Onboard Wind Research Articles

Field validation of a yaw misalignment observer for wind farm control

In this work, a load-based yaw misalignment observer was tested and validated with turbine and mast data collected during a wake steering and characterization campaign. A shallow feed-forward neural network was used to map the relation between the yaw misalignment and the in-and out-of-plane blade load harmonics for a 3.5 MW machine, and its performance was analysed over about 108 full days of useful data. Confirming previous findings, this simple neural network was able to accurately estimate the yaw misalignment, with an average 10-minute absolute error of at most 4°.The performance of the yaw misalignment observer was compared to the one of the standard onboard wind vane during the wake steering campaign. Results indicate that the wind vane may significantly overestimate the misalignment for large angles, possibly on account of the wake rotation and flow distortion effects caused by the nacelle. The observer on the other hand, sampling the flow at the rotor disk and not behind it, is not affected by such phenomena and could therefore provide a more accurate measurement of the misalignment angle, possibly improving the performance of wake steering. When the turbine is already equipped with load sensors, this is obtained without the need to install and maintain extra hardware, which instead is the case with spinner-mounted anemometers or lidars.

Maritime Emission Monitoring: Development and Testing of a UAV-Based Real-Time Wind Sensing Mission Planner Module

Maritime emissions contribute significantly to global pollution, necessitating accurate and efficient monitoring methods. Traditional methods for tracking ship emissions often face limitations in real-time data accuracy, with wind measurement being a critical yet challenging aspect. This paper introduces an innovative mission planner module for unmanned aerial vehicles (UAVs) that leverages onboard wind sensing capabilities to enhance maritime emission monitoring. The module’s primary objective is to assist operators in making informed decisions by providing real-time wind data overlays, thus optimizing flight paths and data collection efficiency. Our experimental setup involves the testing of the module in simulated maritime environments, demonstrating its efficacy in varying wind conditions. The real-time wind data overlays provided by the module enable UAV operators to adjust their flight paths dynamically, reducing unnecessary power expenditure and mitigating the risks associated with low-battery scenarios, especially in challenging maritime conditions. This paper presents the implementation of real-time wind data overlays on an open-source state-of-the-art mission planner as a C# plugin that is seamlessly integrated into the user interface. The factors that affect performance, in terms of communication overheads and real-time operation, are identified and discussed. The operation of the module is evaluated in terms of functional integration and real-time visual representation of wind measurements, and the enhanced situational awareness that it can offer to mission controllers is demonstrated. Beyond presenting a novel application of UAV technology in environmental monitoring, we also provide an extensive discussion of how this work will be extended in the context of complete aerial environmental inspection missions and the future directions in research within the field that can potentially lead to the modernization of maritime emission monitoring practices.

UAV Atmosphere Sounding for Rocket Launch Support.

One of the crucial branches of activity at the Łukasiewicz Research Network-Institute of Aviation is developing a suborbital rocket vehicle capable of launching small payloads beyond the Earth's atmosphere, reaching over 100 km in altitude. Ensuring safety is a primary concern, particularly given the finite flight zone and impact area. Crucial to safety analysis is the wind profile, especially in the very first seconds of a flight, when rocket velocity is of the same order as the wind speed. Traditional near-ground wind data sources, ranging from wind towers to numerical models of the atmosphere, have limitations. Wind towers are costly and unfeasible at many test ranges used for launches, while numerical modeling may not reflect the specific ground profile near the launcher due to their large cell size (2 to +10 km). Meteorological balloons are not favorable for such measurements as they aim to provide the launch operator with a wind profile at high altitudes, and are launched only 1-2 times per flight attempt. Our study sought to prototype a wind measurement system designed to acquire near-ground wind profile data. It focuses on measuring wind direction and speed at near-ground altitudes with higher flight frequency, offering data on demand shortly before launch to help ensure safety. This atmosphere sounding system consists of an Unmanned Aerial Vehicle (UAV) equipped with an onboard ultrasonic wind sensor. Some reports in the literature have discussed the possibility of using UAV-borne anemometers, but the topic of measurement errors introduced by placing the anemometer onboard an UAV remains under studied. Limited research in this area underlines the need for experimental validation of design choices-for specific types of UAVs, anemometers, and mounting. This paper presents a literature review, a detailed overview of the prototyped system, and flight test results in both natural (outdoor) and controlled (indoor, no wind) conditions. Data from the UAV system's anemometer was benchmarked against a stationary reference weather station, in order to examine the influence of the UAV's rotor on the anemometer readings. Our findings show a wind speed Root Mean Square Error (RMSE) of 5 m/s and a directional RMSE of below 5.3° (both averaged for 1 min). The results were also compared with similar UAV-based wind measurements. The prototyped system was successfully used in a suborbital rocket launch campaign, thus demonstrating the feasibility of integrating UAVs with dedicated sensors for performing regular meteorological measurements in automatic mode.

