Polypyrrole Polyethylene Composite for Controllable Linear Actuators in Different Organic Electrolytes

Controllable linear actuation of polypyrrole (PPy) is the envisaged goal where only one ion dominates direction (here anions) in reversible redox cycles. PPy with polyethylene oxide (PEO) doped with dodecylbenzenesulfonate forms PPy-PEO/DBS films (PPy-PEO), which are applied in propylene carbonate (PC) solvent with electrolytes such as 1-ethyl-2,3-dimethylimidazolium trifluoromethanesulfonate (EDMICF3SO3), sodium perchlorate (NaClO4) and tetrabutylammonium hexafluorophosphate (TBAPF6) and compared in their linear actuation properties with pristine PPy/DBS samples. PPy-PEO showed for all applied electrolytes that only expansion at oxidation appeared in cyclic voltammetric studies, while pristine PPy/DBS had mixed-ion actuation in all electrolytes. The electrolyte TBAPF6-PC revealed for PPy-PEO best results with 18% strain (PPy/DBS had 8.5% strain), 2 times better strain rates, 1.8 times higher electronic conductivity, 1.4 times higher charge densities and 1.5 times higher diffusion coefficients in comparison to PPy/DBS. Long-term measurements up to 1000 cycles at 0.1 Hz revealed strain over 4% for PPy-PEO linear actuators, showing that combination of PPy/DBS with PEO gives excellent material for artificial muscle-like applications envisaged for smart textiles and soft robotics. FTIR and Raman spectroscopy confirmed PEO content in PPy. Electrochemical impedance spectroscopy (EIS) of PPy samples revealed 1.3 times higher ion conductivity of PPy-PEO films in PC solvent. Scanning electron microscopy (SEM) was used to investigate morphologies of PPy samples, and EDX spectroscopy was conducted to determine ion contents of oxidized/reduced films.

Polypyrrole with Phosphor Tungsten Acid and Carbide-Derived Carbon: Change of Solvent in Electropolymerization and Linear Actuation

Linear actuators based on polypyrrole (PPy) are envisaged to have only one ion that triggers the actuation direction, either at oxidation (anion-driven) or at reduction (cation-driven). PPy doped with dodecylbenzenesulfonate (PPy/DBS) is the most common applied conducting polymer having cation-driven actuation in aqueous solvent and mainly anion-driven actuation in an organic electrolyte. It is somehow desired to have an actuator that is independent of the applied solvent in the same actuation direction. In this research we made PPy/DBS with the addition of phosphorus tungsten acid, forming PPyPT films, as well with included carbide derived carbon (CDC) resulting in PPyCDC films. The solvent in electropolymerization was changed from an aqueous ethylene glycol mixture to pure EG forming PPyPT-EG and PPyCDC-EG composites. Our goal in this study was to investigate the linear actuation properties of PPy composites applying sodium perchlorate in aqueous (NaClO4-aq) and propylene carbonate (NaClO4-PC) electrolytes. Cyclic voltammetry and square potential steps in combination with electro-chemo-mechanical-deformation (ECMD) measurements of PPy composite films were performed. The PPyPT and PPyCDC had mixed ion-actuation in NaClO4-PC while in NaClO4-aq expansion at reduction (cation-driven) was observed. Those novel PPy composites electropolymerized in EG solvent showed independently which solvent applied mainly expansion at reduction (cation-driven actuator). Chronopotentiometric measurements were performed on all composites, revealing excellent specific capacitance up to 190 F g−1 for PPyCDC-EG (best capacitance retention of 90% after 1000 cycles) and 130 F g−1 for PPyPT-EG in aqueous electrolyte. The films were characterized by scanning electron microscopy (SEM), Raman, Fourier-transform infrared (FTIR) and energy dispersive X-ray spectroscopy (EDX).

Kinematic Analysis of a Parallel Manipulator Driven by Perpendicular Linear Actuators

In this paper, a goniometer-type specimen stage with a linear actuation mechanism mounted on a rotation mechanism is introduced. The linear actuation mechanism was modeled as a spatial parallel manipulator consisting of a moving body, three linear actuators, and an anti-rotation mechanism. The three linear actuators were arranged perpendicular to each other. In the specimen stage, the linear actuators were in ball contact with the surface of a holder designed to hold a specimen. For the parallel manipulator, the ball contact was replaced with two prismatic joints and a spherical joint. The mobility of the manipulator without the anti-rotation mechanism was one degree of freedom greater than the number of actuators. Therefore, the redundant one degree-of-freedom motion was restrained using an anti-rotation mechanism with three rotation joints and two prismatic joints. The inverse and direct kinematics of the goniometer mechanism were derived and verified. In addition, the inverse Jacobian was derived, and local and global performance indices were analyzed by the terms of manipulability and isotropy. Finally, the goniometer-type specimen stage was designed by the global performance indices.

