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Dynamic soaring (DS) is a bio-inspired flight maneuver in which energy can be gained by flying through regions of vertical wind gradient such as wind shear. With reinforcement learning (RL) an agent can learn to control a fixed wi...
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Dynamic soaring (DS) is a bio-inspired flight maneuver in which energy can be gained by flying through regions of vertical wind gradient such as wind shear. With reinforcement learning (RL) an agent can learn to control a fixed wing unmanned aerial vehicle (UAV) to perform DS maneuvers optimally for a variety of wind shear conditions. To accomplish this task a 6-degrees-of-freedom (6D0F) flight simulation environment, derived from an off-the-shelf unmanned aerobatic glider, was developed in MATLAB and Simulink. A complete aerodynamic model of the UAV was constructed from a combination of high-fidelity Reynolds-Averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) and low-fidelity vortex lattice (VLM) method. Deep Deterministic Policy Gradient (DDPG), an actor-critic RL algorithm, was used to train a closed-loop Path-Following (PF) agent and an Unguided Energy-Seeking (UES) agent. The PF agent controls the climb and turn rate of the UAV to follow a closed-loop waypoint path with variable altitude. This must be paired with a waypoint optimizing agent to perform loitering DS. The UES agent was designed to perform traveling DS in a fixed wind shear condition. It was proven to extract energy from the wind shear to extend flight time during training but did not accomplish sustainable dynamic soaring. Further development is required for both agents to perform dynamic soaring in variable wind shear conditions.
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Aeroelastic flutter is a dangerous phenomena that occurs when aerodynamic forces and moments interact with the flexible structural dynamics to cause unstable oscillations. The traditional way of preventing flutter from happening i...
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Aeroelastic flutter is a dangerous phenomena that occurs when aerodynamic forces and moments interact with the flexible structural dynamics to cause unstable oscillations. The traditional way of preventing flutter from happening is using passive methods like structural stiffening. These methods generally add extra weight to the aircraft hence decreasing its performance. Methods for suppressing flutter using active controls have been developed however due to the flight risks associated with flutter, they haven't been tested effectively. By developing a safe and accurate research platform that can resemble a conventional aircraft, great advances can be made in this field. Therefore a UAV with a conventional configuration and flexible structural properties in the lifting surfaces is used in this research to study flutter. Necessary sensors and avionics were placed on the aircraft to measure the desired variables. Ground and flight tests were conducted to identify the rigid and flexible body dynamics. The rigid body model was identified with flight data whereas the structural modes have been identified from ground tests. The next step for this research is to design flight experiments that will identify the flexible dynamics in-flight.
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摘要 :
Aeroelastic flutter is a dangerous phenomena that occurs when aerodynamic forces and moments interact with the flexible structural dynamics to cause unstable oscillations. The traditional way of preventing flutter from happening i...
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Aeroelastic flutter is a dangerous phenomena that occurs when aerodynamic forces and moments interact with the flexible structural dynamics to cause unstable oscillations. The traditional way of preventing flutter from happening is using passive methods like structural stiffening. These methods generally add extra weight to the aircraft hence decreasing its performance. Methods for suppressing flutter using active controls have been developed however due to the flight risks associated with flutter, they haven't been tested effectively. By developing a safe and accurate research platform that can resemble a conventional aircraft, great advances can be made in this field. Therefore a UAV with a conventional configuration and flexible structural properties in the lifting surfaces is used in this research to study flutter. Necessary sensors and avionics were placed on the aircraft to measure the desired variables. Ground and flight tests were conducted to identify the rigid and flexible body dynamics. The rigid body model was identified with flight data whereas the structural modes have been identified from ground tests. The next step for this research is to design flight experiments that will identify the flexible dynamics in-flight.
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With an increase in interest in human missions, engineers are looking towards the outer solar system for human-grade missions. However, there is a great leap for humans to make in order to travel to the outer solar system. Mission...
