Design Optimization of a Miniaturized Pneumatic Artificial Muscle and Experimental Validation
Shakila Zabihollah,
Seyed Alireza Moezi,
Ramin Sedaghati
Abstract:Miniaturized pneumatic artificial muscles (MPAMs) are widely utilized in various applications due to their unique characteristics, such as a high power-to-weight ratio, flexibility, and compatibility with the human environment, as well as being compact enough to fit within small-scale mechanical systems. Maximizing the amount of force generated by these actuators while keeping their dimensions minimized can greatly affect their efficiency. In this study, a formal design optimization problem was formulated to i… Show more
“…Poisson's ratio of PET braid, ν s , is nearly 0.33, and the modulus of elasticity of the braid, E br , is typically around 2 GPa. The dimensional parameters (L 0 , t 0 , R 0 , and α 0 ), are initial parameters which may be obtained through design optimization process [24]. Instantaneous parameters (L, R, t, and α) are obtained as described below: Taking into account that B 0 = B and L = L 0 ± ∆L (where ∆L is subtracted from the initial length during contraction and added to it during expansion), the braid angle can be determined at each state as:…”
“…The dimensions of the fabricated MPAMs are presented in table 1, which are determined using the optimized geometrical parameters obtained in our prior study [24], resulting in an improved design of MPAMs with higher force and contraction outputs compared to the other MPAMs of the same dimensions. To fabricate MPAMs with these specified dimensions, customized cylindrical bladders are made using an in-house fabricated 3D-printed mold.…”
Miniaturized pneumatic artificial muscles (MPAMs), designed to replicate natural muscle actuation, offer unique attributes such as a high power-to-weight ratio, flexibility, easy integration, and compactness, making them favorable for many applications. The present paper aims at the development of an accurate semi-analytical force model considering the effect of the bladder material and friction terms to predict the nonlinear force-deformation response of MPAMs during contraction and expansion cycles. Existing force models for MPAMs exhibit limitations to accurately capturing the force-deformation behaviors due to several simplification factors. This study enhances these models by integrating correction terms to accurately address the nonlinearity and frictional effects exhibited by MPAMs. An analysis of the hysteresis loops resulting from the cyclic loading and unloading of MPAMs under specific pressures is undertaken to compare different methodologies in order to determine the most accurate correction terms. To investigate the nonlinear behavior of MPAMs, the stress-strain relationship of the bladder material and results from force-deformation expermnetal tests on the entire actuator are considered and for the effect of friction term, theoretical and empirical approaches are investigated. Results suggest that the theoretical force model based on analytical and empirical friction forces, respectively, slightly overestimates and underestimates the force experienced by MPAMs during contraction while slightly underestimate and overestimates during expansion, respectively. A comparative analysis between MPAMs featuring Ecoflex-50 silicone and Ecoflex30+PDMS mixture as bladder materials has also been conducted to further investigate the effect of bladder materials on their force and contraction outputs under inlet pressures ranging from 0 kPa to 300 kPa. It is shown that the MPAM feauting Ecoflex-50 bladder, exhibits lower dead-band pressure and an overall reduced blocked force in comparison to MPAM with bladder made of Ecoflex30+PDMS while exhibiting a substantially enhanced free contraction capacity.
“…Poisson's ratio of PET braid, ν s , is nearly 0.33, and the modulus of elasticity of the braid, E br , is typically around 2 GPa. The dimensional parameters (L 0 , t 0 , R 0 , and α 0 ), are initial parameters which may be obtained through design optimization process [24]. Instantaneous parameters (L, R, t, and α) are obtained as described below: Taking into account that B 0 = B and L = L 0 ± ∆L (where ∆L is subtracted from the initial length during contraction and added to it during expansion), the braid angle can be determined at each state as:…”
“…The dimensions of the fabricated MPAMs are presented in table 1, which are determined using the optimized geometrical parameters obtained in our prior study [24], resulting in an improved design of MPAMs with higher force and contraction outputs compared to the other MPAMs of the same dimensions. To fabricate MPAMs with these specified dimensions, customized cylindrical bladders are made using an in-house fabricated 3D-printed mold.…”
Miniaturized pneumatic artificial muscles (MPAMs), designed to replicate natural muscle actuation, offer unique attributes such as a high power-to-weight ratio, flexibility, easy integration, and compactness, making them favorable for many applications. The present paper aims at the development of an accurate semi-analytical force model considering the effect of the bladder material and friction terms to predict the nonlinear force-deformation response of MPAMs during contraction and expansion cycles. Existing force models for MPAMs exhibit limitations to accurately capturing the force-deformation behaviors due to several simplification factors. This study enhances these models by integrating correction terms to accurately address the nonlinearity and frictional effects exhibited by MPAMs. An analysis of the hysteresis loops resulting from the cyclic loading and unloading of MPAMs under specific pressures is undertaken to compare different methodologies in order to determine the most accurate correction terms. To investigate the nonlinear behavior of MPAMs, the stress-strain relationship of the bladder material and results from force-deformation expermnetal tests on the entire actuator are considered and for the effect of friction term, theoretical and empirical approaches are investigated. Results suggest that the theoretical force model based on analytical and empirical friction forces, respectively, slightly overestimates and underestimates the force experienced by MPAMs during contraction while slightly underestimate and overestimates during expansion, respectively. A comparative analysis between MPAMs featuring Ecoflex-50 silicone and Ecoflex30+PDMS mixture as bladder materials has also been conducted to further investigate the effect of bladder materials on their force and contraction outputs under inlet pressures ranging from 0 kPa to 300 kPa. It is shown that the MPAM feauting Ecoflex-50 bladder, exhibits lower dead-band pressure and an overall reduced blocked force in comparison to MPAM with bladder made of Ecoflex30+PDMS while exhibiting a substantially enhanced free contraction capacity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.