Search

Robotic landing gear (RLG) for rotorcraft improves performance in landing on sloped uneven terrain, unprepared areas, and ship decks. The interaction between the feet of the RLG and the landing surface are pivotal to a successful landing event. Slipping or bouncing of the feet can lead to a failed landing and a catastrophic accident. Proposed herein is the use of locking mechanisms on the RLG feet in order to eliminate landing gear slip and bounce during the landing event. Through the use of a comprehensive multibody dynamic simulation, locking mechanisms on the RLG feet are shown to eliminate landing event failures that can occur with nonlocking landing gear configurations, at the expense of a moderate increase in landing gear loads during a landing event. Results indicate that landing event failures are eliminated even in the situation where some feet-locking mechanisms are inoperable or break away. Furthermore, RLG with feet locking mechanisms permit the reduction or elimination of the need for active control of the RLG legs. The results herein give guidance to the development of integrated RLG with locking mechanisms.

The public road setback distance is often an important factor that drives wind farm design. This paper outlines a methodology for assessing the risk imposed by blade throw at various road setbacks using a physics-based simulation approach. Given a road setback distance, Monte Carlo simulation is performed wherein blade throw parameters and vehicle locations are randomized. Potential collisions are determined using an “impact circle” approach which assumes that impact occurs if the vehicle is inside the impact radius of the blade fragment when it lands. This approach is exercised on several example turbines and risk levels are calculated for various road setbacks. The method is also applied to a notional wind farm with turbines located at a typical road setback distance. Results show that the blade throw risk imposed to vehicles on public roads for the example wind farm is extremely small and commensurate with risks imposed by everyday activities.

Robotic technology has given rise to many advances in aviation as well as shaped the design of air vehicles. The goal of this work is to synthesize the recent advances in vehicle design as it pertains to aerial robotics. A secondary use of this work is for guidance on the different vehicle design options one has in the space of aerial robotics. Within aerial robotics, vehicle design and morphology are diversifying to meet the needs of expanding mission profiles. Robotics technology, such as robotic legs and arms, are integrating on to aerial systems with improved results. Aerial robotic missions have grown in diversity, and choice of vehicle to accomplish a mission is important. There are many different aerial robotic platforms: rotorcraft, fixed-wing, rocketry, flapping-wing, canopy, lighter-than-air, and hybrid designs. There are also many robotic features that can be integrated into an aerial system: robotic landing gear, aerial manipulators, and interfacing.

All aspects of biodiversity research, from taxonomy to conservation, rely on data associated with species names. Effective integration of names across multiple fields is paramount and depends on coordination and organization of taxonomic data. We review current efforts and find that even key applications for well-studied taxa still lack taxonomic elements required for interoperability and use. We identify opportunities offered by a metadata structure that supports improved access and integration of taxonomic backbone data, better connects taxonomic communities, and highlights broken linkages that limit the current research capacity. We recommend ways forward to improve interoperability of taxonomic data and resultant downstream use in broad biodiversity research and conservation applications.

This article examines the fundamental aspects of controlling ground resonance in rotorcraft equipped with actively controlled landing gear. Ground resonance is a mechanical instability affecting rotorcraft on the ground. It occurs at certain rotor speeds, where the lead–lag motion of the rotor couples with the motion of fuselage creating a self-excited oscillation. Typically, passive or semi-active lag dampers are used to avoid instability; however, these are undesirable from a design and maintenance perspective. Innovations in active landing gear for rotorcraft, such as articulated robotic legs, have provided an alternate approach to avoid the instability, eliminating the need for lag dampers with respect to ground resonance. This article extends classic ground resonance to include movable landing gear and identifies key physical parameters affecting dynamic behavior. Applying LQ optimal control to this model, it is shown that ground resonance instability can be eliminated using active landing gear as the control mechanism, even when there is no lag damping present in the rotor. In addition, while superior performance is achieved when landing gear movement can occur both longitudinally and laterally, it is still possible to stabilize ground resonance with inputs in a single direction, albeit with reduced performance.

