Controlling a camera in a virtual environment

image-based control or visual servoing approach. It consists of positioning a camera according to the information perceived in the image. This is thus a very intuitive approach of animation. To be able to react automatically to modifications of the environment, we also considered the introduction of constraints into the control. This approach is thus adapted to highly reactive contexts (virtual reality, video games). Numerous examples dealing with classic problems in animation are considered within this framework and presented in this paper. Published online: 19 July 2001     

Linking a CYBER76 to a 3600

In mid-1973, the Division of Computing Research, CSIKO, took delivery of a Control Data CVBER76 computer, which acts as the primary processing power of the CSIRO computer network (CSIRONET), replacing the Control Data 3600. The 3600, running under the DAD operating system, has been retained as a ‘front-end’ to the CYBER76 and continues to support the following functions:

• 1 An interactive system allowing both editing and CYBER76 job submission
• 2 Input of job files centrally from 3600 input devices, remotely from CSIRONET devices, or from interactive console users, and output of results similarly
• 3 A permanent file (document) system, with tape archiving

This paper describes the linking of the CYBER76 to the 3600. Software for a CYBER76 PPU has been written and some changes to the 3600 and CYBER76 operating systems have been required.     

Describing a Robot's Workspace Using a Sequence of Views from a Moving Camera

This correspondence describes a method of building and maintaining a spatial respresentation for the workspace of a robot, using a sensor that moves about in the world. From the known camera position at which an image is obtained, and two-dimensional silhouettes of the image, a series of cones is projected to describe the possible positions of the objects in the space. When an object is seen from several viewpoints, the intersections of the cones constrain the position and size of the object. After several views have been processed, the representation of the object begins to resemble its true shape. At all times, the spatial representation contains the best guess at the true situation in the world with uncertainties in position and shape explicitly represented. An octree is used as the data structure for the representation. It not only provides a relatively compact representation, but also allows fast access to information and enables large parts of the workspace to be ignored. The purpose of constructing this representation is not so much to recognize objects as to describe the volumes in the workspace that are occupied and those that are empty. This enables trajectory planning to be carried out, and also provides a means of spatially indexing objects without needing to represent the objects at an extremely fine resolution. The spatial representation is one part of a more complex representation of the workspace used by the sensory system of a robot manipulator in understanding its environment.     

Combining a monad and a comonad

We give a systematic treatment of distributivity for a monad and a comonad as arises in giving category theoretic accounts of operational and denotational semantics, and in giving an intensional denotational semantics. We do this axiomatically, in terms of a monad and a comonad in a 2-category, giving accounts of the Eilenberg–Moore and Kleisli constructions. We analyse the eight possible relationships, deducing that two pairs are isomorphic, but that the other pairs are all distinct. We develop those 2-categorical definitions necessary to support this analysis.     

Locating a tree in a phylogenetic network

Phylogenetic trees and networks are leaf-labelled graphs that are used to describe evolutionary histories of species. The Tree Containment problem asks whether a given phylogenetic tree is embedded in a given phylogenetic network. Given a phylogenetic network and a cluster of species, the Cluster Containment problem asks whether the given cluster is a cluster of some phylogenetic tree embedded in the network. Both problems are known to be NP-complete in general. In this article, we consider the restriction of these problems to several well-studied classes of phylogenetic networks. We show that Tree Containment is polynomial-time solvable for normal networks, for binary tree-child networks, and for level-k networks. On the other hand, we show that, even for tree-sibling, time-consistent, regular networks, both Tree Containment and Cluster Containment remain NP-complete.     

Design of a hexapod robot with a servo control and a man-machine interface

In this study a hexapod robot is used to explore its immediate environment. The man-machine interface program at the computer end is designed to detect the surroundings, plot simple topographic maps, and execute motion control by means of servos. The servomotor control interface designed and used in this study is based on a CPLD. The device, directly integrated with a single chip, can precisely generate the desired pulse width for PWM to control the robot servos. The control method used significantly reduces the workload on the MCU to allow it to better communicate with external devices. Most commercially available robots capable of making topographic maps and avoiding obstacles have wheels and they do not function well on surfaces that are not flat and even. This work may be continued and tests carried out on a range of different ground surfaces. The servomotor conversion device used here simplifies control and reduces the power needed by the single chip. This allows it to work with more external sensors and accomplish more communications tasks. Although this device uses ultrasonic and infrared sensors, a biaxial accelerometer and an electronic compass, it is desirable for more sensing functions to be incorporated in subsequent studies. The platform of the hexapod robot will also become a design reference for such devices in the engineering and the manufacturing fields and should provide useful options and applications for the commercialization of different industrial robots.     

