper proposes (and elaborates) a novel hardware-in-the-loop simulator with 3D animation capabilities. The developed software, which can be tailored to simulate any dynamic systems in non-real-time, is designed to work in conjunction with a control hardware. In the paper, the specific application of the software to a graduate-level course is presented within the framework of a final term project involving the control of a satellite tracking antenna. The success of the software (along with the methodology) is rigorously evaluated through the information collected in three academic semesters including the course instructors feedback and the questionnaires filled out by the students.

Global Urban Localization of an Outdoor Mobile Robot with Genetic Algorithms

The localization of mobile robots has been studied rigorously in the past. However, only a few studies have focused on developing specific Genetic Algorithms (GAs) to address the localization problem effectively. In this study; the global urban localization of an outdoor mobile platform is considered with the utilization of the odometer, the laser-rangeq finder measurements and the digital maps created from the relevant satellite images on the Internet. The localization issue is formulated as a constrained optimization problem. The study proposes a GA-based technique to solve the problem at hand efficiently.

A novel command generation method with variable feedrate utilizing FGPA for motor drives

This paper focuses on a novel command generator for servo-motor drives to be used as an integral part of their motion controllers. The method, which incorporates a new data compression algorithm, is capable of generating trajectory data at variable rates. In this paradigm, higher-order differences of a given trajectory (i.e. position) are first computed and thus the resulting data are compressed via the proposed technique. The generation of the commands is carried out according to the feedrate (i.e. the speed along the trajectory) set by the external logic dynamically. The paper discusses the implementation of the method on a Field Programmable Gate Array (FPGA). During implementation Very High Speed Integrated Circuit Hardware Description Language (VHDL) is used rather than using embedded processors on the FPGA chip. The performance of the method is assessed according to the resources used in the FPGA chip on the development board and these results are also compared with the same approach without an interpolator.

Direct command generation methods for servo-motor drives

This study focuses on advanced direct command generation paradigms that can be easily incorporated to modern servo-motor drive systems. As an alternative to conventional methods, two new command generation techniques are proposed in this paper. In the first method, higher-order differences of a given trajectory (i.e. position) are computed and the resulting data are compressed via lossless data compression techniques. Besides conventional approaches, a novel compression algorithm is also introduced in the paper. With respect to the second method, the command trajectory is first divided into segments according to the inflection points. The segments are then approximated using various polynomial techniques. The sequence originating from modeling error is included to the generated series. These two command generation techniques are then implemented using Field Programmable Gate Arrays (FPGAs) and their performances are evaluated according to the resources used in FPGAs and the speed of computation.

Performance evaluation of different real-time motion controller topologies implemented on a FPGA

This paper presents a comprehensive comparison of several real-time motion controller topologies implemented on a field programmable gate array (FPGA). Controller topologies are selected as proportional-integral-derivative controller with command feedforward, sliding mode controller, fuzzy controller, and a hysteresis controller. Controllers and other necessary modules are developed using Verilog HDL and they are implemented on a ML505 development board with a Xilinx Virtex-5 FPGA chip. In order to take full advantage of FPGA and to provide a more accurate comparison, an (soft-core) embedded processor is not employed in the design. The developed modules, which include PWM generator, quadrature encoder decoder, velocity estimator, reference profile generator etc, are fully tailored for the application. To perform the necessary calculations for certain controller topologies, an open-core floating point unit (FPU) is also adopted to the design. The performances of the aforementioned controllers are rigorously evaluated via a hardware-in-the-loop simulation of a field-oriented induction motor system.