| 1. |
- Bengtsson, Lars, 1963
(författare)
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Mikrodatorteknik
- 1995
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Första delen behandlar Microchips "Base-line"-kretsar och andra delen behandlar "Midrange"-kretsarna. De flesta funktioner belyses med konstruktionsexempel. Exempel och övningar är mycket hårdvarunära och boken behandlar konstruktion av mikrodatorer från grunden. Boken är avsedd för kurser i mikrodatorteknik på högskolan eller annan högre teknisk utbildning, men kan även användas som självstudiematerial eftersom de flesta exempel ges med detaljerade och verifierade lösningar av såväl hård- som mjukvaran. Tidigare erfarenhet av assemblerprogrammering är inte nödvändig men grundläggande kunskaper i digitalteknik förutsätts. Boken kan med fördel också läsas av rutinerade assemblerprogrammerare som vill veta hur prestanda hos de nya RISC-baserade PIC-controllerna står sig i konkurrensen med de mer etablerade enchipscontrollerna, t ex HC11 och 8751, som bygger på traditionell CISC-arkitektur.
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| 2. |
- Ujvari, Sandor, 1972-, et al.
(författare)
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Simulation and emulation of sensor systems for intelligent vehicles
- 1998
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Ingår i: Mechatronics '98. - : Pergamon Press. - 0080433391 ; , s. 385-390
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Konferensbidrag (refereegranskat)abstract
- Simulation of sensor systems for mobile robots are described in this paper. By simulation of smart sensor systems, the performance of semi-autonomous vehicles / mobile robots can be enhanced. Smart sensor systems used in the field of mobile robotics can utilise adaptive algorithms. e. g. artificial neural nets, fuzzy logic or hybrid variants of these systems. The development, training and evaluation of adaptive algorithms for sensor systems can be done within a virtual environment in which graphical models are built to simulate an intelligent vehicle, its sensors, and its environment. The virtual sensors are validated by comparing the characteristics of the virtual sensors with those of the real devices.
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| 3. |
- Eriksson, Patric, et al.
(författare)
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A role for 'sensor simulation' and 'pre-emptive learning' in computer aided robotics
- 1995
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Ingår i: 26th International Symposium on Industrial Robots, Symposium Proceedings. - : Mechanical Engineering Publ.. - 1860580009 ; , s. 135-140
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Konferensbidrag (refereegranskat)abstract
- Sensor simulation in Computer Aided Robotics (CAR) can enhance the capabilities of such systems to enable off-line generation of programmes for sensor driven robots. However, such sensor simulation is not commonly supported in current computer aided robotic environments. A generic sensor object model for the simulation of sensors in graphical environments is described in this paper. Such a model can be used to simulate a variety of sensors, for example photoelectric, proximity and ultrasonic sensors. Tests results presented here show that this generic sensor model can be customised to emulate the characteristics of the real sensors. The preliminary findings from the first off-line trained mobile robot are presented. The results indicate that sensor simulation within CARs can be used to train robots to adapt to changing environments.
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| 4. |
- Bengtsson, Lars, 1963
(författare)
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Generation and measurement of pulses and delays with RISC-controllers
- 1997
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Ingår i: Measurement Science and Technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 8, s. 679-683
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Tidskriftsartikel (refereegranskat)abstract
- An instrument for the generation of pulses and delays has beendeveloped for applications in laserspectroscopy experiments. The pulses from achopped laserbeam are counted, and when a preset value is reached, two signalsare generated: one delayed trigger pulse with constant length and one delayed‘shutter pulse’ (referred to as the ‘shutter window’ below) which opens a light shutterand allows one light pulse to enter the experimental region and excite the sample.The delays of the trigger pulse and the shutter window and the width of the shutterwindow can all be set independently to any value from 0 up to 50 ms with 0.05 mssteps. A separate microcontroller measures the width of the shutter window with anaccuracy of 1micro seconds. The pulse delays and the width of the shutter window are setwith thumbwheel potentiometers connected as voltage dividers. A microcontrollerreads the set values with a four-channel, 12-bit AD converter. This techniquesaves a lot of hardware wiring as well as software writing when compared to thealternative of using separate, BCD-coded thumbwheels for each timesetting.In total, the instrument consists of two independent RISC-controllers: onePIC16C55 for counting chopper pulses and generating pulses and delays, and onePIC16C74 for measuring (and displaying) the width of the shutter window. Thewidth of the shutter window is measured with 1micro second resolution by taking fulladvantage of two different peripherial I/O devices in the PIC16C74: the 16-bit ‘inputcapture’ module and the external interrupt facility.
