Actuators and Sensors

This paper describes a novel self-sensing ion-conductive polymer metal composite (IPMC) actuator. The actuator gives feedback of its own position and thereby can also be used as a position sensor. Unlike the IPMC sensors reported so far, the working principle of this actuator is based on the observation that the resistance of the IPMC metal surface electrode is correlated to the bending curvature.

Microvalves, as well as pumps and sensors, are some of the most crucial components in microfluidics when the flow has to be controlled. New developments in microvalves for micro-fluidics are looking at reducing the device size, holding higher pressures, improving the time response, and ensuring the bio-compatibility of the components and the technology used for the manufacturing. The most common active microvalves for flow control are based on mechanical actuators (e.g. pneumatic, thermopneumatic, thermomechanical, piezoelectric, electrostatic, electromagnetic, electrochemical, or capillary-force actuators) in order to control/stop the flow, contain the fluid, and isolate regions in the microfl uidic device.

Liquid crystal elastomers (LCE) are currently of great interest due to the conjoining of mesogenic ordering and rubber elasticity, exhibited in their large spontaneous thermally stimulated changes in shape. It has been shown that nanoparticles (nanotubes, photo-isomerisable dyes, magnetic nanoparticles.) can be incorporated into these LCE networks to create a more sensitive network to external stimuli (i.e. strain or stress, optical, electrical, electro-thermal, magnetic.). Here, we briefly summarise the current state of LCE–nanoparticle systems and explain in detail one system utilising carbon nanoparticles integrated at surfaces that may be used for electro-thermal heating of LCE systems.

We present MorePhone, an actuated flexible smartphone
with a thin-film E Ink display. MorePhone uses shape
memory alloys to actuate the entire surface of the display as
well as individual corners. We conducted a participatory
study to determine how users associate urgency and
notification type with full screen, 1 corner, 2 corner and 3
corner actuations of the smartphone. Results suggest that
with the current prototype, actuated shape notifications are
useful for visual feedback. Urgent notifications such as
alarms and voice calls were best matched with actuation of
the entire display surface, while less urgent notifications,
such as software notifications were best matched to
individual corner bends. While different corner actuations
resulted in significantly different matches between
notification types, medium urgency notification types were
treated as similar, and best matched to a single corner bend.
A follow-up study suggested that users prefer to dedicate
each corner to a specific type of notification. Users would
like to personalize the assignment of corners to notification
type. Animation of shape actuation significantly increased
the perceived urgency of any of the presented shapes.

An Emergency Response (ER) Cyber-Physical System (CPS) to avoid landslides and survey areas located on or near slopes is introduced that handles two problems: electronic waste disposal, and environmental disasters. Uncomplicated detection circuits using salvaged components can pinpoint floods in impoverished regions. CPSs simplify hazard prediction and mitigation in disaster supervision. Nonetheless, few green practices and efforts have been accomplished in this regard. Recent technical advances help landslides studies and the evaluation of suitable risk alleviation measures. This work addresses in situ meters, and cameras to observe ground movements more accurately. The ER-CPS identifies and can help mitigate landslides using techniques based on motion detection that can productively predict and monitor the zone conditions to classify it, and the landslide-related data can be transmitted to inspecting stations to lessen the erosion/sedimentation likelihood while increasing security.

3-D printed magnetic soft magnetic helical coil actuators of iron oxide embedded polydimethylsiloxane. Abstract Soft actuators have grown to be a topic of great scientific interest. As the fabrication of soft actuators with conventional microfabrication methods are tedious, expensive, and time consuming, employment of 3-D printing fabrication methods appears promising as they can simplify fabrication and reduce the production cost. Complex structures can be fabricated with 3-D printing such as helical coils that can achieve actuation performances, which otherwise would be impossible with simpler geometries. In this study, development of soft magnetic helical coil actuators of iron oxide embedded polydimethylsiloxane (PDMS) was achieved with embedded 3-D printing techniques. Composites with three different weight ratios of 10%, 20%, and 30% iron nanoparticles to PDMS were formulated. Using iron nanoparticles with the size of 15-20 nm helps preserve viscosity of the printing material low enough to print it with a small-bore needle (30-gauge, 180 micrometers inner diameter). The hydrogel support of Pluronic f-127 bath and the ability to maintain the ratio of the printed fiber's diameter to coil diameter about 0.25 resulted in the successful fabrication and release of fabricated helical coil structures. This enabled 3-D printed structures characterized as magnetic actuators to achieve linear and bending actuation of more than 300% and 80° respectively in the case of composites 1 Preprint: Rasoul Bayaniahangar, Shahab Bayani Ahangar, Zhongtian Zhang, Bruce P.Lee, Joshua M.Pearce. 3-D printed magnetic soft magnetic helical coil actuators of iron oxide embedded polydimethylsiloxane. with 30% iron oxide nanoparticles. Moreover, it was shown that the 3-D printed helical coils with 10% iron oxide nanoparticles can be utilized as untethered soft robots capable of locomotion on 45 and 90 degrees inclines under an applied magnetic field.

We combine tensile strength analysis and X-ray scattering experiments to establish a detailed understanding of the microstructural coupling between liquid-crystalline elastomer (LCE) networks and embedded magnetic core-shell ellipsoidal nanoparticles (NPs). We study the structural and magnetic re-organization at different deformations and NP loadings, and the associated shape and magnetic memory features. In the quantitative analysis of a stretching process, the effect of the incorporated NPs on the smectic LCE is found to be prominent during the reorientation of the smectic domains and the softening of the nanocomposite. Under deformation, the soft response of the nanocomposite material allows the organization of the nanoparticles to yield a permanent macroscopically anisotropic magnetic material. Independent of the particle loading, the shape-memory properties and the smectic phase of the LCEs are preserved.  Detailed studies on the magnetic properties demonstrate that the collective ensemble of individual particles is responsible for the macroscopic magnetic features of the nanocomposite.

