Control Algorithms of the Longitude Motion of the Powered Paraglider

International audienceThe design of remotely controlled and autonomous Unmanned Aerial Vehicles (\emph{UAVs}) is an actual direction in modern aircraft development. A promising aircraft of this type is a powered paraglider (\emph{PPG}). In this paper, a new mathematical model is suggested for the paraglider's longitudinal motion aimed at the study of \emph{PPG} dynamics and the synthesis of its automatic control. \emph{PPG} under consideration is composed of a wing (canopy) and a load (gondola) with propelling unit. The \emph{PPG} mechanical model is constructed as the system of two rigid bodies connected by an elastic joint with four degrees of freedom that executes a 2D motion in a vertical plane. The details of \emph{PPG}'s motion characteristics including steady-states regimes and its stability have been studied. A nonlinear control law, based on the partial feedback linearization, has been designed for the thrust of \emph{PPG}. Simulation results are analyzed. Simulation tests show that the internal dynamics are stable near the steady-state flight regime

Development of Optimized Path Planning and Autonomous Control for Return-to-point Vehicle of High Altitude Ballooning

In 2004, The Atmospheric and Space Threshold Research Oklahoma (ASTRO) program was launched to provide access to the near space environment for both educational and research purposes. Mainly, this ASTRO vehicle consisted of four parts: Sounding weather balloon to produce buoy force during the ascent phase, circular parachute to produce drag force during the descent phase, tracking gear with GPS (Global Positioning System) to check the position from the ground, and experimental payloads. The descent phase utilizes a circular parachute, and as such, there are no means of controlling the landing location of the vehicle and payloads. Without control, the direction the parachute takes is dependent upon the winds aloft which can allow payloads to land in undesirable locations, such as rivers, lakes, or the middle of vast forests. At times, the flight must be cancelled before it even begins if the risks of a long or difficult recovery are predicted. As the ASTRO project has evolved, the necessity of control of the payloads over the descent phase has also become obvious. In order to address this need, a study of a Return-to-Point Vehicle (RPV) has been started. Parafoil vehicles which are used for RPVs have proven to be useful in many situations from the previous research. Once the RPV has reached the desired altitude, generally around 100,000 ft, it is released from the balloon. When the RPV has been released, it will follow a trajectory which is programmed on Autopilot to direct it a desired landing zone. Some researchers tried to analyze and test the parafoil, but there are no reported uses of the parafoil for dropping the payload from high altitudes; in addition, there are not commercial products to be matched with the ASTRO research as well. Therefore, the purpose of this research is to design the RPV and to develop the optimal trajectory to satisfy the requirements of the ASTRO project. In this research, the most important objective is to develop a cost-effective, simple, and reliable autopilot system which can be applied to the payload used in the ASTRO project.Mechanical Engineerin

Development and Testing of a Steerable Cruciform Parachute System

Title from PDF of title page viewed June 18, 2018Thesis advisor: Travis FieldsVitaIncludes bibliographical references (pages 93-99)Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2018This thesis focuses on the development of a parachute payload system which is capable of precision aerial delivery yet only represents a modest cost increase over ballistic unguided systems. In order to develop such a system, first a canopy is selected. The canopy should be simple and inexpensive to make; in this case a cruciform canopy was selected because this design is material efficient and requires far less labor to manufacture compared to parafoil parachutes. Next some method of stabilizing that canopy during flight must be proposed. In this case, the system heading is to be stabilized via a single actuator by asymmetric deflection of the leading edge of one canopy panel. At this stage in the development, a controller must be designed and implemented which stabilizes the system in the proposed way. Outdoor flight testing is the gold standard of parachute testing methodology since it offers the most realistic flight conditions. However, the unmeasured wind disturbances encountered in outdoor flight testing can confound results and interfere with repeatability of experiments. The first experiment explained in this thesis revolves around the testing of a steer able cruciform parachute system using a vertical wind tunnel. The primary goal of the experiment was to develop a heading stabilizing controller. Additionally, a closed-loop system model was identified and a technique was developed for estimating canopy glide ratio (GR). The vertical wind tunnel testing methodology is far faster and less expensive than the outdoor flight testing which would be needed to accomplish the same goals. After proving that a system can be steered via the proposed methodology, the next stage in the developing of a precision guided vehicle is to demonstrate that the stabilization technique is viable. This is accomplished in both outdoor flight testing and a simulation based on the closed-loop model identified earlier. Furthermore, the precision navigation potential of the system must be demonstrated; specifically, the system must be capable of arriving closer to the desired impact point on the ground than an unguided system dropped under the same conditions. The work described in this thesis has advanced the development of the steerable cruciform parachute system beyond the point of simply being a feasibility demonstrator. The vertical wind tunnel experiments demonstrated that the system heading could be stabilized and subsequent navigation experiments demonstrated that the system outperforms an unguided system during real drops. The work done to compare the effectiveness of different navigation strategies in a simulated environment represents the beginning of the next stage in the development of the parachute system. This next stage involves refinement and performance improvements of the existing platform through engineering design in order to advance the technical readiness level of the project.Introduction -- Literature review -- Vertical wind tunnel experiment -- Investigation of navigation strategies -- Conclusions -- Appendix A. Unmanned aerial systems and parachute release mechanisms -- Appendix B. Aerial guidance unit redesig