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| 5. |
- Vlassov, Vladimir, 1957-, et al.
(författare)
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A simulation platform for multi-threaded architectures
- 1996
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Ingår i: Proceedings of the Fourth International Workshop on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems, 1996. MASCOTS '96. - 0818672358 ; , s. 102-108
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Konferensbidrag (refereegranskat)abstract
- Simulation is a powerful tool for studying behavior of novel architectures and improving their performance. However the time, effort and resources invested in developing a reliable simulator with the required level of detail may become prohibitively large. We present a simulation platform specifically designed to simulate the class of multithreaded architectures. The most important features of this simulator are its flexibility and ease of use. The simulation model provides the user with a wide range of design criteria, architectural parameters and workload characteristics. The simulation platform includes several tools, such as: an experiment planner, an interface to Matlab for processing and displaying results, and an interface to PVM for the execution of independent experiments in parallel. The simulation model is validated by comparison of analytical and experimental results.
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| 6. |
- Lindeberg, Tony, 1964-, et al.
(författare)
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Scale-space with causal time direction
- 1996
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Konferensbidrag (refereegranskat)abstract
- This article presents a theory for multi-scale representation of temporal data. Assuming that a real-time vision system should represent the incoming data at different time scales, an additional causality constraint arises compared to traditional scale-space theory—we can only use what has occurred in the past for computing representations at coarser time scales. Based on a previously developed scale-space theory in terms of noncreation of local maxima with increasing scale, a complete classification is given of the scale-space kernels that satisfy this property of non-creation of structure and respect the time direction as causal. It is shown that the cases of continuous and discrete time are inherently different.
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| 7. |
- Viberg, Mats, 1961, et al.
(författare)
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Maximum Likelihood Array Processing in Spatially Correlated Noise Fields Using Parameterized Signals
- 1997
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Ingår i: IEEE Transactions on Signal Processing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1941-0476 .- 1053-587X. ; 45, s. 996-1004
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the problem of estimating signal parameters using an array of sensors. This problem is of interest in a variety of applications, such as radar and sonar source localization. A vast number of estimation techniques have been proposed in the literature during the past two decades. Most of these can deliver consistent estimates only if the covariance matrix of the background noise is known. In many applications, the aforementioned assumption is unrealistic. Recently, a number of contributions have addressed the problem of signal parameter estimation in unknown noise environments based on various assumptions on the noise. Herein, a different approach is taken. We assume instead that the signals are partially known. The received signals are modeled as linear combinations of certain known basis functions. The exact maximum likelihood (ML) estimator for the problem at hand is derived, as well as a computationally more attractive approximation. The Cramer Rao lower bound (CRB) on the estimation error variance is also derived and found to coincide with the CRB, assuming an arbitrary deterministic model and known noise covariance.
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| 8. |
- Wiberg, Per-Arne, 1953-
(författare)
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Graphical programming of time-deterministic real-time systems
- 1996
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Ingår i: Second IEEE International Conference on Engineering of Complex Computer Systems. - Los Alamitos, Calif. : IEEE Computer Society. - 0818676140 ; , s. 173-180
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper we present the Picasso programming language and the underlying design philosophy. Our goal is to provide programmers working with distributed embedded real-time systems with a tool to manage the complexity of this class of systems. The proposed tool allows easy and safe changes of the system software and hardware at any time during the lifetime of the system. This means that even during operation the system can be changed safely. This is not only important for enhancing the design process but is also necessary for a class of systems that need to be in service at all times. We have chosen to call this approach Change-Orientation. The most characteristic properties of the language are that it is graphical and that it shows time explicitly. All processing is described as functional transformations. These transformations are called processes. A very direct way of implementing a process is possible because the semantics of the description maps directly on the computation model of the processor.