Magnetic shape-memory materials are responsive materials with a strong influence of shape changes on the magnetic properties, and vice versa. They offer access to unique applications, including wireless actuators, switches, and magnetic valves. To achieve the required mechanical-magnetic coupling, both inorganic materials and polymer-based hybrid system have been proposed. In inorganic materials, the magneto-crystalline anisotropy and the martensitic transformation are typically exploited to induce magnetic reorganization at the phase transition, but the associated elongation and device sizes, are limited to changes of about 10% and to the millimeter range, respectively, which severely limits their use in the mentioned applications. Polymer-based materials, on the other and,  are more efficiently sizeable and recover easily strains beyond 50% by magnetic stimuli. However, to achieve magnetic properties of serviceable strength, they require the incorporation of inorganic magnetic particles.

We are developing haptic interfaces compatible with functional magnetic resonance imaging (fMRI) for neuroscience studies. The presented prototype with one rotary degree of freedom is actuated by a traveling wave ultrasonic motor operating under admittance control. Torque is sensed from the deflection of an elastic polymer probe via light intensity measurement over optical fibers. This concept allows us to place all electronic components outside the shielded MR room. Hence, the device can be used in conjunction with fMRI, providing torque and motion feedback simultaneously with imaging. Its compactness and simplicity facilitate the construction of multiple degree of freedom systems.

A study was conducted to introduce an actuation mechanism, called shape memory alloy-piezoelectric active structures (SMAPAS) that combined the advantages of the piezoelectric shape memory alloy (SMA) materials to achieve self-resetting bistable composites. The approach used piezoelectric actuation to provide a rapid snap-through with significant degree of control and a relatively slow, but high-strain SMA actuation to reverse the state change. A thin cantilever beam of carbon-fiber or epoxy material was used to demonstrate the two-way actuation. The composite lay-up procedure was a standard method for the manufacturing of carbon laminates through a standard cure cycle to a maximum cure temperature of 125C and a pressure of 85 psi. A macrofiber composite piezoelectric actuator was used to conduct the investigations and it consisted of aligned piezoelectric fibers with an interdigitated electrode to direct the applied electric field along the fiber length.

Morphing aircraft concepts require powerful, compact and lightweight actuators in order to realize the significant changes in shape and aerodynamics desired. One source of inefficiency and lost performance common to all types of actuators is the mismatch between the force versus stroke profile available from the actuator and that required by the load. This work investigates a novel spiral spooling pulley mechanism that allows for kinematic tailoring of the actuator force profile to better match the force required to drive a given load. To show the impact of kinematic tailoring on actuator efficiency, a representative case study is made of a Pneumatic Artificial Muscle driven morphing camber airfoil employing the Fish Bone Active Camber concept. By using an advanced spiral pulley kinematic mechanism, the actuator force profile is successfully tailored to match that required, with an additional torque margin added to account for any unmodeled effects. Genetic algorithm optimization is used to select the geometric parameters of the spiral pulley that maximize energy efficiency of the actuator while ensuring it is able to produce the required torque levels. The performance of the optimized spiral pulley is compared to a baseline case employing an optimized circular pulley which does not alter the shape of the actuator force profile to show the performance improvement provided by the kinematic tailoring.

The actuation mechanism is a crucial aspect in the design of morphing structures due to the very stringent requirements involving actuation torque, consumed power, and allowable size and weight. In the framework of the CRIAQ MD0-505 project, novel design strategies are investigated to enable morphing of aeronautical structures. This paper deals with the design of a morphing aileron with the main focus on the actuation technology. The morphing aileron consists of segmented 'finger-like' ribs capable of changing the aerofoil camber in order to match target aerodynamic shapes. In this work, lightweight and compact actuation kinematics driven by electromechanical actuators are investigated to actuate the morphing device. An unshafted distributed servo-electromechanical actuation arrangement is employed to realise the transition from the baseline configuration to a set of target aerodynamic shapes by also withstanding the aerodynamics loads. Numerical investigations are detailed to identify the optimal actuation architecture matching as well as the system integratability and structural compactness. © Royal Aeronautical Society 2016.

Nature teaches that the flight of the birds succeeds perfectly since they are able to change the shape of their wings in a continuous manner. The careful observation of this phenomenon has re-introduced in the recent research topics the study of "metamorphic" wing structures; these innovative architectures allow for the controlled wing shape adaptation to different flight conditions with the ultimate goal of getting desirable improvements such as the increase of aerodynamic efficiency or load control effectiveness. In this framework, the European research project SARISTU aimed at combining morphing and smart ideas to the leading edge, the trailing edge and the winglet of a large commercial airplane (EASA CS25 category) while assessing integrated technologies validation through high-speed wind tunnel test on a true scale outer wing segment. The design process of the adaptive trailing edge (ATED) addressed by SARISTU is here outlined, from the conceptual definition of the camber-morphing architecture up to the assessment of the device executive layout. Rational design criteria were implemented in order to preliminarily define ATED structural layout and the general configuration of the embedded mechanisms enabling morphing under the action of aerodynamic loads. Advanced FE analyses were then carried out and the robustness of adopted structural arrangements was proven in compliance with applicable airworthiness requirements. © 2016 SPIE.

