Arch W. Naylor

Design of integrated manufacturing system control software

A coordinated multifaceted conceptual framework for the development of real-time control software for integrated manufacturing systems is described. This orderly, rational, and structured approach is based on a blending of modern software concepts and formal semantic models. Using a common distributed language environment and generic (i.e. reusable) software, the authors construct control software as an assemblage of components written in the common distributed language. The semantics of the assemblages are modeled formally.

Some problems in distributing real-time Ada programs across machines

The Ada Research Group of the Robotics Research Laboratory at The University of Michigan is currently developing a real-time distributed computing capability based upon the premises that real-time distributed languages provide the best approach to real-time distributed computing and, given the focus on the language level, that Ada offers an excellent candidate language. The first phase of the groups work was on analysis of real-time distributed computing. The second, and current, phase is the development of a pretranslator which translates an Ada program into n Ada programs, each being targeted for one of a group of processors and each having required communication support software automatically created and attached by the pre-translator. This paper describes the pretranslator being developed and a number of issues which have arisen with regard to the distributed execution of a single Ada program, including language semantics, objects of distribution and their mutual access, network timing, and execution environments.

PROGRESS--A graphical robot programming system

A graphical off-line robot programming system should not only be able to simulate various types of robot movement graphically, it should also be able to use graphics to interact with binary sensors, actuators and etc., in order to simulate logic-related and other functions of robot languages, such as testing and branching, looping, communication and external event handling graphically. We present a graphical off-line robot programming system which has some of these additional features. In particular, it incorporates a geometrical representation of logical conditions into the geometrical representation of the robot and workspace and it allows conditional statements to be programmed in a geometric setting.

Fundamental Structure of Input-Output Stability for Feedback Systems

An approach to the input-output stability of feedback systems is discussed. This approach incorporates the natural inverse operator model to describe these systems. Using this operator, the input-output stability problem is decomposed into five subproblems. One of these subproblems involves the causality of the input-output operator, a property not recognized in previous feedback system stability studies. Following the development of the model and the stability definition some general stability theorems are presented.

The design and implementation of the control and integration software of a flexible manufacturing system

The concepts of a methodology for designing and implementing the control and integration software of computer-integrated manufacturing systems are presented. The goal of this methodology is to build flexible and reusable software. Software flexibility is obtained by decoupling the process plan models from the factory floor model and by designing generic control algorithms. Reusability is achieved by building self-contained software/hardware components with general, possibility parametrized, interfaces. These reusable components can be used to populate manufacturing software libraries. Off-the-shelf components can then be assembled into manufacturing systems. Moreover, the interplay between simulated and actual hardware internals of software/hardware components is used as the basis of a testing strategy that performs offline simulation followed by incremental online testing. The application of the methodology to the design and implementation of the control and integration software of a prismatic machining cell is reported. A highly efficient implementation of this software has been carried out in the Ada programming language and is fully operational.<<ETX>>

On Decomposition Theory: Generalized Dependence

Although system decomposition is a fundamental tool of systems theory, no theory exists that unifies its many manifestations. The beginnings of such a theory are proposed here. The goal of this theory is to understand the structure of decompositions of large complex systems. In particular, it is to uncover those structural features that are implicit in each specific method of decomposition. The key assumption is that any system decomposition is based, either explicitly or implicitly, on some concept of dependence. Therefore, study of decomposition becomes enmeshed with the study of dependence. Three aspects of system decomposition are emphasized. First, various kinds of dependence are employed in system decomposition. Second, refinement of a decomposition to obtain a new one is an important part of decomposition. Third, shifts in point of view and level of detail can lead to different decompositions. No attempt is made to cover all aspects of decomposition theory. Rather, attention is focused on developing some properties of generalized dependences. A number of examples are presented showing the applicability of the ideas presented here to a variety of systems. These include relational data bases, finite-state machines, cognitive maps, Petri nets, and vector processor computation.

A transform technique for multivariable, time-varying, discrete-time, linear systems

It is shown that a transform technique developed for single-input, single-output time-varying, discrete-time, linear systems can be meaningfully extended to multivariable systems.

Developing control and integration software for flexible manufacturing systems

The slow growth of computer-integrated manufacturing is attributed to the complexity of designing and implementing their control and integration software. This article expands on a methodology for designing and implementing this software that was introduced in [16]. The goal of this methodology is to build flexible and resuable control and integration software for computer-integrated manufacturing systems. It hinges upon the concepts of software/hardware components, their assemblages, a distributed common language environment, formal models, and generic controllers. Major sources of flexibility are obtained by decoupling process plan models from the model of the factory floor and by using a generic controller. Reusability is achieved by building selfcontained software/hardware components with general, possibly parametrized, interfaces. The interplay between simulated and actual hardware internals of software/hardware components is used as the basis of a testing strategy that performs off-line simulation followed by on-line testing.The methodology has been applied in designing and implementing the control and integration software of an actual Prismatic Machining Cell. The article also reports on the details of this implementation.