A Low-Profile Vacuum Actuator: Towards a Sit-to-Stand Assist Exosuit

Kulasekera, Asitha L.; Arumathanthri, Rancimal B.; Chathuranga, Damith Suresh; Lalitharatne, Thilina Dulantha; Gopura, R. A. R. C.

doi:10.1109/robosoft48309.2020.9115999

Cited by 11 publications

(12 citation statements)

References 20 publications

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“…In comparison to other vacuum actuators in Table 3 , the scaled force output from our actuator is higher than FOAM actuators with a magazine spring [ 47 ]. Our design has a low stiffness structure, translating to a lower operating pressure and a higher scaled value.…”

Section: Discussionmentioning

confidence: 88%

“…As explained above, our actuator was inspired by the Fluid-driven Origami Artificial Muscle (FOAM) [ 46 ], magazine spring [ 47 ], and the bellows [ 41 ] concepts. In order to adapt the actuator for our application, we considered the following criteria: size, operating pressure, and range of motion.…”

Section: Methodsmentioning

confidence: 99%

“…This actuator can be fabricated at small scales (7.3 mm × 20 mm × 60 mm), but its contraction and force are hindered by unpredictable buckling or sliding of the skeleton inside the skin. Another skeleton-skin system following a similar concept uses a magazine spring (a compression spring of rectangular coil shape) to achieve a linear contraction ratio of 50% at a similar operating pressure to the FOAM, while keeping a low cross-sectional profile [ 47 ]. One major drawback for this actuator is the relatively complex fabrication method of the spring [ 47 ].…”

Section: Introductionmentioning

confidence: 99%

“…Another skeleton-skin system following a similar concept uses a magazine spring (a compression spring of rectangular coil shape) to achieve a linear contraction ratio of 50% at a similar operating pressure to the FOAM, while keeping a low cross-sectional profile [ 47 ]. One major drawback for this actuator is the relatively complex fabrication method of the spring [ 47 ].…”

Section: Introductionmentioning

confidence: 99%

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A Vacuum-Powered Artificial Muscle Designed for Infant Rehabilitation

et al. 2021

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The majority of soft pneumatic actuators for rehabilitation exercises have been designed for adult users. Specifically, there is a paucity of soft rehabilitative devices designed for infants with upper and lower limb motor disabilities. We present a low-profile vacuum-powered artificial muscle (LP-VPAM) with dimensions suitable for infants. The actuator produced a maximum force of 26 N at vacuum pressures of −40 kPa. When implemented in an experimental model of an infant leg in an antagonistic-agonist configuration to measure resultant knee flexion, the actuator generated knee flexion angles of 43° and 61° in the prone and side-lying position, respectively.

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Section: Discussionmentioning

confidence: 88%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Vacuum-Powered Artificial Muscle Designed for Infant Rehabilitation

et al. 2021

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“…1). Part of this work has been previously presented in our recent conference publications [18], [19]. This work extends to further in-depth characterization and performance analysis of the proposed actuator and the integrated sensor.…”

Section: Introductionmentioning

confidence: 77%

A Low-Profile Vacuum Actuator (LPVAc) With Integrated Inductive Displacement Sensing for a Novel Sit-to-Stand Assist Exosuit

et al. 2021

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Stroke, spinal cord injuries, or aging can lead to muscle weakness that can make a person's life sedentary, either temporarily or permanently. Such persons need to be motivated to break their sedentary postures and attempt independent motion. A key motivator in this aspect is the ability to easily transition from seated to standing posture. If this sit-to-stand transition (STSt) is easy, it will encourage further mobility. A soft wearable device that can assist the STSt, would fill this need perfectly. The device would need to be able to seamlessly assist during STSt while being unobtrusive during being seated. A key limitation that is currently holding back the development of soft exosuits in STSt-assist is the lack of low-profile soft actuators with high strain rate and force-to-weight ratio. Hence, we propose a novel lowprofile vacuum actuator (LPVAc) with an integrated inductive displacement sensor that, can be rapidly fabricated, is lightweight (14 g), and can provide high strain (65%) and a high force-to-weight ratio (285 times self-weight). The proposed actuator comprises a low-profile spring encased within a low-density polyethylene film with rapid vacuum actuation and passive quick return. The proposed inductive sensor has a sensitivity of 0.0022 µH/mm and the hysteresis is below 1.5% with an overall absolute average error percentage of 5.24%. The performance of the proposed integrated sensor in displacement control of the LPVAc is experimentally evaluated. The proposed actuator is integrated into a novel mono-articular STStassist exosuit for preliminary testing. Surface electromyography measurements of the gluteus maximus muscles during STSt indicate a mean muscle activity reduction of 45%. This supports the potential use of the proposed actuator in STSt-assist.

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