Real-time Code Research Articles

A Real-Time Joint Source-Channel Coding Based on a Simplified Modeling of the Residual Video Packet Loss

We propose a simplified model of real-time joint source-channel coding, which can be used to adaptively determine the quality-optimal code rate of forward error correction (FEC) coding. The objective is to obtain the maximum video quality in the receiver, while taking time-varying packet loss into consideration. To this end, we propose a simplified model of the threshold set of the residual video packet loss rate (RVPLR). The RVPLR is the rate of residual loss of video packets after channel decoding. The threshold set is defined as a set of discrete RVPLRs in which the FEC code rate must be changed in order to maintain minimum distortion during increases or decreases of channel packet loss. Because the closed form of the proposed model is very simple and has one scene-dependent model parameter, a video sender can be easily implemented with the model. To train the scene-dependent model parameters in real-time, we propose a test-run method. This method accelerates the test-run while remaining sufficiently accurate for training the scene-dependent model parameters. By using the proposed model and test-run, the video sender can always find the optimal code rate on the fly whenever there is a change in the packet loss status in the channel. An experiment shows that the proposed model and test-run can efficiently determine the near-optimal code rate in joint source-channel coding.

Active Noise Control System on multicore DSP

The idea of ANC is concerned with attenuation of unwanted low frequency sound (noise), as the result a three-dimensional zone of quiet is created around the selected microphones. The paper describes ANC system implementation running under the μClinux system on dual core Analog Devices Blackfin DSP. On multi-core Blackfin DSPs, it is possible to overcome main disadvantage of Linux - lack of hard-real time functionality indispensable for signal processing applications. It can be archived by separation of real-time signal processing code and handling it on dedicated core while other core is running Linux. The advantages for using Linux in the ANC system are ease of use, better system control, easy possibility of creating web based user interfaces and improved debugging possibilities by the on-line streaming of data coming form real-time control algorithms. Use of Linux enabled a Web server integration into ANC system, dynamically created web pages can be accessed by any standard browser and become the graphical user interface to the ANC system.

An effective algorithm of bit output management for real-time coders

Real-time video coders place significant restrictions on the computing resources, require one pass processing, and do not leave the possibility for full-fledged quality optimization. A series of approaches to the building of bit output algorithms is known, but the quality problem of encoding optimization leaves room for innovations. The authors propose a modification for one of these methods, which would make it possible to significantly improve the qualitative characteristics of real-time coders.

2nd Issue of Real-Time Image Processing

The first quarter of 2007 started as an active season for the real-time image processing community. The annual SPIE Conference on Real-Time Image Processing, which was held in San Jose, CA, highlighted recent developments in this growing branch of image processing. As one of the few regular events with its focus matching that of JRTIP, one witnessed the growth in applications of real-time image and video processing. The conference served as an effective instrument to foster the dissemination of recent results and to leverage the cohesion of the real time image processing community. The preparations for the next SPIE Conference on Real-Time Image Processing in 2008 are already progressing and its call-for-papers is included at the end of this issue. In 2007, JRTIP is going to seek involvement of more scientists in the field of real-time image and video processing. After 1 year of operation, the editors-in-chief have started to recruit additional associate editors to enlarge the expertise base of the editorial board, to solicit manuscript submissions from potential authors, and to make the reviewing process more efficient. Interested colleagues should contact the editors-in-chief expressing their Associate Editor candidature in support of one or more fields within the focus of JRTIP. In addition, they wish to encourage researchers to act as guest editors for special issues on any real-time image or video processing related topics of interest to them. It is possible to schedule two special issues in 2007, provided that a draft call-for-papers is sent to the editors-in-chief as soon as possible. The third issue of JRTIP presents four articles, two are survey papers and two are original research papers. These articles address different real-time image processing perspectives ranging from algorithmic to hardware issues. The first survey paper deals with the real-time filtering in 2D and 3D using ordered statistics that are supported by a rich set of experimental results derived from several algorithmic variations. Performance measurements are used to demonstrate the effect of noise suppression and preservation of fine image structures and to show the DSP implementation of denoising filters. The second survey paper introduces a non-invasive analysis of dynamic processes in living cells using microscopic computer vision techniques for understanding the interactions between cellular and molecular functional units and for providing novel insights into the cell biology. The third article is an original research paper covering a machine vision application involving vision-based position sensing for aerial refueling of unmanned aerial vehicles in real-time. A full image processing chain is investigated and tested in a MATLAB/Simulink soft real-time environment as well as in a Linux/RTAI hard real-time environment. The feasibility of the real-time implementation is shown using off-the-shelf commercial hardware. The fourth article is another original research paper describing a hardware architecture for real-time fractal coding for image compression. The introduced parallel hardware architecture contains units for domain M. F. Carlsohn (&) Ingenieurberatung fur Computer Vision und Bildkommunikation, Am Heiddamm 36g, 28355 Bremen, Germany e-mail: matthias.carlsohn@t-online.de