Producing electricity on board a ship in motion or stationary using photovoltaic panels

A very important pillar for the world economy is the transport sector. Nowadays, about 80% of freight transport has been done by sea. Besides the recognized economic efficiency, ships are, unfortunately, an important sources of marine environment pollution. It is well known that the IMO is permanently concerned in maritime safety and many measures have been shown to be successful in reducing ship-sourced pollution. But it is not enough, new solutions must be found, and the answer can come from the direction of green energies (electricity produced from renewable sources). On board ships can be used as renewable energy sources wind energy or solar energy. Solar energy is easier to use because photovoltaic panels can be mounted on board the ship to produce electricity (however, provided that the photovoltaic panels do not increase the ship's forward resistance or reduce its manoeuvrability). Studies have shown that offshore wind energy is much more efficient than a ship-mounted wind turbine because an on-board wind turbine greatly reduces a ship's speed and manoeuvrability. The authors of the paper proposed to study the production of electrical energy obtained with the help of photovoltaic panels on board a ship in motion and stationary. The ship marched in the Mediterranean Sea for two months.

Validation of wind measurements from a multirotor RPAS-mounted ultrasonic wind sensor using a ground-based LiDAR system

The aim of this research was to establish the validity of wind measurements from on board a multirotor Remotely Piloted Aircraft System (RPAS) for the purposes of wind monitoring applications. A custom-built hexacopter RPAS recorded wind speed and direction by means of an onboard ultrasonic wind sensor, whilst operating in the inherently highly stochastic nature of open field atmospheric conditions. Experimental data were collected during open field hovering flights subject to different ambient conditions with free stream horizontal wind speeds reaching up to 12 m/s. Flights were conducted at different altitudes above ground level and in proximity to a Light Detection and Ranging (LiDAR) remote wind measurement unit that was used as a low-resolution reference meteorological station. Very good correlation was obtained between the RPAS and LiDAR unit for both wind speed and wind direction measurements across all hovering flight altitudes. The RPAS-based wind speed measurements were found to have a consistent 1 m/s positive offset, whilst the RPAS-based wind direction readings had a 6.16° negative offset. These were potentially caused by differences in the localized wind fields between the LiDAR and RPAS measuring positions, as well as by localized RPAS rotor-induced air flows for wind speed measurements and potential slight misalignments in the instruments’ reference datum for wind direction readings.

Flight trajectory optimization of Fly-Gen airborne wind energy systems through a harmonic balance method

