The Role of Human-Automation Consensus in Multiple Unmanned Vehicle Scheduling

Objective: This study examined the impact of increasing automation replanning rates on operator performance and workload when supervising a decentralized network of heterogeneous unmanned vehicles. Background: Futuristic unmanned vehicles systems will invert the operator-to-vehicle ratio so that one operator can control multiple dissimilar vehicles connected through a decentralized network. Significant human-automation collaboration will be needed because of automation brittleness, but such collaboration could cause high workload. Method: Three increasing levels of replanning were tested on an existing multiple unmanned vehicle simulation environment that leverages decentralized algorithms for vehicle routing and task allocation in conjunction with human supervision. Results: Rapid replanning can cause high operator workload, ultimately resulting in poorer overall system performance. Poor performance was associated with a lack of operator consensus for when to accept the automation’s suggested prompts for new plan consideration as well as negative attitudes toward unmanned aerial vehicles in general. Participants with video game experience tended to collaborate more with the automation, which resulted in better performance. Conclusion: In decentralized unmanned vehicle networks, operators who ignore the automation’s requests for new plan consideration and impose rapid replans both increase their own workload and reduce the ability of the vehicle network to operate at its maximum capacity. Application: These findings have implications for personnel selection and training for futuristic systems involving human collaboration with decentralized algorithms embedded in networks of autonomous systems.Aurora Flight Sciences Corp.United States. Office of Naval Researc

Development of a strontium optical lattice clock for the SOC mission on the ISS

Ultra-precise optical clocks in space will allow new studies in fundamental physics and astronomy. Within an European Space Agency (ESA) program, the Space Optical Clocks (SOC) project aims to install and to operate an optical lattice clock on the International Space Station (ISS) towards the end of this decade. It would be a natural follow-on to the ACES mission, improving its performance by at least one order of magnitude. The payload is planned to include an optical lattice clock, as well as a frequency comb, a microwave link, and an optical link for comparisons of the ISS clock with ground clocks located in several countries and continents. Within the EU-FP7-SPACE-2010-1 project no. 263500, during the years 2011-2015 a compact, modular and robust strontium lattice optical clock demonstrator has been developed. Goal performance is a fractional frequency instability below 1x10^{-15}, tau^{-1/2} and a fractional inaccuracy below 5x10^{-17}. Here we describe the current status of the apparatus' development, including the laser subsystems. Robust preparation of cold {88}^Sr atoms in a second stage magneto-optical trap (MOT) is achieved.Comment: 27 Pages, 15 figures, Comptes Rendus Physique 201

Derivation of ODEs and Bifurcation Analysis of a Two-DOF Airfoil Subjected to Unsteady Incompressible Flow

An airfoil subjected to two-dimensional incompressible inviscid flow is considered. The airfoil is supported via a translational and a torsional springs. The aeroelastic integro-differential equations of motion for the airfoil are reformulated into a system of six first-order autonomous ordinary differential equations. These are the simplest and least number of ODEs that can present this aeroelastic system. The differential equations are then used for the bifurcation analysis of an airfoil with a structural nonlinearity in the pitch direction. Sample bifurcation diagrams showing both stable and unstable limit cycle oscillation are presented. The types of bifurcations are assessed by evaluating the Floquet multipliers. For a specific case, a period doubling route to chaos was detected, and mildly chaotic behavior in a narrow range of velocity was confirmed via the calculation of the Lyapunov exponents

Structural Dynamic Characterization of a Modular Morphing Wing Exploiting Finite Elements and Taguchi Methodology

Detrimental environmental impacts due to the increasing demands of the aviation industry have gained tremendous global attention. With a potential fuel saving, along with high aerodynamic performance and maneuverability during different phases of a flight, adaptable wing design has become a viable alternative to its fixed-shape counterpart. A morphing wing design embraces, and can respond accordingly to, most of the flight condition variations effectively and efficiently. Despite these prospects, morphing wing design comes with some challenges due to its inherent complexity caused by an increased number of degrees of freedom. With the availability of various morphing parameters, the vibration signature of a morphing wing design plays a vital role in terms of its structural as well as aeroelastic characteristics. In the present paper, the dynamic characteristics of a re-configurable modular morphing wing developed in-house by a research team at Toronto Metropolitan University are investigated. This modular morphing wing, developed based on the idea of a parallel robot, consists of a number of structural elements connected to each other and to the wing ribs through eyebolt joints. Timoshenko bending beam theories, in conjunction with finite element methodology, are exploited. The free vibration of un-morphed (original) and morphed configurations undergoing multiple levels of sweep and spanwise morphing is presented through a design of experiment methodology

