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  • 1.
    Abdalmoaty, Mohamed
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Learning Stochastic Nonlinear Dynamical Systems Using Non-stationary Linear Predictors2017Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The estimation problem of stochastic nonlinear parametric models is recognized to be very challenging due to the intractability of the likelihood function. Recently, several methods have been developed to approximate the maximum likelihood estimator and the optimal mean-square error predictor using Monte Carlo methods. Albeit asymptotically optimal, these methods come with several computational challenges and fundamental limitations.

    The contributions of this thesis can be divided into two main parts. In the first part, approximate solutions to the maximum likelihood problem are explored. Both analytical and numerical approaches, based on the expectation-maximization algorithm and the quasi-Newton algorithm, are considered. While analytic approximations are difficult to analyze, asymptotic guarantees can be established for methods based on Monte Carlo approximations. Yet, Monte Carlo methods come with their own computational difficulties; sampling in high-dimensional spaces requires an efficient proposal distribution to reduce the number of required samples to a reasonable value.

    In the second part, relatively simple prediction error method estimators are proposed. They are based on non-stationary one-step ahead predictors which are linear in the observed outputs, but are nonlinear in the (assumed known) input. These predictors rely only on the first two moments of the model and the computation of the likelihood function is not required. Consequently, the resulting estimators are defined via analytically tractable objective functions in several relevant cases. It is shown that, under mild assumptions, the estimators are consistent and asymptotically normal. In cases where the first two moments are analytically intractable due to the complexity of the model, it is possible to resort to vanilla Monte Carlo approximations. Several numerical examples demonstrate a good performance of the suggested estimators in several cases that are usually considered challenging.

  • 2.
    Abdalmoaty, Mohamed R.
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Hjalmarsson, Håkan
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Application of a Linear PEM Estimator to a Stochastic Wiener-Hammerstein Benchmark Problem2018In: 18th IFAC Symposium on System Identification, 2018Conference paper (Refereed)
    Abstract [en]

    The estimation problem of stochastic Wiener-Hammerstein models is recognized to be challenging, mainly due to the analytical intractability of the likelihood function. In this contribution, we apply a computationally attractive prediction error method estimator to a real-data stochastic Wiener-Hammerstein benchmark problem. The estimator is defined using a deterministic predictor that is nonlinear in the input. The prediction error method results in tractable expressions, and Monte Carlo approximations are not necessary. This allows us to tackle several issues considered challenging from the perspective of the current mainstream approach. Under mild conditions, the estimator can be shown to be consistent and asymptotically normal. The results of the method applied to the benchmark data are presentedand discussed.

  • 3.
    Abdalmoaty, Mohamed R.
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Rojas, Cristian R.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Hjalmarsson, Håkan
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Identication of a Class of Nonlinear Dynamical Networks2018Conference paper (Refereed)
    Abstract [en]

    Identifcation of dynamic networks has attracted considerable interest recently. So far the main focus has been on linear time-invariant networks. Meanwhile, most real-life systems exhibit nonlinear behaviors; consider, for example, two stochastic linear time-invariant systems connected in series, each of which has a nonlinearity at its output. The estimation problem in this case is recognized to be challenging, due to the analytical intractability of both the likelihood function and the optimal one-step ahead predictors of the measured nodes. In this contribution, we introduce a relatively simple prediction error method that may be used for the estimation of nonlinear dynamical networks. The estimator is defined using a deterministic predictor that is nonlinear in the known signals. The estimation problem can be defined using closed-form analytical expressions in several non-trivial cases, and Monte Carlo approximations are not necessarily required. We show, that this is the case for some block-oriented networks with no feedback loops and where all the nonlinear modules are polynomials. Consequently, the proposed method can be applied in situations considered challenging by current approaches. The performance of the estimation method is illustrated on a numerical simulation example.

  • 4.
    Abdalmoaty, Mohamed
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Henrion, D.
    Rodrigues, L.
    Measures and LMIs for optimal control of piecewise-affine systems2013In: 2013 European Control Conference, ECC 2013, IEEE, 2013, p. 3173-3178, article id 6669627Conference paper (Refereed)
    Abstract [en]

    This paper considers the class of deterministic continuous-time optimal control problems (OCPs) with piecewise-affine (PWA) vector field, polynomial Lagrangian and semialgebraic input and state constraints. The OCP is first relaxed as an infinite-dimensional linear program (LP) over a space of occupation measures. This LP is then approached by an asymptotically converging hierarchy of linear matrix inequality (LMI) relaxations. The relaxed dual of the original LP returns a polynomial approximation of the value function that solves the Hamilton-Jacobi-Bellman (HJB) equation of the OCP. Based on this polynomial approximation, a suboptimal policy is developed to construct a state feedback in a sample-and-hold manner. The results show that the suboptimal policy succeeds in providing a suboptimal state feedback law that drives the system relatively close to the optimal trajectories and respects the given constraints.

