K. Shehab

Bio: K. Shehab is an academic researcher. The author has contributed to research in topics: Digital clock manager & Clock synchronization. The author has an hindex of 1, co-authored 1 publications receiving 136 citations.

Enhancements to the time synchronization standard IEEE-1588 for a system of cascaded bridges

Abstract: The IEEE-1588 standard for a high precision time synchronization now exists since 2002. For using this standard in bridged networks a so-called boundary clock is defined, where the local clock adjustment can be modeled by a corresponding control loop. At the field level of industrial automation systems, the line topology is very important. By using Ethernet at the field level, the resulting chain of bridges leads to a cascade of control loops and may lead to instabilities and deviations of the distributed clocks, which are not acceptable. For this application a bypass clock instead of the boundary clock is proposed as an enhancement of the IEEE-1588 standard. The effectiveness of this extension to be evaluated by simulation technique.

Ethernet-Based Real-Time and Industrial Communications

Abstract: Despite early attempts to use Ethernet in the industrial context, only recently has it attracted a lot of attention as a support for industrial communication. A number of vendors are offering industrial communication products based on Ethernet and TCP/IP as a means to interconnect field devices to the first level of automation. Others restrict their offer to communication between automation devices such as programmable logic controllers and provide integration means to existing fieldbuses. This paper first details the requirements that an industrial network has to fulfill. It then shows how Ethernet has been enhanced to comply with the real-time requirements in particular in the industrial context. Finally, we show how the requirements that cannot be fulfilled at layer 2 of the OSI model can be addressed in the higher layers adding functionality to existing standard protocols.

Real-Time Ethernet - Industry Prospective

Abstract: After more than ten years of experience with applications of fieldbus in automation technology, the industry has started to develop and adopt Real-Time Ethernet (RTE) solutions. There already exists now more than ten proposed solutions. International Electrotechnical Commission standards are trying to give a guideline and selection criteria based on recognized indicators for the user.

Device for optically scanning and measuring an environment

Abstract: A device for optically scanning and measuring an environment is provided. The device includes a movable scanner having at least one first projector for producing at least one uncoded first pattern on an object in the environment. The scanner includes at least one camera for recording images of the object provided with the pattern and a controller coupled to the first projector and the camera. The device further includes at least one second projector which projects a stationary uncoded second pattern on the object while the scanner is moved. Wherein the controller has a processor configured to determine a set of three-dimensional coordinates of points on a surface of the object from a set of images acquired by the camera based at least in part on the first pattern. The controller is further configured to register the set of images relative based in part on the stationary second pattern.

The Three Generations of Field-Level Networks—Evolution and Compatibility Issues

Abstract: Field-level networks have been one of the keys to modern automation systems. Be it in factory, process, or building automation, networks allow for horizontal and vertical integration of distributed devices and functions. This paper reviews the evolution of field-level networks comprising fieldbus systems, industrial Ethernet, and recent industrial wireless networks. The main focus is on demonstrating the continuity in the development of the three generations that ensured backward compatibility at the expense of radical innovation. Given the wide set of modern communication technologies, this paper then discusses how architectures for future automation networks might look. Particular emphasis is put on hybrid architectures for combined wired/wireless networks. A generic concept for integration of multiple wireless segments will be presented that supports seamless roaming for mobile nodes in industrial environment.