The Festo solution

DN Staff

April 20, 1998

2 Min Read
The Festo solution

Servopneumatic positioning technology is a breakthrough in intelligent motion technology. A true closed-loop dynamic control system, servopneumatics can control the position, velocity, and acceleration of pneumatic actuators.

Unlike their electric and hydraulic counterparts, pneumatic actuators have been extremely difficult to control in a closed loop system until now. Using advanced hardware and control algorithms, Festo has made servopneumatics into a practical industrial technology, capable of fulfilling as many as 70% of all intelligent motion applications. Servopneumatic systems have also been shown to be simpler, and in most cases, more cost effective than competing technologies.

Linear motion in servopneumatics is accomplished by rapidly modulating the air flow to either side of the actuator. The system is composed of: (1) servo valve; (2) double acting pneumatic cylinder; (3) feedback transducer; and (4) axis controller. These basic functional elements are not unlike those found in typical motor control systems.

One important difference, however, is the servopneumatic control algorithm, which is sophisticated enough to compensate for the frictional characteristics of pneumatic actuators, as well as the flow properties and compressibility of air.

Another unique system component is the servo valve, itself a servo device, which is capable of accurately adjusting its orifice in response to a proportional control signal. Its high bandwidth (100 Hz) provides the rapid response necessary to overcome the actuator's "stick-slip" frictional characteristics, thus allowing smooth and precise velocity control.

In consideration of mechanical concerns, Festo offers several options for establishing efficient mechanical transport systems which are constructed with various models of rodless pneumatic actuators. These actuators are fabricated from highly engineered extruded aluminum profiles that also perform well as rigid, compact, and lightweight structural elements. Available options include linear guide bearings which provide excellent resistance to off-axis loads and rotational load moments, and integrated position transducers, which simplify design and installation.

These actuators are part of Festo's line of modular positioning and handling components which include such special purpose devices as precision slides, grippers, and rotary actuators. An off-the-shelf selection of mounting brackets, coupling kits, and adaptors make complete multi-axis part handling systems easy to design and build. The mounting means of these components are also compatible with common extruded machine-framing systems.

With the ability to move loads as heavy as several hundred pounds with an accuracy of 0.01% of stroke, servopneumatic equipment is a viable, low-cost intelligent motion technology for many industrial applications.

Common applications include, but by no means are limited to, pick-and-place, packaging, and automated assembly, as well as "soft" machine set up and adjustment.

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