150 research outputs found
Static kinematics for an antagonistically actuated robot based on a beam-mechanics-based model
Soft robotic structures might play a major role in
the 4th industrial revolution. Researchers have successfully
demonstrated advantages of soft robotics over traditional
robots made of rigid links and joints in several application
areas including manufacturing, healthcare and surgical
interventions. However, soft robots have limited ability to exert
higher forces when it comes to interaction with the
environment, hence, change their stiffness on demand over a
wide range. One stiffness mechanism embodies tendon-driven
and pneumatic air actuation in an antagonistic way achieving
variable stiffness values. In this paper, we apply a beammechanics-based
model to this type of soft stiffness controllable
robot. This mathematical model takes into account the various
stiffness levels of the soft robotic manipulator as well as
interaction forces with the environment at the tip of the
manipulator. The analytical model is implemented into a
robotic actuation system made of motorised linear rails with
load cells (obtaining applied forces to the tendons) and a
pressure regulator. Here, we present and analyse the
performance and limitations of our model
Soft Pneumatic Actuators for Rehabilitation
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
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
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