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Home >Re-imagining machine configuration

Re-imagining machine configuration

12 December 2016

Mike Lomax of Bosch Rexroth examines the role of intelligent drive systems in optimising machine configuration and performance and aiding the adoption of Industry 4.0

Machine manufacturers are under pressure to provide shorter development times for highly advanced machines, with less manpower available to them. This is especially so as the drive towards Industry 4.0 adoption gathers pace with its requirement for real time data to inform operational decision-making. In particular, with Industry 4.0, the keyword is connectivity, between all participants in the production process, whether human or mechanical.

Even in facilities where complete Industry 4.0 adoption may be in the future, it is vital that any components or systems are at least compatible with the requirements of Industry 4.0 – with the ability to connect to and communicate with internal and external networks.

While this may be relatively simple to achieve with new components, completely replacing all systems to ensure compatibility is frequently a costly and unrealistic option. In these instances, there is a versatile range of devices now available which enable even standard components to offer at least basic connectivity to Industry 4.0 systems without impacting on the automation logic.

Modern drive systems now have sufficient intelligence to perform position movements and velocity control

Enhanced functionality is a particular requirement with drives. Modern drive systems now have sufficient intelligence to perform position movements and velocity control – functions that, even a few years ago, would not have been thought capable of. These functions are now regarded in the same way as accessing email via a mobile phone – almost a minimum expectation. A further expectation with Industry 4.0 is that drive systems must be able to acquire data on machine functionality and performance, to then configure and present this data externally. There is also an accompanying requirement for local data storage so data can be sent in batches.

Thanks to advancements in drives, manufacturers can now allocate functions directly to the drive, via in-built technologies that eradicate the need for an external PLC. The latest servo drives, for example, now include the IEC61131-3 PLC operating system, the industry standard for solving most machine control issues. This represents a major step change from the minimal functionality offered by previous generations of drives.

The implications of this new capability can take time to fully understand, but essentially the drive now has the ability to solve control challenges in real time, whenever and wherever they may occur – a key facet of Industry 4.0.

A very simple example would be an axis movement needing to be triggered by a signal input, for instance, from an optical sensing device. The time needed to relay the signal to the central PLC, process the information, perform any calculations needed and then send the command back to the drive can often be excessive, causing production errors. In these instances, removing the PLC and going direct to the drive eradicates this time lapse, and so optimises cycle time and production consistency.

Staying in sync

Even if the drive system selected contains the appropriate problem-solving tools or function blocks, the challenge of synchronising multiple movements on the machine remains. Where the bus system in use is not deterministic, the solution is for the drives to communicate between themselves, without having to refer back to a central control system. This is where technologies such as SERCOSIII – one of the first deterministic bus systems, which can now be installed directly into the drive - come into their own. However, a deterministic system is not necessarily a prerequisite for Industry 4.0 adoption as drives can store real time data and send it in a non-deterministic way to upward systems.

Reducing programming time               

With such a range of function tools available within the drive, it is vital that selecting the right tool for the job is as straightforward as possible. The goal should be that an OEM programmer with perhaps no previous experience of the particular challenge in front of him, can easily access and use these functions.  Indeed these tools are an essential facet of Industry 4.0 compatibility.

The solution lies in the employment of tried and tested PLC function blocks. These function blocks can be used freely in IEC 61131-3 PLCs and can even be incorporated within conventional ladder logic programming.

A variety of function blocks are now available and can be selected depending on the individual application requirements. Their capabilities range from correcting the positions of products on conveyor belts, and the control of winders, to closed loop register control and even the creation of a complete motion profile for cross-cutters and cross sealers. Other options include implementation of a flying shear process; tension control; and crank kinematics. In the future it is likely that they will be configured to communicate key data via the MQTT connectivity protocol.

Creating a machine HMI

Creating an interface between the machine and operator – another vital component of Industry 4.0 - has previously required central PLC involvement along with a bus system, to convey key machine set-up information and variables to the drives. Diagnostics and machine status information is then redirected to the PLC before being displayed on the Human Machine Interface (HMI).

Many modern drive systems also contain all of the tools needed to create a HMI

Although modern bus systems can achieve this, there can be a considerable amount of programming effort when all the required information is already contained within the drive system. To address this, many modern drive systems also contain all of the tools needed to create a HMI. In some instances, a central PLC may not even be required as the drives are capable of using a full range of inputs and outputs which would normally be connected to the PLC.

Minimising commissioning time

A key factor which must be kept under control is the time taken to set up and commission the machine. Intelligent drives now offer a number of tools that can reduce start-up time through the optimisation of the axis movements and process synchronisation.

These rapid start-up tools have been designed to enable the drives to be moved at an early stage of the machine commissioning, even before the machine control software is installed on the system. This results in rapid and easy testing of machine mechanics with only basic IT tools, such as mobile phones or tablets, required to gather information.

Help with maintenance?

Modern drives can now even play a part in a proactive maintenance regime as they can be supplied with a fully integrated series of software tools capable of performing key predictive maintenance functions, with minimal additional programming effort. This software can be set up to continuously monitor in real time the condition of the machine mechanics and process conditions – from waveform analysis through the analysing the rate of temperature change, as well as checking for backlash, increased friction or process overload. If a fault condition arises, a code is generated and passed to the machine HMI. Furthermore, if a critical issue is identified which required the machine to cease operating immediately, this decision can be made inside the drive, minimising lost production and the risk of machine damage resulting from unsafe operation. This can be transmitted in real time to, for example, the mobile phone of a maintenance engineer, bypassing traditionally lengthy manual reporting procedures and so allowing immediate fault diagnosis and remedial action.

Whether or not Industry 4.0 is the immediate goal, what is undeniable is the enhanced processing power and functionality of intelligent drives which present numerous opportunities to optimise programming, production and maintenance. With the need for central PLC’s now eliminated in many instances, not only is component count reduced but more advanced machines can now be created in much shorter timeframes.

Key Points

  • In terms of Industry 4.0 drive systems need to acquire machine functionality and performance data, and configure and present this externally
  • With the latest servo drives including the IEC61131-3 PLC operating system, they have the ability to solve control challenges in real time
  • Modern drives can be supplied with a fully integrated series of software tools capable of performing key predictive maintenance functions