System Integration & Control Systems Design


EtherCAT synchronises the ­movement of 1216 servo axes

August 2013 System Integration & Control Systems Design

What is probably the world’s largest kinetic sculpture was realised in ‘Kinetic Rain’ at Changi Airport in Singapore. The artistic concept of the installation and the calculatory design of the choreography originate from the Berlin-based Art+Com. In allusion to the tropical rain, the installation consists of 1216 brilliantly sparkling, copper-plated aluminium droplets. These are suspended from the ceiling on thin steel wires and each one is moved by a small servomotor. During a 15-minute show, the droplets are formed into different pictures connected with the subject of flying. MKT AG, experts in kinetic installations, took care of the complete technical implementation, including the software. The challenge of moving 1216 servo axes synchronously was solved on the basis of EtherCAT, TwinCAT and the compact servo drives in bus terminal format.

Passengers and visitors who enter Terminal One at the airport are stopped in their tracks by the kinetic sculpture. “The harmonious interaction of more than a thousand droplets also symbolises the many people at the airport who ensure day after day that passengers are positively surprised and have fond memories of it,” says Yeo Kia Thye, vice-director of airport operations.

The demands on the control of ‘Kinetic Rain’ are extraordinarily high, with the precise movement of 1216 axes. In addition to that, the project demanded high availability, compact design of the components and the replacement of components without addressing. “One of the paramount specifications of our customer, Changi Airport, was that the system must run 24 hours a day. Even if an individual axis were to fail, the show must go on,” says MKT director, Peter Haschkamp.

How do you control 1216 axes synchronously?

“The synchronous movement of 1216 axes is one of the absolute highlights of this project,” stresses Raphik Shahmirian from the Beckhoff office in Munich. Beyond that, requirements had to be met where the dynamics, precision and speed of the motion sequences were concerned. The droplets move with a speed of 1,5 m/s and the movement must be dynamic, but at the same time flowing and absolutely free of jerks. MKT found the solution to this task in the PC and EtherCAT-based Beckhoff control platform with compact servo drive technology.

A central C6525 Industrial PC is responsible for the control. It communicates by TwinCAT ADS with the special GUI computer from MKT. At the same time, the PC centrally controls the 1216 axes via TwinCAT NC PTP and acts as the master.

Via the TwinCAT cam table function the master PC coordinates the distribution of the position data to the six slave PCs, to each of which 192 or 208 axes are assigned, and ensures the synchronicity of all axes according to a master axis as reference. Communication takes place in real-time over EtherCAT up to the drives.

The GUI computer from MKT serves for visualisation, but also contains the show in the form of a table containing the position data for each droplet at time intervals of 200 ms. This corresponds to five pictures per second. A flowing movement perceptible by the human eye without jerks is possible only through the interpolation in TwinCAT NC PTP. Here, 100 intermediate positions are calculated for each droplet using a spline algorithm in a 2 ms NC task. These calculations take place on each slave PC for the local axes assigned to it.

The artistic intention to have the synchronous movements of the droplets run like a kind of 3D film is made possible through the use of EtherCAT and TwinCAT NC PTP. While the master keeps all the axes synchronous to one other, the slave PCs calculate the positions of the axes assigned to them every 2 ms and communicate them over EtherCAT in real-time to the servo drives.

Compact servo drive in a 12 mm terminal

The movement of the individual axes is extremely precise and lies in the range of 1 mm for an overall length of 7,6 m.

The maximum offset between two droplets is 0,25 mm. Each droplet is controlled via an EL7201 EtherCAT servomotor terminal and a servomotor of the type AM3121. “In the servo terminals, which fit seamlessly into the EtherCAT terminal row, we found an extremely compact solution that fits the structural conditions perfectly, with limited installation space in the ceiling of the building,” says Haschkamp. In addition, servo drive technology offers dynamic advantages and allows flowing transitions.

Modularity of the controller simplifies commissioning

“The modularity of the control solution was important to us and the fact that an individual axis can be exchanged without addressing. That made partial commissioning possible, for example we were able to work in parallel on software, hardware and the mechanism, allowing us to keep within the narrow timeframe that we had for this project,” explains Haschkamp.

