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- Remote sensing by radar (21)
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- Antenna arrays (5)
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Articles 1 - 30 of 260
Full-Text Articles in Engineering
Assuring Netlist-To-Bitstream Equivalence Using Physical Netlist Generation And Structural Comparison, Reilly Mckendrick, Jeffrey Goeders, Keenan Faulkner
Assuring Netlist-To-Bitstream Equivalence Using Physical Netlist Generation And Structural Comparison, Reilly Mckendrick, Jeffrey Goeders, Keenan Faulkner
Faculty Publications
Hardware netlists are generally converted into a bitstream and loaded onto an FPGA board through vendor-provided tools. Due to the proprietary nature of these tools, it is up to the designer to trust the validity of the design’s conversion to bitstream. However, motivated attackers may alter the CAD tools’ integrity or manipulate the stored bitstream with the intent to disrupt the functionality of the design. This paper proposes a new method to prove functional equivalence between a synthesized netlist, and the produced FPGA bitstream. The novel approach is comprised of two phases: first, we show how we can utilize implementation …
Leveraging Fpga Primitives To Improve Word Reconstruction During Netlist Reverse Engineering, Reilly Mckendrick, Corey Simpson, Brent Nelson, Jeffrey Goeders
Leveraging Fpga Primitives To Improve Word Reconstruction During Netlist Reverse Engineering, Reilly Mckendrick, Corey Simpson, Brent Nelson, Jeffrey Goeders
Faculty Publications
While attempting to perform hardware trojan detection, or other low-level design analyses, it is often necessary to inspect and understand the gate-level netlist of an implemented hardware design. Unfortunately this process is challenging, as at the physical level, the design does not contain any hierarchy, net names, or word groupings. Previous work has shown how gate-level netlists can be analyzed to restore high-level circuit structures, including reconstructing multi-bit signals, which aids a user in understanding the behavior of the design. In this work we explore improvements to the word reconstruction process, specific to FPGA platforms. We demonstrate how hard-block primitives …
Nonlinear Trajectory Tracking Control For Winged Evtol Uavs, Jacob Willis, Randal W. Beard
Nonlinear Trajectory Tracking Control For Winged Evtol Uavs, Jacob Willis, Randal W. Beard
Faculty Publications
Current control methods for winged eVTOL UAVs consider the vehicle primarily as a fixed-wing aircraft with the addition of vertical thrust used only during takeoff and landing. These methods provide good long-range flight handling but fail to consider the full dynamics of the vehicle for tracking complex trajectories. We present a trajectory tracking controller for the full dynamics of a winged eVTOL UAV in hover, fixed-wing, and partially transitioned flight scenarios. We show that in low- to moderate-speed flight, trajectory tracking can be achieved using a variety of pitch angles. In these conditions, the pitch of the vehicle is a …
Pitch And Thrust Allocation For Full-Flight-Regime Control Of Winged Evtol Uavs, Jacob B. Willis, Randal W. Beard
Pitch And Thrust Allocation For Full-Flight-Regime Control Of Winged Evtol Uavs, Jacob B. Willis, Randal W. Beard
Faculty Publications
Trajectory tracking control for winged eVTOL aircraft is complicated by the high-angle-of-attack aerodynamics experienced during navigational flight occurring immediately after takeoff and immediately before landing. The total energy use of the vehicle can be reduced and the control performance can be improved by appropriately considering the pitch angle of the vehicle in varying flight conditions. We present a review of high-angle-of-attack aerodynamic models as well as an algorithm for finding the optimal pitch and thrust of a winged eVTOL throughout its flight regime. We show simulation results demonstrating a 75% reduction in tracking error over our previous work while maintaining …
Relative Navigation: A Keyframe-Based Approach For Observable Gps-Degraded Navigation, David O. Wheeler, Daniel P. Koch, James S. Jackson, Timothy W. Mclain, Randal W. Beard
Relative Navigation: A Keyframe-Based Approach For Observable Gps-Degraded Navigation, David O. Wheeler, Daniel P. Koch, James S. Jackson, Timothy W. Mclain, Randal W. Beard
Faculty Publications
