EFFECTS OF BRAID ANGLE ON PNEUMATIC ARTIFICIAL MUSCLE ACTUATOR PERFORMANCE

ABSTRACT Pneumatic artificial muscles (PAMs) provide numerous advantages for use as actuators in a wide variety of mechanical systems. Our study focused on determining the effects of braid angle on the performance of PAMs. This paper discusses how we constructed a set of PAMs with varying braid angle, predicted their performance using analytical models, gathered empirical data characterizing the PAMs, and compared the analytical predictions with the experimental results. We constructed six PAMs of different braid angles between 38 o and 73 o . To predict PAM performance, we used an analysis based on the force equilibrium equations for a pressurized actuator. We first quantified the performance limits of each actuator in a series of static characterization tests. Then we subjected each PAM to cyclical displacement testing. Finally, a series of cyclical tests were performed with a pre-strain applied to the PAMs, to better approximate their typical use. Our results showed variation of braid angle causes significant differences in performance among the six PAMs tested; PAMs with larger braid angle generated higher blocked force and exhibited greater contraction. The empirical data matched the model predictions based on our estimates for the braid angle of a given PAM

QUASI-STEADY AXISYMMETRIC BINGHAM-PLASTIC MODEL OF MAGNETORHEOLOGICAL FLOW DAMPER BEHAVIOR

ABSTRACT A typical magnetorheological (MR) flow mode damper consists of a piston attached to a shaft that travels in a tightly fitting hydraulic cylinder. The piston motion makes fluid flow through an annular valve in the MR damper. An electro-magnet applies magnetic field to the MR fluid as it flows through the MR valve, and changes its yield stress. An MR fluid, modeled as a Bingham-plastic material, is characterized by a field dependent yield stress, and a (nearly constant) postyield plastic viscosity. Although the analysis of such an annular MR valve is well understood, a closed form solution for the damping capacity of a damper using such an MR valve has proven to be elusive. Closed form solutions for the velocity and shear stress profile across the annular gap are well known. However, the location of the plug must be computed numerically. As a result, closed form solutions for the dynamic range (ratio of field on to field off damper force) cannot be derived. Instead of this conventional theoretic procedure, an approximated closed form solution for a dampers dynamic range, damping capacity and other key performance metrics is derived. And the approximated solution is used to validate a rectangular duct simplified analysis of MR valves for small gap condition. These approximated equations are derived, and the approximation error is also provided

QUASI-STEADY ANALYSIS OF A MAGNETORHEOLOGICAL DASHPOT DAMPER

ABSTRACT This paper addresses quasi-steady analysis of a magnetorheological (MR) INTRODUCTION The inherent characteristics of MR (magnetorheological) fluids such as continuously controllable yield stress and fast response have prompted many researchers to develop novel dampers so as to reduce and isolate vibration and shock motion of devices. Most of dampers have designed and manufactured based on three working fluid modes of damper operation: shear mode [1-3], flow mod

Impact of Nanowires on the Properties of Magnetorheological Fluids and Elastomer Composites

The authors acknowledge funding support from the National Science Foundation (NSF-CBET-0755696), The Pennsylvania State University, and Altoona College. Additional support provided by a DARPA SBIR Phase 2 Contract No. W31P4Q-06-C-0400 (N. M. Wereley). This publication was supported by the Pennsylvania State University Materials Research Institute Nano Fabrication Network, the National Science Foundation Cooperative Agreement No. 0335765, and the National Nanotechnology Infrastructure Network through with Cornell University

Analysis and control of linear periodically time varying systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1991.Includes bibliographical references (p. 217-223).by Norman M. Wereley.Ph.D

IMECE2003-43645 ANALYSIS OF FLEXIBLE FLY FISHING ROD AND CASTING DYNAMICS

ABSTRACT I

Bending Properties of an Extensile Fluidic Artificial Muscle

Partial funding for Open Access provided by the UMD Libraries' Open Access Publishing Fund.Low stiffness, large stroke, and axial force capabilities make Extensile Fluidic Artificial Muscles (EFAMs) a feasible soft actuator for continuum soft robots. EFAMs can be used to construct soft actuated structures that feature large deformation and enable soft robots to access large effective workspaces. Although FAM axial properties have been well studied, their bending behavior is not well characterized in the literature. Static and dynamic bending properties of a cantilevered EFAM specimen were investigated over a pressure range of 5–100 psi. The static properties were then estimated using an Euler-Bernoulli beam model and discrete elastic rod models. The experiments provided data for the determination of bending stiffness, damping ratio, and natural frequency of the tested specimen. The bending stiffness and the damping ratio were found to change fourfold over the pressure range. Experimentally validated bending properties of the EFAM presented insights into structural and control considerations of soft robots. Future work will utilize the data and models obtained in this study to predict the behavior of an EFAM-actuated continuum robot carrying payloads.https://doi.org/10.3389/frobt.2022.80409