Abstract. The optimal control problem for flight trajectories of Fly-Gen airborne wind energy systems (AWESs) is a crucial research topic for the field, as suboptimal paths can lead to a drastic reduction in power production. One of the novelties of the present work is the expression of the optimal control problem in the frequency domain through a harmonic balance formulation. This allows the potential reduction of the problem size by solving only for the main harmonics and allows the implicit imposition of periodicity of the solution. The trajectory is described by the Fourier coefficients of the dynamics (elevation and azimuth angles) and of the control inputs (onboard wind turbine thrust and AWES roll angle). To isolate the effects of each physical phenomenon, optimal trajectories are presented with an increasing level of physical representation from the most idealized case: (i) if the mean thrust power (mechanical power linked to the dynamics) is considered as the objective function, optimal trajectories are characterized by a constant AWES velocity over the loop and a circular shape. This is done by converting all the gravitational potential energy into electrical energy. At low wind speed, onboard wind turbines are then used as propellers in the ascendant part of the loop; (ii) if the mean shaft power (mechanical power after momentum losses) is the objective function, a part of the potential energy is converted into kinetic and the rest into electrical energy. Therefore, the AWES velocity fluctuates over the loop; (iii) if the mean electrical power is considered as the objective function, the onboard wind turbines are never used as propellers because of the power conversion efficiency. Optimal trajectories for case (ii) and (iii) have a circular shape squashed along the vertical direction. The optimal control inputs can be generally modeled with one harmonic for the onboard wind turbine thrust and two for AWES roll angle without a significant loss of power, demonstrating that the absence of high-frequency control is not detrimental to the power generated by Fly-Gen AWESs.

Operational assimilation of Aeolus winds in the Météo‐France global NWP model ARPEGE

AbstractThe European Space Agency's Aeolus satellite was launched in August 2018. Measurements of wind profiles are provided for the first time from space using an onboard Doppler wind lidar. The quality of Aeolus Level‐2B (L2B) wind products has been found suitable for data assimilation in the Météo‐France global model ARPEGE since April 2020, in particular, when applying a suitable bias correction method. This article describes a series of Observing System Experiments (OSEs) conducted in April–May 2020 to assess the impact of Aeolus horizontal line‐of‐sight winds (HLOSW) on Météo‐France's global numerical weather prediction analyses and forecasts. Innovation statistics and a posteriori diagnostics from a period of July–August 2019 were used to scale the random observation errors provided by the L2B processor (mostly for Rayleigh‐clear winds). Although the HLOSW data represent only 0.42% of the total amount of all observations assimilated in ARPEGE, their contribution to the reduction of the global analysis variance is up to 2.3% (measured by the Degree of Freedom for Signal). The assimilation of HLOSW showed improvement in 6 hr short‐range forecasts which is demonstrated by an overall reduction of innovations statistics for various operational observing systems. From a Forecast Sensitivity to Observations impact (FSOi) study Aeolus is found to be the third most effective observing system (per individual observation) at reducing global 24‐hour forecast errors. For longer forecast ranges, the largest positive impacts are noticed over the tropics, particularly in the lower stratosphere up to 102 hr ahead (with up to 2% root‐mean‐square error reduction for wind and temperature), but also in the troposphere up to 72 hr ahead. To a lesser extent, a similar improvement is observed over the Southern Hemisphere. This positive impact of Aeolus HLOSW in OSEs has led to their operational assimilation at Météo‐France starting in June 2020.

Launcher flight control design using robust wind disturbance observation

The development of effective load relief strategies is key to the improvement of launcher flight performance as it enables a joint increase of wind resilience and decrease of mass. This is particularly relevant for reusable launchers, which are aimed at maximising operational availability and payload capacity. Yet, despite various load relief advances in the aeronautics and wind energy sectors, classical feedback-only techniques remain the state-of-practice for launchers. In this article, an improved load relief functionality for reusable vehicles is proposed based on the use of a disturbance observer for on-board wind anticipation and a load relief compensator driven by the estimate of the wind for its amelioration.Two space systems are used to demonstrate the capabilities of the proposed approach. First, it is applied to a 3 degrees-of-freedom nonlinear simulation model of DLR’s EAGLE vertical-flight demonstrator. Then, it is applied to a 6 degrees-of-freedom nonlinear simulation model of a generic lightweight, reusable launch vehicle. For both cases, the results highlight the benefits of using this type of wind-estimation/load-relief compensation schemes. Further, for the second case, which uses thrust vector control and planar fins for ascent and descent attitude control, it is also shown that the use of fins during ascent (which is not common practice), can further improve launcher performance.

