Using force-displacement relations to obtain actuation parameters from artificial muscles

Spinks, Geoffrey M.; Bakarich, Shannon; Aziz, Shazed; Salahuddin, Bidita; Xin, Hai

doi:10.1016/j.sna.2019.03.012

Cited by 6 publications

(9 citation statements)

References 10 publications

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“…These cases are not illustrated here, but are discussed elsewhere. [17] The engine work cycle is quite different to the isobaric process shown in Figure 2 so that the theoretical engine work output can be different to that reported for actuators tested under standard conditions. Engines operate through a loading/stimulus cycle that converts a fuel or energy source to continuous mechanical motion.…”

Section: Correlation Between Engine Output and Actuator Behaviormentioning

confidence: 81%

Actuator Materials for Environmentally Powered Engines

Spinks

Abbasi

Gautam

et al. 2023

Adv Materials Technologies

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The first solid‐state engine that converted heat into continuous mechanical motion using a thermally responsive actuating material was introduced almost a century ago. These engines used vulcanized rubber where the cyclically heating and cooling of the rubber generate continuous mechanical power in pendulum or wheel type engines. The development of solid‐state heat engines has seen several waves of activity with interest stimulated by the introduction of new actuating materials capable of responding to different environmental stimuli. Opportunities for improved engine outputs are afforded by recently developed artificial muscle materials. A theoretical connection between engine output and the characteristics of the actuator material is developed to compare the performances of vulcanized rubber, shape memory alloys (SMAs), and twisted and coiled polymer (TCP) fiber artificial muscles. It is shown that with an engine designed to suit the actuation performance of TCPs engines powered by the tensile actuation of such materials would exceed the output of SMA heat engines. The properties needed in actuator materials to further enhance engine output are identified and polymer structures that may produce such properties are described.

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Section: Correlation Between Engine Output and Actuator Behaviormentioning

confidence: 81%

Actuator Materials for Environmentally Powered Engines

Spinks

Abbasi

Gautam

et al. 2023

Adv Materials Technologies

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“…Using graphical methods as demonstrated by Spinks et al (2019) , we can determine actuation parameters of the SAP-BAM. For the contracted actuator (actuated in DI water), the free stroke of the actuator is 26.1%.…”

Section: Characterisationmentioning

confidence: 99%

Saltwater-responsive bubble artificial muscles using superabsorbent polymers

et al. 2022

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Robots operating in changing underwater environments may be required to adapt to these varying conditions. In tidal estuaries, for example, where the degree of salinity cycles in step with the level of the water, a robot may need to adapt its behaviour depending on the position of the tide. In freshwater bodies, the unexpected presence of a pollutant may also require the robot to respond by altering its behaviour. Embodying this sensing and response in the body of the robot means that adaptivity to the environment can be achieved without resorting to centralised control. This can also allow direct responsivity using ‘free’ environmental energy, actuating without requiring stored onboard energy. In this work we present a soft artificial muscle, the contraction of which varies in response to the salinity the water surrounding it. The novel actuator uses a super-absorbent polymer gel encapsulated within a series of discrete cells. This gel readily absorbs water through the membrane wall of the actuator, and can swell to over 300 times its initial volume. This swelling generates significant pressure, changing the shape of the cells and driving the contraction of the muscle. The degree of swelling is significantly reduced by the presence of salts and pollutants in the surrounding water, so transitioning from a freshwater to a saltwater environment causes the muscle to relax. In this paper, we discuss the design and fabrication of these superabsorbent polymer-based Bubble Artificial Muscle (SAP-BAM) actuators. The tensile properties of the muscle under actuated (fresh water) and relaxed (salt water) conditions are characterised, showing a maximum generated force of 10.96N. The length response under constant load for a full actuation cycle is given, showing a maximum contraction of 27.5% of the initial length at 1N load, and the performance over repeated actuation and relaxation cycles is shown. The SAP-BAM muscles are straightforward to fabricate and are composed of low-cost, freely-available materials. Many existing pneumatically-actuated muscles can be modified to use the approach taken for this muscle. The muscle presented in this work represents the first example of a new class of super-absorbent polymer-driven environmental soft artificial muscles.

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“…This load can be the same or different as that used to form the coil. 31,32,54,55 The work per coil length can be calculated simply by W L ¼ F DL L . Thus, the output of the 1D radial transport/swelling model can be fed into the analytical TCA expressions to determine dynamic actuation and transient work.…”

Section: Boundary Conditionsmentioning

confidence: 99%