Free Vibration Analysis of a Reconfigurable Modular Morphing Wing

Aircraft experience various phases during each flight. Optimal performance, without compromise, during various phases can be achieved through adaptability in the wing design. Morphing wing design encompasses most, if not all, the flight conditions variations, and can respond interactively. In the present work, the dynamic characteristics of a reconfigurable modular morphing wing of two topological architectures, developed in-house by a research group at Toronto Metropolitan University (formerly Ryerso University), were investigated. This modular morphing wing, developed based on the idea of a parallel robot, consists of a number of structural elements connected to each other and to the wing ribs through eye-bolt joints. Euler–Bernoulli and Timoshenko bending beam theories, in conjunction with Finite Element Analysis, were exploited. Free vibration of unmorphed (Original) and morphed configurations subjected to spanwise extensions were studied. The results of systems’ free vibration analyses were validated against those obtained from Ansys and Dynamic Stiffness Matrix (DSM) method. The effect of various spanwise extensions, as well as topology on system’s natural frequencies, was also studied and reported on

A FLUID DYNAMICS STUDY OF A MODIFIED LOW-REYNOLDS-NUMBER FLAPPING MOTION

ABSTRACT The objective of the present study is to investigate the low Reynolds number (LRN) fluid dynamics of an elliptic airfoil performing a novel figure-eight-like motion. To this mean, the influence of phase angle between the pitching and translational (heaving and lagging) motions and the amplitude of translational motions on the fluid flow is simulated. NavierStokes (NS) equations with Finite Volume Method (FVM) are used and the instantaneous force coefficients and the fluid dynamics performance, as well as the corresponding vortical structures are analyzed. Both the phase angle and the amplitudes of horizontal and vertical motions are of great importance to the fluid dynamic characteristics of the model as they are shown to change the peaks of the fluid forces, fluid dynamic performance, and the vortical patterns around the model. INTRODUCTION Forced and flow-induced oscillations are highly prevalent in a wide range of fluid engineering applications. These unsteady conditions could be useful when assisting in the generation of the fluid forces such as wing flapping, or be destructive when becoming the undesired oscillations such as wing flutter. Flapping motions are the most common means of force generation in micro aerial vehicles and swimming robots. The physical characteristics and the fluid phenomena of such motions strongly depend on the governing flow and system parameters. LRN flapping flows are mostly accompanied with non-linear vortex dynamics, such as dynamic stal

Real-time optimal time-critical target assignment for UAVs

In the literature, e.g. [10], one can find the so-called basic UAV mission target assignment in which m UAVs each with a capacity limit q visit n targets in a cooperative manner (and return to their departure points) such that the cost incurred by each UAV’s travel is minimized. In [10], we proposed a mixed integer linear program (MILP) formulation which exactly solves the problem, as well as four alternative MILP formulations which are computationally less intensive (and therefore suited for real-time purposes) yet yield a theoretically guaranteed sub-optimal solution. In this chapter, we further consider timing constraints imposed on some p of the targets, so-called prime targets. This consideration is often required for scenarios in which prime targets must be visited in a pre-defined time interval, and mathematically results in the addition of several integer linear constraints to the previous MILP formulation making the problem computationally intractable. We propose a novel procedure of adding these cumbersome timing constraints to the previous MILP formulation, in order to avoid increasing too much computational cost under practically valid assumptions. We first show that the proposed procedure still guarantees the previously claimed theoretical solution quality associated with the basic mission. We then show through extensive numerical simulations that under certain conditions, our algorithms return solutions which are still computationally manageable