[Truncated abstract] Video sequence synchronization is necessary for any computer vision application that integrates data from multiple simultaneously recorded video sequences. With the increased availability of video cameras as either dedicated devices, or as components within digital cameras or mobile phones, a large volume of video data is available as input for a growing range of computer vision applications that process multiple video sequences. To ensure that the output of these applications is correct, accurate video sequence synchronization is essential. Whilst hardware synchronization methods can embed timestamps into each sequence on-the-fly, they require specialized hardware and it is necessary to set up the camera network in advance. On the other hand, computer vision-based software synchronization algorithms can be used to post-process video sequences recorded by cameras that are not networked, such as common consumer hand-held video cameras or cameras embedded in mobile phones, or to synchronize historical videos for which hardware synchronization was not possible. The current state-of-the-art software algorithms vary in their input and output requirements and camera configuration assumptions. ... Next, I describe an approach that synchronizes two video sequences where an object exhibits ballistic motions. Given the epipolar geometry relating the two cameras and the imaged ballistic trajectory of an object, the algorithm uses a novel iterative approach that exploits object motion to rapidly determine pairs of temporally corresponding frames. This algorithm accurately synchronizes videos recorded at different frame rates and takes few iterations to converge to sub-frame accuracy. Whereas the method presented by the first algorithm integrates tracking data from all frames to synchronize the sequences as a whole, this algorithm recovers the synchronization by locating pairs of temporally corresponding frames in each sequence. Finally, I introduce an algorithm for synchronizing two video sequences recorded by stationary cameras with unknown epipolar geometry. This approach is unique in that it recovers both the frame rate ratio and the frame offset of the two sequences by finding matching space-time interest points that represent events in each sequence; the algorithm does not require object tracking. RANSAC-based approaches that take a set of putatively matching interest points and recover either a homography or a fundamental matrix relating a pair of still images are well known. This algorithm extends these techniques using space-time interest points in place of spatial features, and uses nested instances of RANSAC to also recover the frame rate ratio and frame offset of a pair of video sequences. In this thesis, it is demonstrated that each of the above algorithms can accurately recover the frame rate ratio and frame offset of a range of real video sequences. Each algorithm makes a contribution to the body of video sequence synchronization literature, and it is shown that the synchronization problem can be solved using a range of approaches.

<p><p>The Dual Clutch Transmission (DCT) is a relatively new kind of transmission which shows increased efficiency and comfort compared to manual transmissions. Its construction is much like two parallell manual transmissions, where the gearshifts are controlled automatically. The gear-shift of a manual transmission involves a synchronization process, which synchronizes and locks the input shaft to the output shaft via the desired gear ratio. This process, which means transportation of a synchronizer sleeve, is performed by moving the gear shift lever which is connected to the sleeve. In a DCT, there is no mechanical connection between the gear-shift lever and the sleeve. Hence, an actuator system, controlled by a control system, must be used.</p><p>This report includes modelling, control system design and simulation results of a DCT synchronization process. The thesis work is performed at GM Powertrain (GMPT) in Trollhättan. At the time of this thesis, there is no DCT produced by GM, and therefore the results and conclusions rely on simulations. Most of the used system parameters are reasonable values collected from employees at GMPT and manual transmission literature.</p><p>The focus of the control design is to achieve a smooth, rather than fast, movement of the synchronizer sleeve. Simulations show that a synchronization process can be performed in less than 400 ms under normal conditions. The biggest problems controlling the sleeve position occur if there is a large amount of drag torque affecting the input shaft. Delay problems also worsen the performance a lot. An attempt to predict the synchronizer sleeve position is made and simulations shows advantages of that.</p><p>Some further work is needed before the developed control software can be used on a real DCT. Investigations of sensor noise robustness and the impact of dogging forces are the most important issues to be further investigated. Implementation of additional functionality for handling special conditions are also needed.</p></p>

<p>POTS (Plain Old Telephony Service) systems have traditionally been connected via synchronous connections. When installing new nodes in the telephone network, they may sometimes be connected via packet networks such as Ethernet. Ethernet is an asynchronous network which means that nodes connected to the network don’t have access to the same clock frequency if it is not provided in some other way. If two nodes have different clock frequency, the receiver’s buffer will eventually overflow or starve. While not being a severe problem for telephony, devices used for data transmission, e.g. modems and fax will not be able to function properly. To avoid this it is necessary to synchronize the nodes.</p><p>This thesis investigates methods to synchronize nodes connected over Ethernet by simulating them in Matlab. The simulations show that under certain circumstances it is possible to produce a clock signal conforming to relevant standards.</p>

