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Small unmanned airships_for AFOLU in Latin America
Small unmanned airships_for AFOLU in Latin America
Small unmanned airships_for AFOLU in Latin America
Small unmanned airships_for AFOLU in Latin America
Small unmanned airships_for AFOLU in Latin America
Small unmanned airships_for AFOLU in Latin America
Small unmanned airships_for AFOLU in Latin America
Small unmanned airships_for AFOLU in Latin America
Small unmanned airships_for AFOLU in Latin America
Small unmanned airships_for AFOLU in Latin America
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Small unmanned airships_for AFOLU in Latin America

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In the next years, agricultural, forestry and …

In the next years, agricultural, forestry and
forestation/reforestation programs in Latin America will employ in larger scale aerial vehicles to collect, analyze and making modeling for biomass and soil characterization. In this case, unmanned remote sensing platforms could substantially change the costs and reliability of monitoring and mitigation projects, enabling greater participation even from small-scale agriculture in local communities across the region. The primary tool to map and estimate land cover or land use at the regional and local level could be a low-cost, small unmanned airship, which represents a better
cost-effective platform not needing specialized airfields, including energy efficient electric power plant and dependable new soilanalytical techniques that use visible-near-infrared reflectance (VNIR) and Hyper-spectral camera systems. According to the previous assessment, it is the purpose of this paper to propose the embrace of unmanned airship technology as an affordable remote perception and mapping platform in accordance with Latin American boundary conditions given by the economic and
ecological circumstances.

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  • 1. Proceedings of AUVSI’s Unmanned Systems North America 2011 Conference August, 16-19, 2011, Washington, DC, USA AUVSI11-Peña Cervantes Small Unmanned Airships for Agriculture, Forestry and Other Land Use (AFOLU) programs in Latin America Adrian Peña Cervantes,* Victor X. Enriquez Champutiz UAS Researcher UAS Researcher Mexico City, Mexico. Latacunga, Ecuador. avionicaytelemetria@gmail.com vxenriquez@cidfae.gob.ec In the next years, agricultural, forestry and forestation/reforestation programs in Latin America will employ in larger scale aerial vehicles to collect, analyze and making modeling for biomass and soil characterization. In this case, unmanned remote sensing platforms could substantially change the costs and reliability of monitoring and mitigation projects, enabling greater participation even from small-scale agriculture in local communities across the region. The primary tool to map and estimate land cover or land use at the regional and local level could be a low-cost, small unmanned airship, which represents a better cost-effective platform not needing specialized airfields, including energy efficient electric power plant and dependable new soil- analytical techniques that use visible-near-infrared reflectance (VNIR) and Hyper-spectral camera systems. According to the previous assessment, it is the purpose of this paper to propose the embrace of unmanned airship technology as an affordable remote perception and mapping platform in accordance with Latin American boundary conditions given by the economic and ecological circumstances. INTRODUCTION The local surveys and mapping by forest and agriculture technicians are performed today through a combination of conventional, manned aircraft fly-overs and foot patrols. In fact, Satellite and Manned aircrafts mapping is a widely used tool to obtain statistical models of the spatial dynamics of forest cover, species distribution data, and other GIS (Graphical Interface Systems) information among Latin America countries, in order to identify areas of actual or potential biodiversity loss, and thereby helping to identify priorities for conservation actions.