Within the framework of the JTI-Clean Sky (CS) project, and during the first phase of the Low Noise Configuration Domain of the Green Regional Aircraft - Integrated Technological Demonstration (GRA-ITD, the preliminary design and technological demonstration of a novel wing flap architecture were addressed. Research activities were carried out to substantiate the feasibility of morphing concepts enabling flap camber variation in compliance with the demanding safety requirements applicable to the next generation green regional aircraft, 130- seats with open rotor configuration. The driving motivation for the investigation on such a technology was found in the opportunity to replace a conventional double slotted flap with a single slotted camber-morphing flap assuring similar high lift performances -in terms of maximum attainable lift coefficient and stall angle- while lowering emitted noise and system complexity. Studies and tests were limited to a portion of the flap element obtained by slicing the actual flap geometry with two cutting planes distant 0.8 meters along the wing span. Further activities were then addressed in order to increase the TRL of the validated architecture within the second phase of the CS-GRA. Relying upon the already assessed concept, an innovative and more advanced flap device was designed in order to enable two different morphing modes on the basis of the A/C flight condition / flap setting: Mode1, Overall camber morphing to enhance high-lift performances during take-off and landing (flap deployed); Mode2, Tab-like morphing mode. Upwards and downwards deflection of the flap tip during cruise (flap stowed) for load control at high speed. A true-scale segment of the outer wing flap (4 meters span with a mean chord of 0.9 meters) was selected as investigation domain for the new architecture in order to duly face the challenges posed by real wing installation. Advanced and innovative solutions for the adaptive structure, actuation and control systems were duly analyzed and experimentally validated thus proving the overall device compliance with industrial standards and applicable airworthiness requirements. © 2017 SPIE.

Aircraft wings are usually optimized for a specific design point. However, since they operate in a wide variety of flight regimes, some of these have conflicting impacts on aircraft design, as an aerodynamically efficient configuration in one instance may perform poorly in others.Conventional wing structures preclude any significant adaptation to changing conditions; movable surfaces, such as flaps or slats, lead to limited changes of the overall shape with narrow benefits compared with those that could be obtained from a wing structure that is inherently deformable and adaptable.An adaptive trailing edge concept conceived to enhance wing aerodynamic performance in cruise condition is outlined. The camber of the trailing edge is controlled during flight to compensate the weight reduction following the fuel burning. In this way, the trimmed configuration remains optimal in terms of efficiency (lift to drag ratio) or minimal drag with positive fallouts on aircraft fuel consumption per flight.The main steps concerning the design of the device are reported, with a special focus on each of its relevant architectural elements. In detail, the skin, the structural skeleton, the actuator, sensor, and control systems are dealt with. Some attention is devoted to aspects that are necessary to come to a finalized product of industrial relevance: namely, the aeroelastic and the safety analyses. The former assumes a main relevance because the system has augmented degrees of freedom with respect to a standard layout and then, a more complex dynamic response and a higher risk of instability. The latter is necessary to envisage a future certification process of this kind of device that requires the development of a dedicated path. © 2018 Elsevier Ltd. All rights reserved.

Liquid lens offers a simple solution to achieve tunable optical powers. This approach, however, suffers from deteriorated resolution at high diopters. In this study, a plano-convex liquid lens with aspherical cross-section is developed. Such configuration allows for the lens profiles at high diopters to be close to spherical shapes by alleviating the edge-clamping effects. Resolution tests of a 6mm lens with optimized asphericity exhibit improved resolutions in both center and peripheral regions at 40 and 100 diopters than the lenses with planar membranes. It shows that aspherical membranes can improve the resolving power of liquid lenses at high diopters, thus providing a new route of optimizing the imaging performance of adaptive liquid lenses for various applications.

Pneumatic artificial muscles are a class of pneumatically driven actuators that are remarkable for their simplicity, lightweight, and excellent performance. These actuators are essentially a tubular bladder surrounded by a braided sleeve and sealed at both ends. Pressurization of the actuators generates contraction and tensile forces. Pneumatic artificial muscles have traditionally been used for robotics applications, but there has been recent interest in adapting them to a variety of aerospace actuation applications where their large stroke and force, which are realized at minimal weight penalty, create potential performance improvements over traditional technologies. However, an impediment to wide-spread acceptance of pneumatic artificial muscles is the relatively short fatigue lives of the actuators reported in the literature (typically, less than 18,000 actuation cycles before damage occurs). The purpose of this study is to develop a new construction method designed to greatly increase the number of fatigue cycles before damage occurs. The fabrication methodology employs a swaging process to provide smooth and distributed clamping of the bladder and braided sleeve components onto the end fittings. This approach minimizes stress concentrations and provides high mechanical strength, which can be experimentally validated via testing for the ultimate tensile failure load. Finite element analysis was used to refine the design of the swaged end fittings before extensive fatigue testing began. Long-term fatigue testing of the actuators under realistic operating conditions showed a substantial increase in actuator life, from a maximum of less than 18,000 cycles in previous research studies to more than 120,000,000 cycles in this study.

An active trailing-edge flap system for helicopter rotor blades using pneumatic artificial muscles was investigated, with the goal of generating flap deflections suitable for both vibration mitigation and primary flight control. Prior work with these actuators showed that large deflections were possible under full-scale conditions. This study developed and demonstrated an inner loop feedback controller that enables the flap to track the complex waveforms required to achieve its goal. Control algorithm development began with proportional feedback, but required the addition of a dead time compensator to reduce tracking error and increase bandwidth. The dead time compensator initially had a fixed value, though this transitioned to a variable to cope with potential changes in the dead time due to changing operating conditions. In this case, the system can continuously adjust the dead time estimate from the position error and predict future tracking error using that estimate, and adjust the control action accordingly. This approach requires no system model and no a priori information about the desired command signal. As such, it is well suited to the active rotor problem. Testing of this controller on single sine waves and complex waveforms composed of a sum of the first four odd harmonics of the rotor frequency showed good tracking for all conditions.