Linux real-time framework for fusion devices

A new framework for the development and execution of real-time codes is currently being developed and commissioned at JET. The foundations of the system are Linux, the Real Time Application Interface (RTAI) and a wise exploitation of the new i386 multi-core processors technology. The driving motivation was the need to find a real-time operating system for the i386 platform able to satisfy JET Vertical Stabilisation Enhancement project requirements: 50 μs cycle time. Even if the initial choice was the VxWorks operating system, it was decided to explore an open source alternative, mostly because of the costs involved in the commercial product. The work started with the definition of a precise set of requirements and milestones to achieve: Linux distribution and kernel versions to be used for the real-time operating system; complete characterization of the Linux/RTAI real-time capabilities; exploitation of the multi-core technology; implementation of all the required and missing features; commissioning of the system. Latency and jitter measurements were compared for Linux and RTAI in both user and kernel-space. The best results were attained using the RTAI kernel solution where the time to reschedule a real-time task after an external interrupt is of 2.35 ± 0.35 μs. In order to run the real-time codes in the kernel-space, a solution to provide user-space functionalities to the kernel modules had to be designed. This novel work provided the most common functions from the standard C library and transparent interaction with files and sockets to the kernel real-time modules. Kernel C++ support was also tested, further developed and integrated in the framework. The work has produced very convincing results so far: complete isolation of the processors assigned to real-time from the Linux non real-time activities, high level of stability over several days of benchmarking operations and values well below 3 μs for task rescheduling after external interrupt. From being the alternative option, RTAI has been finally chosen as the platform for the project. A first stable version of the framework has been integrated on the JET system and is already being commissioned. It will be soon be used on the Vertical Stabilisation Enhancement for the Plasma Control Upgrade (PCU) project at JET.

Plant Simulation System for Developing ABWR Automatic Power Regulator System

We developed a plant simulation code system to design and verify an automatic power regulator (APR) system for an advanced boiling water reactor (ABWR). The point kinetic plant simulator AUTSIMU is an off-line and real-time online plant simulation code that can simulate the start-up process from a subcritical condition of cold water to a 100% rated power condition as well as the reactor shutdown process. The three-dimensional effect of neutron detector signals in the core was simulated by combining predetermined three-dimensional analysis and point kinetic analysis results. The AUTSIMU code was tested using ABWR start-up experimental data. The calculated results were in good agreement with the measured ones. Less than one minute was needed in the off-line mode to simulate a ten-hour transient with an ordinary personal computer. We confirmed that simple AUTSIMU models could effectively simulate ABWR start-up behaviors. The APR hardware was effectively verified in the online mode through factory tests before being shipped to the nuclear site.

Development of Human Factors Validation System for the Advanced Control Room of APR1400

A human factors validation system for the main control room (MCR) of Advanced Power Reactor 1400MWe (APR1400) has been developed as it adopts digitalized human-system interfaces (HSIs). The integrated validation system is composed of process/plant models, HSIs, and the human performance evaluation support system (HUPESS). A real-time thermal-hydraulic code, RELAP5 R/T, was used and modified to simulate the dynamic characteristics of the APR1400, and simulation software, 3KeyMaster, was used to model the balance of plant systems. The HSIs developed in this study include all facilities in the APR1400 MCR, such as large display panels, 3 identified operator workstations, and a safety console. In addition, the remote shutdown workstation has been developed. The display systems in the HSIs have been developed using ProcSee, which is a software tool for developing and displaying dynamic graphical user interfaces. This paper describes the configurations of HSIs including display systems, the dynamic models of the APR1400 simulator, the instructor station, and the HUPESS. This paper also presents the results of plant simulation performance tests at transient compared with the results of RELAP5/MOD3.3 calculations. The human factors validation system for the advanced control room of APR1400 provides high degrees of physical, functional, and dynamic fidelities, and can be used in the validation process of the APR1400 HSI design.

