The method of reinforcing elastic items with fibers made of different materials and thus influencing their properties has been around for a long time. Car tires, for example, are given stability and robustness in this way, and garden hoses their flexible and resistant shape. Festo has developed this principle further, resulting in the Fluidic Muscle, a pneumatic drive modeled on the biological muscle.
When the fluidic muscle fills with air, it increases in diameter and contracts in length, enabling a fluid, elastic movement. The use of the fluidic muscle enables motion sequences which approach human movement not only in terms of kinematics, speed and strength, but also sensitivity. The fluidic muscle can exert ten times the force of a comparably sized cylinder, is very sturdy, and can even be used under extreme conditions such as in sand or dust. There are two films of the fluidic muscle available online. Film one and film two.
Membrane technology – precise arrangement of fibers
This technology works because of the precise arrangement of wafer-thin aramid (polymer) fibers on just a few millimeters of a rubber hose. Depending on the size of the muscle, up to 240 fibers are incorporated with a wall thickness of just two millimeters. On the smallest model, around 60 fibers are distributed on two levels with a wall thickness of one millimeter. Despite the high number of fibers, none of them touch anywhere in the membrane. Depending on how the fibers are arranged, the properties of the muscle also vary.
Bernd Lorenz, head of Membrane Technologies at Festo, explains: “The arrangement of every single fiber is exactly determined and checked – that is absolutely critical with this technology. In this way we can have a direct influence on properties such as the rotary or contraction movement of the muscle.” Individual fibers are fine and sensitive, with a diameter of between 0.1 and 0.3 millimeters, depending on the size of the muscle. In conjunction and combined with the elastic material, they are both extremely stable and elastic. At the same time, the physical and chemical properties of the materials used also play a major role.
The pneumatic muscle – interaction between different materials
The muscle consists of a rubber hose with an integrated diamond-shaped fiber structure. Thanks to the combination of fiber matrix and rubber, the muscle is very elastic and can be stretched over a defined length without tearing. The muscle is hermetically sealed, works without any friction or jolting and is very precise. It does not leak and provides more power than comparable conventional pneumatic drives.
Versatile application areas – the Fluidic Muscle in action
The Fluidic Muscle is already used in numerous applications. It has particularly exceled in three large application areas: as a clamping device, for example to fix wood panels in place; to provide fast shaking and vibrating motion, for instance distributing bakery products on a conveyor belt; or as a pneumatic spring, for example in a Jacquard loom.
Submitted by: Frank Langro, Festo Corporation, Director – Marketing and Product Management, Festo
Filed Under: Pneumatic Tips