In morphing structures, actuation is a key system for general aircraft-level functions. Similarly to the demonstration of safety compliance applied to aircraft control surfaces, novel functions resulting from the integration of a morphing device (ATED), imposes a detailed examination of the associated risks. Because of the concept novelty, literature references for a safe design of a morphing trailing edge device are hard to be found. The safety-driven design of ATED requires a thorough examination of the potential hazards resulting from operational faults involving either the actuation chain, such as jamming, or the external interfaces, such as loss of power supplies and control lanes. In this work, a study of ATED functions is qualitatively performed at both subsystem and aircraft levels to identify potential design faults, maintenance and crew faults, as well as external environment risks. The severity of the hazard effects is determined and placed in specific classes, indicative of the maximum tolerable probability of occurrence for a specific event, resulting in safety design objectives. A fault tree is finally produced to evaluate the impact of actuation kinematics on specific aspects of ATED morphing operation and reliability. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA, All rights reserved.

Remotely controlled actuation with wireless sensorial feed-back is desirable for smart materials to obtain fully computer-controlled actuators. A light-con-trollable polymeric material is presented, in which exposure to light couples with a change in magnetic properties, allowing light signal conversion into non-volatile magnetic memory. The same material can serve, additionally, both as actuator and transducer, and allows the monitoring of its two-way elastic shape-changes by magnetic read-out. In order to tune the macroscopic magnetic properties of the material, both the reorientation of i) shape aniso-tropic ferrimagnetic nano-spindles and ii) a mechanically and magnetically coupled liquid-crystalline elastomer (LCE) matrix are controlled. These mate-rials are envisioned to have great potential for the development of innovative functional objects, for example, computer-controlled smart clothing, sensors, signal encoding, micro-valves, and robotic devices.

The Green Regional Aircraft (GRA), one of the six CleanSky platforms, represents the largest European effort toward the greening of next generation air transportation through the implementation of advanced aircraft technologies. In this framework researches were carried out to develop an innovative wing flap enabling airfoil morphing according to two different modes depending on aircraft flight condition and flap setting: - Camber morphing mode. Morphing of the flap camber to enhance high-lift performances during take-off and landing (flap deployed); - Tab-like morphing mode. Upwards and downwards deflection of the flap tip during cruise (flap stowed) for load control at high speed and consequent optimization of aerodynamic efficiency. A true-scale flap segment of a reference aircraft (EASA CS25 category) was selected as investigation domain for the new architecture in order to duly face the challenges posed by real wing installation issues especially with reference to the tapered geometrical layout and 3D aerodynamic loads distributions. The investigation domain covered the flap region spanning 3.6 m from the wing kink and resulted characterized by a taper ratio equal to 0.75 with a root chord of 1.2 m. High TRL solutions for the adaptive structure, actuation and control system were duly analyzed and integrated while assuring overall device compliance with industrial standards and applicable airworthiness requirements. © 2016 SPIE.

Differential-damper (DD) elements can provide a high bandwidth means for decoupling a high inertia, high friction, non-backdrivable actuator from its output and can enable high fidelity force control. In this paper, a port-based decomposition is used to analyze the energetic behavior of such actuators in various physical domains. The general concepts are then applied to a prototype DD actuator for illustration and discussion. It is shown that, within physical bounds, the output torque from a DD actuator can be controlled independently from the input speed. This concept holds the potential to be scaled up and integrated in a compact and lightweight package powerful enough for incorporation with a portable lower limb orthotic or prosthetic device.

Adaptive structures that allow large deformations under the application of a low and noncontinuous energy input are gaining increasing interest in the aerospace industry. One potential mechanism of realizing shape control is piezoelectric actuation of asymmetric composite laminates. This article presents an optimization study for the design of bistable laminates for a reversible snap-through enabled by two orthogonal piezoelectric layers. The formulation optimizes the load-carrying capability of the structure subject to deflection and actuation limits through a variation in ply orientations and laminate geometry. We find the problem to be multimodal with the multiple optima to be dependent on the loading and snap-through directions and the complex constraint boundary interactions. A reduction in the total actuation voltage is achieved through the simultaneous use of the positive and negative working ranges of the two piezoelectric layers.

Burgeoning transendoscopic procedures, such as endoscopic submucosal dissection (ESD), provide a promising means of treating early-stage gastric neoplasia in a minimally-invasive way. However, the remote locations of these lesions, coupled with their origination in the submucosal layers of the gastrointestinal tract, often lead to extreme technical, cogni-tive and ergonomic challenges which combat the widespread applicability and adoption of these techniques. Among these challenges is achieving the in vivo dexterity required to retract and dissect tissue. By leveraging workspace and force data obtained through clinical studies, we developed a modular, disposable, distally-mounted actuator (an 'active endcap') that can augment an endoscopist's distal dexterity in ways that are not achievable with the endoscope's built-in degrees-of-freedom. The device consists of a flexible articulating 'exoskeleton' manufactured via printed-circuit MEMS (PCMEMS) which engages and deflects electrosurgical tools that are passed through the endoscopic working channel. Embedded proprioceptive sensing is implemented on-board using distributed LED/phototransistor pairs and the principle of light intensity modulation (LIM). The distal degree-of-freedom is actuated using shape memory alloy (SMA) technology, and the actuation transmission system is fully contained within a 1-inch-long end cap that can be mounted on the distal end of the endoscope, thereby obviating the need for a mechanical connection to a proximal source. Proof-of-concept tests demonstrate that the actuator adds over 50 degrees of distal articulation to existing tools and can generate 450 mN of lateral force which has been clinically determined to be sufficient for performing circumferential incisions in ESD.

