Raúl Mateos

A DSP- and FPGA-Based Industrial Control With High-Speed Communication Interfaces for Grid Converters Applied to Distributed Power Generation Systems

New energy concepts such as distributed power generation systems (DPGSs) are changing the face of electric distribution and transmission. Power electronics researchers try to apply new electronic controller solutions with the capacity of implementing new and more complex control algorithms combined with internal high-speed communication interfaces. Thus, it is possible to monitor, store, and transfer a large number of internal variables that can be sent online to local or remote hosts in order to take new set points of different generation units. With this objective, this paper presents the design, implementation, and test of an industrial multiprocessor controller based on a floating-point digital signal processor (DSP) and a field-programmable gate array, which operate cooperatively. The communication architecture, which has been added to the proposed electronic solution, consists of a universal serial bus (USB), implemented with a minimum use of the DSP core, and a controller area network (CAN) bus that permits distributed control. Although the proposed system can be readily applied to any DPGS, in this paper, it is focused on a 150-kVA back-to-back three-level neutral-point-clamped voltage source converter for wind turbine applications.

Optimized design of a back-to-back NPC converter to be used as interface for renewable energies

As the number of wind power with power electronics interfaces in the grid increases, it becomes unacceptable to disconnect the generating units every time a disturbance occurs, as was a common practice in the past. Keeping the converter online during unbalanced voltage and guaranteeing the actual standards of the converter connected to the grid becomes a very critical issue. From these goals, the design of a robust back-to-back NPC (three levels) converter of 100 KVA is researched in this work. The converter is divided into two main parts: the power electronics system and the control electronics system. In both designs, some important contributions are shown. Concerning the first part, the paper presents primarily the converter limitations to compensate unbalanced dips, the grid filter design and the DC-bus capacitor design. Concerning the control electronics system, the chosen electronic structure and the tasks distribution between the chosen processors are shown.

Application of advanced digital control techniques to the drive and trajectory tracking system of a wheelchair for the disabled

Presents the basis and results of the application of advanced digital control techniques to the drive and trajectory tracking systems of a wheelchair for the disabled. The adaptive optimal control of the differential drive of the vehicle contributes to improve the guidance system safety and reliability. Furthermore, the incorporation of an optimal controller in order to minimise the location error and of another fuzzy one to adapt the linear velocity of the vehicle to the characteristics of the trajectory provide the vehicle with a high degree of intelligence and autonomy, even when faced with obstacles.

Correction of Omnidirectional Camera Images using Reconfigurable Hardware

The use of omnidirectional cameras in computer vision algorithms is an additional computational load if the processing algorithm needs to extract the rectangular transformed image. There exist different alternatives to deal with this task inside desktop computers but it would be desirable to design a hardware correction unit in order to operate in real-time while using minimal silicon area resources. The proposed design allows the online transformation of a circular grayscale image coming from an omnidirectional camera to obtain the corresponding rectangular image. The model parameters include the image size and radial center. The processing time is one output pixel per clock cycle (50 MHz) which allows the image to be transformed before the arrival of the next one in most applications. It is possible to insert the developed FPGA core in the digital interface of the current omnidirectional cameras

Advanced and Intelligent Control Techniques Applied to the Drive Control and Path Tracking Systems on a Robotic Wheelchair

This paper presents the theoretical support and experimental results of the application of advanced and intelligent control techniques to the drive control and trajectory tracking systems on a robotic wheelchair. The adaptive optimal control of the differential drive helps to improve the automatic guidance systems safety and comfort taking into consideration operating conditions such as load and distribution changes or motion actuator limitations. Furthermore, the incorporation of an optimal controller to minimize location errors and a fuzzy controller to adapt the linear velocity to the characteristics of the trajectory, provide the vehicle with a high degree of intelligence and autonomy, even when faced with obstacles. The global control solution implemented increases the features of the wheelchair for handicapped people, especially for those with a high degree of disability.

FPGA-based implementation of a filter bank-based transmultiplexer for multicarrier communications

Authors propose with the real-time implementation of a transmultiplexer based on an embedded filter bank as a medium access technique for multicarrier communications, such as in broadband PLC (power-line communications). For that purpose, the signal processing algorithms have been analyzed, not only to determine the corresponding requirements, but also to optimize them for a suitable implementation. The definition of an efficient SoC-based architecture to achieve real-time performance has been carried out. The proposed architecture has been optimized in terms of datawidth, data rates and frequencies, as well as resource consumption.

Real-Time Image Distortion Correction using FPGA-based System

The correction of images with geometric distortion, in cameras with short-focal length lenses, can be achieved by integrating the solution into the cameras electronic hardware. By analyzing the distortion problem, the calibration parameters for a given camera are obtained to correct the image distortion. Every pixel from the original image is weighted and used to modify several pixels of influence in the output image. The weights are computed by bilinear interpolation. The final design is generic and configurable to different values of zoom and focus. It has been oriented to an FPGA, being possible the correction of the image distortion in real-time, and providing an undistorted digital video stream

FPGA implementation of harmonic detector based on Second Order Generalized Integrators

A system-on-chip harmonic detector, based on FPGA technology, is proposed in this paper by using second order generalized integrators (SOGI). Two structures denominated DSOGI-QSG (dual SOGI- quadrature signal generation) tuned to a specific frequency allow detecting the positive and negative sequences of the specified harmonic. A bank of DSOGI-QSGs is presented as a multiple harmonic detector by adding multiple feedbacks between the DSOGIQSGs. This scheme is called MSOGI-QSG. This paper proposes a discrete fixed-point FPGA-based design of a MSOGI-QSG which is focused on the algorithm refinement and modularity. The approach is implemented and tested with a Spartan 3 (XC3S200) FPGA (field-programmable gate array).

Hardware/software co-simulation environment for CSoC with soft processors

Co-simulation is one of the most efficient verification techniques for embedded systems. For the case of FPGAs there are no available tools for CSoCs using soft processors. Only in the case of hard processors the same tools, originally developed for ASIC designs, can be used. This work presents an efficient and modular co-simulation framework for soft processors. Increased efficiency is obtained using a compiled instruction set simulator. Additional co-simulation speed improvement is achieved by tightly coupling the framework to the development environment.

Mobile Robot with Wide Capture Active Laser Sensor and Environment Definition

The sensorial system developed is based on the emission of an infrared beam, recovering the reflected beam and measuring distances to significant points in the environment. This system is able to detect and model obstacles in unknown environments. Features of the capture system allow large fields of view to be caught at short distances, aiding the robots mobility. Several algorithms are used to find the formation centre of the image and so model the distortion introduced by the wide-angle lens. Parameters of the optical model are inserted into the calibration matrix to obtain the camera model. We present also an algorithm which extracts the points on the image that belong to the laser beam. All of the above work is in unknown environments with variable conditions of illumination. The robots trajectory is obtained and modified in real time, with a spline function, using four different reference systems. Finally, empirical tests have been carried out on a mobile platform, using a CCD camera with a wide-angle lens of 65° and 110°, a 15 mW laser emitter and a frame grabber for image processing.