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This paper presents a model-based approach for wind velocity estimation from the motion of a multirotor unmanned aircraft systems (UAS) in vertical ascent. A state estimation framework is adapted to a set of closed-loop rigid body...
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This paper presents a model-based approach for wind velocity estimation from the motion of a multirotor unmanned aircraft systems (UAS) in vertical ascent. A state estimation framework is adapted to a set of closed-loop rigid body models identified for a 3DR Solo quadrotor for ascent steady velocities ranging between 0 and 2 m/s. The closed-loop models used for wind velocity estimation were identified from input-output measurements using system identification algorithms for model structure determination and parameter estimation. Results from an analysis of collinearity, a decomposition of parameter variance, and flight validation were used to assess the quality of each identified model. The effectiveness of model-based wind inference from quadrotor motion in vertical ascent was experimentally validated at Virginia Tech's Kentland Experimental Aerial Systems (KEAS) Laboratory through flight testing conducted next to two separate SoDAR sensors and a 2-D sonic anemometer mounted on a 10-m tower.
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摘要 :
This paper presents a model-based approach for wind velocity estimation from the motion of a multirotor unmanned aircraft systems (UAS) in vertical ascent. A state estimation framework is adapted to a set of closed-loop rigid body...
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This paper presents a model-based approach for wind velocity estimation from the motion of a multirotor unmanned aircraft systems (UAS) in vertical ascent. A state estimation framework is adapted to a set of closed-loop rigid body models identified for a 3DR Solo quadrotor for ascent steady velocities ranging between 0 and 2 m/s. The closed-loop models used for wind velocity estimation were identified from input-output measurements using system identification algorithms for model structure determination and parameter estimation. Results from an analysis of collinearity, a decomposition of parameter variance, and flight validation were used to assess the quality of each identified model. The effectiveness of model-based wind inference from quadrotor motion in vertical ascent was experimentally validated at Virginia Tech's Kentland Experimental Aerial Systems (KEAS) Laboratory through flight testing conducted next to two separate SoDAR sensors and a 2-D sonic anemometer mounted on a 10-m tower.
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System identification of a nonlinear aerodynamic model was conducted on a fixed-wing, small unmanned aircraft using flight test data. A flight test experiment was designed and conducted including remotely piloted and automated con...
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System identification of a nonlinear aerodynamic model was conducted on a fixed-wing, small unmanned aircraft using flight test data. A flight test experiment was designed and conducted including remotely piloted and automated conventional and advanced flight test maneuvers. Flight test techniques were developed for implementing the novel remote uncorrelated pilot input excitation and lessons learned are documented here. Results from the models developed from various input techniques were compared. Time-domain analysis techniques were used with equation-error methods for model structure development and output-error methods for parameter estimation. The aerodynamic models developed using various input types were validated with independently collected flight test data from automated maneuvers with different input waveforms. These validation results allow qualitative and quantitative comparisons of the system identification outcomes using the various excitation methods.
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This paper describes methods to identify an integrated propulsion-airframe aerodynamic model and a decoupled propulsion model for fixed-wing aircraft with propellers using flight data. Propulsion aerodynamics and airframe aerodyna...
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This paper describes methods to identify an integrated propulsion-airframe aerodynamic model and a decoupled propulsion model for fixed-wing aircraft with propellers using flight data. Propulsion aerodynamics and airframe aerodynamics for propeller aircraft are usually modeled separately, which fails to describe unavoidable interaction effects and propeller performance deviations when integrated on an aircraft. Two novel flight test system identification approaches are presented to develop flight dynamics models with improved characterization of propeller aerodynamics compared to conventional methods. Orthogonal phase-optimized multisine inputs are applied to both the control surfaces and propulsion system to generate data with high-quality information content for model identification. Propulsion explanatory variables derived from propeller aerodynamics theory combined with traditional aircraft modeling variables yield accurate aero-propulsive modeling results and provide propeller performance estimates which are compared to isolated propeller wind tunnel data. An assessment of model adequacy using flight maneuvers withheld from model identification indicates that the models have good prediction capability. The paper describes application of these methods to a small unmanned aircraft, but the methods are generalizable to many propeller-driven aircraft.
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A nonlinear energy-based control law was flight tested on a small, fixed-wing unmanned aircraft. This paper summarizes the selected aircraft, instrumentation system, data processing techniques, system identification methods, and t...
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A nonlinear energy-based control law was flight tested on a small, fixed-wing unmanned aircraft. This paper summarizes the selected aircraft, instrumentation system, data processing techniques, system identification methods, and the control laws that were implemented. The flight test campaign used a build up approach with increasingly complex computer generated system identification excitations and then increasingly complex control laws. This build up approach allowed the team to overcome technical challenges in a progressive manner and then finally test an advanced nonlinear control law in flight. Automated multistep, frequency sweep, and multisine excitation inputs were implemented for system identification. System identification methods were leveraged to develop linear and nonlinear aerodynamic models. A servoactuator model was developed from ground test data and data processing techniques were used to condition the flight test data for analysis. A proportional-derivative attitude commanded system was implemented and tuned using pilot comments, without the use of an a priori model. A linear quadratic regulator was tuned using the linear aerodynamic model, and refined during flight tests to improve handling qualities. A port-Hamiltonian energy-based nonlinear control law was tuned in simulation using the nonlinear model, and gains refined during flight tests to improve directional tracking and perturbation response. Implementation techniques for automated system identification maneuvers, as well as feedback control using a Pixhawk and Raspberry Pi co-computer are documented and made available by means of a publicly accessible web repository. Flight test results illustrate the utility of the experimental data collection and analysis methods for testing advanced flight control schemes.