With TwinCAT NC PTP it is additionally possible to ‘jog’ the whole show, i.e. one can fast forward and rewind like a film. That very much simplified the commissioning for MKT. If an individual passage of the sequence was not yet 100% satisfactory, the engineers could repeat it continuously. “A big advantage,” stresses Haschkamp. “With other solutions this is not possible and you are forced to start the show from the beginning each time until you reach the desired position, it is very time consuming.”

In contrast to comparable kinetic sculptures realised in the past over decentralised hardware controllers, ‘Kinetic Rain’ is controlled via a central PC and software and transmitted over EtherCAT. The cam table function, which MKT accommodated locally in the drive amplifier in earlier control solutions, is now executed by the software. In this way, the position data can be managed centrally and distributed in real-time to the axes over EtherCAT.

View the official airport video at http://tinyurl.com/pxyghlg

For more information contact Kenneth McPherson, Beckhoff Automation, +27 (0)11 795 2898, k.mcpherson@beckhoff.com, www.beckhoff.co.za



Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Four ways the global parts shortage has led to innovation and openness
System Integration & Control Systems Design
For those who use automation parts, the unpredictable nature of the supply chain is one of the biggest problems faced today. The shortfall has impacted every industry, but automation components have been especially affected.

Read more...
Complete system for transparent energy monitoring
Beckhoff Automation Editor's Choice Electrical Power & Protection
Transparent energy monitoring reduces both machine downtime and the necessity to oversize the corresponding components. Added to these advantages are simplified preventive maintenance, and increased production efficiency. The wide range of PC-based control technology from Beckhoff offers a solution that can be optimally adapted to individual applications.

Read more...
Iritron’s year of consolidation
Iritron Editor's Choice System Integration & Control Systems Design
Despite the multiple challenges faced by businesses in South Africa, the buoyancy of the technology sector worldwide has produced some green shoots for automation specialist, Iritron.

Read more...
Five edge opportunities for SIs to maximise revenue in 2024
Editor's Choice System Integration & Control Systems Design
System integrators continue to face the challenge of doing more with less – supporting complex operations, while meeting production schedules with limited resources, and innovating to increase efficiency, maximise safety and reduce risk.

Read more...
Condition monitoring in a forging press retrofit
Beckhoff Automation System Integration & Control Systems Design
Significantly increased vibration on machines can result in many forms of negative impacts such as reduced system performance or damage to the machine and foundation. Using the example of retrofitting a forging press with a maximum press force of 2000 tons, Wölfel Engineering explains how efficiently the process was tailored and implemented with PC-based control and measurement technology from Beckhoff.

Read more...
Thermoforming machine automation
Beckhoff Automation Editor's Choice Motion Control & Drives
Hamer has joined forces with Beckhoff to develop a thermoforming machine for water-based cellulose pulp to produce fully recyclable and environmentally-friendly cellulose packaging.

Read more...
System integration in the digital age
System Integration & Control Systems Design
To meet the challenges of an increasingly competitive marketplace, many manufacturers (end users) must focus on their core competencies and outsource the rest to experts.

Read more...
TwinCAT Chat integrates LLMs into the automation environment
Beckhoff Automation IT in Manufacturing
Large language models offer a number of benefits for both automation engineers and enterprise management. For automation engineers, LLMs have the potential to revolutionise the development process by automatically generating and completing code. From an enterprise management perspective, LLMs promote knowledge transfer within the organisation.

Read more...
Compact and integrated EtherCAT stepper motor drives
Beckhoff Automation Motion Control & Drives
The integrated ASI8100 stepper motor drive from Beckhoff’s range of compact drive technology products up to 48 V DC combines a stepper motor, stepper motor output stage and fieldbus connection in a space-saving design. As an EtherCAT slave, it can be placed directly on the machine without a control cabinet or upstream I/O level, allowing for highly compact, control cabinet-free machines.

Read more...
Precise detection of complex rotational movements
Beckhoff Automation Sensors & Transducers
The EP3751-0260 EtherCAT Box module by Beckhoff connects an acceleration sensor with an inertial measurement unit - a gyroscope. This provides accurate detection of acceleration and rotational motion in addition to shock, vibration and tilt measurement, both as preprocessed values and as raw sensor data.

Read more...