Synthesis of a stabilizing control for a wheeled robot following a curvilinear path

The synthesis control problem for the plane motion of a wheeled robot with constrained control resource is studied. The goal of the control is to bring the robot to an assigned curvilinear trajectory and to stabilize its motion along it. A new change of variable is suggested that reduces the problem of stabilizing robot’s motion to that of stabilizing the zero solution in the form that admits feedback linearization. A control law stabilizing robot’s motion along an arbitrary curvilinear target trajectory is synthesized. For a straight target path, the closed-loop system is shown to be asymptotically stable for any initial conditions except for the case where the initial direction of motion is perpendicular to the target path.     

Transposing a matrix on a vector computer

There are many published algorithms for transposing a rectangular matrix in place, however none of these are suited to a vector processor. In this work we describe four methods and compare their speed and memory requirements to copying the matrix into workspace then back again in transposed order.     

Toward a Service-Oriented Development Through a Case Study

The rapidly emerging technology of Web services paves a new cost-effective way of engineering software to quickly develop and deploy Web applications by dynamically integrating other independently developed Web-service components to conduct new business transactions. This paper reports our efforts on designing and developing a Web service of pass-through authentication (PTA) for 12 online electronic-payment Web applications. In accordance with how a PTA service is developed and integrated with a corresponding back-end e-payment system, our strategies can be categorized in three stages: end-to-end integration stage, Web-services-enabled stage, and Web-services-oriented stage. Derived from real-world industrial experience, this three-stage pathway can be applied to a broad range of Web-application development projects to guide smooth transformation from a specific application-oriented design and development model toward a reusable Web-services-oriented model. Furthermore, this paper contributes to an engineering process that leads to practical Web-services-oriented software development. New research issues revealed by this project are also reported.     

A design of a controller as a component of a robotic manufacturing system

This paper specifies the functional design of a robot or machine tool controller suitable for inclusion in robotic manufacturing systems. The principle interest is the unmanned manufacturing cells which are being developed as major components of new manufacturing facilities. The functional specifications are motivated by recent experiences with the creation of a prototype cell for an open die forging process. There are two key technical design requirements. The first relates to the robot or machine tool being controlled. The controller must direct the machine actions, and, for unmanned operation, the controller must receive and process sensor information for process modification and for fault tolerance. The second relates to communication with the central cell computer (the host). The operation of an unmanned system requires a robot communication channel between the host and the controller; the controller must also respond to a variety of instructions transmitted from the host. Additional controller design requirements are imposed by economics. The proposed controller can be used today, and can develop in an evolutionary manner to meet the needs of future manufacturing systems. The evolutionary development is made possible by modular design, organized in a hierarchical manner.     

Learning the insertion operation of a flexible beam into a hole with a manipulator

Flexible objects are widely used in the aerospace, automobile, electronics, and medical industries, but automated assembly of flexible objects is difficult to realize. In most cases, flexible objects are still handled and assembled by people. This article researches a typical flexible objects assembly operation, i.e., to insert a flexible beam into a hole. A learning method is proposed to learn the mapping from the sensed force to the end-effector's motion, by which the insertion operation can be achieved efficiently. The mapping is decomposed in Cartesian space. Agents based on a learning automaton are defined between the input space, formed by the sensed force, and the output space, formed by the end-effector's motion, to implement the functions of the decomposed mappings. The input space is partitioned into different contexts. Through learning, agents can learn optimal actions according to different contexts, and then fulfill the insertion task cooperatively and efficiently. Simulation results of a 2D insertion operation prove the feasibility of the proposed method.     

Transferring a macro program to a micro machine

A powerful graphical PASCAL extension has transferred from a large computer to a microcomputer. The graphical extension, called M1RA-2D, allows the user to program computer graphics applications in a modern, structured and efficient language. The problems encountered were mainly due to the limits of a microcomputer-based system and to the size of the project. Problems involved memory space, documentation, low-power peripherals, PASCAL restrictions and hardware robustness and quality. Finally, M1RA-2D is compared with two other graphics software packages implemented on microcomputers: Applegraphics and an implementation of a 2D, level 2 Core System.     