  • 5.
    Abdalmoaty, Mohamed
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Hjalmarsson, Håkan
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    A Simulated Maximum Likelihood Method for Estimation of Stochastic Wiener Systems2016In: 2016 IEEE 55th Conference on Decision and Control, CDC 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 3060-3065, article id 7798727Conference paper (Refereed)
    Abstract [en]

    This paper introduces a simulation-based method for maximum likelihood estimation of stochastic Wienersystems. It is well known that the likelihood function ofthe observed outputs for the general class of stochasticWiener systems is analytically intractable. However, when the distributions of the process disturbance and the measurement noise are available, the likelihood can be approximated byrunning a Monte-Carlo simulation on the model. We suggest the use of Laplace importance sampling techniques for the likelihood approximation. The algorithm is tested on a simple first order linear example which is excited only by the process disturbance. Further, we demonstrate the algorithm on an FIR system with cubic nonlinearity. The performance of the algorithm is compared to the maximum likelihood method and other recent techniques.

  • 6.
    Abdalmoaty, Mohamed
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Hjalmarsson, Håkan
    KTH, School of Electrical Engineering (EES), Automatic Control.
    On Re-Weighting, Regularization Selection, and Transient in Nuclear Norm Based Identification2015Conference paper (Refereed)
    Abstract [en]

    In this contribution, we consider the classical problem of estimating an Output Error model given a set of input-output measurements. First, we develop a regularization method based on the re-weighted nuclear norm heuristic. We show that the re-weighting improves the estimate in terms of better fit. Second, we suggest an implementation method that helps in eliminating the regularization parameters from the problem by introducing a constant based on a validation criterion. Finally, we develop a method for considering the effect of the transient when the initial conditions are unknown. A simple numerical example is used to demonstrate the proposed method in comparison to classical and another recent method based on the nuclear norm heuristic.

  • 7.
    Abdalmoaty, Mohamed
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH Royal Institute of Technology.
    Hjalmarsson, Håkan
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Simulated Pseudo Maximum Likelihood Identification of Nonlinear Models2017In: The 20th IFAC World Congress, Elsevier, 2017, Vol. 50, p. 14058-14063Conference paper (Refereed)
    Abstract [en]

    Nonlinear stochastic parametric models are widely used in various fields. However, for these models, the problem of maximum likelihood identification is very challenging due to the intractability of the likelihood function. Recently, several methods have been developed to approximate the analytically intractable likelihood function and compute either the maximum likelihood or a Bayesian estimator. These methods, albeit asymptotically optimal, are computationally expensive. In this contribution, we present a simulation-based pseudo likelihood estimator for nonlinear stochastic models. It relies only on the first two moments of the model, which are easy to approximate using Monte-Carlo simulations on the model. The resulting estimator is consistent and asymptotically normal. We show that the pseudo maximum likelihood estimator, based on a multivariate normal family, solves a prediction error minimization problem using a parameterized norm and an implicit linear predictor. In the light of this interpretation, we compare with the predictor defined by an ensemble Kalman filter. Although not identical, simulations indicate a close relationship. The performance of the simulated pseudo maximum likelihood method is illustrated in three examples. They include a challenging state-space model of dimension 100 with one output and 2 unknown parameters, as well as an application-motivated model with 5 states, 2 outputs and 5 unknown parameters.

  • 8.
    Abdul- Rasool, Mustafa
    KTH, School of Electrical Engineering (EES), Automatic Control.
    THE IMPACT OF ECOROLL ON FUEL CONSUMPTION - USING LOOK AHEAD2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    EcoRoll reduces fuel consumption with small development costs, since no additional hardware is required. It is a function that enables a more efficient conversion of potential to kinetic energy, when travelling downhill. This is achieved by opening the powertrain, and let the engine run on idle to reduce engine losses. In this Master’s thesis, two control strategies were developed, where one is based on prevailing conditions and one utilizes Look-Ahead data. Compared to a vehicle with a conventional cruise control, the first strategy gave a fuel reduction of approximately 3.4% and the other 3.7%. This was simulated on the highway between Södertälje and Norrköping in Sweden.