Ionic polymer-metal composites (IPMCs) are electroactive materials that bend under an applied electric field. Existing work has typically dealt with the control of IPMC actuators themselves. In this paper we investigate the stabilization of an inverted pendulum on a cart using an IPMC actuator. Different from the traditional setting of cart- pendulum systems, we require that the voltage on the IPMC actuator stay close to zero, to prolong the actuator life and reduce power consumption. A state-space model is developed for the system, based on which an LQR controller together with an observer is designed. The proposed control scheme is able to stabilize the inverted pendulum for the entire duration of the experiment (five minutes). These results indicate that IPMC actuators hold potential for more sophisticated control applications.

IPMCs are electroactive materials that bend in electric field. This paper describes a linked manipulator using IPMC joints. We argue that this design reduces the control complexity of an IPMC manipulator and increases the precision of the device. The design rationale stems from our theoretical work in material modeling. It suggests that when electrically decoupled short IPMC strips are connected to rigid links, the control of the IPMC manipulator, which is currently vaguely understood and highly non-linear, can be reduced to simple inverse kinematics serial chain manipulator control without the loss in efficiency. We validate our design by comparing the prototype device to a simple IPMC manipulator commonly investigated in the literature. The results show increased precision, reaction time and reachable workspace. We suggest that such a manipulator is suitable for soft and micromanipulation.

The study herein described is aimed at investigating the feasibility of an innovative full-scale camber morphing aileron device. In the framework of the "Adaptive Aileron" project, an international cooperation between Italy and Canada, this goal was carried out with the integration of different morphing concepts in a wing-Tip prototype. As widely demonstrated in recent European projects such as Clean Sky JTI and SARISTU, wing trailing edge morphing may lead to significant drag reduction (up to 6%) in off-design flight points by adapting chord-wise camber variations in cruise to compensate A/C weight reduction following fuel consumption. Those researches focused on the flap region as the most immediate solution to implement structural adaptations. However, there is also a growing interest in extending morphing functionalities to the aileron region preserving its main functionality in controlling aircraft directional stability. In fact, the external region of the wing seems to be the most effective in producing "lift over drag" improvements by morphing. Thus, the objective of the presented research is to achieve a certain drag reduction in off-design flight points by adapting wing shape and lift distribution following static deflections. In perspective, the developed device could also be used as a load alleviation system to reduce gust effects, augmenting its frequency bandwidth. In this paper, the preliminary design of the adaptive aileron is first presented, assessed on the base of the external aerodynamic loads. The primary structure is made of 5 segmented ribs, distributed along 4 bays, each splitted into three consecutive parts, connected with spanwise stringers. The aileron shape modification is then implemented by means of an actuation system, based on a classical quick-return mechanism, opportunely suited for the presented application. Finite element analyses were assessed for properly sizing the load-bearing structure and actuation systems and for characterizing their dynamic behavior. Obtained results are reported and widely discussed. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

Modern aerospace research programs are increasingly oriented towards adaptive wing structures for greening the air transport in the near future. New structural concepts implementing and integrating innovative technologies are mandatory for succeeding in this critical task. Among these, the so-called morphing structures are taken into account in aerospace applications, since they ensure the structural shape control in order to optimize the aerodynamic efficiency during the different flight phases. Among the most ambitious research projects launched in Europe, the JTI - Green Regional Aircraft (GRA) is placed in foreground for the design and the demonstration of a true-scale morphing flap applicable to the Natural Laminar Flow (NLF) wing of a 130-seats reference aircraft belonging to EASA CS25 category. In this framework, the authors intensively worked on the definition of a specific actuation and control system layout properly enabling two flap operational modes: overall camber morphing in deployed configuration, during take-off and landing, to enhance high lift performances; upwards and downwards deflection of the flap trailing edge (nearly the 10% of the local chord) in stowed configuration, to improve wing aerodynamic efficiency in cruise. For this purpose, a digital logic control law was opportunely implemented into controller devices by using LTI DriveManager® software. Obtained results have been presented in terms of controlled morphed shapes, showing an excellent correlation with respect to the target geometries imposed by design requirements. © 2016 IEEE.

To model a magnet, the surface charge model can be used. This results in fast and accurate analytical solutions when the relative permeability is equal to one. If this is not the case, the model has to be calculated numerically and the computational time increases significantly. In this paper, a polynomial approximation of the surface charge is therefore proposed to obtain a semianalytical model. The results are less accurate than the numerical model. It is, however, about 300 times faster. This 3-D model is used to model, a magnet, a soft-magnetic block in an external field, and a gravity compensator, which is a combination of magnets and a soft-magnetic plate.