  • 2. AUVSI’s Unmanned Systems North America 2011 2 According to this reality, we can appreciate for environmental and agro-forestry purposes that manned aircraft have a high cost rate, very high greenhouse gas emissions, are dangerous, intrusive in ecosystems and are not very good platforms for long and detailed imagery aerial photography due to their normal high speed - high altitude above ground level flight conditions. In the other hand, conventional patrols are obviously very labor intensive, and thus slow and dangerous for human beings. Also, over the past two decades, Sustainable Forest Management (SFM) has become an environmental issue in Latin America; where there is a widespread concern about high rates of forest loss and degradation in many areas. This states the need for new efforts by local agro-forestry communities and governments to collect new field data for model parameterization, as existing forest inventory data are few and in constant change. This is a critical biodiversity issue that faces most of the countries across Latin America region, fig 1. [1] Fig.1: Forests at Risk in Latin America, with Assessment of Level of Threat. Image taken from the United Nations Environment Program through its global environment outlook (GEO) website [2]. A key current challenge for SMF is to develop adequate cost/benefit methods for mapping the value of different ecosystem services on which livelihoods depend so this information may be incorporated in a high rate in spatial planning. Such analyses obtained in a big scale could potentially be integrated with spatially explicit models of forest dynamics, providing a tool for exploring provision of ecosystem services under different scenarios of environmental change. The research outputs obtained are also requested to support the development and implementation of policies relating to SFM, through the development of decision- support tools and management recommendations. These decision-support tools mentioned before allow the adequate production of map-based research outputs using survey techniques and GIS (Graphical Interface Systems) and greatly facilitate data integration and presentation in a form that can be understood by decision makers and provide a tool for exploring the potential impacts of different policy interventions. However, it is desirable to find decision- support tools that perform the same mapping activities, but with better cost-benefit conditions for the FSM challenges previously mentioned in this introduction. Additionally to SFM actions, in recent years, Latin American Biologists have indicated more frequently that forests in the region may be subjected to a variety of different activities simultaneously, which may have interactive effects on ecological processes and the exploration of such interactions remains a significant modeling challenge in environment protection in the region [2]. This is the reason because in this project we propose the embrace of UAV Lighter-Than- air technology through the use of small unmanned airships for remote perception in forest and agriculture industry. They represent a viable option capable to efficiently complement satellites, offering an excellent reactivity and a more permanent
  • 3. AUVSI’s Unmanned Systems North America 2011 3 availability to the relevant environment specialists This small unmanned airship vehicle is believed to be a successful technology development project that brings recent advances in ultra-lightweight fabrics, composites, thin-film solar cells and unmanned control techniques, to create a small unmanned airship as outlined in this paper to become a viable decision-support tool for agro-forestry communities and environment protection organizations in Latin America. SMALL UNMANNED AIRSHIP DESIGN In order to conduct highly dependable flight operations for AFOLU environments in Latin America at different altitudes ranging from 0 – 9000 feet above sea level, the technical characteristics of the small unmanned airships are planned as follows: • Test bed platforms versions ranging 7.8 m – 14m long, 3.0m, maximum diameter. Figure 2. • Equipped with 4 control rudders in a ``X shape'' configuration, shown in figure 3. • 2 electric motors power plant as main thrusters providing a maximum speed 45 km/h, decreasing in wind gusts to 25 km/h. One Electric motor as stern propulsion thruster for Yaw control at low speeds is optional depending upon versions and missions requirements. • Flight endurance: 1- 2 hours with 25Km/h cruising speed. • Maximum available payload prospected for 8 kg (18 lb). • Two envelopes in the airship hull body. Inner envelope works as pressure-resistant gas helium bag. • Semi rigid configuration with outer envelope engineered to maintain rigidity necessary for the integration of an optional solar cell array, gondola, stern thruster and rudders in the airship. • Flight range according to electrical propulsion system (25Km/hr cruise speed) and autopilot capabilities is calculated for 5Km (3 Miles). Fig.2: Small unmanned airship concept in a forest deployment example. Fig. 3: Control rudders in a “X shape” configuration. Photo courtesy of the CIDFAE’s digital archives
