摘要 :
Full engineering design experiences often require months to accomplish. In an effort to incorporate design, design thinking, and design innovation into curriculum without consuming extensive time, the use of shortened design exper...
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Full engineering design experiences often require months to accomplish. In an effort to incorporate design, design thinking, and design innovation into curriculum without consuming extensive time, the use of shortened design experiences, referred to as "designettes," has been undertaken. A designette can provide a partial or concentrated design experience by either removing certain parts of a full design process, or by focusing on certain steps, or both. A designette allows students various experiences with the design process that can provide a "learning scaffold" for their implementation of the full suite of design methods over the course of a longer project. Designettes likewise provide a mechanism and construct for learning multi-disciplinary technical content and skill sets. In the current educational research, the project focus of a designette was selected from one of two options: either a small, related portion of a larger project, or a totally unrelated project with respect to a larger project. The advantage of a designette being a small part of a larger project is that the time spent on the designette is directly related to the project goals of that larger project. The advantage of having an unrelated designette is that the students feel freedom to take risks and focus on creativity and innovation because they do not experience the stress related to satisfying the sponsor that comes with the larger project. Faculty and student feedback was primarily used to characterize and compare the designette's effectiveness. The current research shows that there are distinct advantages and disadvantages to having the designette project either related, or unrelated to a longer term, sponsored project, such as in a capstone experience. Those who implement designettes can use the detailed data provided in this research to determine which approach best matches their capstone program's distinctive attributes and goals.
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As time progresses, space becomes more congested with micrometeoroids and orbital debris (MMOD). This increase in debris flux poses a critical threat to satellites already in orbit, manned missions, and future orbiting spacecraft....
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As time progresses, space becomes more congested with micrometeoroids and orbital debris (MMOD). This increase in debris flux poses a critical threat to satellites already in orbit, manned missions, and future orbiting spacecraft. To reduce the operational impact of MMOD collisions, current protection schemes use Whipple Shields, an aluminum plate with a prescribed standoff distance, as the basis for protection. These aluminum shields are manufactured and installed on the space vehicle while on Earth, which constrains their size and shape, and ultimately, their effectiveness. These fixed shields also cannot be repaired if they are damaged during service. This work describes a prototype shield system that can be additively manufactured and installed while the vehicle is in orbit. This system, designed for manufacture via three-dimensional printing in space, would allow an operator to add shielding to a vehicle once in orbit, protecting it against MMOD traveling at hyper velocities. These on-orbit manufactured shields allow specific tailoring to more-efficiently and effectively meet mission requirements. CTH finite element code was used to simulate hypervelocity impacts (HVI) on computer-aided design (CAD) models of the prototypes. These simulations used structures made of analogous materials such as polycarbonate to make and evaluate new design parameters. The performance of different design parameters in simulations drove a redesign of the original prototype. These new designs were additively manufactured with ULTEM 9085, and underwent testing at a hypervelocity impact laboratory. Six prototypes were tested and successfully survived a hypervelocity projectile impact, indicating their potential effectiveness as spacecraft MMOD shielding.
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摘要 :
As time progresses, space becomes more congested with micrometeoroids and orbital debris (MMOD). This increase in debris flux poses a critical threat to satellites already in orbit, manned missions, and future orbiting spacecraft....
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As time progresses, space becomes more congested with micrometeoroids and orbital debris (MMOD). This increase in debris flux poses a critical threat to satellites already in orbit, manned missions, and future orbiting spacecraft. To reduce the operational impact of MMOD collisions, current protection schemes use Whipple Shields, an aluminum plate with a prescribed standoff distance, as the basis for protection. These aluminum shields are manufactured and installed on the space vehicle while on Earth, which constrains their size and shape, and ultimately, their effectiveness. These fixed shields also cannot be repaired if they are damaged during service. This work describes a prototype shield system that can be additively manufactured and installed while the vehicle is in orbit. This system, designed for manufacture via three-dimensional printing in space, would allow an operator to add shielding to a vehicle once in orbit, protecting it against MMOD traveling at hyper velocities. These on-orbit manufactured shields allow specific tailoring to more-efficiently and effectively meet mission requirements. CTH finite element code was used to simulate hypervelocity impacts (HVI) on computer-aided design (CAD) models of the prototypes. These simulations used structures made of analogous materials such as polycarbonate to make and evaluate new design parameters. The performance of different design parameters in simulations drove a redesign of the original prototype. These new designs were additively manufactured with ULTEM 9085, and underwent testing at a hypervelocity impact laboratory. Six prototypes were tested and successfully survived a hypervelocity projectile impact, indicating their potential effectiveness as spacecraft MMOD shielding.