This research focuses on the development of an active rotor system capable of primary control and vibration reduction for rotorcraft.  The objective is to investigate the feasibility of a novel Trailing Edge Flap (TEF) actuation system driven by Pneumatic Artificial Muscles (PAMs).  A significant design effort led to a series of experimental apparatuses which tested various aspects of the performance of the actuators themselves and of TEF systems driven by them.  Analytical models were developed in parallel to predict the quasistatic and dynamic behavior of these systems.
Initial testing of a prototype blade section with an integrated PAM driven TEF proved the viability of the concept through successful benchtop testing under simulated M = 0.3 loading and open jet wind tunnel tests under airspeeds up to M = 0.13.  This prototype showed the ability of PAM actuators to generate significant flap deflections over the bandwidth of interest for primary control and vibration reduction on a rotorcraft.  It also identified the importance of high pneumatic system mass flow rate for maintaining performance at higher operating frequencies.
Research into the development and improvement of PAM actuators centered around a new manufacturing technique which was invented to directly address the weaknesses of previous designs.  Detailed finite element model (FEM) analysis of the design allowed for the mitigation of stress concentrations, leading to increased strength.  Tensile testing of the swaged actuators showed a factor of safety over 5, and burst pressure testing showed a factor of safety of 3.  Over 120,000,000 load cycles were applied to the actuators without failure.  Characterization testing before, during, and after the fatigue tests showed no reduction in PAM performance.
Wind tunnel testing of a full scale Bell 407 blade retrofitted with a PAM TEF system showed excellent control authority.  At the maximum wind tunnel test speed of M  = 0.3 and a derated PAM operating pressure of 28 psi, 18.8° half-peak-to-peak flap deflections were achieved at 1/rev (7 Hz), and 17.1° of half-peak-to-peak flap deflection was still available at 5/rev (35 Hz).  A quasistatic system model was developed which combined PAM forces, kinematics and flap aerodynamics to predict flap deflection amplitudes.  This model agreed well with experimental data.
Whirl testing of a sub-span whirl rig under full scale loading conditions showed the ability of PAM TEF systems to operate under full scale levels of centrifugal (CF), aerodynamic, and inertia loading.  A commercial pneumatic rotary union was used to provide air in the rotating frame.  Extrapolation of the results to 100% of CF acceleration predicts 15.4° of half-peak-to-peak flap deflection at 1/rev (7 Hz), and 7.7° of half-peak-to-peak flap deflection at 5/rev (35 Hz).
A dynamic model was developed which successfully predicted the time domain behavior of the PAM actuators and PAM TEF system.  This model includes control valve dynamics, frictional tubing losses, pressure dynamics, PAM forces, mechanism kinematics, aerodynamic hinge moments, system stiffness, damping, and inertia to solve for the rotational dynamics of the flap.
Control system development led to a closed loop control system for PAM TEF systems capable of tracking complex, multi-sinusoid flap deflections representative of a combined primary control and vibration reduction flap actuation scheme.
This research shows the promise that PAM actuators have as drivers for trailing edge flaps on active helicopter rotors.  The robustness, ease of integration, control authority and tracking accuracy of these actuators have been established, thereby motivating further research.

This paper proposes a new design of shape memory alloy (SMA) wire actuated gripper for open mode operation. SMA can generate smooth muscle movements during actuation which make them potentially good contenders in designing grippers. The principle of the shape memory alloy gripper is to convert the linear displacement of the SMA wire actuator into the angular displacement of the gripping jaw. Steady state analysis is performed to design the wire diameter of the bias spring for a known SMA wire. The gripper is designed to open about an angle of 22.5° when actuated using pulsating electric current from a constant current source. The safe operating power range of the gripper is determined and verified theoretically. Experimental evaluation for the uncontrolled gripper showed a rotation of 19.97°. Forced cooling techniques were employed to speed up the cooling process. The gripper is simple and robust in design (single movable jaw), easy to fabricate, low cost, and exhibits wide handling capabilities like longer object handling time and handling wide sizes of objects with minimum utilization of power since power is required only to grasp and release operations.

A new temperature-controlled smart soft material micropillar array has been fabricated via in situ integration of the liquid-crystalline elastomer-based component into the hybrid microdevice. Such design allows for developing pushing elements with fast lifetime values of ca. 5 s, and opens huge opportunities for the use of hybrid smart microdevices with total control on the actuation time/response, repeatability, stability and energy saving.

Shape control of adaptive wings has the potential to improve wing aerodynamic performance in off-design conditions. A possible way to attain this objective is to implement specific technologies for trailing edge morphing, aimed at changing the airfoil camber. In the framework of SARISTU project (EU-FP7), an innovative structural system incorporating a gapless deformable trailing edge was developed. A related key technology is the capability to emulate and maintain pre-selected target wing shapes within an established margin, enabling optimal aerodynamic performance under current operational pressure loads. In this paper, the actuation and control logics aimed at preserving prescribed geometries of an adaptive trailing edge under variable conditions are numerically and experimentally detailed. The actuation concept relies on a quick-return mechanism, driven by load-bearing actuators acting on morphing ribs, directly and individually. The adopted unshafted distributed electromechanical system arrangement uses servo-rotary actuators, each rated for the torque of a single adaptive rib of the morphing structure. The adopted layout ensures compactness and weight limitations , essential to produce a clean aerodynamic system. A Fiber Bragg Grating (FBG)-based distributed sensor system generates the information for appropriate open-and closed-loop control actions and, at the same time, monitors possible failures in the actuation mechanism.

This paper develops a model based on an original lumped-parameter network configuration for the thermal transient analysis of a permanent magnet synchronous motor (PMSM). The specific PMSM was designed and optimized for a demanding aerospace application. The validity of the proposed lumped-parameter model is verified by measurements carried out in a thermal chamber.

electrothermally actuated microgripper has been designed and simulated using COMSOL 4.3b based on finite element method (FEM). Electrothermal mechanism is the most widely used mechanism for providing large displacements at very small voltages. The new model is designed by combining asymmetric arm structure and a thin gold layer is inserted in the asymmetric arms which make it a typical bimorph structure. The microgripper presented here is electro-thermally actuated and optimized geometrically and materially to explore the effect of dimensional variation and material change on its performance. The in-plane, out of plane displacements, strain, stress, current density and temperature has been analyzed and the results are discussed.