The feasibility of twin-screw corotating extruder as a continuous process mixer to prepare dry powder inhalation (DPI) powders was investigated. Interactive mixtures of 1% micronized budesonide, 0.3% magnesium stearate and 98.7% alpha-lactose monohydrate were manufactured using a Leistritz Nano-16 extruder at various processing conditions. One set of GFM (grooved mixing) elements were included in the screw profile to provide distributive mixing of conveyed powders with the goal of resulting in a homogeneous mixture. Residence time in the twin-screw mixer was modelled to quantify mixing efficiency. Comparative powders were also prepared using either low or high-shear batch mixing to compare the effect of mixing methods on the properties of the budesonide dry powder inhalation formulation. Twin screw mixing results in homogeneous mixtures with aerosol performance comparable to that of high-shear batch mixing. Scanning electron microscopy confirmed that twin screw mixing produces particles with morphology like that of low and high-shear batch mixing. X-ray diffraction (XRD) analysis verified that there was no form change of the drug due to twin-screw processing. Statistical regression was used to probe the relationship between twin screw mixing process parameters such as screw speed and feed rate and aerosol performance. The twin screw mixing process was found to be robust, as no significant differences in aerosol performance were found for various processing parameters.

Aero-driven bleed-air (ADB) is a flow control technology that offers a unique alternative to novel aircraft concepts that are not conducive to traditional flapped control surfaces. The primary sour...

In this work a novel crashworthy cable-driven four-bar link mechanism is designed, manufactured, and tested for the development of robotic landing gear for rotorcraft. The paper will demonstrate ho...

Assessing and addressing biodiversity needs are of critical and time-sensitive importance, with the post-2020 Global Biodiversity Framework’s Global Taxonomy Initiative underscoring the need to build capacity in how we conceptualize biodiversity (Abrahamse et al. 2021). Species—as biological units—and their names are the backbone for the data integration and synthesis needed for biodiversity research and conservation decision-making (Grace et al. 2021). In integrating name sources for a single taxonomic group, barriers frequently limit linking species names across regional and global authoritative sources. In response to such challenges, we present a case study testing a Globally Integrated Structure of Taxonomy (GIST) to ensure the integration of taxonomy in biodiversity and conservation sciences. This framework characterizes the components enabling transparent association of species names through synonymy (alternate names or spellings), authorship, specimens, versions and timestamps, and taxonomic relationships in space and time. Taxonomy provides a critical link between biodiversity data types and databases. Efforts towards global taxonomic integration are confounded by insufficient connectivity between taxonomic assemblages, with implications for research, monitoring, and conservation practice (Christie et al. 2021, Jetz et al. 2019, McClure et al. 2020). In attempting to match multiple taxonomic groups across databases, we highlight current progress and remaining challenges to produce and use a GIST. We evaluate the standardized, comprehensive taxonomies of mammals, birds, reptiles, amphibians, dragonflies and damselflies, butterflies, ants, plants, and crabs produced for the Map of Life project (Jetz et al. 2012), identifying which missing components impede their utility. We show that for terrestrial mammals, GIST standards are almost fulfilled, but for invertebrate taxa, such as butterflies, GIST standards are unmet, resulting in broken taxonomic links between aggregators of genetic, spatial, functional, and physical data. We find that even the comprehensive taxonomies we examine do not harmonize well with taxonomies of global genetics, phylogenetics, macroecology, and conservation databases. This is because current taxonomic data infrastructures on biodiversity respositories lack the necessary structural components, searchability, and name source transparency to fully integrate taxonomies, as different independently advancing data sources lack standard metadata practices and operable interfaces. The GIST components enable data linkage and provide clear sourcing and metadata, enabling taxonomic data accessibility, reuse, and interoperability. This structure can act as a step toward open and FAIR (Findable, Accessible, Interoperable, and Reusable) data practice as it relates to taxon names (Wilkinson et al. 2016). Without transparent, integrated, accessible, and updated taxonomic information, macroecological inferences and conservation decisions for even charismatic groups are impeded.

Parameter estimation and system identification of smart projectiles is an important and commonly used industrial tool. Existing methods rely on good initial estimates of the parameters to avoid loc...