  • 9.
    Abebe, Zelalem Teffera
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Process Control over Wireless Sensor Networks2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A signicant growth was witnessed in the led of Wireless Sensor Networks (WSNs), the previous decade. Advances in hardware miniaturization coupled with increased processing capabilities and memory capacity have extended the application domains of WSNs. In light of this, standardization organizations led by academia and industries initiated activities for the design of protocols such as IEEE 802.15.4 and IETF RPL (Routing Protocol for Low power and Lossy Networks). IEEE 802.15.4 denes physical and media access layers for WSNs while IETF RPL denes the functionality of the routing layer.

    This thesis investigates research issues in wireless sensor networks and network controlled systems that control micro-biological processes for water treatment plants. By choosing a process model that can relate to an industrial process, feasibility of control over IEEE 802.15.4 and RPL protocols is evaluated for stability with regards to network delay and packet loss. Settling time and overshoot are measured to indicate control performance. Control messages related to routing and routing table lengths are measured to indicate network stability and scalability. The system model used is a centralized discrete controller controlling a thermal processes running on the sensors. This model is chosen for representing wide industrial networked control systems while adding a WSN dimension based on IEEE 802.15.4 and RPL. The main contribution of this thesis is an experimental study where both the network and controller performance is validated while utilizing commercial o-theshelf sensor platforms. The results from this experimental work include rst the use of established theorems for analyzing control using WSNs. Moreover, the ability of IEEE 802.15.4 and RPL to provide stable communication that is reliable enough for actual industrial control implementation is validated.

  • 10. Abrardo, A.
    et al.
    Belleschi, M.
    Fodor, Gábor
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Moretti, M.
    A message passing approach for resource allocation in cellular OFDMA communications2012In: Global Communications Conference (GLOBECOM), 2012 IEEE, IEEE , 2012, p. 4583-4588Conference paper (Refereed)
    Abstract [en]

    This paper proposes a distributed and low-complexity resource allocation scheme for cellular OFDMA networks. In particular, we consider ReMP, a reweighted message passing algorithm that perturbs the standard max-sum algorithm by suitably reweighting messages. In a single-cell scenario, such a scheme allows to achieve convergence to a fixed and provably optimum point without employing any central controller. The ReMP algorithm is then adapted to a multi-cell environment. To this aim, we devise X-ReMP, a ReMP-based algorithm that combines cross-cell signaling and the regular ReMP routine that still runs within each cell. The cross-signaling among cells aids ReMP to deal with the inter-cell multiple-access interference, so that X-ReMP allows convergence to a good working point in terms of system throughput even in presence of strong inter-cell interference.

  • 11. Abrardo, A
    et al.
    Fodor, Gabor
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Tola, B.
    Network coding schemes for Device-To-Device communications based relaying for cellular coverage extension2015In: IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC, 2015, p. 670-674Conference paper (Refereed)
    Abstract [en]

    In this paper, we study the performance of device-To-device (D2D) based range extension in terms of sum rate and power efficiency when a relaying user equipment (UE) helps to improve the coverage for cell-edge UEs. In our design, the relaying UE has own traffic to transmit and receive to/from the cellular base station (BS) and can operate either in amplify-And-forward (AF) or decode-And-forward (DF) modes and can make use of either digital or analogue (PHY layer) network coding. In this rather general setting, we propose mode selection, resource allocation and power control schemes and study their performance by means of system simulations. We find that the performance of the DF scheme with network coding is superior both to the traditional cellular and the AF based relaying schemes, including AF with two-slot or three-slot PHY layer network coding.

  • 12.
    Abrardo, Andrea
    et al.
    University of Siena, Italy.
    Fodor, Gabor
    KTH, School of Electrical Engineering (EES), Automatic Control. Ericsson Research, Stockholm.
    Tola, Besmir
    University of Siena, Italy.
    Network Coding Schemes for Device-to-Device Communications Based Relaying for Cellular Coverage Extension2015Report (Other academic)
    Abstract [en]

    Although network assisted device-to-device (D2D) communications is known to improve the spectraland energy efficiency of proximal communications, its performance is less understood when employedto extend the coverage of cellular networks.In this paper, we study the performance of D2D basedrange extension in terms of sum rate and power efficiency when a relaying user equipment (UE) helps to improvethe coverage for cell-edge UEs.In our design, the relaying UE has own traffic to transmit and receive to/from the cellular base station (BS) andcan operate either in amplify-and-forward (AF) or decode-and-forward (DF) modes and can make use of either digital oranalogue (PHY layer) network coding.In this rather general setting, we propose mode selection, resource allocation and power control schemesand study their performance by means of system simulations.We find that the performance of the DF scheme with network coding is superior both to the traditional cellularand the AF based relaying schemes, including AF with two-slot or three-slot PHY layer network coding.