State estimation for micro air vehicles (MAVs) often depends heavily on reliable global measurements such as GPS. When global measurements are unavailable, additional sensors, such as cameras or laser scanners, are commonly used to provide measurements of the MAV’s translation and rotation relative to a previously observed keyframe image or scan. With the use of only relative sensors, however, the global position and heading of the vehicle are unobservable and cannot be reliably reconstructed. Many existing approaches work with respect to a global reference frame, resulting in a loss of state observability. This article highlights that unobservability leads to inconsistency …
3d Printed High Density, Reversible, Chip-To-Chip Microfluidic Interconnects, Hua Gong, Adam T. Woolley, Gregory P. Nordin
3d Printed High Density, Reversible, Chip-To-Chip Microfluidic Interconnects, Hua Gong, Adam T. Woolley, Gregory P. Nordin
Faculty Publications
Our latest developments in miniaturizing 3D printed microfluidics [Gong et al., Lab Chip, 2016, 16, 2450; Gong et al., Lab Chip, 2017, 17, 2899] offer the opportunity to fabricate highly integrated chips that measure only a few mm on a side. For such small chips, an interconnection method is needed to provide the necessary world-to-chip reagent and pneumatic connections. In this paper, we introduce simple integrated microgaskets (SIMs) and controlled-compression integrated microgaskets (CCIMs) to connect a small device chip to a larger interface chip that implements world-to-chip connections. SIMs or CCIMs are directly 3D printed as part of the device …
Relative Navigation Of Autonomous Gps-Degraded Micro Air Vehicles, David O. Wheeler, Daniel P. Koch, James S. Jackson, Gary J. Ellingson, Paul W. Nyholm, Timothy W. Mclain, Randal W. Beard
Relative Navigation Of Autonomous Gps-Degraded Micro Air Vehicles, David O. Wheeler, Daniel P. Koch, James S. Jackson, Gary J. Ellingson, Paul W. Nyholm, Timothy W. Mclain, Randal W. Beard
Faculty Publications
Many current approaches for navigation of micro air vehicles (MAVs) in GPS-degraded environments use a globally-referenced state for estimation and control, even though this state is not observable when GPS is unavailable. By working with respect to a local reference frame, the relative navigation (RN) framework presented in this paper ensures that the state maintains observability and that the uncertainty remains bounded, consistent, and normally-distributed. RN further insulates flight-critical estimation and control processes from the large global updates common in GPS-degraded MAV flight. This paper provides a thorough description of the details needed to successfully implement the RN framework on …
High Density 3d Printed Microfluidic Valves, Pumps, And Multiplexers, Hua Gong, Adam T. Woolley, Gregory P. Nordin
High Density 3d Printed Microfluidic Valves, Pumps, And Multiplexers, Hua Gong, Adam T. Woolley, Gregory P. Nordin
Faculty Publications
In this paper we demonstrate that 3D printing with a Digital Light Processor stereolithographic (DLP-SLA) 3D printer can be used to create high density microfluidic devices with active components such as valves and pumps. Leveraging our previous work on optical formulation of inexpensive resins (RSC Adv. 5, 106621, 2015), we demonstrate valves with only 10% of the volume of our original 3D printed valves (Biomicrofluidics 9, 016501, 2015), which were already the smallest that have been reported. Moreover, we show that inclusion of a thermal initiator in the resin formulation along with a post-print bake can dramatically improve the durability …
Optical Approach To Resin Formulation For 3d Printed Microfluidics, Hua Gong, Michael Beauchamp, Steven Perry, Adam T. Woolley, Gregory P. Nordin
Optical Approach To Resin Formulation For 3d Printed Microfluidics, Hua Gong, Michael Beauchamp, Steven Perry, Adam T. Woolley, Gregory P. Nordin
Faculty Publications
Microfluidics imposes different requirements on 3D printing compared to many applications because the critical features for microfluidics consist of internal microvoids. Resins for general 3D printing applications, however, are not necessarily formulated to meet the requirements of microfluidics and minimize the size of fabricated voids. In this paper we use an optical approach to guide custom formulation of resins to minimize the cross sectional size of fabricated flow channels as exemplars of such voids. We focus on stereolithgraphy (SL) 3D printing with Digital Light Processing (DLP) based on a micromirror array and use a commercially available 3D printer. We develop …
Phase 1 Final Report: Preamble Assisted Equalization For Aeronautical Telemetry (Paq), Michael Rice, Mohammad Saquib, Arlene Cole-Rhodes, Farzad Moazzami, Erik Perrins
Phase 1 Final Report: Preamble Assisted Equalization For Aeronautical Telemetry (Paq), Michael Rice, Mohammad Saquib, Arlene Cole-Rhodes, Farzad Moazzami, Erik Perrins
Faculty Publications
This is the Phase 1 report for Preamble Assisted Equalization for Aeronautical Telemetry (PAQ).
