Hydraulic Artificial Muscles (HAMs) consisting of a polymer tube constrained by a nylon mesh are presented in this
paper. Despite the actuation mechanism being similar to its popular counterpart, which are pneumatically actuated
(PAM), HAMs have not been studied in depth. HAMs offer the advantage of compliance, large force to weight ratio, low
maintenance, and low cost over traditional hydraulic cylinders. Muscle characterization for isometric and isobaric tests
are discussed and compared to PAMs. A model incorporating the effect of mesh angle and friction have also been
developed. In addition, differential swelling of the muscle on actuation has also been included in the model. An
application of lab fabricated HAMs for a meso-scale robotic system is also presented.
KEYWORDS: Capacitors, Energy harvesting, Solar energy, Electronics, Wind energy, Control systems, Device simulation, Sensors, Feedback control, Systems modeling
Much of the work on improving energy harvesting systems currently focuses on tasks beyond geometric optimization
and has shifted to using complex feedback control circuitry. While the specific technique and effectiveness
of the circuits have varied, an important goal is still out of reach for many desired applications: to produce
sufficient and sustained power. This is due in part to the power requirements of the control circuits themselves.
One method for increasing the robustness and versatility of energy harvesting systems which has started to
receive some attention would be to utilize multiple energy sources simultaneously. If some or all of the present
energy sources were harvested, the amount of constant power which could be provided to the system electronics
would increase dramatically. This work examines two passive circuit topologies, parallel and series, for combining
multiple piezoelectric energy harvesters onto a single storage capacitor using an LTspice simulation. The
issue of the relative phase between the two piezoelectric signals is explored to show that the advantages of both
configurations are significantly affected by increased relative phase values.
Piezoelectric energy harvester (PEH) has been commonly considered as energy sources for self-reliant systems or
wireless sensor nodes. They mainly consist a vibration source, an energy harvesting circuit and a storage device like
battery. Currently, PEH suffers from low efficiency energy harvesting circuit and lack of battery model. Most of the
energy harvesting circuits exploits switching techniques with inductor, which require peak detection or zero crossing
detection. This paper discusses the balance between the harvested energy and the energy costs of the switching. In
addition, a battery model is developed to predict the real-time charge on the battery.
KEYWORDS: Aerospace engineering, Microcontrollers, Composites, Control systems, Abdomen, Magnetic sensors, Analog electronics, Energy harvesting, System integration, Biomimetics
The study of Tobacco hawkmoths, Manduca sexta, with respect to the relationships between muscle activation
and flight response has progressed to a point that closed loop heading control is possible on the live, tethered
animals. We present a method of control through stimulation of the dorsoventral muscle (DVM) groups that are
responsible for the upward motion of the wings. An experimental setup allowing for only yaw in flying moths
was developed. A 10% duty cycle square wave input was used to stimulate the DVM on the side of the moth
inboard of the desired turn. Both continuous and discontinuous signals were used and the results suggest that
the moth is able to compensate for consistent input stimulation.
The majority of double-acting hydraulic cylinders are controlled via a 4/3 spool valve, which allows for the active
movement of the cylinder in two directions, as well as holding its current position. These control valves lack the ability
to "dangle," or rather, the ability to permit the hydraulic cylinder to freely sway passively in response to external forces.
Including the ability to dangle within a control valve is of particular interest for a number of reasons. It allows for much
more naturalistic actuation of the hydraulic cylinder, making it further compatible with bio-inspired platforms, such as
driving the legs of a prosthetic limb or an exoskeleton for human augmentation. Additionally, dangle offers an
opportunity for considerable efficiency gains. This is possible because the momentum of the load, gravity, among other
external forces, can be utilized to move the actuator instead of solely relying on an active input. A novel control valve
that integrates all of the features of a 4/3 spool valve in addition to dangle is reported herein.
This paper aims to introduce newly developed Ionic Polymer-metal Composites (opto-IPMCs) targeting optical applications.
The thin optical film of ZnO was deposited on IPMC by an electroless deposition method. This ZnO/Pt IPMC
demonstrates photoluminescence (PL) quenching phenomenon, which is reduction in PL intensity (PLI) with an increase in
applied electric fields. The crystal structure, morphology and atomic compositions of the resulting ZnO incorporated IPMCs
were proved by X-ray diffraction, scanning electron microscopy, and the energy dispersive X-ray spectroscopy, respectively.