Track-Based Aerodynamic Testing of a Two-Truck Platoon

<div class="section abstract"><div class="htmlview paragraph">Fuel savings from truck platooning are generally attributed to an aerodynamic drag-reduction phenomena associated with close-proximity driving. The current paper is the third in a series of papers documenting track testing of a two-truck platoon with a Cooperative Adaptive Cruise Control (CACC) system where fuel savings and aerodynamics measurements were performed simultaneously. Constant-speed road-load measurements from instrumented driveshafts and on-board wind anemometry were combined with vehicle measurements to calculate the aerodynamic drag-area of the vehicles.</div><div class="htmlview paragraph">The drag-area results are presented for each vehicle in the two-truck platoon, and the corresponding drag-area reductions are shown for a variety of conditions: gap separation distances (9 m to 87 m), lateral offsets (up to 1.3 m), dry-van and flatbed trailers, and in the presence of surrounding traffic. For the standard aligned platoon, the results demonstrate up to 8% drag reduction for the lead vehicle, with drag reductions exceeding 20% for the trailing vehicle at some yaw angles. Wind-velocity measurements on the following truck suggest that the drag-area reductions are due to a combined effect of reduced apparent wind speed and reduced effective yaw angle in the wake of the lead truck. In the presence of a three-vehicle traffic pattern forward of a single truck, drag-area reductions on the order of 10% were observed relative to the same truck travelling in isolation. When platooning with this surrounding-traffic pattern, the trends and magnitudes of aerodynamic drag reduction are shown to be retained, relative to the platoon in the absence of other traffic, corroborating observed trends in of fuel-savings performed simultaneously.</div><div class="htmlview paragraph">As a supplement to the current study, a first-of-its-kind coast-down test was undertaken with the two-truck platoon where the CACC system was used to maintain a constant distance between the vehicles during each coast. The CACC system was used on the following vehicle when the lead vehicle was coasting and on the lead vehicle when the follower was coasting. Despite some scatter in the data from this proof-of-concept study, the results are consistent with those of the principal constant-speed measurement technique of this paper. This preliminary study demonstrates that the coast-down test method, which previously was only applied for single vehicles, is also applicable to vehicle platoons.</div></div>

Multirotor-assisted measurements of wind-induced drift of irregularly shaped objects in aquatic environments

Ocean hazardous spills and search and rescue incidents are becoming more prevalent as maritime activities increase across all sectors of society. However, emergency response time remains a factor due to the lack of information available to accurately forecast the location of small objects. Existing drifting characterization techniques are limited to objects whose drifting properties are not affected by on-board wind and surface current sensors. To address this challenge, we study the application of multirotor small unmanned aerial systems (sUAS), and embedded navigation technology, for on-demand wind velocity and surface flow measurements to characterize drifting properties of small objects. An off-the-shelf quadrotor sUAS was used to measure the speed and direction of the wind field at 10 m above surface level near a drifting object. We also leveraged sUAS-grade attitude and heading reference systems and GPS antennas to build water-proof tracking modules that recorded the position and orientation, as well of translational and rotational velocities, of objects drifting in water. The quadrotor and water-proof tracking modules were deployed during field experiments conducted in Claytor Lake, Virginia and the Atlantic Ocean south of Martha’s Vineyard, Massachusetts to characterize the leeway parameters of manikins that simulated a person in water. Leeway parameters were found to be an order of magnitude within previous estimates that were derived using conventional wind and surface current observations. We also determined that multirotor sUAS and water-proof tracking modules can provide accurate and high-resolution ambient information that is critical to understand how changes in orientation affect the downwind displacement and jibing characteristics of small objects floating in water. These findings support further development and application of multirotor sUAS technology for leeway characterization and understanding the effect of an object’s downwind-relative orientation on its drifting characteristics.

