AIM: Acoustic Inertial Measurement for Indoor Drone Localization and Tracking

We present Acoustic Inertial Measurement (AIM), a one-of-a-kind technique for indoor drone localization and tracking. Indoor drone localization and tracking are arguably a crucial, yet unsolved challenge: in GPS-denied environments, existing approaches enjoy limited applicability, especially in Non-Line of Sight (NLoS), require extensive environment instrumentation, or demand considerable hardware/software changes on drones. In contrast, AIM exploits the acoustic characteristics of the drones to estimate their location and derive their motion, even in NLoS settings. We tame location estimation errors using a dedicated Kalman filter and the Interquartile Range rule (IQR). We implement AIM using an off-the-shelf microphone array and evaluate its performance with a commercial drone under varied settings. Results indicate that the mean localization error of AIM is 46% lower than commercial UWB-based systems in complex indoor scenarios, where state-of-the-art infrared systems would not even work because of NLoS settings. We further demonstrate that AIM can be extended to support indoor spaces with arbitrary ranges and layouts without loss of accuracy by deploying distributed microphone arrays

Acoustic and oceanographic observations and configuration information for the WHOI moorings from the SW06 experiment

This document describes data, sensors, and other useful information pertaining to the moorings that were deployed from the R/V Knorr from July 24th to August 4th, 2006 in support of the SW06 experiment. The SW06 experiment was a large, multi-disciplinary effort performed 100 miles east of the New Jersey coast. A total of 62 acoustic and oceanographic moorings were deployed and recovered. The moorings were deployed in a “T” geometry to create an along-shelf path along the 80 meter isobath and an across-shelf path starting at 600 meters depth and going shoreward to a depth of 60 meters. A cluster of moorings was placed at the intersection of the two paths to create a dense sensor-populated area to measure a 3-dimensional physical oceanography. Environmental moorings were deployed along both along-shelf and across-shelf paths to measure the physical oceanography along those paths. Moorings with acoustic sources were placed at the outer ends of the “T” to propagate various signals along these paths. Five single hydrophone receivers were positioned on the across shelf path and a vertical and horizontal hydrophone array was positioned at the intersection of the “T” to get receptions from all the acoustics assets that were used during SW06.Funding was provided by the Office of Naval Research under Contract No. N00014-04-1014

Images and depth for high resolution, low-latency sensing and security applications

The thesis focuses on using images and depths for high resolution, low latency sensing, and then using these sensing techniques to build security applications. First, we introduce the usefulness of high quality depth sensing, and the difficulty to acquire such depth stream via pure hardware approach. Then, we propose our sensor fusion approach, which combines depth camera and color camera. Chapter 2 puts forward a low cost approach to use a high spatial resolution color stream to help aggressively increase the spatial resolution of the depth stream. Continuing this direction, Chapter 3 proposes to use optical ow to forward warp the depth stream according to a high frequency, low latency CMOS color stream. The warping can create a high frequency, low latency depth stream. In both Chapter 2 and Chapter 3, we show that the improved depth sensing can benefit lots of applications. In Chapter 4, we propose a SafetyNet, which can reliably detecting and rejecting adversarial examples. With the revolutionary SafetyNet architecture and the advanced depth sensing, we can reliably prove to users whether a picture of a scene is real or not. In sum, the thesis focuses on improving sensing technologies and building vision and security applications around the sensing technologies

Time-of-flight range image measurement in the presence of transverse motion using the Kalman filter

Time-of-flight range imaging cameras measure distance to objects in their field of view, but are prone to error when objects move. At least three raw frames are required to obtain one range image, and the standard method is to read out raw frames into separate sets and process to find one range image per set. Motion during the acquisition of a set causes error in the corresponding range image. In this paper, the problem of motion is addressed by regarding the raw data from each pixel as a noisy time series, and using the Kalman filter to efficiently perform time-series analysis. The proposed method adapts to the effects of transverse motion, measuring a sharp range image at each raw frame. The error in the proposed method is less than the traditional approach in 80% of tests, with no detected increase in the STD due to noise. In the qualitative experimental results, the visible blur is reduced

The Development of Unique Focal Planes for High-Resolution Suborbital and Ground-Based Exploration

abstract: The development of new Ultra-Violet/Visible/IR range (UV/Vis/IR) astronomical instrumentation that use novel approaches for imaging and increase the accessibility of observing time for more research groups is essential for rapid innovation within the community. Unique focal planes that are rapid-prototyped, low cost, and provide high resolution are key. In this dissertation the emergent designs of three unique focal planes are discussed. These focal planes were each designed for a different astronomical platform: suborbital balloon, suborbital rocket, and ground-based observatory. The balloon-based payload is a hexapod-actuated focal plane that uses tip-tilt motion to increase angular resolution through the removal of jitter – known as the HExapod Resolution-Enhancement SYstem (HERESY), the suborbital rocket imaging payload is a Jet Propulsion Laboratory (JPL) delta-doped charge-coupled device (CCD) packaged to survive the rigors of launch and image far-ultra-violet (FUV) spectra, and the ground-based observatory payload is a star centroid tracking modification to the balloon version of HERESY for the tip-tilt correction of atmospheric turbulence. The design, construction, verification, and validation of each focal plane payload is discussed in detail. For HERESY’s balloon implementation, pointing error data from the Stratospheric Terahertz Observatory (STO) Antarctic balloon mission was used to form an experimental lab test setup to demonstrate the hexapod can eliminate jitter in flight-like conditions. For the suborbital rocket focal plane, a harsh set of unit-level tests to ensure the payload could survive launch and space conditions, as well as the characterization and optimization of the JPL detector, are detailed. Finally, a modification of co-mounting a fast-read detector to the HERESY focal plane, for use on ground-based observatories, intended to reduce atmospherically induced tip-tilt error through the centroid tracking of bright natural guidestars, is described.Dissertation/ThesisDoctoral Dissertation Exploration Systems Design 201

