– Integrated Safety and Motion article by Frank Bartos
The challenges facing safe automation are reflected in the trends. The market wants overall, compatible solutions from the sensor to the actuator. Ethernet is gaining ground as a universal communication system. As a result, the worlds of information technology and automation are growing closer together, which brings new challenges not just for safety, but for security, too.
The trend is moving away from exclusively centralized control structures toward decentralized, independent cell automation and the mechatronic, modular approach that this enables. However, networking several control systems must not increase the level of complexity. The future belongs to solutions that simplify user operation, while significantly increasing the level of flexibility.
Along with the ongoing technological development, standards also have a key role to play—a fact that is also reflected in the trends.
There are currently a whole range of standards and directives on machinery safety that are entirely new or are due to replace existing editions. The two most important changes are the new Machinery Directive (2006/42/EC), which will come into force on Dec. 29, 2009, and EN ISO 13849-1, which will replace EN 954-1. To that, add DIN EN 62061 as a sector standard of DIN EN 61508. The general expectation is that the conversion process will not make the safety solution any easier for end users or system integrators.
For the first time, methods will be available that permit a quantitative interpretation and verification of all the protective devices. Manufacturers need to design products with this in mind. Users need to see this change as an opportunity and try to promote active implementation.
The new standards essentially consider the whole life cycle of a plant or machine, from design to scrapping. A quantitative assessment also provides a method by which to calculate each impact chain universally, from the sensor to the actuator, and to compare this with requirements established from the risk analysis. As manufacturers, it’s vital to be represented in each segment of this chain and offer users compatible solutions to reduce the complexity and the interface investment for the user.
The future belongs to systemic solutions that support users from engineering to maintenance, which dovetails process control and safety within automation. Intelligent dovetailing of safety and standard control technologies considers the various requirements of both environments in equal measure. The requirement for short reaction times and the absence of feedback can only be implemented if the development has taken both environments into account right from the outset. Accordingly, the benefits are on the side of combined systems designed along these lines.
Merging safe motion into drive
A further trend in this respect is safe motion, in other words, the integration of safety into drive technology. The integration of safety functions will continue to grow in this area, offering users all-in-one solutions. However, products and systems will only be one side of the coin. Services that support users with targeted expertise specific to their application will continue to grow in importance, particularly when you consider that this allows companies to concentrate on their core competencies and place safety as a company value into competent hands.
In terms of networking and data transfer, office communication has been moving into the world of automation with Ethernet. This is following a similar development to that of the standard fieldbus systems where a safety layer is being added to existing protocols retrospectively. Those systems in which specific properties and requirements of feedback-free, high performance safety technology have been considered from the start are following a different route.
The merging of office and automation means that aspects of security and availability will have to become more important, particularly with regard to the open interfaces on an Ethernet system and the industrial use of wireless systems. This requires that automation be examined in its entirety in terms of safety and security.
The decentralization of control functionalities will also continue to progress, whereby it’s important to distinguish between two different aspects. As a first step, the decentralization of periphery enables you to reduce the amount of wiring needed as well as associated costs. As a second step, it’s possible to decentralize identical control programs and subfunctions that enable complete modularization in the form of machine elements. The aim is to be able to reuse as many identical parts as possible, making it easier to standardize automation projects. This principle is already used successfully in mechanics and on components, although decentralization of control technology still has shortcomings.
The centralized perspective
Today’s solutions for networking multiple control systems bring with them a considerably higher level of complexity for the user. In this case, we believe that the solutions that become established will be those that make it easier for users to handle networking of multiple control systems and avoid interface problems right from the start. In an ideal scenario, the dividing limits in the mechanics, hardware and control software will remain the same. The benefit of this distributed control concept is that the user maintains a centralized perspective of a distributed control system.
An evaluative assessment of the overall life cycle of plant and machinery requires all the relevant project phases to be reproduced via modern, software-based tools from the proposal phase right through to commissioning. This guarantees the availability of subtotals and individual work steps for subsequent tasks, and fewer discrepancies in information.
Furthermore, it can be said that software tools that simplify the use of programming or configuration of products are increasingly becoming the distinguishing feature on hardware, as it is now more difficult to distinguish between the technical properties than it was in the past.
Where units used to be interconnected using a variety of wiring methods, today the trend is toward user-friendly software solutions. With a greater function range and therefore increased complexity, the aim is to simplify engineering and servicing through excellent diagnostics. For tools to be useful, they must work intuitively and guide users through a project without restricting them.
Previously, safe automation has been characterized by a physical separation between people and a hazardous movement, for example. If access was required, the process was transferred to a safe condition using switching sensors (safety gate switches). This is now a proven procedure based on simple, robust principles. But having to regularly stop and restart the production process is also a disadvantage. New technologies resulting from image processing open up a range of possibilities for optimizing human/machine interaction and create the potential for higher productivity and cost-effectiveness.
|Armin Glaser is head of product management for Pilz Automation. For more information, visit www.pilz.com .|