Executive Summary:
To fully leverage the benefits of a periodically inserted preamble, the preamble is used to estimate the state of the channel. To this end the following algorithms have been developed, tested in simulation, and ported to the GPU-based real-time system:
1. The preamble detector, which scans the received samples searching for the presence of the preamble. The location of the preamble in the received samples is required to use the received samples to estimate the frequency offset, channel impulse response, and noise variance. The …
Microfluidic Valves Made From Polymerized Polyethylene Glycol Diacrylate, Gregory P. Nordin
Microfluidic Valves Made From Polymerized Polyethylene Glycol Diacrylate, Gregory P. Nordin
Faculty Publications
Pneumatically actuated, non-elastomeric membrane valves fabricated from polymerized polyethylene glycol diacrylate (poly-PEGDA) have been characterized for temporal response, valve closure, and long-term durability. A ∼100 ms valve opening time and a ∼20 ms closure time offer valve operation as fast as 8 Hz with potential for further improvement. Comparison of circular and rectangular valve geometries indicates that the surface area for membrane interaction in the valve region is important for valve performance. After initial fabrication, the fluid pressure required to open a closed circular valve is ∼50 kPa higher than the control pressure holding the valve closed. However, after ∼1000 …
Analysis Of An Improved Imu-Based Observer For Multirotor Helicopters, John Charles Macdonald, Robert C. Leishman, Randal W. Beard, Timothy W. Mclain
Analysis Of An Improved Imu-Based Observer For Multirotor Helicopters, John Charles Macdonald, Robert C. Leishman, Randal W. Beard, Timothy W. Mclain
Faculty Publications
Multirotor helicopters are increasingly popular platforms in the robotics community. Making them fully autonomous requires accurate state estimation. We review an improved dynamic model for multirotor helicopters and analyze the observability properties of an estimator based on this model. The model allows better use of IMU data to facilitate accurate state estimates even when updates from a sensor measuring position become less frequent and less accurate. We demonstrate that the position update rate can be cut in half versus typical approaches while maintaining the same accuracy. We also find that velocity estimates are at least twice as accurate no matter …
Final Report: Multipath Modeling And Mitigation Using Multiple Antennas (M4a), Michael Rice
Final Report: Multipath Modeling And Mitigation Using Multiple Antennas (M4a), Michael Rice
Faculty Publications
This report documents the effort under contract W900KK-09-C-0016. The contract comprised four phases spanning 15 April 2009 to 1 December 2012. The relationship between the effort associated with each phase and the contents of this report are as follows: Phase 1 was devoted exclusively to the channel sounding experiments with the UH-1H helicopter. The experimental setup, procedure, and results for the channel sounding experiments at Cairns Army Airfield and Patuxent River are described in Chapter 2. Good, usable data at upper L-band was captured during the Cairns Army Airfield experiments. Phase 2 was devoted to the channel sounding experiments with …
Bonding Of Polydimethylsiloxane Microfluidics To Silicon-Based Sensors, Long-Fang Tsai, William C. Dahlquist, Seunghyun Kim, Gregory P. Nordin
Bonding Of Polydimethylsiloxane Microfluidics To Silicon-Based Sensors, Long-Fang Tsai, William C. Dahlquist, Seunghyun Kim, Gregory P. Nordin