Vector Magnetograph Design

This report covers work performed during the period of November 1994 through March 1996 on the design of a Space-borne Solar Vector Magnetograph. This work has been performed as part of a design team under the supervision of Dr. Mona Hagyard and Dr. Alan Gary of the Space Science Laboratory. Many tasks were performed and this report documents the results from some of those tasks, each contained in the corresponding appendix. Appendices are organized in chronological order

Shear wave rheometry with applications in elastography

The goal of elastography is to map the mechanical properties of soft tissues associated with health and disease. The mechanical property of interest in this work is the complex shear modulus, composed of a real part, the storage modulus, which is a measure of elasticity, and an imaginary part, the loss modulus, which is a measure of viscosity. Together, they determine the speed and attenuation of shear waves in the medium. Elastography techniques based on either ultrasound imaging or MRI can image shear wave propagation and thus are capable of measuring shear wave speed and attenuation. Dispersion, or the frequency-dependence of material parameters, is a primary confounding factor when comparing measurements between different shear wave elastography implementations. Prior attempts at quantifying this frequency-dependence suffered from inaccurate modeling assumptions and low signal-to-noise ratios (SNR). To overcome these limitations, a high-fidelity forward model of shear wave propagation in homogeneous media was developed. The model is an exact semi-analytical solution of Navier's equation and is well-suited for acoustic radiation force impulse shear wave elastography (ARFI-SWE) because it does not require precise knowledge of the strength of the source, nor its spatial or temporal distribution. Unlike models used in ARFI-SWE heretofore, it accounts for the vector polarization of shear waves and exactly represents geometric spreading of the shear wavefield, whether spherical, cylindrical, or neither. Furthermore, it is material-model independent, i.e. it makes no assumption about the frequency-dependence of material parameters. It overcomes the problem of low SNR through spatial averaging and enables estimation of the frequency-dependent complex shear modulus over a wider frequency range than has hitherto been possible. This improved ARFI-SWE was named Shear Wave Rheometry (SWR). By combining SWR with a novel torsional vibration rheometry, dispersion in tissue-mimicking gels was quantified from 1--1800 Hz. The measurements show sizable frequency-dependent variation in the shear modulus of gelatin, a material often assumed to be non-dispersive based on narrow-band measurements. SWR measurements in ex vivo bovine liver tissue yielded complex shear modulus estimates from 25--250 Hz and showed that liver tissue exhibits significant dispersion in this frequency range: a factor of 4 increase in the storage modulus and a factor of 10 increase in the loss modulus. Quality metrics showed that liver tissue can be reasonably approximated as homogeneous and isotropic for ARFI-SWE measurements in this frequency range. Results demonstrate that accounting for dispersion is essential for meaningful comparisons of measurements between systems. Moreover, improved tissue characterization enabled by SWR may have clinical relevance, for example, in the diagnosis and monitoring of chronic liver disease

Biomechanical evaluation of distance running during training and competition

Middle-distance athletes are faced with a unique challenge to generate high running velocities (between 6.00 and 8.00 m∙s-1) while making movements as economical as possible (Williams & Cavanagh, 1987). Research suggests that 54% of the variation in running economy can be attributed to gait and spring-mass characteristics. The aims of this thesis were to establish a valid means of measuring gait and spring-mass characteristics away from the laboratory environment and then to provide a biomechanical evaluation of middle-distance running during competition and training in order to identify gait and spring-mass characteristics that influence performance time. Accordingly this thesis has demonstrated that high-speed, Optojump and laser distance measurement (LDM) device all provided a valid measurement of gait and spring-mass characteristics. Spring-mass characteristics obtained through mathematical modelling (estimations based on high-speed video data only) during running were comparable to the gold standard direct measurement (using a force platform). These mathematical models allow for estimations of Kvert and Kleg to be reported away from the laboratory environment on an outdoor 400 m synthetic athletics track.During outdoor track competition international-level athletes achieved a lower performance time as a consequence of a longer step length and lower Kvert¬ and Kleg. For the first time this suggests that a longer step length, greater knee flexion, lower Kvert and Kleg are differentiating factors associated with a reduced middle-distance performance time. Whereas, over a single training session and training block regional-level athletes maintained running velocity by significantly increased step frequency and a reduction in Kvert/BW. Overall, this thesis implies that middle-distance training should monitor how athletes sustain a high running velocity with more emphasis placed on step length to develop competitive performance by increasing flight distance. To increase the travel during flight it is suggested that athletes increase vertical ground reaction forces through plyometric exercises (e.g. stretch-shortening cycle) and continual development of middle-distance training history