Soft Pneumatic Actuators for Rehabilitation

Guido Belforte,Gabriella Eula,Alexandre Ivanov,Silvia Sirolli

doi:10.3390/act3020084

Abstract

Pneumatic artificial muscles are pneumatic devices with practical and various applications as common actuators. They, as human muscles, work in agonistic-antagonistic way, giving a traction force only when supplied by compressed air. The state of the art of soft pneumatic actuators is here analyzed: different models of pneumatic muscles are considered and evolution lines are presented. Then, the use of Pneumatic Muscles (PAM) in rehabilitation apparatus is described and the general characteristics required in different applications are considered, analyzing the use of proper soft actuators with various technical properties. Therefore, research activity carried out in the Department of Mechanical and Aerospace Engineering in the field of soft and textile actuators is presented here. In particular, pneumatic textile muscles useful for active suits design are described. These components are made of a tubular structure, with an inner layer of latex coated with a deformable outer fabric sewn along the edge. In order to increase pneumatic muscles forces and contractions Braided Pneumatic Muscles are studied. In this paper, new prototypes are presented, based on a fabric construction and various kinds of geometry. Pressure-force-deformation tests results are carried out and analyzed. These actuators are useful for rehabilitation applications. In order to reproduce the whole upper limb movements, new kind of soft actuators are studied, based on the same principle of planar membranes deformation. As an example, the bellows muscle model and worm muscle model are developed and described. In both cases, wide deformations are expected. Another issue for soft actuators is the pressure therapy. Some textile sleeve prototypes developed for massage therapy on patients suffering of lymph edema are analyzed. Different types of fabric and assembly techniques have been tested. In general, these Pressure Soft Actuators are useful for upper/lower limbs treatments, according to medical requirements. In particular devices useful for arms massage treatments are considered. Finally some applications are considered.

Highlights

The need for rehabilitation therapies and equipment is continually increasing as a result of two factors: population ageing and the large number of injuries from traffic accidents.Population ageing [1] is one of the most significant trends of the 21st century, with important implications for all aspects of society
Soft pneumatic actuators are generally known as Pneumatic Muscles (PAM), or Pneumatic Artificial Muscles
Prototypes with different bores have been manufactured in order to test various geometries, generally used with a maximum supply pressure equal to 4 bar relative pressure

Summary

Introduction

The need for rehabilitation therapies and equipment is continually increasing as a result of two factors: population ageing and the large number of injuries from traffic accidents.Population ageing [1] is one of the most significant trends of the 21st century, with important implications for all aspects of society. In the more developed countries, 23 percent of the population is already aged 60 years or over and that proportion is projected to reach 32 percent in 2050 and 34 percent in 2100. In developing countries as a whole, 9 percent of the population today is aged 60 years or over, but that proportion will more than double by 2050, reaching 19 percent that year, and triple by 2100, reaching 27 percent. Soft pneumatic actuators are generally known as PAMs, or Pneumatic Artificial Muscles. They feature a number of geometric configurations that have been developed over the years. The actuator’s deformation is limited by the threads’ pitch angle and their density, as well as by the type of sleeve (e.g., braided or woven) (Figure 1)

Results

Discussion

Conclusion