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George W. Woodruff School of Mechanical Engineering

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Robust Autonomous Landing of a Quadcopter on a Mobile Vehicle Using Infrared

2023-01 , Garlow, Adam , Kemp, Samuel , Skinner, Katherine A. , Kamienski, Emily , Debate, Alex , Fernandez, Joshua , Dotterweich, James , Mazumdar, Anirban , Rogers, Jonathan D.

Landing an autonomous air vehicle on a moving ground platform is an important capability for many missions but presents unique engineering challenges. This paper presents a robust autonomous landing system for unmanned aerial vehicles (UAVs) consisting of a magnetic dock and a visual servoing controller that uses a tailored set of infrared (IR) beacons. The UAV is equipped with actuated magnetic feet that allow it to “stick” to the docking pad during landing, but easily release from it during takeoff. The IR beacon array is designed so that landing can be performed in a variety of lighting and weather conditions, adding significant robustness to the system. The system is also designed to recharge the UAV battery after landing. Experimental results demonstrate that the prototype system can execute autonomous landings on a moving ground vehicle in outdoor environments at up to 4.5m/s (10 mph).

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Establishing Functional Concepts Vital for Design by Analogy

2015-10 , Tomko, Megan , Lucero, Briana , Turner, Cameron , Linsey, Julie

Student designers and professionals alike have difficulty accessing appropriate analogies for design problems. Recognizing the advantages of Design-by-Analogy (DbA), the Design-Analogy Performance Parameter System (D-APPS) tool was developed to include a library of analogy entries and a matching algorithm. These components are combined into the Design Repository & Analogy Computation via Unit-Language Analysis (DRACULA) software package that maps functions across domains in order to present analogies to designers as initiated through engineering performance metrics and critical functions. Most tools developed for DbA emphasize the searching by function feature. Since analogies are based on more than function, DRACULA incorporates both performance and function for the user to identify relevant analogous solutions. Prior to exposing engineering students to this tool, we investigated their ability to use analogies when crossing domains. During this process, we identified three function concepts to be vital for students to effectively use analogies across domains: reoccurring functions, critical functions, and mapping functions. The results establish a better understanding of the information that students utilize in order to formulate appropriate and creative analogous design solutions.

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Auto-Calibration Based Control for Independent Metering of Hydraulic Actuators

2011-05 , Opdenbosch, Patrick , Sadegh, Nader , Enes, Aaron R. , Book, Wayne J.

This paper describes a novel auto-calibration state-trajectory-based control method and its application to electronic flow control for independent metering systems. In this paper, the independent metering architecture that is considered uses five Electro-Hydraulic Poppet Valves (EHPV’s). The proposed control method is applied to four of these valves, arranged in a Wheatstone bridge configuration, to regulate the flow of hydraulic oil coming into and out of an actuator. For simplicity, the fifth valve is operated via open-loop to control the supply pressure. Experimental data presented herein demonstrate that the control method learns the valve’s conductance characteristics (i.e. the inverse input-state dynamic map of the valve) while simultaneously controlling the motion of the hydraulic actuator.

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An Excavator Simulator for Determining the Principles of Operator Efficiency for Hydraulic Multi-DOF Systems

2011-03 , Elton, Mark D. , Book, Wayne J.

This paper discusses an excavator simulator constructed to evaluate the effects of human-machine interfaces (HMIs) on operator productivity. Simulation allows for standardization of the machine and environment and is less time consuming and cheaper than implementing the controller on the machine. The simulator discussed in this paper includes a realistic graphical display that exceeds the current academic simulators, audio, and a new soil model that accounts for all possible trajectories of the bucket through the soil. Two coordinated control schemes were implemented on the simulator and preliminary tests were performed to demonstrate that the simulator can be used to evaluate HMIs.