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With an increase in interest in human missions, engineers are looking towards the outer solar system for human-grade missions. However, there is a great leap for humans to make in order to travel to the outer solar system. Mission ECHO proposes a long-term crewed mission to the dwarf planet, Ceres. This mission examines the feasibility of long-term manned missions far from Earth by using new and innovative technologies. This paper outlines the practicality of each technology used in the mission and how it can benefit the astronauts. While the astronauts are on the surface of Ceres, they will focus on exploration and examination of the Ceres terrain. This will be the first step toward in-situ resource utilization of the dwarf planet, which can assist in future missions to Ceres or the outer solar system. Additionally, the technologies and techniques proposed in this mission focus on preserving the mental and physical health of the crew for the duration of the mission. This mission utilizes new and innovative technologies such as a nuclear thermal propulsion system, an advanced inflatable habitation module for both in-orbit and surface operations, a self-sufficient life support system using an Astofarm, optical communication systems, and more to expand our understanding of the composition and history of Ceres and further humanity's journey in deep space exploration.
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We address the development of a dynamic-soaring (DS) capable unmanned aerial vehicle (UAV) optimized for long-duration flight with minimal on-board power consumption. In order to perform DS without engine thrust, our aerodynamic m...
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We address the development of a dynamic-soaring (DS) capable unmanned aerial vehicle (UAV) optimized for long-duration flight with minimal on-board power consumption. In order to perform DS without engine thrust, our aerodynamic model had to be significantly improved. Multiple wind-shear scenarios were created to study the overall energy gain in the DS maneuver. The feasibility of low and high-altitude DS is discussed. DS was performed both manually by pilot control and autonomously by autopilot control. The efficiency of the autopilot control laws is compared with human-piloted DS cycles. The current paper thus focuses on the UAV's energy neutrality in performing dynamic soaring cycles.
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Scientific payloads preparation and testing is an expensive and technically challenging task. Suborbital spaceflights provide a unique opportunity for researchers to test their scientific experiments and gather data at low costs w...
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Scientific payloads preparation and testing is an expensive and technically challenging task. Suborbital spaceflights provide a unique opportunity for researchers to test their scientific experiments and gather data at low costs with rapid turnaround times. The purpose of this study is to provide a benchmark of the testing process for several demanding scientific payloads planned aboard PLD Space's MIURA-1 rocket in 2022. The initial research conducted in the development and integration of the proposed experiments highlights the complexities and challenges of this demanding setup of experimental payloads, which will allow prospective researchers to optimize their protocols and minimize unforeseen incidents during suborbital flights. The first payload consists of the Magneto-Active Propellant Management Device (MAPMD) used as a proof-of-concept to demonstrate the slosh-suppression effectiveness of the device under continuous microgravity for about 4 minutes which has been tested in lab settings under 1g conditions. A dual telemetry package payload will be housed with a redundant suite of sensors to monitor and characterize the environment inside the rocket's payload compartment. Another experiment is comprised of a bio-printing technology targeted to recreate the 3D tumor microenvironment consisting of aggressive phenotypes of breast and colon cancer cells surrounded by the endothelial cells layer. The goal of this experiment is to test cell behavior under various flight stressors and investigate whether these manipulations force cells to migrate faster through the endothelial barrier leading to an acquisition of more distinctive characteristics than compared to ground controls.
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The work presented in this paper focuses on the design of an attitude determination and control subsystem (ADCS) for a proximity operation and imaging satellite mission. The ARAPAIMA (Application for Resident Space Object Proximit...
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The work presented in this paper focuses on the design of an attitude determination and control subsystem (ADCS) for a proximity operation and imaging satellite mission. The ARAPAIMA (Application for Resident Space Object Proximity Analysis and IMAg-ing) mission is carried out by a 6U CubeSat class satellite equipped with a warm gas propulsion system. The propulsion system comprises a set of 16 reaction control system (RCS) thrusters, of 25 mN each, installed in pairs that generate torques about each of the satellite body axes and provide up to 100mN of thrust in two directions for orbital maneuvering. The thrust of the RCS thrusters can be modulated over the entire range in steps of 1% due to rapid solenoid valve actuation. The requirement of the control system is to provide pointing control accuracy of 1 arcmin at 3 σ in the desired imaging direction. The ADCS employs two control laws. One control law, for large angle maneuvers, implements eigenaxis maneuvering and the other, for accurate pointing, is implemented with PID controllers about each body axis. Simulations performed for tracking the resident space object flying in a circular orbit of 500 km altitude from a relative orbit of 250 m are used to test the performance of the ADCS. A comparison between a "traditional" ADCS system with reaction wheels and RCS thrusters for their off-loading, and a system with only RCS thrusters has been performed. The accuracy of the pointing is comparable, the pointing performance as well as the propellant usage for both options are further discussed in the paper. The integration of both controllers within the ADCS and switching are also discussed.