Two‐step onboard hydrogen generation from Black Sea H 2 S reserves

This paper investigates the exergy and energy rationality of a near-future, two-step hydrogen production system in the Black Sea on a custom-built hydrogen ship with 100% onboard wind, wave, and solar energy system. In the first step of this concept, hydrogen will be produced from the low-salinity seawater by electrolysis utilizing the onboard renewable energy. Part of the hydrogen produced will be used in the second step, which is the major production step, claiming the H2S gas, which is exceptionally rich in the seawater. The hydrogen and sulfur products will be shipped by hydrogen-powered shuttle ships to the nearby city of Sinop to blend hydrogen with the natural gas (NG) to form a hydrogen city. Thus this project presents a novel coupling of the land-side and the sea-side operations with renewable energy and hydrogen in an exergy-based minimum CO2 emissions responsibilities. This on-board H2S exploration concept for hydrogen and sulfur production is compared with the current NG explorations in the Black Sea and the use of NG on the landside. A detailed comparison of the total carbon footprint shows that NG explorations in the Black Sea will be responsible for direct and indirect-nearly avoidable (due to exergy destructions) CO2 emissions, while the ever-increasing H2S threat faced by all Black Sea countries will remain at an increasing rate. A new exergy-based optimum H2S claim depth calculation and control algorithm for onboard operations have also been developed and designed, which shows that economy-based optimization—if ever exists—will be responsible for nearly avoidable CO2 emissions, while the on-board hydrogen production and utilization on the land side have a minimal environmental footprint. None of the earlier studies available in the literature concerning the exact harmful effects of hydrocarbons address exergy rationality. Renewable energy systems like wind turbines and solar energy systems, along with other renewable and waste energy systems like geothermal and wave energy are mostly treated individually, which are not free from large exergy destructions. Therefore, future energy plans with environmental concerns must be carried out from the source to the very last point of demand sectors. This is the specific attribute of this research. Novelty Statement None of the studies about the exact harmful effects of hydrocarbons involve exergy rationality and the consequences of this ignorance on the environment and overall energy budget and economy. Renewable energy systems like wind turbines and solar energy systems, along with other renewable and waste energy systems like geothermal and wave energy are mostly treated individually, which are not free from exergy destructions. For example, a solar photovoltaic (PV) plant generates power but releases heat back without claiming it. This unclaimed heat represents about 50% of the unit exergy of the available solar energy and leads to exergy destruction that is responsible for nearly avoidable CO2 emissions because destroyed thermal exergy has to be offset by spending additional fuel in another system, which most likely is using fossil fuels in a boiler. The term nearly precedes the word avoidable, because exergy destructions may not be completely avoided. Even solar and wind energy systems have exergy destruction components during their operation. Yet, a solar PV and heat system would be a much better choice from the exergy rationality point of view. Although the ongoing increase in the renewable shares in the energy stock, it is essential to follow where the power is used in the built environment. For example, according to Global Wind Energy Council, within the next 10 years 234 GW, within the next 30 years 1400 GW offshore wind power capacity is expected to be installed. However, these installations will never know where this electricity and how this electricity is used in an energy/exergy balance and rationality when coupled to the landside through national and international grids. Therefore, future energy plans with environmental concerns must be carried out from the source to the very last point of demand sectors. Whether off-shore or land-based, wind turbines just generate electric power without asking where the electricity goes and how rational it is used in the built environment. There is no control over the best way of utilizing this wind energy. Instead, hydrogen production with renewables and utilization in next-generation fuel cells produces power and heat (pending on heat distribution tariffs for the fifth-generation district energy systems and LowEx applications, the temperature is the best fit for LowEx applications). The interrupted and unpredictable characteristics of renewables are offset by hydrogen storage.