Development and Implementation of a Low-cost Automatic Dual-axis Solar Tracker through Hardware/Software Embedded Program Control

A solar tracker is a system that is used for the mechanical orientation of solar payloads (collectors and photovoltaic panels) towards the sun. A simple, low-cost, but effective open-loop dual axis solar tracking system was developed in this work. The tracker is an embedded system that consists of a microcontroller integrated with other components in an electronic circuit to coordinate the activities of the circuit in driving out and in the motor shafts of electrically powered linear actuators used to move the payload. The work is divided into two parts: hardware and software. The hardware part consists of two movable (tilting and axial moving) rectangular frames fixed together and used to hold the payload and two electrically powered linear actuators (jacks) used to move the rectangular frames in the tilting and axial directions. The software part was a code written in the C programming language following an algorithm developed from measured parameters of the jacks and the sun’s position and embedded into a microcontroller. The testing of the dual-axis solar tracker was done by measuring a parabolic trough collector’s position with respect to the sun hour angles and solar declination angles and comparing the values with the calculated angles for two days. The results obtained showed that the tracker followed the sun with deviation of ±2o (percentage errors that ranged between 0.01% and 3.26%).

Design and Fabrication of Low Cost Modified Maneuverable Standing Stretcher Wheelchair Transport System

Wheel Chairs are one of the convenient man made structure which are highly useful for person with disability. The major problem of this wheelchair is the architectural obstacles such as stairs etc. Many researchers around the globe have worked on wheel chair design so as to make the user independent. The question of overcoming these obstacles by a wheelchair always is the most discussed topics in recent days. This paper involves in fabricating a wheel chair which is motor operated. It is stair climbing wheelchair design which concept which overcomes the structural obstacles. The fabrication of an ergonomically designed battery operated wheel chair for multi usage is done. Concept of stairs climbing function is embedded in the design by adopting new design and mechanism. The design considerations of the wheelchair are based on the standard design of the stairs which are constructed in India. The work deals with design and fabrication of wheelchair convertible to bed. It is also equipped with a standing aid which helps the disabled individual to stand up and perform certain work. The design involves the use of electrical linear actuators which consists of an assembly of motor driven power screw to make the transformation from sitting to a bed by using a hand held remote, overcoming the need of a another person to shift the patient from wheelchair to bed. This project offers multiple features over a standard wheelchair and is very economical in comparison to commercially available wheelchairs.

TEMPERATURE CONTROL SYSTEM FOR MINT DEHYDRATION IN DOUBLE-CHAMBER MARQUEE USING LINEAR ACTUATORS

The objective of this research was to determine the thermal performance of a solar dehydration system that allows controlling the temperature for the dehydration of aromatic herbs such as mint. The use of a double chamber marquee allowed obtaining high thermal values, even with low radiation levels. For temperature control, a system of vertical mobile beds was used in order to reach the programmed temperature. This temperature was monitored using an embedded Arduino-type system that allows both monitoring and controlling motors, as well as recording temperature information. It was possible to keep the temperature approximately constant at 40°C, the ideal value for drying aromatic and medicinal herbs.

Blower-Powered Soft Inflatable Joints for Physical Human-Robot Interaction

Inflatables are safe and lightweight structures even at the human scale. Inflatable robots are expected to be applied to physical human-robot interaction (pHRI). Although active joint mechanisms are essential for developing inflatable robots, the existing mechanisms are complex in structure and it is difficult to integrate actuators, which diminish the advantages of inflatables. This study proposes blower-powered soft inflatable joints that are easy to fabricate and contain enough space for an actuation inside. The joints are driven by tendon wires pulled by linear actuators. We derived a theoretical model for both unilateral and bilateral joints and demonstrated a hugging robot with multiple joints as an application of the proposed joint mechanism. The novelty of the proposed joint mechanism and the inflatable robot is that rigid parts have been thoroughly eliminated and the tendons for actuation have been successfully hidden inside. Moreover, the active control of the internal pressure makes inflatables resistant to punctures. We expect that the contact safety of inflatable robots will facilitate advancement of the pHRI field.

A Pareto Front Mechanism Optimization for Controlling an Aircraft Using a Bio-Inspired Rotating Empennage

This paper presents a mechanism design optimization for actuating the horizontal stabilizers of an aircraft using a rotating empennage without a vertical stabilizer. Birds do not have vertical stabilizers and rotate their tail feathers to control agile maneuvers. A rotating empennage concept will mimic this motion and enable the bio-inspired flight of a fixed wing aircraft. To maintain control, the bio-inspired rotating empennage (BIRE) will incorporate three degrees of freedom: independent rotation of each horizontal stabilizer and rotation of the empennage relative to the main axis of the fuselage. The primary benefits of an aircraft without a vertical stabilizer is reduced drag and weight, which in turn results in more efficient operation. In order to reduce inertia of the rotating empennage, the linear actuators that position the horizontal stabilizers will be placed within the fuselage. Mechanisms that couple the linear translation of the actuators with the rotation of the horizontal stabilizers ideally require a low peak force and short stroke from the actuator. With two conflicting objectives, a Pareto front optimization was conducted to determine appropriate link lengths of candidate solutions and to understand the effectiveness of alternate mechanisms. The study considers a rack & pinon, scotch-yoke, slider-crank, inverted slider-crank, Watt, and Stephenson mechanisms.