Most of the signal processing that we will study in this course involves local operations on a signal, namely transforming the signal by applying linear combinations of values in the neighborhood of each sample point. You are familiar with such operations from Calculus, namely, taking derivatives and you are also familiar with this from optics namely blurring a signal. We will be looking at sampled signals only. Let's start with a few basic examples. Local difference Suppose we have a 1D image and we take the local difference of intensities, DI(x) = 1 2 (I(x + 1) − I(x − 1)) which give a discrete approximation to a partial derivative. (We compute this for each x in the image.) What is the effect of such a transformation? One key idea is that such a derivative would be useful for marking positions where the intensity changes. Such a change is called an edge. It is important to detect edges in images because they often mark locations at which object properties change. These can include changes in illumination along a surface due to a shadow boundary, or a material (pigment) change, or a change in depth as when one object ends and another begins. The computational problem of finding intensity edges in images is called edge detection. We could look for positions at which DI(x) has a large negative or positive value. Large positive values indicate an edge that goes from low to high intensity, and large negative values indicate an edge that goes from high to low intensity. Example Suppose the image consists of a single (slightly sloped) edge:

http://ieeexplore.ieee.org/iel5/5/31307/01456462.pdf

Linear systems

Bilateral teleoperation: An historical survey

Summary) The abstract should follow the structure of the article (relevance, degree of exploration of the problem, the goal, the main results, conclusion) and characterize the theoretical and practical significance of the study results. The abstract should not contain wording echoing the title, cumbersome grammatical structures and abbreviations. The text should be written in scientific style. The volume of abstracts (summaries) depends on the content of the article, but should not be less than 250 words. All abbreviations must be disclosed in the summary (in spite of the fact that they will be disclosed in the main text of the article), references to the numbers of publications from reference list should not be made. The sentences of the abstract should constitute an integral text, which can be made by use of the words “consequently”, “for example”, “as a result”. Avoid the use of unnecessary introductory phrases (eg, “the author of the article considers...”, “The article presents...” and so on.)

/pdf/ministry-of-education-and-science-of-the-russian-federation-7m2jn0xnm1.pdf

Ministry of Education and Science of the Russian Federation

One of the most important design problems for multi-UAV (Unmanned Air Vehicle) systems is the communication which is crucial for cooperation and collaboration between the UAVs. If all UAVs are directly connected to an infrastructure, such as a ground base or a satellite, the communication between UAVs can be realized through the in-frastructure. However, this infrastructure based communication architecture restricts the capabilities of the multi-UAV systems. Ad-hoc networking between UAVs can solve the problems arising from a fully infrastructure based UAV networks. In this paper, Flying Ad-Hoc Networks (FANETs) are surveyed which is an ad hoc network connecting the UAVs. The differences between FANETs, MANETs (Mobile Ad-hoc Networks) and VANETs (Vehicle Ad-Hoc Networks) are clarified first, and then the main FANET design challenges are introduced. Along with the existing FANET protocols, open research issues are also discussed.

Flying Ad-Hoc Networks (FANETs)

Aircraft wings are a compromise that allows the aircraft to fly at a range of flight conditions, but the performance at each condition is sub-optimal. The ability of a wing surface to change its geometry during flight has interested researchers and designers over the years as this reduces the design compromises required. Morphing is the short form for metamorphose; however, there is neither an exact definition nor an agreement between the researchers about the type or the extent of the geometrical changes necessary to qualify an aircraft for the title ‘shape morphing.’ Geometrical parameters that can be affected by morphing solutions can be categorized into: planform alteration (span, sweep, and chord), out-of-plane transformation (twist, dihedral/gull, and span-wise bending), and airfoil adjustment (camber and thickness). Changing the wing shape or geometry is not new. Historically, morphing solutions always led to penalties in terms of cost, complexity, or weight, although in certain circumstances, thes...