<p>This master thesis is as a final project in the Division of Computer Engineering at the Department of Electrical of Engineering, Linköping University, Sweden. The purpose of the project is to set up a baseband behavioral model for a Bluetooth system based on standards. In the model, synchronization in demodulation part has been focused on. Simulation results are analyzed later in the report to see how the method in demodulation works. Some suggestions and future works for receiver are provided to improve the performances of the model.</p>

<p>The main issue of this thesis is making the behaviour model of Bluetooth EDR (enhanced data rate) baseband signal processing. This Bluetooth baseband project is part of the soft defined radio project at electrical engineering department, Linköping University.</p><p>In this project, both the basic rate and EDR model were built and simulated. The GFSK and π/4 DQPSK digital modulation and demodulation were implemented in C code. The BER was tested to evaluate the demodulation results. Furthermore, the error correction (FEC) and the error checking (HEC,CRC) were also implemented according to the Bluetooth standards. The CRC flag was detected to test the payload demodulation results.</p><p>Especially, GFSK and π/4 DQPSK specifications have to be combined with each other at sample rate of ADC.</p><p>Finally, the basic rate and EDR model were simulated to measure the BER and CRC performance.</p><p>From the simulation results, the receiver filter, synchronization and channel condition were three key points in this Bluetooth EDR system implementation.</p><p>So we get further understanding about the Bluetooth system specification and DSP implementation methods.</p>

<p>This thesis involved a research of mechanisms of MAC layer in the ad-hoc networks environment, the ad-hoc networks in the terminology of the standard are called IBSS Independent Basic Service, these type of networks are very useful in real situation where there are not the possibility of display a infrastructure, when there isn’t a network previous planning. </p><p>The connection to a new network is one of the different with the most common type of Wireless Local Area Networks (WLAN) that are the ones with infrastructure. The connection is established without the presence of a central station, instead the stations discover the others with broadcast messages in the coverage area of each station. In the context of standard 802.11 networks the communication between the stations is peer to peer, only with one hop. To continue with initiation process is necessary the synchronization between the different stations of his timers.</p><p>The other capital mechanism that is treated is the medium access mechanism, to hold a shared and unreliable medium, all the heavy of this issue goes to the distributed coordination function DCF.</p><p>In this moment there is an emergent technology, WIMAX or standard IEEE 802.16, like the standard 802.11 is a wireless communication protocol. Some comparison between the MAC layer mechanisms would be realized between these two standards</p>

<p>his thesis proposes two motion synchronization approaches to coordinate the motion of a follower to a leader within the Euler-Lagrange system framework. The information requirements from the leader are that of position and orientation only, i.e. the mathematical model with its parameters and the velocity and acceleration of the leader are considered unknown and unmeasured.</p><p>The follower is responsible for the control action necessary to coordinate the systems, and the leader system is free to manoeuvre independently of the follower. There is no off-line synchronization of the systems through predefined paths or trajectories. %The parameters of the dynamic model of the leader are unknown, and its unmeasured system states (velocity and acceleration) must be estimated in order to be utilized in the coordination controller of the follower.</p><p>The concept of motion control of multiple objects is discussed in terms of the different forms of synchronization; cooperation (where all objects contribute equally) and coordination (where one object governs the motion of the others). Motivating examples and literature provide the motivation for the definition of two motion coordination problems. The output reference state feedback synchronization problem is defined by utilizing only output feedback from the desired motion reference, while assuming state feedback for the follower in the coordination control law. Furthermore, to increase the usefulness of the proposed control schemes and to provide robustness towards loss or poor quality of velocity measurements, the requirements of state information for the follower are alleviated in the definition of the output reference output feedback synchronization problem utilizing only output information of both the leader and the follower in the synchronization design. Furthermore, the necessary tools of stability are presented to prove that the proposed coordination schemes are uniformly ultimately bounded or practically asymptotically stable closed-loop systems.</p><p>In order to solve the output reference state feedback and the output reference output feedback synchronization problems, an observer-controller scheme is proposed that estimates the unknown states of the leader indirectly through a nonlinear model-based error observer. The observer-controller approach makes the follower system a physical observer of the leader system through the coupled observer and controller error-dynamics. A second nonlinear model-based observer is introduced for the follower to remove the state feedback assumption. The observer-controller scheme is proven to be uniformly globally ultimately bounded when utilizing state feedback of the follower in the coordination control law, and to be uniformly semiglobally ultimately bounded when utilizing only output feedback of the follower in the coordination control law. The observer-controller approach to motion coordination is studied through simulations and experiments, and a back-to-back comparison between ideal simulations and practical experiments is presented to allow for a discussion on the performance of the scheme under modelling errors, measurement noise and external disturbances. The observer-controller scheme is demonstrated to be suitable for practical applications.</p><p>Furthermore, a virtual vehicle scheme is proposed to solve the output reference state/ output feedback synchronization problems through a cascaded approach. The virtual vehicle approach is based on a two-level control structure to decouple the estimation and coordination error dynamics in the stability analysis and the tuning process. The virtual vehicle scheme estimates the unknown states of the leader through a virtual kinematic vehicle stabilized to the output of the leader system. A stable first-order velocity filter is introduced for the follower to remove the state feedback assumption. The virtual vehicle scheme is proven to be uniformly globally practically asymptotically stable when utilizing state feedback of the follower in the coordination control law, and to be uniformly semiglobally practically asymptotically stable when utilizing only output feedback of the follower in the coordination control law. Application of the virtual vehicle scheme to both vehicle coordination and robot manipulator coordination is presented, and the virtual vehicle approach to motion coordination is studied through simulations and experiments. The virtual vehicle scheme is demonstrated to be suitable for practical applications. In addition, an extension to a dynamic synchronization scheme is proposed to impose a smooth behaviour on the follower during a change of relative position.</p><p>The proposed coordination schemes are compared in terms of estimation principle, performance and robustness. Simulation studies compare the performance of the proposed schemes in terms of gain tuning and bounds on the closed-loop errors, and in terms of impact from external disturbances, modelling errors and measurement noise. The two coordination schemes are distinguished by concept rather than by performance, and both of the proposed schemes are believed to be suitable for practical implementation in coordination applications.</p>

