New degrees of freedom for factory automation

01 October 2007

Manfred Grundke, Chairman of the Executive Board of Bosch Rexroth AG, explains his company’s vision of factory automation: the integration of electromechanical and electrohydraulic functions into one control system.

Factory automation has reached a new level in its development: Increasing function integration is boosting decentralised intelligence in all drive technologies, allowing them for the first time to make optimum use of their respective strengths with a single control system.

Like suppliers in the automotive industry, automation manufacturers are increasingly assuming system
responsibility for complete modules. This is characterised by a combination of open communication interfaces, consistent control software, uniform engineering tools, and innovative simulation tools. This development is accelerating the project planning and commissioning of machines and at the same time reducing the total cost of ownership.

Faster, less expensive automation that is still tailored to meet the specific requirements of different applications—these apparently contradictory core demands on mechanical engineering require new approaches. The path to this goal leads through the modularisation of machine concepts. In this way,
manufacturers are quickly able to combine modules that are scalable in both size and function into a single
basic design.

Three-dimensional integration
Automation technology is creating the basis for this with three-dimensional integration. That is the integration of additional functions in hardware and software, and the horizontal and vertical integration in automation solutions.

Moreover, the ever increasing degree of decentralised intelligence is taking over tasks that were previously
performed by the control system. For example, safety functions integrated in the drive system and working
independently of the higher-level control system have superseded the additional components that used to be necessary.

This trend towards greater intelligence makes systematic use of electrohydraulics and offers a broad spectrum of ready-toconnect, controlled axes with external control board electronics or in valveintegral
motion control systems. The integrated software covers the special physical features of fluid technology and allows commissioning, parameterisation, and diagnostics without the need for detailed knowledge of the hydraulics.

The degree to which the dynamics and precision of electrohydraulic axes have developed can be seen with a few examples of the current technical standards: acceleration rates of up to 80G, rapid travel of up to 10 m/sec, and control cycles measured in milliseconds have become established as standard industrial practice. In nibbling machines Rexroth axes move 30 tons of power with up to 1,500 double strokes per
minute—in engraving mode even up to 4,000 double strokes.

Rexroth offers the same communications mechanisms regardless of the drive technology used, and the
same degree of comfort for electromechanical and electrohydraulic system solutions. Both drive technologies use decentralised control architecture to close the control circuits in the axes and communicate through open interfaces with the higher-level control system, which works in the same way for all drive systems.

Horizontal, vertical integration
In horizontal integration, automation manufacturers combine different drive technologies to form complete modules. In this way, Rexroth has combined linear motion modules with electric and pneumatic actuators and a single control system to create camoLINE, a module for handling systems. The innovative, positive
locking connection technology means that even in its basic configuration, this module is immediately able to offer a high degree of precision without the need for complex alignment. This reduces design costs by
around 30 per cent and at the same time allows savings of up to 75 per cent for the production parts that were previously necessary. The user is free to decide where he wants to set the interface to his solution: at the engine or at the valve, at the intelligent drive system or as a complete module at the drive- or controller-based motion control system.

Here, the key is vertical integration using universal, open interfaces and standardised software. These allow the simple integration of third-party components and modules. The user is thus no longer dependent on a single automation supplier and is able to optimally combine solutions offered by different suppliers.

Here, the user is able to choose a tailor-made solution from manufacturers of open control architecture offering a wide range of motion logic integration and CNC and PLC control systems that are precisely scalable in their hardware and software.

An especially high degree of freedom is opened up by automation manufacturers who consistently use an
open PLC control system complying with IEC 61131-3 with function modules compatible with PLCopen in all their versions of their control system hardware. This means that drive-based, controller-based and PC-based control systems all use the same, universal software. That makes modularisation considerably easier, for once they have been written, the user can simply copy sections of programs, or even whole
programs, for use in the current automation level.

Open communications
Openness in communications has a great influence on the total cost of ownership of automation solutions. Drive and control systems that support all standard field bus systems reduce dependence on any one supplier. In addition, machine manufacturers can satisfy customer wishes for the locally preferred
communication system without incurring significant additional expense.

Users can enjoy an even greater degree of freedom—with reduced total cost of ownership—by employing
universally standardised control communications systems that are independent of any one manufacturer,
for example SERCOS III. The third generation SERCOS combines hardened real-time mechanisms with Ethernet physics. The globally accepted standard is currently establishing itself as the universal communications system in mechanical engineering. Moreover, Ethernet physics guarantee SERCOS III a
seamless flow of information from the drive to the factory level.

Above all, numerous manufacturers of control, drive and input/output systems support this new standard. This means that the user benefits from open competition between suppliers, competition in which—in contrast to proprietary systems—every component can be exchanged. Here, only those products will survive that are especially efficient, especially inexpensive or which have special functions.

A new engineering environment
Later developments make working with open systems considerably simpler. Innovative, modular, universal
engineering environments include all project planning, programming and parameterising tools needed for
automation tasks. The content of the modular package is adapted to the automation level concerned, reducing complexity.

In the minimum configuration level, the user is given a dialogue-supported parameterisation tool for the drive systems. In the maximum level he is given a uniform complete system for all engineering tasks. This significantly reduces engineering time, as all tools can access all data once they have been recorded, and the operator can work through all his tasks with a uniform look and feel.

In addition, simulation tools support the machine manufacturer with timesaving project planning ahead of actual design. For example, the mathematical models developed by Rexroth reflect the performance data of the components for all technology fields, the process factors and the control parameters. This interplay
allows realistic statements to be derived about the overall characteristics of the machine. Machine manufacturers can thus optimally configure the individual components of the drive system and test complete automation solutions.

Simulation tools also help to
significantly shorten commissioning times. Newly developed simulation software for CNC control systems contain all the necessary functions on a standard PC. The simulator even takes the individual features of the control system into account and always reflects the firmware used with the corresponding technology
package and functions.

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