We analyzed recordings of the Clinician-Administered PTSD Scale (CAPS) interview from military personnel diagnosed as PTSD positive versus negative.
Robotics, sensors, & devices publications
Cross-corpus depression prediction from speech
We study a new corpus of patient-clinician interactions recorded when patients are admitted to a hospital for suicide risk and again when they are released.
The Effect of the Earth’s and Stray Magnetic Fields on Mobile Mass Spectrometer Systems
Development of small, field-portable mass spectrometers has enabled a rapid growth of in-field measurements on mobile platforms. In such in-field measurements, unexpected signal variability has been observed by the authors in portable ion traps with internal electron ionization. The orientation of magnetic fields (such as the Earth’s) relative to the ionization electron beam trajectory can significantly alter the electron flux into a quadrupole ion trap, resulting in significant changes in the instrumental sensitivity. Instrument simulations and experiments were performed relative to the earth’s magnetic field to assess the importance of (1) nonpoint-source electron sources, (2) vertical versus horizontal electron beam orientation, and (3) secondary magnetic fields created by the instrument itself. Electron lens focus effects were explored by additional simulations, and were paralleled by experiments performed with a mass spectrometer mounted on a rotating platform. Additionally, magnetically permeable metals were used to shield (1) the entire instrument from the Earth’s magnetic field, and (2) the electron beam from both the Earth’s and instrument’s magnetic fields. Both simulation and experimental results suggest the predominant influence on directionally dependent signal variability is the result of the summation of two magnetic vectors. As such, the most effective method for reducing this effect is the shielding of the electron beam from both magnetic vectors, thus improving electron beam alignment and removing any directional dependency. The improved ionizing electron beam alignment also allows for significant improvements in overall instrument sensitivity.
Determining the Threshold of Time-Delay for Teleoperation Accuracy and Efficiency in Relation to Telesurgery
In this study a suite of experiments was performed to investigate the influence of time-delay on teleoperation accuracy and efficiency during a path-following task.
Bipedal Hopping Pattern Generation for Passively Compliant Humanoids: Exploiting the Resonance
This paper describes a novel technique to analytically generate feasible hopping trajectories that can be applied to passively compliant bipedal humanoid robots.
A Novel Planar Ion Funnel Design for Miniature Ion Optics
The novel planar ion funnel (PIF) design presented in this article emphasizes simple fabrication, assembly, and operation, making it amenable to extreme miniaturization.
Comprehensive Analysis and Measurement of Frequency-Tuned and Impedance-Tuned Wireless Non-Radiative Power-Transfer Systems
This paper theoretically and experimentally investigates frequency-tuned and impedance-tuned wireless nonradiative power transfer (WNPT) systems. Closed-form expressions for the efficiencies of both systems, as a function of frequency and system (circuit) parameters, are presented. In the frequency-tuned system, the operating frequency is adjusted to compensate for changes in mutual inductance that occur for variations of transmitter and receiver loop positions. Frequencytuning is employed for a range of distances over which the loops are strongly coupled. In contrast, the impedance-tuned system employs varactor-based matching networks to compensate for changes in mutual inductance and achieve a simultaneous conjugate impedance match over a range of distances. The frequencytuned system is simpler to implement, while the impedance-tuned system is more complex but can achieve higher efficiencies. Both of the experimental WNPT systems studied employ resonant shielded loops as transmitting and receiving devices.
Clock Synchronization on the RAX Spacecraft
The Radio Aurora Explorer (RAX) is a CubeSat that was developed to study space weather in Earth׳s ionosphere. The scientific payload is a bistatic radar system in which an onboard receiver works in cooperation with a ground-based transmitter. Accuracy of the onboard clock is critical for processing the radar measurements. The RAX timing system utilizes commercial off-the-shelf components integrated into custom subsystems. GPS is used to maintain absolute timing accuracy better than 1 μs, but the subsystem is not always available due to power constraints, so a method has been developed to correct the onboard clock error without the use of GPS. The clock correction utilizes range measurements extracted from the pulses emitted by the transmitter, and resulting absolute clock accuracies of better than 0.20 s with drift of less than 21 ns/s have been demonstrated. The RAX timing system and the clock correction algorithm are presented as a reference for other spacecraft designers and are critical for those analyzing RAX data.
Mechatronic Design of an Integrated Robotic Hand
Historically, robotic hand research has tended to focus on two areas: severely underactuated hands, and high-degree-of-freedom fully actuated hands. Comparatively little research has been done in between those spaces. Furthermore, despite the large number of robotic hand designs that have been proposed in the past few decades, very few robot hands are available for purchase on the commercial market. In this paper, we present a hand designed for minimalistic dexterous manipulation, in which every stage of the design process also considered its manufacturing cost. We discuss the various trade-offs made in the design. Finally, we present the results of experiments in which the robotic hand was affixed to a manipulator arm and teleoperated to grasp and manipulate a variety of objects.