Guided airdrop systems have traditionally used position and velocity information from a GPS receiver as their only source of feedback. The use of additional sensors in the guidance units is challenging because sensors in the guidance unit are in close proximity to powerful electric motors. Furthermore, there is a large amount of relative motion between the guidance unit and the parachute as they are coupled by a flexible network of rigging lines. By placing sensors in the parachute itself, it is possible to obtain accurate estimates of the canopy motion and orientation with low-cost sensors requiring minimal calibration. Specialized in-canopy sensor pods were developed to provide distributed sensing throughout a parachute canopy and a sensor fusion algorithm was developed to combine the raw data from these sensor pods into useful canopy state estimates. The effectiveness of this approach is demonstrated first in simulation, and then with flight test results on full-scale airdrop systems. The rich feedback signal available from in-canopy sensors can provide improved datasets for more detailed system identification as well as enabling novel guidance, navigation and control approaches which will lead directly to improved landing accuracy.

Advances in guided airdrop technology including guidance, navigation, and control algorithms, novel control mechanisms and wind sensing algorithms have led to significant improvements over unguided airdrop systems. Guided systems are autonomously controlled with an embedded microprocessor using position and velocity feedback. While capable of highly accurate landing, these systems struggle to overcome deviations from expected flight dynamics due to canopy damage or cargo imbalance, complex terrain at the drop zone, and loss of sensor feedback. Human operators are intelligent, highly adaptive, and can innately judge the flight vehicle and environment to steer the vehicle to the desired impact point provided sufficient information. This work experimentally explores operators' abilities to accurately land an airdrop system using different sensing modalities. Human operator landing results are compared with a state of the art fully autonomous airdrop system. Across the methods analyzed, human operators attained up to a 40% increase in landing accuracy over the fully autonomous control algorithm.

The recent publication of the Roadmap to Digital Transition for Ireland's Construction Industry 2018-2021 clearly identified training and education as key priorities in the development of core BIM competences to stimulate the transition towards a more collaborative digital working environment. It identified an urgent need for a consistent and coherent digital experience for students in Irish education and industry to help grow capacity and maturity in the use of BIM and other innovative techniques. The higher education sector has a vital role to play. Key to this will be ensuring appropriate graduate knowledge, skills and competences, ongoing professional development and upskilling of higher education staff, and significant collaboration with industry. This chapter will present a best practice example of academic-industry collaboration, which resulted in the delivery of a flexible Level 8 programme for industry, the implementation of a BIM strategy within an academic context, and the establishment of a focused research group, which is currently engaged in ongoing applied research.

A logistics issue for guided air-drop systems is maintaining batteries inside the airborne guidance unit so that when the system is deployed the batteries are adequately charged to power onboard el...

The bulk of research in the field of precision guided airdrop systems has focused on improving landing accuracy in the presence of atmospheric winds that can exceed vehicle airspeed. One important ...

Uncertainty in atmospheric winds represents one of the primary sources of landing error in airdrop systems. In this work, a ground-based LIDAR system samples the wind field at discrete points above the target and transmits real-time data to approaching autonomous airdrop systems. In simulation and experimentation, the inclusion of a light detection and ranging (LIDAR) system showed a maximum of 40% improvement over unaided autonomous airdrop systems. Wind information nearest ground level has the largest impact on improving accuracy.

Many towed systems consist of a parent platform moving along the ground, air, or water surface connected to a towed vehicle via a tether line. Motion of a towed parafoil system can be complex and is driven by motion of the parent platform, canopy control inputs, and wind disturbances. A particularly problematic flight dynamic instability for this system is canopy lockout, in which the canopy attains a large lateral offset and bank angle resulting in high line tension. It is possible to use left and right brakes to return the system to its nominal position; however, if the lateral offset and bank angle are too large, it is not possible to restore the system to a nominal position, and the lateral offset and bank angle grows until impact with a ground surface. This paper explores the lockout phenomena using a multibody simulation and identifies passive means to avoid the instability by locating the tether connection point forward on the cradle in combination with sufficiently high cradle–canopy yaw stiffness...