We observed that ZnO incorporated IPMCs show stable and large displacement under a square current pulse. Also, the
electro-optical responses of the manufactured opto-IPMCs were characterized by the PL spectra. The working range of the
newly developed electro-optical system was measured to be within the 375-475 nm wavelength.
Conventionally, energy harvesting from IPMC is studied in the bender configuration. However, for
energy harvesting from uncontrolled or multi-directional vibration, there is a need to produce 2-D
and/or 3-D energy harvester. This paper discusses the use of IPMC for energy harvesting using
disc-shaped IPMCs. Making disc imparts more flexibility to the sample and enables energy
harvesting from all around the perimeter of the disc without increase in size. Disc-shaped IPMCs
were prepared from Nafion granules using a hot press method. The manufactured discs are
flexible and suitable for bending not only along the diameter but also side ways. The sample was
vibrated along the diameter at 1Hz, 0.25 inch displacement using a TIRA shaker for the testing.
In this paper we are reporting a newely developed IPMC fabrication method, "IPMC Paint", which can be directly
sprayed onto any complex surface. In order to fabricate the IPMC paint, liquid NafionTM was used for the ionic
conducting polymer instead of the typical film/sheet type NafionTM. The viscosity of liquid NafionTM was adjusted by
adding Polyvinylpyrrolidone (PVP) to perform spray painting. Modified Nafion was sprayed onto the conducting
substrate, PolyfoilTM which acts as base electrode layer. After three times spraying, ionic polymer layer has 45 μm
thickness and 10 μm of surface roughness. Sensing tests show that IPMC paint sensor has more sensitivity (± 0.06 of
producing voltage) than that of the typical IPMC (± 0.005 of producing voltage) when dynamic bending with 10 Hz
frequency and 1.3 cm of displacement is applied to.
Ionic Polymer Metal Composite (IPMC) is a nano-scale metal deposited ionic polymer and may be used as soft actuator
and sensor. Numerous researches have been conducted to study IPMC as actuator. Many other applications like energy
harvesting, impact sensing and velocity sensing use IPMC as a sensor, thus making it necessary to understand sensing
nature of IPMC. It has been demonstrated that production of charge under the influence of mechanical deformation in
IPMC, is a combined effect of chemical, mechanical and electrical response which may be affected by nature of existing
cation and, conductivity and morphology of electrodes. This paper presents a comparison between the sensing behavior
of IPMC under the influence of different cations like Li+, Na+ and H+. In addition, experiments were also performed to
study the effect of nano-to-micro scale surface cracks in IPMC. It was also discovered that inducing nano-to-micro scale
surface cracks in IPMC improves the sensing characteristics of IPMC. Experiments were also performed to compare the
effect of electrode surface morphology and conductivity on sensing performance of IPMC. These effects were also
compared for energy harvesting applications of IPMC.
The Ionic Polymer Metal Composite (IPMC) is an Electroactive Polymer (EAP) capable of soft sensing as well as soft
actuation under low driving voltage. Typically, the transduction model includes two resistors and two capacitors, which
primarily accounts for the effective electrodes on the surface of the IPMC (top and bottom). There is a resistor placed
between the two RC circuits to account for material between the electrodes and the resistance due to ion migration
through the polymer matrix. In this paper we report our recent effort on IPMCs in connection with the application in
energy harvesters. The experiments conducted use IPMC samples with various lengths, various widths and various
thicknesses, and compare the charging rates of the different transducer sizes. The experimental results clearly indicate
that IPMCs are attractive applicants for energy harvesting.
For military applications, the availability of safe, disposable, and robust infusion pumps for intravenous fluid and drug
delivery would provide a significant improvement in combat healthcare. To meet these needs, we have developed a
miniature infusion prototype pump for safe and accurate fluid and drug delivery that is programmable, lightweight, and
disposable. In this paper we present techniques regarding inter-digitated IPMCs and a scaleable IPMC that exhibits
significantly improved force performance over the conventional IPMCs. The results of this project will be a low cost
accurate infusion device that can be scaled from a disposable small volume liquid drug delivery patch to disposable large
volume fluid resuscitation infusion pumps for trauma victims in both the government and private sectors of the health
industry.
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