  • 4. AUVSI’s Unmanned Systems North America 2011 4 The propulsion is provided by a group of electric brushless motors (2 motors) attached to each side of the gondola below the center line of the airship and controlled by a dedicated DSP controller module that takes part of the GN & C design. A third electrical motor will be installed in the stern portion of the hull to provide Yaw control under specific maneuvers at low speeds. This motor will be driven by the GN & C system as well as the other power plant equipment and will have a control algorithm defined under software simulations and energy management. The power for electric engines is supplied by a bank of Lithium-Polymer batteries (14.8V 4-6 cells 1600mAh X 2) carried at the gondola’s compartment with 1250W maximum electric consumption for each motor as well as associated wiring with low current waste cables along the entire electrical system. The propeller (14” x 7”) and motors are protected by a plastic ducted fence mounted at the end of a bar, which rotates driven by a servomotor and a gear system to provide plurality of controllable pitch thrust vector, in order to ascend, descend or gain speed in level flight. The mechanical characteristics of proposed power plant with an internal combustion engine version can be shown in the following figure (Figure 4): Fig. 4: Power plant mounted on the gondola with a controllable pitch thrust vector mechanism. Photo courtesy of the CIDFAE’s digital archives Autonomous GN & C (Guidance, Navigation and Control) design The GN & C (Guidance, Navigation and Control) system provides an autopilot capability to the small unmanned airship, so that its flight path meets the high-level objectives commanded by the forestry and agriculture operators. Figure 5 shows the scheme of the proposed autopilot system framework. Fig. 5: Scheme of the Autopilot System Framework. The onboard GN & C (guidance, navigation and control) system will work autonomously to perform station keeping in the presence of varying winds and rising/falling atmospheric density. The GNC is under construction and designed under a R&D program starting with the creation of control algorithms for the unmanned airship in accordance to efficient operational qualities for agro- forestry operators and portable Ground Control Stations.
  • 5. AUVSI’s Unmanned Systems North America 2011 5 These control algorithms are under test employing dynamic simulations through MATLAB – SIMULINK software. Some of the simulations activities are the following: • Dynamics of the aircraft • Guidance and navigation • Control System • external disturbances (wind, etc ...) Previous experience in our group with Unmanned Aerial Vehicles platforms has allowed the input of new control theories in airship technology. Also, at the project we are considering different control theories from other Mexican UAV researchers that have worked in the design and development of new theories of GN & C for different UAV platforms and have established interesting concepts even for autonomous recovery of UAV’s [3] Data Link – RF Modem The Small Unmanned Airship missions require the use of a dependable data link to control and command the unmanned GN & C (Guidance, Navigation and Control) system. A second data link will be installed on-board to down-link the real-time hyper spectral camera, as well an optional gyro- stabilized video streaming payload. According to general operational terms, the Data Link will operate mainly in the line-of- sight of the unmanned airship and in continuous presence of radio coverage. The knowledge of all flying parameters (down- linked to the control station by telemetry) is essential to ensure the appropriate handling of the airship. In addition, when automatic phases of flight are conducted, the pilot must be able to take over direct control of the unmanned airship during take-off and landing stages as well as in the case of unexpected or emergency situations along the mission path with radio coverage availability. An outside line-of-sight operation or radio coverage lost strategy will relay to the autopilot’s GNC (Guidance, Navigation and Control) system to autonomous command the airship for a “back home” maneuver and tracking the aircraft position in real time under emergency RF signal beacons. This will help the operators in the GCS (Ground Control Station) to track and maintain command of the aircraft under different emergency conditions. PID Controllers for GN & C operation The autopilot system has a decision making concept based in PID (Proportional– Integral–Derivative) control loops. This control concept is under test to provide station-keeping, altitude-hold, direction- hold, velocity-hold, and trajectory-hold for the small unmanned airship under design. Figure 6 shows an example of PID’s closed feedback loop operation. Fig. 6: Example of a PID Closed feedback loop for operation of elevator control. A PID is the most commonly used feedback controller. It calculates an "error" value as the difference between a measured process variable and a desired set-point. For our
