Experimental and Simulation-Based Investigation of Polycentric Motion of an Inherent Compliant Pneumatic Bending Actuator with Skewed Rotary Elastic Chambers

Abstract

Abstract:To offer a functionality that could not be found in traditional rigid robots, compliant actuators are in development worldwide for a variety of applications and especially for human-robot interaction. Pneumatic bending actuators are a special kind of such actuators. Due to the absence of fixed mechanical axes and their soft behavior, these actuators generally possess a polycentric motion ability. This can be very useful to provide an implicit self-alignment to human joint axes in exoskeleton-like rehabilitation devices. As a possible realization, a novel bending actuator (BA) was developed using patented pneumatic skewed rotary elastic chambers (sREC). To analyze the actuator self-alignment properties, knowledge about the motion of this bending actuator type, the so-called skewed rotary elastic chambers bending actuator (sRECBA), is of high interest and this paper presents experimental and simulation-based kinematic investigations. First, to describe actuator motion, the finite helical axes (FHA) of basic actuator elements are determined using a three-dimensional (3D) camera system. Afterwards, a simplified two-dimensional (2D) kinematic simulation model based on a four-bar linkage was developed and the motion was compared to the experimental data by calculating the instantaneous center of rotation (ICR). The equivalent kinematic model of the sRECBA was realized using a series of four-bar linkages and the resulting ICR was analyzed in simulation. Finally, the FHA of the sRECBA were determined and analyzed for three different specific motions. The results show that the actuator's FHA adapt to different motions performed and it can be assumed that implicit self-alignment to the polycentric motion of the human joint axis will be provided.

Überprüfung von Sicherheit und Anwenderfreundlichkeit einer assistiv-aktiven Kniebewegungsschiene mit Selbstanpassung an den Patienten (SE_BURG)

“…Mithilfe eines Maßbandes wurden Ober-und Unterschenkellänge sowie -umfang und Kniegelenksumfang gemessen [9].…”

Characteristic Analysis and Design Optimization of Bubble Artificial Muscles

“…Pneumatic artificial muscles (PAMs) are one of the most commonly used actuators to drive assistive soft exoskeletons. 3 Although pneumatic exoskeletons were initially made of mostly rigid components, 4,5 more recently they have been developed with more flexible, compliant elements. [6][7][8][9][10][11][12][13][14][15] Soft exoskeletons and artificial muscles have also used a range of power sources, including cable-tendon-driven mechanisms, that is, Exosuit, 16 Myosuit, 17 and XoSoft 18 ; direct electro-mechanical energy transduction in polymers, for example, polyvinyl chloride (PVC) gel, 19,20 dielectric elastomers, 21,22 dielectrophoretic liquid zipping actuators, 23 and Peano-HASEL 24 ; and thermomechanical actuation such as coiled polymer.…”