Faculty Publications
We investigate bonding polydimethylsiloxane (PDMS) to silicon using a thin (~2μm) intermediate adhesive layer stamped onto a PDMS piece prior to bonding. In particular, we compare as adhesive layers Sylgard 184 and 182 curing agents and a UV curable adhesive (NOA 75). We examine the effect of both curing temperature and duration on curing agent bond strength. Bond strengths for the different adhesives are determined by measuring the average burst pressure at a PDMS-silicon interface using a PDMS test design. We find that Sylgard 184 curing agent gives the highest bond strength with burst pressure of 700 kPa or more …
Byu Indoor Flight System Circa June 2011, John C. Macdonald, Robert Leishman
Byu Indoor Flight System Circa June 2011, John C. Macdonald, Robert Leishman
Faculty Publications
This report documents the state of our indoor flight platform as of June 2011, the time of its first flight without a human in the loop. The report is intended to give enough detail that someone might have a reasonable hope of replicating our work from scratch.
Observability Analysis Of Cooperative Localization Using Graph Theory And Lie Derivatives, Rajnikant Sharma
Observability Analysis Of Cooperative Localization Using Graph Theory And Lie Derivatives, Rajnikant Sharma
Faculty Publications
In this report we derive the observability matrix for an edge between two robots and an edge between a robot and a landmark.
Nonlinear Observability Analysis Of Bearing-Only Cooperative Localization Using Graph Theory, Rajnikant Sharma
Nonlinear Observability Analysis Of Bearing-Only Cooperative Localization Using Graph Theory, Rajnikant Sharma
Faculty Publications
In this report we investigate the nonlinear observability properties of bearing-only cooperative localization. We establish a link between observability and a graph representing measurements and communication between the robots.
Observability Analysis Of Bearing-Only Cooperative Localization, Rajnikant Sharma
Observability Analysis Of Bearing-Only Cooperative Localization, Rajnikant Sharma
Faculty Publications
In this report we investigate the nonlinear observability properties of bearing-only cooperative localization. We establish a link between observability and a graph representing measurements and communication between the robots. It is shown that graph theoretic properties like the connectivity and the existence of a path between two nodes can be used to explain the observability of the system.
Qpsk And Oqpsk In Frequency Nonselective Fading, Michael D. Rice
Qpsk And Oqpsk In Frequency Nonselective Fading, Michael D. Rice
Faculty Publications
The maximum likelihood estimator for the fading gain in a frequency non-selective fading channel is derived and analyzed for offset QPSK (OQPSK). The corresponding impact of estimator errors on the bit error probability performance for OQPSK is also derived.
Summary Of Feedback Edge Set Papers, Jonathan Johnson
Summary Of Feedback Edge Set Papers, Jonathan Johnson
Faculty Publications
The problem of finding a set of edges F from a directed graph G = (V,E) such that the graph G0 = (V,E − F) contains no cycles is known as the feedback edge set (FES) problem or the feedback arc set problem. A related problem is the minimum feedback edge set problem, in which the feedback edge set F must be minimal. The feedback edge set problem has application in applying a common reliability technique called triple modular redundancy to FPGA circuit designs where configuration memory scrubbing is employed [1].