  • 6. AUVSI’s Unmanned Systems North America 2011 6 autopilot design the PID controllers attempt to minimize the error by adjusting the process control inputs. [4] As mentioned previously, a final goal of our GN & C work is to develop an Autopilot system with PID feedback loop controllers. At present, use of the PID’s in our flights is limited to simulation in Mathlab and Simulink software because a development plan of a technical demonstrator is under preparation. A block diagram of the proposed PID feedback controller concept is presented in the next figure (Fig. 7) Fig. 7: Block diagram of proposed PID feedback control loop in the GN & C System. Ground Control Station Since the small unmanned airship development intended must be practical and easy to operate, the operator’s interface will have a custom design based in portable and rugged Ground Control Stations. The design and development of the ground control station is carried out under the graphical programming language LABVIEW to display the following control and status data from the airship’s autopilot, sensors and basic instrumentation telemetry: • Latitude, longitude and altitude from the GPS system on board. • Latitude, longitude and altitude from the Kalman filter. • Airship’s Euler angles. • Acceleration. • Angular velocity. • Airship’s magnetic bearing. • Static Pressure. • Dynamic pressure (Pitot-Tube) according to airship’s performance at low speeds. The GCS also provides for the creation of the following parameters for transmission to the airship: • Configuration parameters control system • Static pressure in the ground station. • Operation Mode. • Points of programmed path on the route or planned mission It has been agreed that a condition of up to 2 hours endurance is required. Therefore, for the final system, larger capacity batteries will be required and designed in a strategic plan for Solar Cells chargers and local electrical power when available at mission’s localities.
  • 7. AUVSI’s Unmanned Systems North America 2011 7 PAYLOAD The small unmanned airship will employ spectral imaging and photogrammetry techniques to identify spectral features that are related to surveys of forest and agriculture land, obtaining high spatial, spectral, and temporal resolution imagery from biophysical parameters as water stress, nutrient deficiency, pest infestation in woodland and soils as many others. Hyper-Spectral Camera In order to obtain AFOLU data acquisition and image sequence into the system’s payload port, we have selected a very small, lightweight, and robust hyper spectral imaging instrument capable of being deployed in harsh environments such as those encountered in the forest monitoring activities. This hyper spectral imaging instrument, built by the company Headwall Photonics Inc. (Fitchburg MA, USA), has a totally-reflective, aberration-corrected concentric imager design with an f/2.8 optical aperture, covering spectral ranges in the VNIR- Visible and Near-Infrared (400 - 1000 nm) and in the SWIR-Short- Wavelength Infrared (900 - 1700 nm). The aberration-corrected, concentric imager design delivers extremely low distortion over an exceptionally large Field of View, a large aperture for high signal to noise ratio (SNR), and very low stray light for accurate radiometric measurements, all very critical specifications in a spectral imaging instrument. The fully-integrated Micro- Hyperspec™ (Fig 8) Imaging Spectrometer model weighs 2.2 lbs including fore optic lens and 2-D camera. In the other hand, the weight of the additional technical equipment mounted on the payload port is a critical constraint expected to become around 10 lb including shock resistant fanless Industrial PC built by the Nematron Corporation Company, the Data Link equipment as well as associated power supplies and batteries for the support of the hyper spectral payload tasks. Fig 8: Micro-Hyperspec™ Imaging Spectrometer. Photography, courtesy of Headwell Photonics, Inc. PHOTOGRAMMETRY For photogrammetry techniques, our research group at Mexico is partnering with the Canadian company ACCUAS Inc, one of the leaders in the field of UAS-based remote sensing and located in British Columbia, Canada [3]. The ACCUAS Inc Company uses a number of low cost UAVs for surveys of small areas. Typical horizontal accuracies achieved by the company are better than 15 cm, while vertical accuracies on most jobs are better than 20 cm. To put this in perspective the American Society for Photogrammetry and Remote Sensing (ASPRS) has drawn up a number of accuracy standards for photogrammetric surveys. The horizontal and vertical accuracies which ACCUAS achieves exceed ASPRS class 1 accuracy for 1:1,000 scale surveys, with a half meter contour interval. This level of accuracy is better than can normally be achieved from higher altitude manned photogrammetric surveys. In general UAS-based photogrammetry is similar to traditional photogrammetry
  • 8. AUVSI’s Unmanned Systems North America 2011 8 undertaken from a manned aircraft. There are however a number of important differences: Flying height A typical UAV survey is carried out at an altitude of around 300 m above ground level. This is around a tenth of the flying height for a traditional photogrammetric survey. The low flying height means that low cost compact cameras may be used, since their relatively low resolution is compensated for by the low altitude of the survey. Camera calibration The procedure for UAS mounted cameras differs from the procedure used for traditional aerial cameras. These are precision calibrated and have an associated calibration certificate, which details interior orientation parameters, such as focal length and lens distortion coefficients. The low flying height and low sensor resolution means that calibration requirements for cameras carried by small unmanned airships are generally less rigorous. Typically an off the shelf calibration package, such as Photo- Modeler, is used to establish a base calibration. Compact cameras tend to have relatively poor sensor geometry, and this may vary after several rough landings. One approach