The present dissertation studies specific issues related to the coordination of a set of "agents" evolving on a nonlinear manifold, more particularly a homogeneous manifold or a Lie group. The viewpoint is somewhere between control algorithm design and system analysis, as algorithms are derived from simple principles --- often retrieving existing models --- to highlight specific behaviors. With a fair amount of approximation, the objective of the dissertation can be summarized by the following question: Given a swarm of identical agents evolving on a nonlinear, nonconvex configuration space with high symmetry, how can you define specific collective behavior, and how can you design individual agent control laws to get a collective behavior, without introducing hierarchy nor external reference points that would break the symmetry of the configuration space? Maintaining the basic symmetries of the coordination problem lies at the heart of the contributions. The main focus is on the global geometric invariance of the configuration space. This contrasts with most existing work on coordination, where either the agents evolve on vector spaces --- which, to some extent, can cover local behavior on manifolds --- or coordination is coupled to external reference tracking such that the reference can serve as a beacon around which the geometry is distorted towards vector space-like properties. A second, more standard symmetry is to treat all agents identically. Another basic ingredient of the coordination problem that has important implications in this dissertation is the reduced agent interconnectivity: each agent only gets information from a limited set of other agents, which can be varying. In order to focus on issues related to geometry / symmetry and reduced interconnectivity, individual agent dynamics are drastically simplified to simple integrators. This is justified at a "planning" level. Making the step towards realistic dynamics is illustrated for the specific case of rigid body attitude synchronization. The main contributions of this dissertation are * I. an extensive study of synchronization on the circle, (a) highlighting difficulties encountered for coordination and (b) proposing simple strategies to overcome these difficulties; * II. (a) a geometric definition and related control law for "consensus" configurations on compact homogeneous manifolds, of which synchronization --- all agents at the same point --- is a special case, and (b) control laws to (almost) globally reach synchronization and "balancing", its opposite, under general interconnectivity conditions; * III. several propositions for rigid body attitude synchronization under mechanical dynamics; * IV. a geometric framework for "coordinated motion" on Lie groups, (a) giving a geometric definition of coordinated motion and investigating its implications, and (b) providing systematic methods to design control laws for coordinated motion. Examples treated for illustration of the theoretical concepts are the circle S^1 (sometimes the sphere S^n), the rotation group SO(n), the rigid-body motion groups SE(2) and SE(3) and the Grassmann manifolds Grass(p,n). The developments in this dissertation remain at a rather theoretical level; potential applications are briefly discussed.