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Secure Teleoperation Control Using Somewhat Homomorphic Encryption

2022-10 , Kosieradzki, Shane , Zhao, Xiaofeng , Kawase, Hiroki , Qiu, Yingxin , Kogiso, Kiminao , Ueda, Jun

The goal of this research is to establish control theoretic methods to enhance cyber security of networked motion control systems by utilizing somewhat homomorphic encryption. The proposed approach will encrypt the entire motion control schemes including: sensor signals, model parameters, feedback gains, and performs computation in the ciphertext space to generate motion commands to servo systems without a security hole. The paper will discuss implementation of encrypted bilateral teleoperation control schemes with nonlinear friction compensation. The paper will present (1) encrypted teleoperation control realization with somewhat homomorphic encryption and (2) simulation results.

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Tutorial: Principles and Rationale of the Fusion-Fission Hybrid Burner Reactor

2011-09-13 , Stacey, Weston M.

The potential advantages of Fusion-Fission Hybrid (FFH) reactors (relative to critical fast reactors) for closing the back end of the nuclear fuel cycle are discussed. The choices of fission and fusion technologies for FFH burner reactors that would fission the transuranics remaining in spent fuel discharged from nuclear power reactors are summarized. The conceptual design and fuel cycle performance of the SABR FFH burner reactor are presented, and a fusion power development schedule with a symbiotic dual FFH path is outlined.

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Compensation for Biodynamic Feedthrough in Backhoe Operation by Cab Vibration Control

2011-05 , Humphreys, Heather C. , Huggins, James D. , Book, Wayne J.

This research investigates and seeks to mitigate the undesirable effects of biodynamic feedthrough in backhoe operation. Biodynamic feedthrough occurs when motion of the controlled machine excites motion of the human operator, which is fed back into the control input device. This unwanted input can cause significant performance degradation, which can include limit cycles or even instability. Backhoe user interface designers indicate that this is a problem in many conventional machines, and it has also proved to degrade performance in this testbed. A particular backhoe control system, including the biodynamic feedthrough, is modeled and simulated. Cab vibration control is selected as a means to mitigate the biodynamic feedthrough effect. Two controller based methods are developed based on these models and presented, both of which use the working implement itself to reduce the cab motion. In this case, the backhoe arm has dual functionality, to perform excavation operations and to cancel cab vibration. Results show that significant reductions in cab motion can be obtained with minimal tracking performance degradation, without additional actuators.

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Communicating Materials Systems Knowledge through Processing-Structure-Properties-Performance (PSPP) Maps

2018-01 , Goulding, Ashley N. , Leung, Jonathan F.W. , Neu, Richard W.

Knowledge about the behavior of a specific materials system is concisely summarized in a Processing-Structure-Properties-Performance (PSPP) map. This is a useful tool that can effectively serve as a standard method of communication regarding the physical and chemical mechanisms that control the performance of a materials system, and gives guidance on the type of data required to accurately characterize that materials system in its entirety. This article describes a workflow to generate a map for any materials system, and then applies these steps to develop a map for Ni-base superalloy synthesized by additive manufacturing.

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Recursive Algorithm for Motion Primitive Estimation

2011-05 , Enes, Aaron R. , Book, Wayne J.

The need for knowing future manipulator motion arises in several robotics applications, including notification or avoidance of imminent collisions and real-time optimization of velocity commands. This paper presents a real-time, low overhead algorithm for identification of future manipulator motions, based on measurements of prior motions and the instantaneous sensed actuator velocity commanded by an operator. Experimental results with a human-controlled, two degree of-freedom manipulator demonstrate the ability to quickly learn and accurately estimate future manipulator motions.

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A Robust Nonlinear Observation Strategy for the Control of Flexible Manipulators

2011-05 , Post, Brian K. , Book, Wayne J.

Flexibility is often an unavoidable consequence of the desire for high speed and performance manipulators. This paper proposes a method that improves the performance of flexible manipulators through the employment of robust state estimation techniques. These techniques are based on discrete time Kalman filtering and sliding mode principles. A simple model for a single degree of freedom flexible manipulator is derived and a control scheme is chosen and implemented. The latter includes a robust non-linear estimator. Simulation and preliminary experimental results are presented that demonstrate the validity of the proposed control scheme.

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