to dealing with this is to recalibrate the camera frequently on the job, using a correction grid generated from observations of reliable ground control points. This approach is well suited to small- scale UAV surveys, where dense ground control may be established with relative ease. Image processing Small unmanned airship flights are planned in advance using dedicated flight planning software. This allows parameters such as flying height, strip orientation, and photo overlap to be specified in order to obtain the optimal coverage of the area to be surveyed. When the flight plan is complete, it is uploaded to the autopilot of the UAV. The aircraft will then fly the prepared flight plan, taking photos at the specified intervals. On landing, a dedicated log file can be downloaded from the aircraft. This contains information on the GPS position and camera attitude information for each of the photo centers. The image processing is generally similar to the procedures used in a conventional photogrammetric survey. The log file information is used to provide initial estimates of photo positions and orientations. A rigorous block adjustment procedure, involving the use of ground control points is then used to reconstruct the correct photo geometry. Once triangulation and block adjustment are complete, detailed elevation models can be produced, which can be used to produce accurate orthophotos. CONCLUSIONS This paper has presented a framework for integrating small unmanned airships to AFOLU programs in Latin America due to its real advantages in terms of modularity, silence, substantial autonomy and high degree of controllability during normal and scheduled day and night hours. Given the economic constrains, the procurement of these small unmanned airship system is facilitated by the low required financial outlay and the less sophisticated payload requirements (when compared to military and manned aircraft) despite the lower training burden for forestry and agro-forestry operators. These unmanned airships will bridge the gap between what can be measured by satellites and what is measured at static ground-based, research stations. They are easy to transport, relatively simple to deploy in forest or remote geographic areas as well as easy to
  • 9. AUVSI’s Unmanned Systems North America 2011 9 launch and recover by on-field operators and agro-forestry specialists. Most of Its missions will take place within visual line-of-sight and at altitudes ranging from 150 to 500 feet and are therefore outside airspaces used by manned aircraft. Consequently, a significant number of remote perception applications could rapidly be fulfilled with this UAV Lighter-than-air technology. Additional to technological benefits, these systems reduce human life exposure in long, dull, intrusive and dangerous air missions for forestry and agriculture use. They provide potential economic savings and environmental benefits with less fuel consumption, less greenhouse gas emission, and less disruptive noise than for manned aircraft. It is difficult to speculate by the moment about legal and regulatory implications with civil authorities like FAA (Federal Aviation Administration), DGAC (Dirección de Aviación Civil, in spanish –General Direction of Civil Aeronautics, in English) in Mexico and ICAO (International Civil Aviation). The reason is that in Latin America, UAV/UAS regulations are a very unclear subject, but the project outlined in this paper means an opportunity to open discussions about the way to introduce new standardizations for lighter-than-air unmanned aerial vehicles in the region. The proposed concepts offered by this UAV Lighter-Than-air project while only in its starting stages of development, looks to keep the basic ideas of spearhead the research and development of Small Unmanned airships that can be widely used in Latin America for additional monitoring of wildlife and nature observation. These vehicles reveal excellent capabilities in support of the Sustainable Forest Management (SFM) policies and actions by the use of hyper-spectral imagers and SWIR spectrum. These cameras have a world-wide use in various manned and unmanned environment projects. They represent the most growing technology tools in remote perception techniques to identify spectral features that are related to water stress, nutrient deficiency, pest infestation and invasive weeds among many other biophysical characteristics. ACKNOWLEDGEMENTS • The authors express their deepest gratitude to the National Council for Science and Technology (CONACYT) of Mexico [5] and the Research and Development Center of the Ecuadorian Air force (CIDFAE) for its funding and technical support to airships and unmanned vehicles research programs in previous years. Without the government policies to support science, technology and innovation, this research project could not be possible. • We express sincere appreciation for the intense and dedicated work performed by funders, members and collaborators of the International Airship Association to promote the airship technology. Their advice and enthusiasm are invaluable for Latin American airship researchers. • The authors express deepest gratitude to the Western Hemisphere Information Exchange and the U.S. Southern Command for their support to our research activities thorough the invitation to join conferences and forums devoted to unmanned vehicles systems and environmental projects in Latin America [6].