Conducting polymers are soft, wet and reactive gels capable of mimicking biological functions. They are the
electrochemomechanical actuators having the ability to sense the surrounding variables simultaneously. The
sensing and actuating signals are sent/received back through the same two connecting wires in these materials. The
sensing ability is a general property of all conducting polymers arises from the unique electrochemical reaction
taking place in them. This sensing ability is verified for two different conducting polymers here – for an
electrochemically generated polypyrrole triple layer bending actuator exchanging cations and for a chemically
generated polytoluidine linear actuator exchanging anions. The configuration of the polypyrrole actuator device
corresponds to polypyrrole-dodecyl benzene sulfonate (pPy-DBS) film/tape/ pPy-DBS film in which the film on
one side of the triple layer is acted as anode and the film on the other side acted as cathode simultaneously, and the
films interchanged their role when move in the opposite direction. The polytoluidine linear actuator was
fabricated using a hydrgel microfiber through in situ chemical polymerization. The sensing characteristics of these
two actuators were studied as a function of their working conditions: applied current, electrolyte concentration and
temperature in aqueous electrolytes. The chronopotentiometric responses were studied by applying square electrical
currents for a specified time. For the pPy actuator it was set to produce angular movement of ± 45º by the free end
of the actuator, consuming constant charges of 60 mC. In both the actuators the evolution of the muscle potential
along the electrical current cycle was found to be a function of chemical and physical variables acting on the
polymer reaction rates: electrolyte concentration, temperature or driving electrical current. The muscle potential
evolved decreases with increasing electrolyte concentrations, increasing temperatures or decreasing driving
electrical currents. The electrical energy consumed during reaction was a linear function of the working
temperature or of the driving electrical current and a double logarithmic function of the electrolyte concentration.
Thus, the conducting polymer based actuators exchanging cations or anions during electrical current flow is a
sensor of the working physical and chemical conditions which is a general property of all conducting polymers.

A linear, empirical, low-order-model was developed with the aim of describing the
evolution of a 2D vortex-pair ejected into a boundary layer from a slot-in-the-wall.
The model describes the evolution of a counter-rotating pair of Lamb-Oseen vortices in
the proximity of a wall on which a cross-flow Blasius boundary layer exits. Two inputs
from experimental measurements are used. First, the initial locations where the vortices
form and pinch-off from the excitation slot boundary layers. Second, the time evolution
of the vortex circulation in still-air. With this input, the model predicts the trajectories
and vorticity distribution during the interaction. Such a model could be a viable tool
for the development of a low-order-model to be implemented as a simplified boundary
condition in CFD simulations, with the aim of reducing the requirement to fully resolve
the vicinity of the excitation slot in active flow control simulations.

Functional liquid-crystalline elastomers (FULCE) are a new class of smart materials that show a reversible change of shape when heated or irradiated with UV light. These materials have a high potential for use as actuators with large deformation and small forces in micromechanical systems. Within an EU project, we investigate the possibility
of integration of the materials in MEMS. We did show compatibility with standard MEMS technologies, and tested a method for hybrid assembly of FULCEs on silicon and glass substrates without the use of adhesives. All these processes were found suitable for application.

This paper deals with the geometrically non-linear analysis of thin plate/shell laminated structures with embedded integrated piezoelectric actuators or sensors layers and/or patches. The model is based on the Kirchhoff classical laminated theory and can be applied to plate and shell adaptive structures with arbitrary shape, general mechanical and electrical loadings. The finite element model is a nonconforming single layer triangular plate/shell element with 18 degrees of freedom for the generalized displacements and one electrical potential degree of freedom for each piezoelectric layer or patch. An updated Lagrangian formulation associated to Newton-Raphson technique is used to solve incrementally and iteratively the equilibrium equations.The model is applied in the solution of four illustrative cases, and the results are compared and discussed with alternative solutions when available.

Communication is the act of transferring information between entities. Existing architectural communication approaches provide solutions for data transfer from the sender to the receiver. While those solutions are targeting different domains, we can find a lot of similarities in their architectures. In this paper, we follow the interpersonal communication process principles with its communication components for defining a whole communication chain that combines the sensor actuator and data transfer items in one concept, pointing to the person to person and device to device communication similarities. We come with an approach of a methodology for the Internet of Things abstracted by the Spread-out Electronic Device concept. We consider the whole IoT as a single electronic device with cutout and broken wires and replaced with communication chains.