  • 13. Abu-Rmileh, Amjad
    et al.
    Garcia-Gabin, Winston
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Detection and Prevention of Hypoglycemia in Automated Insulin Delivery Systems for Type 1 Diabetes Patients2012In: Advances in Medicine and Biology / [ed] Leon V. Berhardt, Nova Science Publishers, Inc., 2012, p. 249-266Chapter in book (Refereed)
  • 14. Abu-Rmileh, Amjad
    et al.
    Garcia-Gabin, Winston
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Hypoglycemia prevention in closed-loop artificial pancreas for patients with type 1 diabetes2011In: Diabetes: Damages and treatments / [ed] Everlon Cid Rigobelo, IN-TECH, 2011, p. 207-226Chapter in book (Refereed)
  • 15.
    Abu-Rmileh, Amjad
    et al.
    Universidad de Gerona.
    Garcia-Gabin, Winston
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Smith Predictor Sliding Mode Closed-loop Glucose Controller in Type 1 Diabetes2011In: Proceedings of the 18th IFAC World Congress, 2011, 2011Conference paper (Refereed)
    Abstract [en]

    Type 1 diabetic patients depend on external insulin delivery to keep their blood glucose within near-normal ranges. In this work, two robust closed-loop controllers for blood glucose control are developed to prevent the life-threatening hypoglycemia, as well as to avoid extended hyperglycemia. The proposed controllers are designed by using the sliding mode control technique in a Smith predictor structure. To improve meal disturbance rejection, a simple feedforward controller is added to inject meal-time insulin bolus. Simulation studies were used to test the controllers, and shown the controllers ability to regulate the blood glucose within the safe limits in the presence of errors in measurements, modeling, and meal estimation.

  • 16. Abu-Rmileh, Amjad
    et al.
    Garcia-Gabin, Winston
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Wiener sliding-mode control for artificial pancreas: A new nonlinear approach to glucose regulation2012In: Computer Methods and Programs in Biomedicine, ISSN 0169-2607, E-ISSN 1872-7565, ISSN 0169-2607, Vol. 107, no 2, p. 327-340Article in journal (Refereed)
    Abstract [en]

    Type 1 diabetic patients need insulin therapy to keep their blood glucose close to normal. In this paper an attempt is made to show how nonlinear control-oriented model may be used to improve the performance of closed-loop control of blood glucose in diabetic patients. The nonlinear Wiener model is used as a novel modeling approach to be applied to the glucose control problem. The identified Wiener model is used in the design of a robust nonlinear sliding mode control strategy. Two configurations of the nonlinear controller are tested and compared to a controller designed with a linear model. The controllers are designed in a Smith predictor structure to reduce the effect of system time delay. To improve the meal compensation features, the controllers are provided with a simple feedforward controller to inject an insulin bolus at meal time. Different simulation scenarios have been used to evaluate the proposed controllers. The obtained results show that the new approach out-performs the linear control scheme, and regulates the glucose level within safe limits in the presence of measurement and modeling errors, meal uncertainty and patient variations.

  • 17.
    Ackeberg, Anders
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Control of Periodic Solutions in Chemical Reactors2003Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 18.
    Adaldo, Antonio
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Event-triggered control of multi-agent systems: pinning control, cloud coordination, and sensor coverage2016Licentiate thesis, monograph (Other academic)
    Abstract [en]

    A multi-agent system is composed of interconnected subsystems, or agents. In control of multi-agent systems, the aim is to obtain a coordinated behavior of the overall system through local interactions among the agents. Communication among the agents often occurs over a wireless medium with finite capacity. In this thesis, we investigate multiagent control systems where inter-agent communication is modelled by discrete events triggered by state conditions.

    In the first part, we consider event-triggered pinning control for a network of agents with nonlinear dynamics and time-varying topologies. Pinning control is a strategy to steer the behavior of a multi-agent system in a desired manner by controlling only a small fraction of the agents. We express the controllability of the network in terms of an average value of the network connectivity over time, and we show that all the agents can be driven to a desired reference trajectory.