Development of Human Factors Validation System for the Advanced Control Room of APR1400

A human factors validation system for the main control room (MCR) of Advanced Power Reactor 1400MWe (APR1400) has been developed as it adopts digitalized human-system interfaces (HSIs). The integrated validation system is composed of process/plant models, HSIs, and the human performance evaluation support system (HUPESS). A real-time thermal-hydraulic code, RELAP5 R/T, was used and modified to simulate the dynamic characteristics of the APR1400, and simulation software, 3KeyMaster, was used to model the balance of plant systems. The HSIs developed in this study include all facilities in the APR1400 MCR, such as large display panels, 3 identified operator workstations, and a safety console. In addition, the remote shutdown workstation has been developed. The display systems in the HSIs have been developed using ProcSee, which is a software tool for developing and displaying dynamic graphical user interfaces. This paper describes the configurations of HSIs including display systems, the dynamic models of the APR1400 simulator, the instructor station, and the HUPESS. This paper also presents the results of plant simulation performance tests at transient compared with the results of RELAP5/MOD3.3 calculations. The human factors validation system for the advanced control room of APR1400 provides high degrees of physical, functional, and dynamic fidelities, and can be used in the validation process of the APR1400 HSI design.

MoDEST: From Model-driven design towards real-time code generation for embedded control systems

This paper presents a model-driven methodology and tool for Embedded Control System (ECS) design. This methodology defines a common metamodel that unifies the design steps and ensures the consistency of models along the design cycle. It uses an approach based, in one side, on the software components that increase models reusability to face the increasing complexity of ECS; in the other side, on the aspect-oriented paradigm that allows to model transversal real time properties to support models analysis and validation in the earliest steps of the design cycle. Our methodology supports the control and scheduling co-design in order to evaluate the performance and stability of ECS during their design. A tool called MoDEST implements this methodology and provides real-time code generation. It should help designers to choose the best scheduling that preserves the control performance and quality of the designed ECS.

Testing Performance and Reliability of Magnetic Suspension Controllers

The aim of this paper is to present an experiment realized with the support of magnetic levitation system equipped with additional electromagnet. This extra unit allows to realize more experiments including identification and control, diagnose the performance of the closed loop system and design controllers for single axis of the active magnetic bearing. The test rig consists of two electromagnets, distance and current sensors and ferromagnetic object. The system is controlled by the personal computer or embedded system. The MATLAB/Simulink software allows to perform identification, signal analysis, controller design and real-time code generation for the selected target. The experimental controllers reliability test under external pulse excitation is presented.

Joint Source-Channel Distortion Modeling for MPEG-4 Video

Multimedia communication has become one of the main applications in commercial wireless systems. Multimedia sources, mainly consisting of digital images and videos, have high bandwidth requirements. Since bandwidth is a valuable resource, it is important that its use should be optimized for image and video communication. Therefore, interest in developing new joint source-channel coding (JSCC) methods for image and video communication is increasing. Design of any JSCC scheme requires an estimate of the distortion at different source coding rates and under different channel conditions. The common approach to obtain this estimate is via simulations or operational rate-distortion curves. These approaches, however, are computationally intensive and, hence, not feasible for real-time coding and transmission applications. A more feasible approach to estimate distortion is to develop models that predict distortion at different source coding rates and under different channel conditions. Based on this idea, we present a distortion model for estimating the distortion due to quantization and channel errors in MPEG-4 compressed video streams at different source coding rates and channel bit error rates. This model takes into account important aspects of video compression such as transform coding, motion compensation, and variable length coding. Results show that our model estimates distortion within 1.5 dB of actual simulation values in terms of peak-signal-to-noise ratio.