On-Board Wind Scatterometry

Real-time (RT) ocean surface wind can make key improvements to disaster alarmingand safety of maritime navigation to avoid loss in property and human lives. Wind scatterometry is a well-acquainted way of obtaining good quality ocean surface winds, and it has been in application for decades. Existing wind-obtaining chains employ ground stations for receiving observations and can, at best, provide products in around 30 minutes for limited regions. In recent years, a satellite information-obtaining and transmission network is the new trend of Earth observation. In this research, on-board wind retrieval environment and procedures, which are different from traditional wind-obtaining chains, are proposed. First, the establishment of the on-board environment is instructed. Structures of each module are provided. The ground simulation system is been established based on this. After that, existing observing and processing routines of wind scatterometry are described, and then an on-board processing chain proposed and described. Modifications to existing satellite-ground chains are highlighted. The proposed method is validated in Level 0 data from the Chinese–French Oceanic SATellite (CFOSAT). Experiments indicate that the proposed on-board processing procedure can provide comparable results to ground-processed wind products. The root-mean-square error (RMSE) of wind speed for a track of data used in the experiment was about 0.26 m/s, and it was about 0.8° for wind direction. By decreasing wind field result quality, calculation time can be lessened in the on-board environment. However, it is found that in the whole chain of on-board wind generation, the most time-consuming procedure is observation-obtaining. The proposed on-board processing method can achieve good wind accuracy while meeting RT applications with good processing time. This provides a good complement to existing on-board-observing-ground-processing chains for RT applications.

Integrating Wind Electrical Energy for the Marine Electrical Power System

Utilization of renewable energy for the reduction of fuel consumption and green house gas (GHG) emissions in the shipping industry has been increased rapidly in the recent years. Wind energy is a clean renewable energy with no pollution which is abundantly available at sea. This paper proposes two different possible configurations of connecting wind power energy into the ship’s main grid bus system . Wind electrical energy output has been connected to ship’s main ac bus system in one configuration and it is connected to ship’s main dc bus system. Even though Wind assisted ship propulsion (WASP) had been started already in the last decades in the form of wing sails, kites, Flettener rotor etc which could assist auxiliary propulsion of the ships, the application of wind power generator on the ship is not often applied. Therefore this paper has a relevant significance in applying wind electrical energy for the marine electrical power system needs. This paper also reveals the benefits and challenges in the area of onboard wind generation and opens future research possibilities in integrating wind energy into marine industry.

Temporal Evolution of Heavy-Ion Spectra in Solar Energetic Particle Events

Solar energetic particles (SEPs) are released into the heliosphere by solar flares and coronal mass ejections (CMEs). They are mostly protons, with smaller amounts of heavy ions from helium to iron, and lesser amounts of species heavier than iron. The spectra of heavy ions have been previously studied mostly by using the fluence of the particles in an event-integrated spectrum in a small number of spectral snapshots. In this article, we analyze the temporal evolution of the heavy-ion spectra using two large SEP events (27 January 2012 and 7 January 2014) from the Solar TErrestrial Relations Observatory (STEREO) era using Advanced Composition Explorer (ACE) Solar Isotope Spectrometer (SIS) and Ultra Low Energy Isotope Spectrometer (ULEIS), Energetic Particles: Acceleration, Composition and Transport (EPACT) onboard Wind, and the STEREO-A (Ahead) and -B (Behind) Low-Energy Telescope (LET) and Suprathermal Ion Telescope (SIT) instruments, taking a large number of snapshots covering the temporal evolution of the event. We find large differences in the spectra of the ions after the main flux enhancement in terms of the grouping of similar species, but also in terms of the location of the instruments. Although it is somewhat less noticeable than in the case of the temporal evolution of protons (Doran and Dalla, Solar Phys. 291, 2071, 2016), we observe a wave-like pattern travelling through the heavy ion spectra from the highest energies to the lowest, creating an “arch” structure that later straightens into a power law after 18 to 24 hours.