  • 10. AUVSI’s Unmanned Systems North America 2011 10 • We express sincere appreciation for the valuable engagement and technical advice in photogrammetry and aerial mapping techniques from the Canadian company Accuas Inc, particularly from Scott McTavish, Darryl Jacobs and Ken Whitehead [7]. • We express deep gratitude to James K. Yarger II, Industrial designer from the Art Institute of Portland for his valuable help in the platform design and sketches for the presentation of this paper. • We would like to express our deepest gratitude to the Monterrey Institute of Technology and Higher Education, Campus Estado de México (CEM) through its departments of Research and Project coordination for their valuable advice in this R&D project [8]. REFERENCES [1]http://www.unep.org/geo/. United Nations Environment Programme. Global Environment Outlook. [2]Toward Integrated Analysis of Human Impacts on Forest Biodiversity: Lessons from Latin America. Copyright © 2009 by the author(s). Published here under license by the Resilience Alliance.Newton, A. C., L. Cayuela, C. Echeverría, J. J. Armesto, R. F. Del Castillo, D. Golicher, D. Geneletti, M. Gonzalez-Espinosa, A. Huth, F. López- Barrera, L. Malizia, R. Manson, A. Premoli, N. Ramírez-Marcial, J. Rey Benayas, N. Rüger, C. Smith-Ramírez, and G. Williams-Linera. 2009. Toward integrated analysis of human impacts on forest biodiversity: lessons from Latin America. Ecology and Society 14(2): 2. [online] URL: http://www.ecologyandsociety.org/vol1 4/iss2/art2/ [3] M. Lizarraga, V. Dobrokhodov, I. Kaminer. “Implementación de un Sistema de control para Recuperación Autónoma de un Vehiculo Aéreo no Tripulado (UAV). http://users.soe.ucsc.edu/~malife/assets/At errizaje%20Autonomo%20Version%20 Final.pdf [4] Roy Langton, “Stability and Control of Aircraft Systems Introduction to Classical Feedback Control”, Aerospace Series-Wiley. [5] The National Council for Science and Technology of Mexico (CONACyT) URL: http://www.conacyt.gob.mx/ CIDFAE, Ecuadorian Air force, http://fuerzaaereaecuatoriana.mil.ec/ne w/?option=com_content&view=article &id=112&Itemid=222&fontstyle=f- larger [6]Latin America Fuel and & Unmanned Vehicles Conference. Panama City, December 2009. http://www.arc.fiu.edu/WHIXConferen ce/Default.aspx [7] Accuas Inc. CANADA. http://www.accuas.com/ [8] Instituto Tecnológico de Estudios Superiores de Monterrey, Campus Estado de México (CEM). http://www.itesm.edu/wps/portal?WC M_GLOBAL_CONTEXT=/migration/ CEM2/Estado+de+M_xico/Soluciones +empresariales/Consultor_as

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