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摘要 :
As time progresses, space becomes more congested with micrometeoroids and orbital debris (MMOD). This increase in debris flux poses a critical threat to satellites already in orbit, manned missions, and future orbiting spacecraft....
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As time progresses, space becomes more congested with micrometeoroids and orbital debris (MMOD). This increase in debris flux poses a critical threat to satellites already in orbit, manned missions, and future orbiting spacecraft. To reduce the operational impact of MMOD collisions, current protection schemes use Whipple Shields, an aluminum plate with a prescribed standoff distance, as the basis for protection. These aluminum shields are manufactured and installed on the space vehicle while on Earth, which constrains their size and shape, and ultimately, their effectiveness. These fixed shields also cannot be repaired if they are damaged during service. This work describes a prototype shield system that can be additively manufactured and installed while the vehicle is in orbit. This system, designed for manufacture via three-dimensional printing in space, would allow an operator to add shielding to a vehicle once in orbit, protecting it against MMOD traveling at hyper velocities. These on-orbit manufactured shields allow specific tailoring to more-efficiently and effectively meet mission requirements. CTH finite element code was used to simulate hypervelocity impacts (HVI) on computer-aided design (CAD) models of the prototypes. These simulations used structures made of analogous materials such as polycarbonate to make and evaluate new design parameters. The performance of different design parameters in simulations drove a redesign of the original prototype. These new designs were additively manufactured with ULTEM 9085, and underwent testing at a hypervelocity impact laboratory. Six prototypes were tested and successfully survived a hypervelocity projectile impact, indicating their potential effectiveness as spacecraft MMOD shielding.
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The United States Air Force Academy Department of Mechanical Engineering has nearly two decades of experience executing senor capstone design projects that pursue technology solutions to real-world warfighting needs. This program ...
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The United States Air Force Academy Department of Mechanical Engineering has nearly two decades of experience executing senor capstone design projects that pursue technology solutions to real-world warfighting needs. This program operates in collaboration with Department of Defense (DoD) sponsors who provide challenging design problems often including aerospace systems, and who desire novel solutions that might not otherwise be proposed by career engineers. Department faculty deliver a curriculum in design engineering that encourages and facilitates innovative thinking, and many of the capstone projects have resulted in publications and/or patents. In this work, this curriculum and innovative design process are described in the context of one the latest projects; to develop a device that covertly transports and attaches a payload to a vehicle at least 500 feet away. This capstone team consisted of four students in their final year of their engineering programs. The team completed several concept generation methods and other design activities to develop a novel solution: To disguise a remote-controlled robot as a piece of trash on the ground that could drive itself underneath a truck and attach itself. A tubular design was selected to disguise the robot as a piece of trash because cans and water bottles are common around the world. The proposed concept device was fully designed, analyzed, prototyped and successfully tested during the nine month academic year.
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Flapping wing Micro Air Vehicles (MAV's) continues to be a growing field, with ongoing research into unsteady, low Re aerodynamics, micro-fabrication, and fluid-structure interaction. However, research into flapping wing control o...
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Flapping wing Micro Air Vehicles (MAV's) continues to be a growing field, with ongoing research into unsteady, low Re aerodynamics, micro-fabrication, and fluid-structure interaction. However, research into flapping wing control of such MAVs continues to lag. Existing research uniformly consists of proposed control laws that are validated by computer simulations of quasi-steady blade element formulae. Such simulations use numerous assumptions and cannot be trusted to fully describe the flow physics. Instead, such control laws must be validated on hardware. In earlier work, a novel control technique called Bi-harmonic Amplitude and Bias Modulation (BABM) was proposed and tested on a MAV prototype, but the results were inconclusive. In this work, an improved prototype is developed and tested on a 6-component force/torque balance. These experiments verified that the prototype can generate uncoupled forces and moments for motion in five degrees of freedom when using the BABM control technique, and that these forces can be reasonably predicted by the blade-element formulae. Finally, the prototype performed preliminary controlled flight in tethered experiments, further demonstrating the feasibility of BABM.