Mother–infant interaction and children’s socio-emotional development with high- and low-risk mothers

Charting the dynamic character of mother–infant interaction requires using observational systems of sequential coding in real time. A longitudinal study was designed to approach maternal sensitivity in a more complex way using sequential analysis. The study was conducted with 20 high- and 20 low-risk mothers and their infants (aged: 3, 12 and 15 months) to examine the relation among mothers’ risk status for physical abuse and their maternal interactive profiles, using micro-social sequential analyses, and the subsequent quality of attachment developed by their children at 15 months of age. Results showed significantly different timings in maternal responses in high- and low-risk groups, that the high-risk mothers were less sensitive: more intrusive and less discriminate regarding their infant’s behavior. Significant differences between groups were also found after infant difficult behavior. High-risk mothers’ infants were significantly more likely to develop insecure attachment. Sensitivity is proposed as a constellation of timings in early mother–infant interaction.

A Real-time Multiview Video Coding System using Fast Disparity Estimation

In this paper, a real-time multiview video coding system using fast disparity estimation is proposed, In the multiview encoder, adaptive disparity-motion estimation (DME) for an effective 3-dimensional (3D) processing are proposed, That is, by adaptively predicting the mutual correlation between stereo images in the key-frame using the proposed algorithm, the bandwidth of stereo input images can be compressed to the level of a conventional 2D image and a predicted image also can be effectively reconstructed using a reference image and adaptive disparity vectors. Also, in multiview decoder, intermediate view reconstruction (IVR) using adaptive disparity search algorithm (DSA) for real-time multiview video processing is proposed, The proposed IVR can reduce a processing time of disparity estimation by selecting adaptively disparity search range. Accordingly, the proposed multiview video coding system is able to increase the efficiency of the coding rate and improve the resolution.

Fuel optimal control of parallel hybrid electric vehicles

A mathematical model for fuel optimal control and its corresponding dynamic programming (DP) recursive equation were established for an existing parallel hybrid electric vehicle (HEV). Two augmented cost functions for gear shifting and engine stop-starting were designed to limit their frequency. To overcome the problem of numerical DP dimensionality, an algorithm to restrict the exploring region was proposed. The algorithm significantly reduced the computational complexity. The system model was converted into real-time simulation code by using MATLAB/RTW to improve computation efficiency. Comparison between the results of a chassis dynamometer test, simulation, and DP proves that the proposed method can compute the performance limitation of the HEV within an acceptable time period and can be used to evaluate and optimize the control strategy.

DIII-D Integrated plasma control solutions for ITER and next-generation tokamaks

Plasma control design approaches and solutions developed at DIII-D to address its control-intensive advanced tokamak (AT) mission are applicable to many problems facing ITER and other next-generation devices. A systematic approach to algorithm design, termed “integrated plasma control,” enables new tokamak controllers to be applied operationally with minimal machine time required for tuning. Such high confidence plasma control algorithms are designed using relatively simple (“control-level”) models validated against experimental response data and are verified in simulation prior to operational use. A key element of DIII-D integrated plasma control, also required in the ITER baseline control approach, is the ability to verify both controller performance and implementation by running simulations that connect directly to the actual plasma control system (PCS) that is used to operate the tokamak itself. The DIII-D PCS comprises a powerful and flexible C-based realtime code and programming infrastructure, as well as an arbitrarily scalable hardware and realtime network architecture. This software infrastructure provides a general platform for implementation and verification of realtime algorithms with arbitrary complexity, limited only by speed of execution requirements. We present a complete suite of tools (known collectively as TokSys) supporting the integrated plasma control design process, along with recent examples of control algorithms designed for the DIII-D PCS. The use of validated physics-based models and a systematic model-based design and verification process enables these control solutions to be directly applied to ITER and other next-generation tokamaks.

Worldwide collaborative efforts in plasma control software development

This presentation will describe the DIII-D collaborations with various tokamak experiments throughout the world which have adapted custom versions of the DIII-D plasma control system (PCS) software for their own use. Originally developed by General Atomics for use on the DIII-D tokamak, the PCS has been successfully installed and used for the NSTX experiment in Princeton, the MAST experiment in Culham UK, the EAST experiment in China, and the Pegasus experiment in the University of Wisconsin. In addition to these sites, a version of the PCS is currently being developed for use by the KSTAR tokamak in Korea. A well-defined and robust PCS software infrastructure has been developed to provide a common foundation for implementing the real-time data acquisition and feedback control codes. The PCS infrastructure provides a flexible framework that has allowed the PCS to be easily adapted to fulfill the unique needs of each site. The software has also demonstrated great flexibility in allowing for different computing, data acquisition and real-time networking hardware to be used. A description of the current PCS software architecture will be given along with experiences in developing and supporting the various PCS installations throughout the world.