In this paper we present an approach to recover the dynamics from recurrences of a system and then generate (multivariate) twin surrogate (TS) trajectories. In contrast to other approaches, such as the linear-like surrogates, this technique produces surrogates which correspond to an independent copy of the underlying system, i. e. they induce a trajectory of the underlying system visiting the attractor in a different way. We show that these surrogates are well suited to test for complex synchronization, which makes it possible to systematically assess the reliability of synchronization analyses. We then apply the TS to study binocular fixational movements and find strong indications that the fixational movements of the left and right eye are phase synchronized. This result indicates that there might be one centre only in the brain that produces the fixational movements in both eyes or a close link between two centres.

In nature one commonly finds interacting complex oscillators which by the coupling scheme form small and large networks, e.g. neural networks. Surprisingly, the oscillators can synchronize, still preserving the complex behavior. Synchronization is a fundamental phenomenon in coupled nonlinear oscillators. Synchronization can be enhanced at different levels, that is, the constraints on which the synchronization appears. Those can be in the trajectory amplitude, requiring the amplitudes of both oscillators to be equal, giving place to complete synchronization. Conversely, the constraint could also be in a function of the trajectory, e.g. the phase, giving place to phase synchronization (PS). In this case, one requires the phase difference between both oscillators to be finite for all times, while the trajectory amplitude may be uncorrelated. The study of PS has shown its relevance to important technological problems, e.g. communication, collective behavior in neural networks, pattern formation, Parkinson disease, epilepsy, as well as behavioral activities. It has been reported that it mediates processes of information transmission and collective behavior in neural and active networks and communication processes in the Human brain. In this work, we have pursed a general way to analyze the onset of PS in small and large networks. Firstly, we have analyzed many phase coordinates for compact attractors. We have shown that for a broad class of attractors the PS phenomenon is invariant under the phase definition. Our method enables to state about the existence of phase synchronization in coupled chaotic oscillators without having to measure the phase. This is done by observing the oscillators at special times, and analyzing whether this set of points is localized. We have show that this approach is fruitful to analyze the onset of phase synchronization in chaotic attractors whose phases are not well defined, as well as, in networks of non-identical spiking/bursting neurons connected by chemical synapses. Moreover, we have also related the synchronization and the information transmission through the conditional observations. In particular, we have found that inside a network clusters may appear. These can be used to transmit more than one information, which provides a multi-processing of information. Furthermore, These clusters provide a multichannel communication, that is, one can integrate a large number of neurons into a single communication system, and information can arrive simultaneously at different places of the network. / In oder Natur sind interagierende komplexe Oszillatoren, die Netzwerke bilden, häufig anzutreffen. Erstaunlich ist, dass sich diese Oszillatoren synchronisieren, ohne ihr eigenes komplexes Verhalten zu verlieren. Diese Fähigkeit zur Synchronisation ist eine wesentliche Eigenschaft von gekoppelten nichtlinearen Oszillatoren. Die Fähigkeit zur Synchronisation kann auf unterschiedliche Weise durch Eingriff in die Bedingungen, die zur Synchronisation führen, verbessert werden. Es kann sowohl eine Synchronisation der Amplituden als auch der Phasen stattfinden bzw. erzwungen werden. Insbesondere Phase Synchronisation über die Phase (PS) hat sich in den wichtigen Bereichen der Technik, Kommunikation, Soziologie und Neurologie als Modellierungsgrundlage bewiesen. Bekannte Beispiele aus der Neurologie sind Parkinson und Epilepsie. In der vorliegenden Arbeit haben wir nach einem verallgemeinerten Weg gesucht, das Phänomen der PS in Netzwerken analysieren zu können. Zuerst haben wir viele Phasendefinitionen für einfache Attraktoren (Oszillatoren mit definierten Phaseneigenschaften) untersucht und festgestellt, dass das Phänomen der PS unabhängig von der Definition der Phase ist. Als nächstes haben wir begonnen, die maximale Abweichungen abzuschätzen, bei der die Synchronisation für bei einer gegebene Phase nicht verlorengeht. Abschließend haben wir eine Methode entwickelt, mittels derer Synchronisation in chaotischen System festgestellt werden kann, ohne die Phase selbst messen zu müssen. Dazu wird zu geeigneten Zeitpunkten der Zustandsraum untersucht. Wir können zeigen, dass mittels dieser Methode in chaotisch Systemen sowohl die Grössenordnung der Synchronisation als auch die Bereiche, in denen Synchronisation stattfindet, untersucht werden können. Dabei kann festgestellt werden, dass der Grad der Synchronisation mit der Menge an Information in Beziehung steht, die an verschieden Stellen eines Netzwerks gleichzeitig übermittelt wird. Dies kann zur Modellierung der Informationsübertragung über die Synapsen im Gehirn verwendet werden.