The prototypes of a McKibben actuator and a straight fibre muscle are presented. Their experimental characteristics are shown. For both kind of typology a mathematical model, able to evaluate the traction force as a function of the contraction ratio and the supply pressure, has been developed, taking into account the geometrical dimensions of the muscles and the mechanical characteristics of the materials. The models have been validated experimentally. Finally, by means of such models, a comparison between the behaviour and performance of the two kinds of actuator has been carried out.

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This article describes the design of a new test rig for measuring the friction force in pneumatic components and seals. The test rig was designed in order to measure both the overall friction force in a pneumatic cylinder or a valve as a whole, and the single contribution to friction force caused by the sliding seals. To this end, special fixtures and devices were designed and manufactured in order to measure the friction force in piston seals, rod seals and cartridge valve seals individually. Results of friction measurements carried out on pneumatic cylinders with similar characteristics but produced by different manufacturers are presented and compared. A test procedure and a methodology, in order to separate the contributions of the individual seals from the overall friction of the cylinders, is presented

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