Compact Trench-Based Silicon-On-Insulator Rib Waveguide Ring Resonator With Large Free Spectral Range, Seunghyun Kim, Gregory P. Nordin, Weisheng Hu, Yusheng Qian, Jiguo Song, Gregory L. Wojcik
Compact Trench-Based Silicon-On-Insulator Rib Waveguide Ring Resonator With Large Free Spectral Range, Seunghyun Kim, Gregory P. Nordin, Weisheng Hu, Yusheng Qian, Jiguo Song, Gregory L. Wojcik
Faculty Publications
We demonstrate a compact trench-based silicon-on-insulator (SOI) rib waveguide ring resonator comprised of trench-based bends and splitters. It has a perimeter of 50 μm and occupies an area of only 25×25 μm. The measured free spectral range (FSR) is 13.2 nm, which the largest reported for an SOI rib waveguide ring resonator. The measured FSR, full width at half maximum, and quality factor match reasonably well with analytical calculations. Further calculation shows that a FSR of 50.8 nm is achievable for an SOI rib waveguide ring resonator with a perimeter of 15 μm.
In-Plane All-Photonic Transduction With Differential Splitter Using Double-Step Rib Waveguide For Photonic Microcantilever Arrays, Ryan Anderson, Seunghyun Kim, Gregory P. Nordin, Jong Wook Noh, Weisheng Hu
In-Plane All-Photonic Transduction With Differential Splitter Using Double-Step Rib Waveguide For Photonic Microcantilever Arrays, Ryan Anderson, Seunghyun Kim, Gregory P. Nordin, Jong Wook Noh, Weisheng Hu
Faculty Publications
We report a differential splitter consisting of an asymmetric double-step multimode rib waveguide and a Y-branch splitter for in-plane photonic transduction of photonic microcantilever deflection. Arrays of photonic microcantilevers are integrated with differential splitters and an optical waveguide network to demonstrate uniformity and sensitivity of transduction. Measurement results from multiple arrays indicate a sensitivity of 0.32 x 10-3 nm-1 and minimum detectable deflection of 141 pm for a 3.5 Hz measurement bandwidth.
New Low-Complexity Equalizers For Offset Qpsk, Qiang Lei, Michael D. Rice
New Low-Complexity Equalizers For Offset Qpsk, Qiang Lei, Michael D. Rice
Faculty Publications
Reduced-complexity linear and decision-feedback equalizers for use with offset QPSK are described and analyzed. The analysis and simulations show that reduced-complexity equalizers have 1/4 the complexity and achieve this at a loss that depends on the channel. As an example, the loss for the “Proakis B” channel is 2.7 dB for the linear equalizer and 0.8 dB for the decision feedback equalizer.
Dynamics And Control Of Cable-Drogue System In Aerial Recovery Of Micro Air Vehicles Based On Gauss's Principle, Liang Sun, Randal W. Beard, Mark B. Colton, Timothy W. Mclain
Dynamics And Control Of Cable-Drogue System In Aerial Recovery Of Micro Air Vehicles Based On Gauss's Principle, Liang Sun, Randal W. Beard, Mark B. Colton, Timothy W. Mclain
Faculty Publications
This paper presents a new concept for aerial recovery of Micro Air Vehicles (ARMAVs) using a large mothership and a recovery drogue. The mothership drags a drogue attached to a cable and the drogue is controlled to match the flight patten of the MAV. This paper uses Gauss’s Principle to derive the dynamic model of the cable-drogue systems. A controllable drogue plays a key role in recovering MAVs in windy conditions. We develop a control approach for the drogue using its drag coefficient. Simulation results based on multilink cable-drogue systems present the feasibility of the aerial recovery concept and the …
Payload Directed Flight Of Miniature Air Vehicles, Randal W. Beard, Clark Taylor, Jeff Saunders, Ryan Holt, Timothy W. Mclain
Payload Directed Flight Of Miniature Air Vehicles, Randal W. Beard, Clark Taylor, Jeff Saunders, Ryan Holt, Timothy W. Mclain
Faculty Publications
This paper describes three applications of payload directed flight using miniature air vehicles: vision-based road following, vision-based target tracking, and vision-based mapping. A general overview of each application is given, followed by simulation and flight-test results. Results demonstrate the viability of utilizing electo-optical video imagery to directly control the air vehicle flight path to enhance performance relative to the sensing objective.