Strain Gauge Utilization for Aerial Vehicle Dynamic Load Measurement

Title from PDF of title page, viewed on July 11, 2016Thesis advisor: Travis FieldsVitaIncludes bibliographical references (pages 83-90)Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2016The strain gauge is a commonly used tool for dynamic load and strain measurement of a system. The work presented in this thesis describes the development and evaluation of strain gauges applied to both an aerodynamic decelerator system and an unmanned aerial vehicle. This thesis has three main objectives: (1)develop and evaluate test a circular parachute strain gauge-based load distribution measurement system, (2) develop and evaluate a strain gauge thrust estimation system for a quadrotor unmanned aircraft, and (3)compare the developed strain gauge-based thrust estimation technique with an indirect real time parameter estimation technique for motor fault detection. In pursuit of the first thesis objective, a load distribution measurement system for the suspension lines of circular parachutes was developed. The motivation to create a load distribution measurement system stems from parachute system design traditionally requiring an extensive flight testing regimen. Numerical solution-based design is difficult due to the highly nonlinear deformation behavior of the parachute canopy. Traditionally, circular parachutes are assumed to have symmetric canopy loading upon inflation and during terminal descent. Asymmetric canopy loading can have a significant impact on circular parachute suspension line loads, but is typically neglected. The developed strain gauge-based load distribution measurement system for circular parachutes has wireless capabilities and can be readily applied to a wide variety of aerodynamic declarator systems. The developed system can be used to observe asymmetric behaviors in order to help determine the significance of asymmetric canopy loading. Custom strain gauge load cells with mounted custom circuitry to calibrate, amplify, and transmit the load data were fixed to canopy suspension lines. Parachute drop testing was performed to evaluate the effectiveness to identify any significant asymmetric canopy loading behavior. Drop testing was performed with a 1.2m (4.0ft) quarter-spherical cross based canopy with a payload of 2.0kg (4.4lbs). A 12m (39ft) guide-line based drop rig was implemented to prevent canopy rotational movement that could hinder testing repeatability. Load distribution data was first verified via both static calibration and in-flight total canopy load measurements. Drop testing was then conducted to identify loading asymmetry during both inflation and terminal descent. Results demonstrated the use of the strain gauge-based load distribution measurement system for measuring significant asymmetric canopy loading patterns. In pursuit of the second thesis objective, strain gauges were used to aid in the development of a thrust estimation system for individual motors/propellers of a small quadrotor unmanned aerial vehicle (UAV). Small UAVs have become increasingly utilized for a wide range of applications; however, such aircraft typically do not undergo the same rigorous safety protocols as their larger human-piloted counterparts. A thrust estimation technique for a quadrotor unmanned aircraft was developed and evaluated that could potentially improve flight control design by increasing sensory feedback information. Strain gauges were integrated into the quadrotor frame to provide total force measurements on each arm of the aircraft. A dynamic model coupled with state information from motion capture and on-board measurement data was implemented to compensate for inertial forces caused by rotational and translational acceleration. Testing was conducted to evaluate the accuracy of the individual load cells, inertial compensation,and free-flight motor thrust estimates. Results demonstrate inertial force compensation during high frequency aircraft motion, which could potentially be useful for detecting an in-flight failure. The measurement system therefore has the potential to quickly detect an in-flight failure. The focus of the third thesis objective is to expand on the development of the thrust estimation system by performing an evaluation of the fault detection capabilities. A comparative study was conducted of the thrust estimation system along with a real time parameter estimation in the frequency domain during two motor failure scenarios of a small quadrotor UAV. Detecting and mitigating disturbances caused by in-flight mo tor/propeller failures is an important aspect of a robust flight controller for multirotor aircraft. The comparative study was performed in an attempt to determine whether direct thrust estimation (strain gauge-based) or indirect thrust estimation (parameter estimation using on-board measurement) more accurately and quickly capture an in-flight failure. Flight test results were post-processed to mimic real-time parameter estimation and strain gauged-based fault detection. Results show the strain gauge-based parameter estimation exhibits noisy estimates, but does have faster response to the failure. The parameter estimation using onboard data does not respond to failures as quickly as the strain-gauge based technique, but does produce better parameter estimate stability. Although both estimation techniques display strengths and weaknesses, neither technique is optimal for real time failure detection individually. A combination of the real-time parameter estimation in the frequency domain and the strain gauge-based thrust estimation techniques may yield a fast yet stable fault detection system. The evaluation of the fault detection capabilities of the thrust estimation system did not prove unsuccessful, however it has warranted further investigation into the overall effectiveness of the system for fault detection.Introduction -- Literature review -- Validation and flight testing of a wireless load distribution measurement system -- Feasibility of in-flight quadrotor individual motor thrust measurements -- Conclusio