Finding a k-tree core and a k-tree center of a tree network inparallel

A k-tree core of a tree network is a subtree with exactly k leaves that minimizes the total distance from vertices to the subtree. A k-tree center of a tree network is a subtree with exactly k leaves that minimizes the distance from the farthest vertex to the subtree. In this paper, two efficient parallel algorithms are proposed for finding a k-tree core and a k-tree center of a tree network, respectively. Both the proposed algorithms perform on the EREW PRAM in O(log n log n) time using O(n) work (time-processor product). Besides being efficient on the EREW PRAM, in the sequential case, our algorithm for finding a k-tree core of a tree network improves the two algorithms previously proposed     

Tracking of a moving ground target by a quadrotor using a backstepping approach based on a full state cascaded dynamics

In this paper, a tracking controller is formulated for a quadrotor to track a moving ground target. The quadrotor exhibits distinct hierarchical dynamics that allows its position to be controlled by its attitude. This motivates the use of backstepping control on the underactuated quadrotor. Most backstepping architecture controls the quadrotor position and attitude independently, and couples them with inverse kinematics. Inverse kinematics computes the attitude angles required to achieve a desired acceleration. However unmodeled effects are shown to cause inexact inversion resulting in tracking error. The approach proposed in this paper uses a re-formulated full state cascaded dynamics to eliminate the need for inverse kinematics in a full state backstepping control architecture. It is shown that zero steady state error is achieved in the presence of unmodeled aerodynamics effect and wind disturbance despite no integral action. In addition, a backstepping formulation is derived using contraction theory that guarantees the boundedness of state response under bounded disturbances such as wind. This improves the system performance. Numerical simulations are performed using the proposed controller to track a target moving along predefined paths and the results are compared with a benchmark controller derived using inverse kinematics. The results show that the proposed controller is able to achieve better tracking performance under unmodeled aerodynamic effects and wind disturbance as compared with the benchmark controller.     

Cooperative Strategy for a Wheelchair and a Robot to Climb and Descend a Step

This paper discusses a cooperative strategy that enables a wheelchair and a wheeled robot to climb and descend a step. In this method, not only does the robot assist the wheelchair user, but also the user assists the robot to overcome the step. The research indicates the feasibility of this new cooperative strategy between a physically disabled person and a personal robot that is not designed for high-level performance. The two vehicles (the wheelchair and the wheeled robot) are connected by a simple link mechanism, the two connecting positions of which are free joints. This method is especially affected by the link positions. A numerical calculation clarifies the combinations of the two link positions to avoid a collision between each vehicle and to overcome a step at the same time. The result of the simulations indicate that it is necessary to change the link positions to climb and descend a step safely. The experimental results show that this method is effective.     

Using a Microprocessor in a Walsh-Fourier Spectral Analyzer

The spectrum of a frequency-limited periodic wave may be obtained rapidly by measuring its truncated Walsh spectrum, and then converting from Walsh spectrum to Fourier spectrum after the measurement. The conversion process consists of a matrix multiplication in which a measured Walsh spectrum vector, of dimension 2^k, is multiplied by a 2^kX 2^kconversion matrix that is compensated for Walsh-spectrum truncation, to yield the corresponding Fourier spectrum vector. The microprocessor is well suited to this end; it is also useful in monitoring instrument panel switches and driving a display and print-out. This paper compares available microprocessors from the viewpoint of BCD processing—and concludes that the Fairchild PPS25 processor is the one best suited to meet the requirements.     

Approximation of a diffusion induced on a kinetic equation by a dynamical system

This work is devoted to the macroscopic behavior of the particles enclosed between two parallel plates within a small distance h of up to a few mean free paths. We show that, under physically realistic assumptions of the nature of the collisions, the macroscopic behavior of the gas is described by a diffusion equation. The present paper is an extension of a previous one [1] where only T-reflection law were considered.     

Imagining a non-biological machine as a legal person

As non-biological machines come to be designed in ways which exhibit characteristics comparable to human mental states, the manner in which the law treats these entities will become increasingly important both to designers and to society at large. The direct question will become whether, given certain attributes, a non-biological machine could ever be viewed as a “legal person.” In order to begin to understand the ramifications of this question, this paper starts by exploring the distinction between the related concepts of “human,” “person,” and “property.” Once it is understood that person in the legal sense can apply to a non-biological entity such as a corporation, the inquiry then goes on to examine the folk psychology view of intentionality and the concept of autonomy. The conclusion reached is that these two attributes can support the view that a non-biological machine, at least in theory, can be viewed as a legal person.

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Adding a relational interface to a nonrelational database

Today, thanks to more powerful machines and more robust data models, relational databases have gained broad industry acceptance. As relational databases grow in power and popularity, developers face pressure to convert legacy databases to this newer model. The author proposes a technique for doing so efficiently. The approach involves a bridge program that adds a relational software layer atop the nonrelational database management system. The interface translates the relational database management language into the nonrelational database management language to access the existing nonrelational database