Ichiro Mizunuma

Middleware for distributed industrial real-time systems on ATM networks

We address the problem of middleware design for constructing ATM LAN based distributed industrial plant monitoring and control systems. In particular, we present a real-time client-server programming model based on a uniform ATM network. This model is being realized in our middleware called MidART. The middleware provides a set of industrial application specific but network transparent programming abstractions and application programming interface (API) that support individual application QoS requirements. In order to achieve on-demand transmission of plant data, we have developed a concept called selective real-time channels to be supported by MidART. We present the design and protocols of selective real-time channels and describe how QoS requirements of applications are guaranteed.

Acquisition and service of temporal data for real-time plant monitoring

Data sampled from plants are registered as temporal data, combined with time stamps. We developed a real-time data server which periodically acquires temporal data and transmits them to clients for graphic presentation. The real-time data server consists of multi threads scheduled based on the rate monotonic theory. This paper explains the design of a real-time data server. The prediction for schedulability of it based on the rate monotonic theory has been verified with an experiment on an actual system.<<ETX>>

Real-time communication in plant-monitoring/controlling systems with ATM networks

We propose a method for a schedulability check in ATM networks which provide fixed prioritized virtual connections. Our method does not need any run-time scheduling other than fixed priority scheduling at each output link of all switch nodes and traffic shaping at each output link of cell terminal nodes in a network. Rate monotonic analysis assumes a critical instance in which all tasks arrive at the same time. We, however, can obtain information on the times when messages arrive at switch nodes in a network. Using such information, our method can check the schedulability of a set of channels more exactly than the method assuming a critical instance.

RT-CRM: Real-Time Channel-based Reflective Memory

The authors propose and present Real-Time Channel-based Reflective Memory (RT-CRM)-a useful programming model and middleware communication service for constructing distributed real-time industrial monitoring and control applications on commercially available open systems. RT-CRM provides remote real-time data reflection abstraction using a simple writer-push model. This writer-push approach enables one to easily decouple the QoS characteristics of the writers from that of the readers. This decoupling is crucial in supporting different kinds of remote data transfer and access needs that one often finds in distributed industrial systems. They describe the design of RT-CRM, along with a set of easy-to-use API to access the RT-CRM service. They have implemented RT-CRM as part of a larger real-time middleware project, MidART. They address many of the important implementation issues including buffer management and QoS support. They demonstrate the feasibility of RT-CRM through a discussion of their application programming support and preliminary performance data.

New architecture of industrial systems with real-time ATM middleware

We propose a programming model, a real-time client-server model, for distributed real-time systems for monitoring and controlling plant. With the model we can make a system scalable in a flat architecture with an ATM network. The system can be scalable because it has no bottlenecks in plant data transmission as traditional systems has with their cyclic transmissions. On-demand transmission of plant data realizes this scalability. The architecture can be flat with the ATM network integrating various kinds of traffics transmitted separately in traditional systems. We also propose using our middleware which provides application program interfaces (APIs) based on the model and guarantees application-to-application QoS. In addition, to achieve on-demand transmission of plant data, we propose a concept of selective real-time channels. We show an example of an application with our middleware, a plant monitoring system with an operator station and a programmable logic controller.

Digital Audio and Video in Industrial Systems

In industrial environments such as power plants, automated factories, sewage treatment facilities, railways, etc., digital audio and video play at least three important roles:, On-line documentation and training. Pre-stored video in documentation databases is typically viewed interactively, both during routine operation and during emergency situations. 9 Monitoring and surveillance. Video cameras posted around plants allow operators to keep track of security and proper operation and to provide a visual record for subsequent auditing and analysis. 9 Sensors for plant control. Video and image processing are being used increasingly in the automated operation of the plant i t se l f for example, in equipment to measure speeds, count objects, search for production flaws, detect wear of machinery, etc. In these kinds of settings, it is often desirable to integrate many different functions into the same network for example, functions or applications with hard real-time requirements, continuous media such as audio and video, functions requiring rapid response, and traditional applications using traditional data protocols such as TCP/IP. At first glance, this may not seem too difficult if one simply dedicates a portion of total network bandwidth to the traffic with hard real-time requirements, then a portion of the remainder to audio and video, etc. However, bandwidth is only one of the resources and problems that must be considered in a complete network system. Because of the widely different communication requirements of these functions, the demands of their traffic characteristics, flow control, constraints, and performance criteria are typically more challenging than they would be in typical local area or office networks with workstations, PCs, client and server machines, etc. In this position paper, we discuss a number of issues regarding industrial networks, digital audio and video in those networks, and implications on current research directions. These are considered in the context of ATM (Asynchronous Transfer Mode) networks having speeds ranging from 100 megabits/second to one gigabit/second.

Real-time middleware based on the rate-monotonic theory

We have developed real-time middleware which is laid on a POSIX 1003.4,.4a compliant operating system. This real-time middleware supports programming of real-time systems based on rate-monotonic analysis (RMA) and an active object model (real-time object model). RMA is a method to guarantee timing constraints in real-time systems, and an active object model provides us with timing encapsulation for programs. Therefore, the middleware enables us to develop predictable and flexible real-time systems. A data acquisition system, which is a part of a monitoring system, is a target of the middleware. We show that the system is proved to be schedulable as predicted.<<ETX>>

Multi-authority virtual network for intelligent transportation systems

Dedicated information networks for transportation systems will be integrated with public networks as wired- and wireless-phone networks and Internet. When we realize such an integrated network, a difficulty lies in the fact that the integrated network does nor have any single authority that can decide priorities between competing communication requests. To treat multiple authorities, we propose an auction scheme to prioritize services in the information network. In the scheme, messages that pay higher prices get higher priorities. We also propose to use a technology of a mobile agent to realize the scheme. We show some examples of mobile agents and how they can solve competition between different authorities in the auction model. We are now developing an integrated network, called IQnet (integrated and qualified network), for intelligent transportation systems. The auction scheme and the mobile agent technology proposed in this paper will be implemented as portions of the functions of IQnet.