Chatter is a self-excited vibration phenomenon, which is caused due to mutual interaction between the dynamics of slender cutting tool and the cutting process dynamics. It is the most important type of dynamic instability in metal cutting operations. For long overhang boring bars with high Length to Diameter (L:D) ratios, the dynamic stiffness of cutting tool substantially reduces as well as the critical limiting depth of cut, and the cutting process becomes unstable for almost any cutting conditions. Hence, active damping methods must be utilized in order to improve the stability of slender boring bars. The active vibration control methods can drastically increase the damping ratio and stiffness of the cutting tool, compared to passive vibration control methods. This PhD dissertation deals with the problem of chatter vibration control in deep internal turning operations. A long overhang boring bar is designed and manufactured in CAD/CAM laboratory of Ferdowsi University of Mashhad. The characteristics of chatter vibrations in deep internal turning process are experimentally observed in terms of acceleration signals and machined surface texture for L:D ratios of 4-7. The stable cutting is absolutely impossible beyond L:D ratio of 6 with the steel boring bar, owing to the fact that the slender cutting tool becomes susceptible to chatter vibrations. An electrodynamic shaker is both utilized for identification of forward path dynamics (as external exciter) as well as active damping of chatter vibrations (as controllable actuator). It is installed on an especially designed moveable bed, which is connected to the carriage of lathe machine tool. The dynamic models for the actuator and boring bar are identified using the fundamental concepts of system identification theory. It is observed that the actuator dynamics is linear in terms of excitation amplitude, while the boring bar shows non-linear behavior. Hence, a parameter-varying transfer function is proposed for describing the dynamics of forward path, i.e. actuator-boring bar assembly. The obtained dynamic model is then used for the purpose of model-based controller design. The non-collocated SISO control system includes an accelerometer sensor which measures the boring bar vibrations in the radial direction adjacent to tool tip, and the electrodynamic shaker which exerts an active control force to the boring bar body in the radial direction away from the tool tip. Three different control algorithms are designed, analyzed and implemented on the closed-loop control system in order to suppress chatter vibrations in deep internal turning operations. The slender boring bar with L:D ratio of 8 and the radial acceleration at tool tip, as the feedback signal, is used for all controllers. The control algorithms include an optimal PID controller as well as an adaptive PID controller. Both controllers have neglected the effect of proportional and derivative gains due to stability issues, and are thus Direct Velocity Feedback (DVF) controllers. The optimal PID controller is designed according to the theoretical transfer function of the closed-loop control system. The optimal controller gain is defined according to the disturbance rejection criterion. In addition, by considering the dynamic characteristics of actuator and boring bar, the adaptive PID controller dynamically adjusts the controller gain in accordance with the intensity of chatter vibrations. Moreover, a feedback version of adaptive inverse control methods, which is known as Filtered-x Normalized LMS algorithm with Internal Model Control, i.e. FxNLMS-IMC algorithm, is utilized as the third benchmark controller for chatter suppression in deep internal turning operations. This algorithm is originally developed for the active attenuation of acoustic noise. Both impact tests and cutting experiments are performed in order to experimentally verify the efficiency of the proposed active damping control methods. The experimental cutting tests are performed on Aluminum alloy 6063. According to obtained results, the magnitude of chatter vibrations is effectively suppressed around the dominant bending mode of boring bar. All controllers show similar performance with a significant vibration attenuation level of at least 60 dBs up to 70 dBs. As a direct consequence of chatter attenuation, the machined surface roughness is highly improved in various cutting conditions. Finally, the performance of FxNLMS-IMC controller for suppression of regenerative chatter vibrations, reduction of actuator cost and enhancement of surface roughness is proved to be relatively better than the PID controllers.

The design and application of adaptive devices are currently ambitious targets in the field of aviation research addressed at new generation aircraft. The development of intelligent structures involves aspects of multidisciplinary nature: the combination of compact architectures, embedded electrical systems and smart materials, allows for developing a highly innovative device. The paper aims to present the control system design of an innovative morphing flap tailored for the next generation regional aircraft, within Clean Sky 2 - Airgreen 2 European Research Scenario. A distributed system of electromechanical actuators (EMAs) has been sized to enable up to three operating modes of a structure arranged in four blocks along the chord-wise direction: •overall camber-morphing; •upwards/downwards deflection and twisting of the final tip segment. A state-of-art feedback logic based on a decentralized control strategy for shape control is outlined, including the results of dynamic stability analysis based on the blocks rational schematization within Matlab/Simulink® environment. Such study has been performed implementing a state-space model, considering also design parameters as the torsional stiffness and damping of the actuation chain. The design process is flowing towards an increasingly "robotized" system, which can be externally controlled to perform certain operations. Future developments will be the control laws implementation as well as the functionality test on a real flap prototype. © 2018 SPIE.

The ambitions of current neuroscience, understanding neurological disease progression and mapping the connectome, demonstrate a need for safe in vivo tools for creating intricate maps of brain circuitry. Present in vivo contrast agents are often limited by their specificity, uptake, resolvability, and/or clearance. We describe an aptamer-functionalized sensor for high-resolution imaging that can switch imaging targets by an induced multi-stage aptamer reaction. Included are synthetic methods as well as calculations of sensor efficacy based on known kinetics. Calculations show that 10 distinct targets may be imaged in a living brain at the submicron scale within 42 hours.

"Electromagnetic vibratory drives offer easy and simple
control of the mass flow of particulate and bulk materials. In
comparison to mechanical drives (pneumatics, hydraulics, or
inertial), these have a more simple construction and they are
compact, robust, and reliable in operation. The absence of
wearing mechanical parts, such as gears, cams belts, bearings,
eccentrics, or rotational actuators, makes the vibratory drives
(conveyors, bins, hoppers, feeders etc.) as most economical
equipment. Vibrations of bins or hoppers, in which the
particulate material is placed, produced by electromagnetic
linear exciter induce the movement of material particles, so that
they resemble a highly viscous liquid, and the material becomes
easier to transport and to dose. A mathematical model of
electromagnetic vibratory exciter is presented in this paper.
Based on this mathematical model is generate the simulation
circuit for analysis of vibratory exciter behavior in the stationary
and transient regimes. Simulation and experimental results and
their comparisons are exposed in this paper. Experimental
results are recorded on practically realized vibratory drive for
efficient discharge of collecting hoppers in electrostatic
precipitator plants."

A strategy for adaptive control and energetic optimization of aerobic fermentors was implemented, with both air flow and agitation speed as manipulated variables. This strategy is separable in its components: control, optimization, estimation. We optimized parameter’s estimation (from the usual KLa correlation) using sinusoidal excitation of air flow and agitation speed. We have implemented parameter’s estimation trough recursive least squares algorithm with forgetting factor. We carried separate essays on control, optimization and estimation algorithms. We carried our essays using an original computational simulation environment, with noise and delay generating facilities for data sampling and filtering.

Our results show the convergence and robustness of the estimation algorithm used, improved with use of both forgetting factor and KLa dead-band facilities. Control algorithm used in our work compares favorably with PID using the integrated area criteria for deviation between oxygen molarity and critical molarity (set point). Optimization algorithm clearly reduces energetic consumption, respecting critical molarity. Integration of control, optimization and adaptive algorithms was implemented, but future work is needed for stability. Methods were defined and implemented for stability improvement. We have implemented data acquisition and computer manipulation of air flow and agitation speed for actual fermentors.