EPAM: Eversive Pneumatic Artificial Muscle

Pneumatic Artificial Muscles, which are lightweight actuators with inherently compliant behavior, are broadly recognized as safe actuators for devices that assist or interact with humans. This paper presents the design and implementation of a soft pneumatic muscle based on the eversion principle - Eversive Pneumatic Artificial Muscle (EPAM). The proposed pneumatic muscle exerts a pulling force when elongating based on the eversion (growing) principle. It is capable of extending its length by a minimum of 100% when fully inflated. In contrast to other soft pneumatic actuators, such as the McKibben’s muscle, which contract when pressurized, our EPAM extends when pressure is increased. Additionally, important advantages of employing the eversion principle are the capability to achieve high pulling forces and an efficient force to pressure ratio. In a pivoting joint/link mechanism configuration the proposed muscle provides motion comparable to human arm flexion and extension. In this work, we present the design of the proposed EPAM, study its behavior, and evaluate its displacement capability and generated forces in an agonistic and antagonistic joint/link arrangement. The developed EPAM prototype with a diameter of 25 mm and a length of 250 mm shows promising results, capable of exerting 10 N force when pressurized up to 62 KPa

An elastomer-based force and tactile sensor

Tactile and force sensing devices that are capable to interactively explore the external environment have attracted a lot of research interest. Optical-based tactile sensors are be-coming popular because they do not suffer from electromag-netic interference and because improved signal processing techniques enable intelligent sensor data classification. Howev-er, there is still no implementation of a sensor that measures both force and tactile information concurrently in an efficient manner in terms of material efficiency. In this research, we present a novel design for an elastomer-based tactile and force sensing device that senses both information within one elasto-mer. In addition, the tactile information is measured in the form of pressure distribution from the surface of objects. The pro-posed sensor has a soft and compliant design employing an opaque elastomer. The optical sensing method is used to meas-ure both force and tactile information simultaneously based on the deformation of the reflective elastomer structure and a flexure structure. Here, we present the fabrication and devel-opment principles of the overall sensor. The experimental evaluation shows that the prototype is capable of sensing normal forces up to 70 N with an error of 6.6%