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| 9. |
- Jonsson, Erland, 1946, et al.
(författare)
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Security intrusion process: an empirical model
- 1997
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Ingår i: IEEE Aerospace and Electronic Systems Magazine. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8985. ; 12:4, s. 7-17
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a security model developed from empirical data collected from a realistic intrusion experiment in which a number of undergraduate students were invited to attack a distributed computer system. Relevant data, with respect to their intrusion activities, were recorded continuously. We have worked out a hypothesis on typical attacker behavior based on experiences from this and other similar experiments. The hypothesis suggests that the attacking process can be split into three phases: the learningphase, the standard attack phase and the innovative attack phase. The probability for successful attacks during the learning phase is expected to be small and, if a breach occurs, it is rather a result of pure luck than deliberate action. During the standard attack phase, this probability is considerably higher, whereas it decreases again in the innovative attack phase. The collected data indicates that the breaches during the standard attack phase are statistically equivalent. Furthermore, the times between breaches seem to be exponentially distributed, which means that traditional methods for reliability modelling of component failures may be applicable.
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| 10. |
- Eriksson, Patric Tony
(författare)
-
Enhancements in virtual robotics : Through simulation of sensors, events and 6pre-emptive' learning
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Virtual robotics can be used to dramatically improve the capabilities and performance of industrial robotic systems. Virtual robotics encapsulates graphical off-line programming systems and Computer Aided Robotics (CAR). However current virtual robotic tools suffer from a number of major limitations which severely restrict the ways in which they can be deployed and the performance advantages they offer to the industrial user. The research study focuses on simulation of sensors, programming of event based robotic systerns and demonstrates how intelligent robots can be trained adaptive behaviours in virtual environments. Contemporary graphical programming systems for robots can only be used to program limited sections of a robot program, since i) they do not support methods for the simulation of sensors and event detection; ii) they normally use a post-processor to translate programs from a general language to a controller specific language; iii) conternporary robots can not easily adapt to changes in their environments; and iv) robot programs created off-line must be calibrated to adjust to differences between the virtual and real robotic workcells.The thesis introduces a generic sensor model which can be used to model a variety of sensor types. This model allows virtual sensors to work as independent devices. It is demonstrated that using simulated sensors, event-based robot programs can be created and debugged entirely off-line. Off-line programming of event-based robotic systems demands methods for realistic handling of the communication between independent devices and process. The system must also possess the ability to manage and store information describing status and events in the environment. A blackboard architecture has been used in this research study to store environmental conditions and manage inter-process communication.Self-learning robots is a possible strategy to allow robots to adapt to environmental changes and to learn from their experience. If suitable learning regimes are developed robots can learn to detect changes between virtual and real environments thus minimising the need for calibration. Most learning is based on experience and this requires experimental data to be fed to the learning system. This thesis demonstrates that robot controllers using artificial neural networks for knowledge acquisition and storage can be 'pre-emptively learnt' in virtual robotic environments using virtual robots and simulated sensors. The controllers are able to generalise from the information acquired by the virtual sensors operating in the virtual environment. Arguably the biggest obstacle to the use of self learning robotic systems in real applications has been the need to train the 'real robots' extensively in the 'real environment'. 'Pre-emptive learning' removes this problem. Furthermore, it is therefore possible to develop and evaluate new learning regimes using virtual robotic systems. This approach provides an opportunity to create a variety of environments and conditions which would be impractical to create in a real environment (due to constraints of time, cost and availability).
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