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We consider the problem of inferring wind velocity from the perturbations induced in the motion of an autopilot-controlled quadrotor. Three aircraft motion models are presented which can be used for model-based wind velocity estim...
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We consider the problem of inferring wind velocity from the perturbations induced in the motion of an autopilot-controlled quadrotor. Three aircraft motion models are presented which can be used for model-based wind velocity estimation: a kinematic particle model, a dynamic particle model, and a rigid body model. Here, we focus on the two particle models, using wind tunnel and flight test data to identify motion model parameters in order to infer wind velocity from measurements obtained in field experiments. Wind tunnel tests of a single quadrotor thruster are used to create a thrust model for the vehicle. To develop this model, the force and moment acting on a single electric thruster with an 8-inch, 2-blade propeller was measured in Virginia Tech's 0.7m Open Jet Wind Tunnel while varying three parameters: angle of flow, flow speed, and propeller spin rate. Data for quadrotor motion model parameter identification were collected in flight tests performed at Virginia Tech. The quadrotor was flown at several steady speeds and at constant altitude in order to relate the (steady) air-relative speed to the tilt attitude and the lateral component of thrust. Finally, wind velocity estimation experiments were performed at Innisfree, Virginia in close proximity to a sonic anemometer mounted atop a 10 meter tower.
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摘要 :
We consider the problem of inferring wind velocity from the perturbations induced in the motion of an autopilot-controlled quadrotor. Three aircraft motion models are presented which can be used for model-based wind velocity estim...
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We consider the problem of inferring wind velocity from the perturbations induced in the motion of an autopilot-controlled quadrotor. Three aircraft motion models are presented which can be used for model-based wind velocity estimation: a kinematic particle model, a dynamic particle model, and a rigid body model. Here, we focus on the two particle models, using wind tunnel and flight test data to identify motion model parameters in order to infer wind velocity from measurements obtained in field experiments. Wind tunnel tests of a single quadrotor thruster are used to create a thrust model for the vehicle. To develop this model, the force and moment acting on a single electric thruster with an 8-inch, 2-blade propeller was measured in Virginia Tech's 0.7m Open Jet Wind Tunnel while varying three parameters: angle of flow, flow speed, and propeller spin rate. Data for quadrotor motion model parameter identification were collected in flight tests performed at Virginia Tech. The quadrotor was flown at several steady speeds and at constant altitude in order to relate the (steady) air-relative speed to the tilt attitude and the lateral component of thrust. Finally, wind velocity estimation experiments were performed at Innisfree, Virginia in close proximity to a sonic anemometer mounted atop a 10 meter tower.
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Disturbance estimation can be used to to characterize the dynamics of an environment or to improve control system performance by compensating for undesired, unmeasured inputs. This paper considers the application of disturbance es...
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Disturbance estimation can be used to to characterize the dynamics of an environment or to improve control system performance by compensating for undesired, unmeasured inputs. This paper considers the application of disturbance estimation for a small unmanned aircraft system that is used as a wind sensor. The aircraft's small mass and high wing loading make it sensitive to environmental disturbances, but the aircraft motion is not well modeled as a linear system suggesting that the disturbance observer should be based on a nonlinear dynamic model. In this paper, a newly developed nonlinear-model-based disturbance observer is applied to the task of estimating the disturbance force and moment on a small fixed-wing aircraft. The disturbance observer is demonstrated using simulations of a small aircraft subject to deterministic disturbances and to atmospheric turbulence.
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Disturbance estimation can be used to to characterize the dynamics of an environment or to improve control system performance by compensating for undesired, unmeasured inputs. This paper considers the application of disturbance es...
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Disturbance estimation can be used to to characterize the dynamics of an environment or to improve control system performance by compensating for undesired, unmeasured inputs. This paper considers the application of disturbance estimation for a small unmanned aircraft system that is used as a wind sensor. The aircraft's small mass and high wing loading make it sensitive to environmental disturbances, but the aircraft motion is not well modeled as a linear system suggesting that the disturbance observer should be based on a nonlinear dynamic model. In this paper, a newly developed nonlinear-model-based disturbance observer is applied to the task of estimating the disturbance force and moment on a small fixed-wing aircraft. The disturbance observer is demonstrated using simulations of a small aircraft subject to deterministic disturbances and to atmospheric turbulence.
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One of the most enticing targets for space exploration is Europa. It is widely believed that there is an ocean of liquid water, perhaps a hundred kilometers deep, a few kilometers beneath Europa's icy surface. The conditions in th...
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One of the most enticing targets for space exploration is Europa. It is widely believed that there is an ocean of liquid water, perhaps a hundred kilometers deep, a few kilometers beneath Europa's icy surface. The conditions in this ocean are likely similar to Earth's oceans. Furthermore, the ocean floor may have hydrothermal vents, providing energy and elements necessary for life. Therefore, Europa is considered one of the most likely locations beyond Earth and within the solar system for extant life. In this paper, detailed analysis of the primary engineering challenges of a mission to explore the ocean on Europa is presented. Candidate system designs and a timeline, or "roadmap," for the development of these systems is then discussed. A range of mission architectures are presented and evaluated relative to the various science objectives that an Europan exploration mission might address. In order to compare the various architectures, a value system has been designed following an analytical hierarchy process. Lastly, a science traceability matrix for the proposed mission is evaluated.
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