Aerial cargo delivery, also known as airdrop, systems are heavily affected by atmospheric wind conditions. Guided airdrop systems typically employ onboard wind velocity estimation methods to predict the wind in real time as the systems descend, but these methods provide no foresight of the winds near the ground. Unexpected ground winds can result in large errors in landing location, and they can even lead to damage or complete loss of the cargo if the system impacts the ground while traveling downwind. This paper reports on a ground-based mechatronic system consisting of a cup and vane anemometer coupled to a guided airdrop system through a wireless transceiver. The guidance logic running on the airdrop system's onboard autopilot is modified to integrate the anemometer measurements at ground level near the intended landing zone with onboard wind estimates to provide an improved, real-time estimate of the wind profile. The concept was first developed in the framework of a rigorous simulation model and then validated in the flight test. Both simulation and subsequent flight tests with the prototype system demonstrate reductions in the landing position error by more than 30% as well as a complete elimination of potentially dangerous downwind landings.

Precision placement of guided airdrop systems necessarily requires some mechanism enabling effective directional control of the vehicle. Often this mechanism is realized through asymmetric deflection of the parafoil canopy trailing-edge brakes. In contrast to conventional trailing-edge deflection used primarily for lateral steering, upper-surface bleed air spoilers have been shown to be extremely effective for both lateral and longitudinal (i.e., glide slope) control of parafoil and payload systems. Bleed air spoilers operate by opening and closing several spanwise slits in the upper surface of the parafoil canopy, thus creating a virtual spoiler from the stream of expelled ram air. The work reported here considers the autonomous landing performance of a small-scale parafoil and payload system using upper-surface bleed air spoilers exclusively for both lateral steering and glide slope control. Landing accuracy statistics computed from a series of Monte Carlo simulations in a variety of atmospheric conditi...

In flight estimations of helicopter mass and center of gravity are critical for health and lifecycle maintenance, flight control system feedback, and mission planning. This paper explores the use of an extended state observer for online estimation of helicopter mass and center-of-gravity location. The core algorithm is a nonlinear observer that offers provable stability properties. After describing the methodology, it is applied to a simulation of a commercial radio-controlled microcoaxial helicopter. Monte Carlo trade studies employing a comprehensive rotorcraft flight dynamics model are used to assess the algorithm’s estimation accuracy in the presence of model and measurement errors. Results show the helicopter mass, longitudinal center-of-gravity location, and lateral center-of-gravity location are estimated accurately in the presence of expected errors. The vertical center-of-gravity position is more difficult to estimate due to its limited observability during typical maneuvers.

The nexus of advanced manufacturing methods, computer-aided design tools, and modern structural-analysis software has enabled the design and fabrication of structurally complex wing structures with unique features. This is particularly true for small unmanned aircraft, in which discrete structural hinges can easily be integrated into the overall vehicle design. This paper examines the use of discrete structural hinges for tailoring the low-frequency flight dynamics of the vehicle. For sufficiently soft discrete structural hinges, substantial coupling between flexible and rigid modes occurs, leading to the potential to modify the flight dynamic behavior through structural flexibility. Using a multibody flight dynamics simulation tool with a nonlinear lifting-line aerodynamic representation, different structural-hinge elastic properties, orientation, and location on the aircraft are examined. The results for a small unmanned aircraft indicate that flexibility mostly affects the longitudinal modes and associ...

To create highly maneuverable projectiles, some physical control mechanism is needed that is capable of altering the projectile trajectory in a desired manner. The work reported here considers a small flow control device, termed a microspoiler system, located between the rear stabilizing fins of a projectile. Such a mechanism relies on the boundary-layer shock interaction between the projectile body, rear stabilizing fins, and microspoilers to provide a multiplicative effect on controllable forces and moments. To investigate performance of the microspoiler control mechanism, projectile trajectories with microspoilers were generated both computationally using a coupled CFD and rigid-body dynamic simulation and experimentally from spark range testing. Using this computational and experimental trajectory information, aerodynamic coefficients both with and without microspoilers were estimated and found to be in good agreement where the major effect of the microspoiler system is the addition of trim forces and...