Ship speed prediction based on full scale sensor measurements of shaft thrust and environmental conditions

The primary goal of this study is to adapt and validate various regression models to predict a ship's speed through water based on relevant and available full scale sensor measurements from a ship, including measurements of external environmental forces. The wind is measured by on-board wind sensors, and the effect of the waves is measured by motion reference units (MRUs) installed on the ship, measuring motions in six degrees of freedom; three translational motions and rotations about these. Accurate speed estimates, which relate directly to the estimates of the propulsion efficiency, fuel efficiency and pollution, are vital to be able to optimize ship design and operation. We demonstrate how regression models such as linear regression, projection pursuit (PPT) and generalized additive models (GAM) can be easily implemented for this application. A simple regression model based on the well-established relationship between ship speed and shaft thrust represent a benchmark model towards which the other models are compared.

Aircraft aerodynamic coefficients identification using flight tests data

This paper discusses the problems of aerodynamic coefficients identification from flight test data. The principal stages of identification procedure are considered, the more sophisticated stages such as data compatibility check and parameter estimation from flight data are discussed in details. The paper also presents the examples of flight test data processing, which confirm the opportunities for on-board measurement systematic error detection and wind tunnel aerodynamic parameter values correction.

Drag power kite with very high lift coefficient

Abstract As an alternative to conventional wind turbines, this study considered kites with onboard wind turbines driven by a high airspeed due to crosswind flight (“drag power”). The hypothesis of this study was, that if the kite's lift coefficient is maximized, then the power, energy yield, allowed costs and profit margin are also maximized. This hypothesis was confirmed based on a kite power system model extended from Loyd's model. The performance of small-scale and utility-scale kites in monoplane and biplane configurations were examined for increasing lift coefficients. Moreover, several parameters of the utility-scale system were optimized with a genetic algorithm. With an optimal lift coefficient of 4.5, the biplane outperformed the monoplane. A 40 m wing span kite was expected to achieve a rated power of about 4.1 MW with a power density of about 52 kW/m2. A parameter sensitivity analysis of the optimized design was performed. Moreover, to demonstrate the feasibility of very high lift coefficients and the validity of a utilized simplified airfoil polar model, CFDs of a proposed high-lift multi-element airfoil were performed and the airfoil polars were recorded. Finally, a planform design of a biplane kite was proposed.

Measuring Gas Concentration and Wind Intensity in a Turbulent Wind Tunnel with a Mobile Robot

This paper presents the measurement of gas concentration and wind intensity performed with a mobile robot in a custom turbulent wind tunnel designed for experimentation with customizable wind and gas leak sources. This paper presents the representation in different information layers of the measurements obtained in the turbulent wind tunnel under different controlled environmental conditions in order to describe the plume of the gas and wind intensities inside the experimentation chamber. The information layers have been generated from the measurements gathered by individual onboard gas and wind sensors carried out by an autonomous mobile robot. On the one hand, the assumption was that the size and cost of these specialized sensors do not allow the creation of a net of sensors or other measurement alternatives based on the simultaneous use of several sensors, and on the other hand, the assumption is that the information layers created will have application on the development and test of automatic gas source location procedures based on reactive or nonreactive algorithms.

Autonomous Airdrop Systems Employing Ground Wind Measurements for Improved Landing Accuracy

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.

Validation of a wind misalignment observer using field test data

A previously described observer of wind misalignment is validated using field test data collected on the NREL CART3 wind turbine. The observer uses blade root bending moment 1P harmonics, computed using the transformation of Coleman and Feingold, to infer the rotor-equivalent relative wind direction. The observation model parameters are determined by a least squares fitting using recorded blade loads and met-mast measured wind direction and speed; a random sample consensus (RANSAC) algorithm is used to robustify the parameter estimation procedure while detecting outliers in the experimental samples. The observer is validated using an independent verification data set: recorded blade bending loads are fed to the observer and the estimated wind misalignment is compared to both the one provided by the met-mast vanes, assumed as the ground truth, and by an on-board nacelle-mounted wind vane. Results show that the rotor-equivalent wind misalignment estimates provided by the proposed observer are well correlated in the low frequency spectrum with the met-mast reference, and in general are in much better accordance with it than the on-board wind vane measurements.