A Review of Morphing Aircraft

Solar sails equipped with 4 control vanes are examined for their capabilities i n trajectory tracking control. T he additional degree of freedom inherent in positioning 4 control vanes to produce 3 degrees of freedom attitude control is used to effect control of the resultant sail craft thrust vector amplitude. T he advantages in translationa l controllability and initial condition error recovery are compared with the traditional 2 degree of freedom thrust control approach, which does not independently modulate thrust magnitude. T rajectories considered include trans fer from Earth -Su n L1 to sub -L1 pseudo -equilibria , and stationkeeping trajectories to track these pseudo -equilibria. Nomenclature z y x ˆ , ˆ , ˆ = Sun -Earth Barycentric Inertial (SEBI) frame unit vectors s s s z y x ˆ , ˆ

Integrated Trajectory and Attitude Control for a Four -Vane Solar Sail

Results from recent NASA sponsored research on the structural dynamics, stability, and control characteristics of heliogyro solar sails are summarized. Specific areas under investigation include coupled nonlinear finite element analysis of heliogyro membrane blade with solar radiation pressure effects, system identification of spinning membrane structures, and solarelastic stability analysis of heliogyro solar sails, including stability during blade deployment. Recent results from terrestrial 1-g blade dynamics and control experiments on "rope ladder" membrane blade analogs, and small-scale in vacuo system identification experiments with hanging and spinning high-aspect ratio membranes will also be presented. A low-cost, rideshare payload heliogyro technology demonstration mission concept is used as a mission context for these heliogyro structural dynamics and solarelasticity investigations, and is also described. Blade torsional dynamic response and control are also shown to be significantly improved through the use of edge stiffening structural features or inclusion of modest tip masses to increase centrifugal stiffening of the blade structure. An output-only system identification procedure suitable for on-orbit blade dynamics investigations is also developed and validated using ground tests of spinning sub-scale heliogyro blade models. Overall, analytical and experimental investigations to date indicate no intractable stability or control issues for the heliogyro solar sail concept.

https://ntrs.nasa.gov/api/citations/20150006037/downloads/20150006037.pdf

Recent Advances in Heliogyro Solar Sail Structural Dynamics, Stability, and Control Research

Small Unmanned Aerial System Attitude Estimation for Flight in Wind

The heliogyro is a high-performance solar sail design because the sail is divided into long, thin blades stiffened by the centripetal acceleration of the spacecraft’s spin alone, reducing structural mass. A principal concern for heliogyros is the dynamic response of their long, unsupported blades. The linearized dynamics of a single rotating heliogyro blade in twist are studied using finite element analysis, and a root control law is designed using frequency response techniques. Proportional/Derivative/Feed-Forward compensation is implemented at the root to track and damp blade pitch maneuvers. This system is analyzed for performance and stability as a function of controller bandwidth and material damping. Since the material damping of these gossamer sheets is not known, this relationship is critical to blade controller design. Dynamic simulations reveal that a control system bandwidth of 3 cycles/rev (0.017 Hz) is required to meet Low Earth Orbit settling time requirements. These low bandwidths are well within realistic actuator capabilities, making this a promising result for the feasibility of heliogyros.

Performance of a Heliogyro Blade Twist Controller with Finite Bandwidth

Control techniques for managing a large Sensor Flock are described, consisting of decentralized potential gradient and sensed data gradient guidance laws. Guidance potentials are defined to improve sensed data qu ality in both a scalar signal to -noise ratio sense, and in a vector gradient estimation sense. Examples are provided showing that a 147 vehicle flock autonomously produces desired behavior under suitable choices of design parameters. A portion of the flo ck clusters in regions of high data signal -to -noise ratio, while other vehicles spread out to cover un -sensed areas within a specified coverage volume. Clustered vehicles use measured data gradients to seek the margins and the source of a simulated toxic p lume emission.

Dale Lawrence

Papers

Integrated Trajectory and Attitude Control for a Four -Vane Solar Sail

Recent Advances in Heliogyro Solar Sail Structural Dynamics, Stability, and Control Research

Small Unmanned Aerial System Attitude Estimation for Flight in Wind

Performance of a Heliogyro Blade Twist Controller with Finite Bandwidth

Concentration Gradient and Inform ation Energy for Decentralized UAV Control 1