Demonstration Of Microcantilever Array With Simultaneous Readout Using An In-Plane Photonic Transduction Method, Seunghyun Kim, Gregory P. Nordin, Ryan Anderson, Weisheng Hu, Yusheng Qian, Jiguo Song, Jong Wook Noh
Demonstration Of Microcantilever Array With Simultaneous Readout Using An In-Plane Photonic Transduction Method, Seunghyun Kim, Gregory P. Nordin, Ryan Anderson, Weisheng Hu, Yusheng Qian, Jiguo Song, Jong Wook Noh
Faculty Publications
We demonstrate a microcantilever array with an in-plane photonic transduction method for simultaneous readout of each microcantilever. The array is fabricated on a silicon-on-insulator substrate. Rib waveguides in conjunction with a compact waveguide splitter network comprised of trench-based splitters and trench-based bends route light from a single optical input to each microcantilever on the chip. Light propagates down a rib waveguide integrated into the microcantilever and, at the free end of the microcantilever, crosses a small gap. Light is captured in static asymmetric multimode waveguides that terminate in Y-branches, the outputs of which are imaged onto an InGaAs line scan …
Estimating Tmr Reliability On Fpgas Using Markov Models, Daniel Mcmurtrey, Keith S. Morgan, Brian Pratt, Michael J. Wirthlin
Estimating Tmr Reliability On Fpgas Using Markov Models, Daniel Mcmurtrey, Keith S. Morgan, Brian Pratt, Michael J. Wirthlin
Faculty Publications
This paper summarizes several reliability models for modeling FPGA reliability using Markov models.
Decentralized Perimeter Surveillance Using A Team Of Uavs, Randal Beard, David Casbeer, Derek Kingston
Decentralized Perimeter Surveillance Using A Team Of Uavs, Randal Beard, David Casbeer, Derek Kingston
Faculty Publications
Sponsorship: NASA, AFOSR. This paper develops a distributed algorithm to maintain a current estimate of the state of the perimeter using a team of UAVs. Using notions of consensus, an algorithm is developed and shown to distribute a UAV team uniformly around the perimeter.
A C-Band Scatterometer Simultaneous Wind/Rain Retrieval Method, David G. Long, Congling Nie
A C-Band Scatterometer Simultaneous Wind/Rain Retrieval Method, David G. Long, Congling Nie
Faculty Publications
Using collocated ERS scatterometer (ESCAT), Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), and European Centre for Medium-Range Weather Forecasts (ECMWF) data, the effects of rain on ESCAT wind-only retrieval are evaluated. Additional scattering from rain causes estimated wind speeds to appear higher than expected. Selected directions of the rain-corrupted wind vectors are biased toward along-track directions under conditions of heavy rain, which is regardless of the true wind direction. Rain becomes more significant for data acquired at a high incidence angle. To compensate for rain-induced backscatter, a simultaneous wind/rain retrieval (SWRR) method, which simultaneously retrieves wind velocity and surface …
Theory And Application Of Motion Compensation For Lfm-Cw Sar, David G. Long, Evan C. Zaugg
Theory And Application Of Motion Compensation For Lfm-Cw Sar, David G. Long, Evan C. Zaugg
Faculty Publications
Small low-cost high-resolution synthetic aperture radar (SAR) systems are made possible by using a linear frequency-modulated continuous-wave (LFM-CW) signal. SAR processing assumes that the sensor is moving in a straight line at a constant speed, but in actuality, an unmanned aerial vehicle (UAV) or airplane will often significantly deviate from this ideal. This nonideal motion can seriously degrade the SAR image quality. In a continuous-wave system, this motion happens during the radar pulse, which means that existing motion compensation techniques that approximate the position as constant over a pulse are limited for LFM-CW SAR. Small aircraft and UAVs are particularly …