Analytical dynamic model for planar close-chain linkages with alterable length and inertia parameters based on parallel calculation

Analytical dynamic model based on the sub model of links and a parallel algorithm for planar close-chain mechanisms, in which lengths and inertia parameters of links can be changed, is established based on Kane dynamic equation and numeric-symbolic approach. The influence of lengths and mass of driving links on driving force/torque are also studied. The close vector is applied in the kinematical analysis of planar close-chain mechanisms and expressions of velocity and acceleration of links are derived. Real-time code of matrix elements of each sub model, in which lengths and inertia parameters of links as well as generalized coordinates are expressed as symbols, the other variables as numeral, are derived off-line. Then the total driving force/torque of planar close-chain mechanisms are obtained by piled add. An optimization method of real-time code based on the parallel algorithm of sub model of links is proposed. The procedures of dynamic modeling and real-time code optimization can be performed off-line, and parallel calculation structure is adopted, therefore on-line calculation time can be reduced greatly, which is of advantage to real-time control of mechanisms. The examples of dynamic simulation are given for illustration.

Optimal control of fuel economy in parallel hybrid electric vehicles

A mathematical model of optimal control of fuel economy for parallel hybrid electric vehicles (HEVs) and its dynamic programming (DP) recursive equation and numerical DP algorithm are presented. The effect of frequent gear shifting and engine stop-starting on drivability and fuel economy are both taken into account in the cost function. To overcome the curse of dimensionality of numerical DP, an algorithm restricting the exploring region is proposed to reduce largely the computational complexity, and the quantization increments are carefully selected to balance computation accuracy and efficiency. Furthermore, instead of being simplified, the system model is converted into a real-time simulation code by using MATLAB/RTW to improve the computation efficiency. Finally, a case study is presented. The vehicle testing results, the simulation results, and the DP results are compared and analysed, indicating that the maximum performance and the optimal control policy of the HEV can be determined by the algorithm proposed in this paper within an acceptable time and that the results can be used to evaluate and improve the real-time control strategy.

Packet-by-Packet Adaptive Scheme for Video Coding and Transmission Over Wireless IP Networks Using Rate-Compatible Punctured Turbo (RCPT) Codes

In this paper, we consider real-time video coding and transmission over packet-switched wireless IP networks, such as WLAN, using RCPT codes and joint source-channel coding (JSCC) with concentration on a packet-by-packet adaptive scheme. We present a systematic design methodology to enable the applicability of JSCC techniques. The performance of H.263+ video coding and transmission over wireless channel modeled as slow Rician fading channels using this approach is studied. Results indicate that a packet-by-packet adaptive RCPT-JSCC approach is of significant advantage for real-time video applications and leads to more acceptable video delivery quality over interference-limited and time-varying wireless networks.

Implementation of Hybrid Control for Motor Drives

This paper presents the implementation of a hybrid-control strategy applied to a permanent-magnet synchronous-motor (PMSM) drive. Hybrid control is a general approach for control of a switching-based hybrid system (HS). This class of HS includes a continuous process controlled by a discrete controller with a finite number of states. In the case of ac motor drives, in contrast to conventional vector control like proportional-integral control or predictive control, where the inverter is not taken into account by the controller, hybrid control integrates the inverter model and considers the state of the inverter as a control variable. It allows to obtain faster torque dynamics than vector-control algorithms. The hybrid control algorithm requires both computing velocity for real-time implementation and code flexibility for management of low-performance functions and analog-digital interfaces. Codesign appears as a promising methodology for partitioning hybrid-control algorithm between software (flexible) and hardware (velocity) while taking care of overall time constrains. In this paper, the implementation of hybrid-control algorithm for a PMSM drive is performed through a codesign approach on an Excalibur board, embedding a CPU-core (Nios-2 by Altera) inside an APEX20KE200EFC484-2X field-programmable gate array. The partitioning of software and hardware parts is explained. Experimental results show the effectiveness of the implementation. Performances, advantages, and limitations are discussed.