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摘要 :
Flapping wing Micro Air Vehicles (MAV's) continues to be a growing field, with ongoing research into unsteady, low Re aerodynamics, micro-fabrication, and fluid-structure interaction. However, research into flapping wing control o...
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Flapping wing Micro Air Vehicles (MAV's) continues to be a growing field, with ongoing research into unsteady, low Re aerodynamics, micro-fabrication, and fluid-structure interaction. However, research into flapping wing control of such MAVs continues to lag. Existing research uniformly consists of proposed control laws that are validated by computer simulations of quasi-steady blade element formulae. Such simulations use numerous assumptions and cannot be trusted to fully describe the flow physics. Instead, such control laws must be validated on hardware. In earlier work, a novel control technique called Bi-harmonic Amplitude and Bias Modulation (BABM) was proposed and tested on a MAV prototype, but the results were inconclusive. In this work, an improved prototype is developed and tested on a 6-component force/torque balance. These experiments verified that the prototype can generate uncoupled forces and moments for motion in five degrees of freedom when using the BABM control technique, and that these forces can be reasonably predicted by the blade-element formulae. Finally, the prototype performed preliminary controlled flight in tethered experiments, further demonstrating the feasibility of BABM.
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The frequency response of a Micro Air Vehicle wing flapping actuator to non-harmonic forcing is measured and improved. These forcing functions are split-cycle, constant period frequency modulated inputs that have been proposed for...
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The frequency response of a Micro Air Vehicle wing flapping actuator to non-harmonic forcing is measured and improved. These forcing functions are split-cycle, constant period frequency modulated inputs that have been proposed for control of flapping wing vehicles. The non-harmonic actuator input was generated by a dSpace system running Simulink while the actuator's response was measured with a single axis laser vibrometer. Initially, the actuator was unable to track the non-harmonic trajectory at frequencies approaching resonance. This is a result of high frequency content present in the piecewise split-cycle waveform being amplified by the actuator's dynamics. To improve this response, discrete harmonic plant compensation was used to precondition the input signal based on the actuator's frequency response function. When driven with this preconditioned input, the actuator demonstrated the desired non-harmonic trajectory even while flapping at resonance. These results suggest that it is possible to flap MAV wings with non-harmonic trajectories at resonance, paving the way for the control of flapping wing MAVs with simple, 1-DOF wings.
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Unmanned systems are proliferating into increasingly difficult operational environments, especially indoors, where navigation, locomotion and communication are all challenged. With increasing capabilities, unmanned systems are bei...
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Unmanned systems are proliferating into increasingly difficult operational environments, especially indoors, where navigation, locomotion and communication are all challenged. With increasing capabilities, unmanned systems are being considered for even the most difficult missions, such as breaching and exploring subterranean spaces, which may encompass a range of challenging, underground facilities. In this work, the development of an unmanned ground vehicle is described which includes a unique ability to launch small articles that can increase access into otherwise secured regions. The proposed system is equipped with Red-Green-Blue-Depth cameras for visual navigation and obstacle avoidance to explore underground facilities, and a spring loaded cannon to identify and infiltrate personnel doors. An algorithm is included to identify doors, position the robot appropriately in front of the door, calculate a trajectory, and place the article at the desired location on the door. A prototype of the proposed system was developed and, in testing, demonstrated all of the critical functions.
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Unmanned aerial systems have become common in modern life, but many rely heavily on teleoperation and external sensors, such as Global Positioning System (GPS) information. Numerous potential applications exist for indoor UAS oper...
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Unmanned aerial systems have become common in modern life, but many rely heavily on teleoperation and external sensors, such as Global Positioning System (GPS) information. Numerous potential applications exist for indoor UAS operation, but additional advances in autonomy are required to realize these. In this work, a proven estimator and controller are modified to accept updated hardware and augmented with an adaptive controller and autonomous landing algorithm. These additional features will facilitate a larger system-of-systems to place relay-sensor devices throughout an underground facility and to perform indoor surveillance. In testing, both the adaptive controller and auto-landing algorithms performed successfully. This work ultimately demonstrates the feasibility of red, green, blue, depth cameras to provide reliable state estimates and position information to support additional autonomous behaviors for UAS in the conduct of indoor exploration.
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