2020 NASA Technology Taxonomy

This document is an update (new photos used) of the PDF version of the 2020 NASA Technology Taxonomy that will be available to download on the OCT Public Website. The updated 2020 NASA Technology Taxonomy, or "technology dictionary", uses a technology discipline based approach that realigns like-technologies independent of their application within the NASA mission portfolio. This tool is meant to serve as a common technology discipline-based communication tool across the agency and with its partners in other government agencies, academia, industry, and across the world

Aeronautical engineering: A continuing bibliography with indexes (supplement 305)

This bibliography lists 239 reports, articles, and other documents recently introduced into the NASA scientific and technical information system. Subject coverage includes the following: the design, construction, and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Control system design using evolutionary algorithms for autonomous shipboard recovery of unmanned aerial vehicles

The capability of autonomous operation of ship-based Unmanned Aerial Vehicles (UAVs) in extreme sea conditions would greatly extend the usefulness of these aircraft for both military and civilian maritime purposes. Maritime operations are often associated with Vertical Take-Off and Landing (VTOL) procedures, even though the advantages of conventional fixed-wing aircraft over VTOL aircraft in terms of flight speed, range and endurance are well known. In this work, current methods of shipboard recovery are analysed and the problems associated with recovery in adverse weather conditions are identified. Based on this analysis, a novel recovery method is proposed. This method, named Cable Hook Recovery, is intended to recover small to medium-size fixed-wing UAVs on frigate-size vessels. It is expected to have greater operational capabilities than the Recovery Net technique, which is currently the most widely employed method of recovery for similar class of UAVs, potentially providing safe recovery even in very rough sea and allowing the choice of approach directions. The recovery method is supported by the development of a UAV controller that realises the most demanding stage of recovery, the final approach. The controller provides both flight control and guidance strategy that allow fully autonomous recovery of a fixed-wing UAV. The development process involves extensive use of specially tailored Evolutionary Algorithms and represents the major contribution of this work. The Evolutionary Design algorithm developed in this work combines the power of Evolutionary Strategies and Genetic Programming, enabling automatic evolution of both the structure and parameters of the controller. The controller is evolved using a fully coupled nonlinear six-degree-of-freedom UAV model, making linearisation and trimming of the model unnecessary. The developed algorithm is applied to both flight control and guidance problems with several variations, from optimisation of a routine PID controller to automatic control laws synthesis where no a priori data available. It is demonstrated that Evolutionary Design is capable of not only optimising, but also solving automatically the real-world problems, producing human-competitive solutions. The designed UAV controller has been tested comprehensively for both performance and robustness in a nonlinear simulation environment and has been found to allow the aircraft to be recovered in the presence of both large external disturbances and uncertainty in the simulation models

Proceedings of the 6th Annual Summer Conference: NASA/USRA University Advanced Design Program

The NASA/USRA University Advanced Design Program is a unique program that brings together NASA engineers, students, and faculty from United States engineering schools by integrating current and future NASA space/aeronautics engineering design projects into the university curriculum. The Program was conceived in the fall of 1984 as a pilot project to foster engineering design education in the universities and to supplement NASA's in-house efforts in advanced planning for space and aeronautics design. Nine universities and five NASA centers participated in the first year of the pilot project. The study topics cover a broad range of potential space and aeronautics projects that could be undertaken during a 20 to 30 year period beginning with the deployment of the Space Station Freedom scheduled for the mid-1990s. Both manned and unmanned endeavors are embraced, and the systems approach to the design problem is emphasized

Aeronautical enginnering: A cumulative index to a continuing bibliography (supplement 312)

This is a cumulative index to the abstracts contained in NASA SP-7037 (301) through NASA SP-7073 (311) of Aeronautical Engineering: A Continuing Bibliography. NASA SP-7037 and its supplements have been compiled by the Center for AeroSpace Information of the National Aeronautics and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, foreign technology, contract number, report number, and accession number indexes