Control of Discrete Event Systems

Discrete Event Systems (DES) are a special type of dynamic systems. The state of these systems changes only at discrete instants of time and the term event is used to represent the occurrence of discontinuous changes (at possibly unknown intervals). Different Discrete Event Systems models are currently used for specification, verification, synthesis as well as for analysis and evaluation of different qualitative and quantitative properties of existing physical systems. The main focus of this paper is the presentation of the automata and formal language model for DES introduced by Raniadge and Wonham in 1985. This model is suitable for the examination of some important control theoretic issues, such as controllability and observability from the qualitative point of view, and provides a good basis for modular synthesis of controllers. We will also discuss an Extended State Machine and Real-Time Temporal Logic model introduced by Ostroff and Wonham in [OW87]. It incorporates an explicit notion of time and means for specification and verification of discrete event systems using a temporal logic approach. An attempt is made to compare this model of DES with other ones

Cooperative Material Handling by Human and Robotic Agents:Module Development and System Synthesis

In this paper we present the results of a collaborative effort to design and implement a system for cooperative material handling by a small team of human and robotic agents in an unstructured indoor environment. Our approach makes fundamental use of human agents\u27 expertise for aspects of task planning, task monitoring, and error recovery. Our system is neither fully autonomous nor fully teleoperated. It is designed to make effective use of human abilities within the present state of the art of autonomous systems. It is designed to allow for and promote cooperative interaction between distributed agents with various capabilities and resources. Our robotic agents refer to systems which are each equipped with at least one sensing modality and which possess some capability for self-orientation and/or mobility. Our robotic agents are not required to be homogeneous with respect to either capabilities or function. Our research stresses both paradigms and testbed experimentation. Theory issues include the requisite coordination principles and techniques which are fundamental to the basic functioning of such a cooperative multi-agent system. We have constructed a testbed facility for experimenting with distributed multi-agent architectures. The required modular components of this testbed are currently operational and have been tested individually. Our current research focuses on the integration of agents in a scenario for cooperative material handling

New Rank Deficiency Condition for Multiple View Geometry of Line Features

In this paper, a new rank deficiency condition for multiple images of a line is presented. It is shown that a set of m image lines correspond to a unique 3-D line if and only if an associated (m-1 x 4 matrix Hl is of maximum rank 1. This condition is shown to be equivalent to all multilinear constraints among image lines, but it tremendously simplifies previously known derivations. Since rank deficiency is a purely linear algebraic condition, it gives rise to a set of natural linear algorithms for line matching, line transfer to a new view and motion estimation from images of multiple lines. These linear algorithms use all available data simultaneously without specifying a particular choice of image triplets. Hence apart from the initialization, the algorithms allow us to bypass trifocal tensors used for similar purposes. The theory and algorithms for the line case are developed in exact parallel to that for the point case. Geometric interpretation of the Hl matrix and the duality between point and line are also clearly revealed through this approach.Ope

Special Issue on Robot Vision

International audienceThe International Journal of Robotics Research (IJRR) has a long history of publishing the state-of-the-art in the field of robotic vision. This is the fourth special issue devoted to the topic. Previous special issues were published in. In a closely related field was the special issue on Visual Servoing published in IJRR, 2003 (Volume 22, Nos 10–11). These issues nicely summarize the highlights and progress of the past 12 years of research devoted to the use of visual perception for robotics. Looking back across these issues we see perennial topics such as calibration; feature detection, description and matching; multi-view geometry; and filtering and prediction. Of course for robotic vision we have also seen many papers with a strong control focus and also a focus on high-speed operation. Perennial challenges over that period, perhaps still open problems, include robustness and vision-guided manipulation. Happily, many techniques have matured over this period and become an integral part of many robotic vision systems, for example visual odometry, visual Simultaneous Localization and Mapping (SLAM), visual place recognition and the fusion of vision with other sensors, most notably inertial sensors. This period has truly seen amazing technological change, not just the constant progress due to Moore's law but major innovations such as field-programmable gate arrays (FPGAs) and graphics processing units (GPUs), mobile computing architectures, low-cost high-performance inertial sensors and RGB-D sensors. Many of these have been driven by demand for consumer products such as smartphones and games, but have also provided a rich bounty for roboticists. The ready availability of capable low-cost off-the-shelf robotic platforms for domains such as underwater autonomous unmanned vehicles (AUVs), flying unmanned aerial vehicles (UAVs) and humanoid robots, all of which could usefully use vision sensors, is also helping to advance the field. Finally, the staple of all robotic vision systems, the camera, is evolving in very interesting directions. We now have cameras that are small, cheap and lightweight, that have progressive scan and global shutters, high dynamic range, high frame rate and wide fields of view obtained by catadioptrics or by multiple cameras with stitched imagery

Rank Conditions of the Multiple View Matrix in Multiple View Geometry

The report number is incorrectly printed as DC-220 on the cover and in the front matter. This is in fact report DC-202.This technical report is a comprehensive collection of four self-contained technical papers which I have jointly written with my PhD student Kun Huang (UIUC ECE), PhD student Rene Vidal (UCB EECS), professor Jana Košecká (GMU CS) and professor Shankar Sastry (UCB EECS). It consists of a coherent treatment of multiple view geometry from a linear algebraic viewpoint. In particular, a newly introduced concept of multiple view matrix and its associated rank deficiency condition have been extensively studied for the purpose of 2-D to 3-D reconstruction. The proposed framework provides a brand new approach to multiple view geometry, which is independent of previous approaches based on projective geometry, tensor analysis or algebraic geometry, and which has, nonetheless, demonstrated significant theoretical and algorithmic advantages. The technical report adopts a homogeneous terminology - which makes it slightly different from each original paper. Each chapter corresponds to an original paper and it is still kept rather self-contained in this report. Although we are still in the process of grasping the full implication of the developed theory and algorithms and carrying out more experiments on real images, the report is contrived for the purpose of communicating among researchers who share the same interest in multiple view geometry and would like to try to extend the theory and apply to other applications.U.S. Army Research Office / DAAD19-00-1-0466National Science Foundation KDI initiative / SBC-MIT-5710000330ONR / N00014-00-1-0621GMU CS department startup fundUIUC ECE department startup fundOpe