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The work presented in this paper focuses on the design of an attitude determination and control subsystem (ADCS) for a proximity operation and imaging satellite mission. The ARAPAIMA (Application for Resident Space Object Proximit...
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The work presented in this paper focuses on the design of an attitude determination and control subsystem (ADCS) for a proximity operation and imaging satellite mission. The ARAPAIMA (Application for Resident Space Object Proximity Analysis and IMAg-ing) mission is carried out by a 6U CubeSat class satellite equipped with a warm gas propulsion system. The propulsion system comprises a set of 16 reaction control system (RCS) thrusters, of 25 mN each, installed in pairs that generate torques about each of the satellite body axes and provide up to 100mN of thrust in two directions for orbital maneuvering. The thrust of the RCS thrusters can be modulated over the entire range in steps of 1% due to rapid solenoid valve actuation. The requirement of the control system is to provide pointing control accuracy of 1 arcmin at 3 σ in the desired imaging direction. The ADCS employs two control laws. One control law, for large angle maneuvers, implements eigenaxis maneuvering and the other, for accurate pointing, is implemented with PID controllers about each body axis. Simulations performed for tracking the resident space object flying in a circular orbit of 500 km altitude from a relative orbit of 250 m are used to test the performance of the ADCS. A comparison between a "traditional" ADCS system with reaction wheels and RCS thrusters for their off-loading, and a system with only RCS thrusters has been performed. The accuracy of the pointing is comparable, the pointing performance as well as the propellant usage for both options are further discussed in the paper. The integration of both controllers within the ADCS and switching are also discussed.
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The use of Linearized Euler Equations for direct prediction of supersonic jet noise issued from a rectangular nozzle is explored and noise directivity is compared with the previous traditional approaches of Large-Eddy Simulations ...
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The use of Linearized Euler Equations for direct prediction of supersonic jet noise issued from a rectangular nozzle is explored and noise directivity is compared with the previous traditional approaches of Large-Eddy Simulations accompanied with Ffowcs-Williams Hawkings method. A new versatile Linearized Euler Equations solver is developed using the OpenFOAM API named "leeFoam". Special treatment of boundary reflections such as implementation of non-reflecting boundary condition along with a sponge zone is introduces. Artificial Acoustic Damping is implemented as a source term to prevent spurious numerical instabilities. It is shown that a finite-volume numerical scheme coupled with proper boundary treatment can produce a stable solution nearly free from reflections. Verification is conducted against analytical results for the propagation of an acoustic pulse in uniform flow. Applicability of this approach to real jets is explored by taking the inflow disturbances to be related to the fundamental frequency of jet and comparing with experimentally measured noise.
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The objective of the current work is the development and comparative analysis of a novel, nonlinear, robust, closed-loop control of airfoil boundary-layer transition employing local dynamic surface modification as part of the cont...
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The objective of the current work is the development and comparative analysis of a novel, nonlinear, robust, closed-loop control of airfoil boundary-layer transition employing local dynamic surface modification as part of the control system design. Two approaches in the closed-loop control of the boundary-layer instability waves are examined including both the linear and nonlinear controller designs. The effectiveness of the implemented feedback-loop flow control strategies is examined vis-a-vie the reduced-order descriptions of the flow states on which the controller designs are grounded. Particularly, in the nonlinear robust control approach, the flow states in the selected flow control window are extracted by means of the reduced-order model (ROM) based on proper orthogonal decomposition (POD) of flow solutions obtained from high-fidelity simulations for the selected benchmark case study. Various issues related to the effective implementation of the POD-ROM based control strategy are addressed and will be further investigated.
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