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Professor Asko Ellman:
What's new in pneumatics
Pneumatics is traditionally thought to be a simple and somewhat obsolete operating technique where actuators are controlled sequentially between the fixed ends of the actuators. However, thanks to new developments in pneumatic components, new control techniques are possible that enable the adaptation of pneumatic operation in a completely new and innovative way also in materials-handling technology.
In valve technology, interesting new components include adjustable, electronically controlled pressure valves that can be used to produce continuously adjustable pressure. The valves also often include a pressure feedback coupling which enables the valve to compensate for any deviations to the pressure level caused by the process.
Another interesting component group is high-speed valves and so-called high-speed technique. In these components, the valve seat is directly controlled by a powerful solenoid resulting in valves with a switching time of a few milliseconds. As the name suggests, these valves can be used to implement high-speed couplings.
A third interesting component group is the McKibben actuator, which Festo GmbH has named Fluid Muscle. The component consists of a fibre-enforced tube that contracts when pressurised. This component includes some unique features: the component's structure is hermetic; it has no seals or gliding parts. The hermetic structure makes the component interesting in two ways: the actuator does not leak and because it is always overpressurised it can be used in facilities that require cleanliness, but also in facilities where uncleanliness would pose a problem for a traditional cylinder. Thanks to its structure, friction relating to the component's movement is minimal. This is a great advantage when adjusting position and force with the component, as friction has traditionally caused a significant problem where position and force are concerned.
However, applications for the McKibben actuator have been slow to discover. The most important reason for the minor application of this component lies in its peculiarity, which is why people do not know how to exploit it for its appropriate use.
With the help of these new components and the developed control technique, an actuator's position and force can be adjusted incredibly quickly and precisely.
Done Logistics Oy is taking part in a research venture at the Tampere University of Technology studying the force and movement control techniques enabled by the new pneumatic components. Better techniques in force and movement benefit the customer investing in an intralogistics system, because it results in even more precise robot-grabbing techniques and item handling.
Asko Ellman
Institute of Machine Design
Tampere University of Technology
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