    In the second part, we propose a control algorithm for multi-agent systems where inter-agent communication is substituted with a shared remote repository hosted on a cloud. Communication between each agent and the cloud is modelled as a sequence of events scheduled recursively by the agent. We quantify the connectivity of the network and we show that it is possible to synchronize the multi-agent system to the same state trajectory, while guaranteeing that two consecutive cloud accesses by the same agent are separated by a finite time interval.

    In the third part, we propose a family of distributed algorithms for coverage and inspection tasks for a network of mobile sensors with asymmetric footprints. We develop an abstract model of the environment under inspection and define a measure of the coverage attained by the sensor network. We show that the sensor network attains nondecreasing coverage, and we characterize the equilibrium configurations. The results presented in the thesis are corroborated by simulations or experiments.

  • 19.
    Adaldo, Antonio
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Pinning Control of Networks: Choosing the Pinned Sites2013Student paper other, 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this master thesis we address the problem of optimal pin selection in four elementary topologies. The augmented connectivity of a graph is defined as an extension of the algebraic connectivity in a pinning control scenario, and its key role in the pinning control problem is illustrated. For each of the considered topologies several pinning configurations are examined and they are compared in terms of the control strength they require to yield a desired value for the augmented connectivity. For each of the examined configurations a direct expression is provided for the control strength as a function of the augmented connectivity.

  • 20.
    Adaldo, Antonio
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Alderisio, Francesco
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Liuzza, Davide
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Shi, Guodong
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Dimarogonas, Dimos V.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    di Bernardo, Mario
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Event-triggered pinning control of complex networks with switching topologies2014In: Proceedings of the 53rd annual IEEE Conference on Decision and Control, 2014, p. 2783-2788Conference paper (Refereed)
    Abstract [en]

    This paper investigates the problem of eventtriggered pinning control for the synchronization of networks of nonlinear dynamical agents onto a desired reference trajectory. The pinned agents are those that have access to the reference trajectory. We consider both static and switching topologies. We prove that the system is well posed and identify conditions under which the network achieves exponential convergence. A lower bound for the rate of convergence is also derived. Numerical examples demonstrating the effectiveness of the results are provided.

  • 21.
    Adaldo, Antonio
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Alderisio, Francesco
    Liuzza, Davide
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Shi, Guodong
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    di Bernardo, Mario
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. University of Naples Federico II, Italy.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Event-Triggered Pinning Control of Switching Networks2015In: IEEE Transactions on Control of Network Systems, ISSN 2325-5870, Vol. 2, no 2, p. 204-213, article id 7098382Article in journal (Refereed)
    Abstract [en]

    This paper investigates event-triggered pinning control for the synchronization of complex networks of nonlinear dynamical systems. We consider networks described by time-varying weighted graphs and featuring generic linear interaction protocols. Sufficient conditions for the absence of Zeno behavior are derived and exponential convergence of a global normed error function is proven. Static networks are considered as a special case, wherein the existence of a lower bound for interevent times is also proven. Numerical examples demonstrate the effectiveness of the proposed control strategy.

  • 22.
    Adaldo, Antonio
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Hybrid coverage and inspection control for anisotropic mobile sensor teams2017In: IFAC-PapersOnLine, ISSN 2405-8963, Vol. 50, no 1, p. 613-618Article in journal (Refereed)
    Abstract [en]

    In this paper, we present an algorithm for pose control of a team of mobile sensors for coverage and inspection applications. The region to cover is abstracted into a finite set of landmarks, and each sensor is responsible to cover some of the landmarks. The sensors progressively improve their coverage by adjusting their poses and by transferring the ownership of some landmarks to each other. Inter-sensor communication is pairwise and intermittent. The sensor team is formally modeled as a multi-agent hybrid system, and an invariance argument formally shows that the team reaches an equilibrium configuration, while a global coverage measure is improving monotonically. A numerical simulation corroborates the theoretical results.

  • 23.
    Adaldo, Antonio
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Liuzza, D.
    Dimarogonas, Dimos V.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Coordination of multi-agent systems with intermittent access to a cloud repository2017In: Workshop on Sensing and Control for Autonomous Vehicles: Applications to Land, Water and Air Vehicles, 2017, Springer, 2017, Vol. 474, p. 453-471Conference paper (Refereed)
    Abstract [en]

    A cloud-supported multi-agent system is composed of autonomous agents required to achieve a common coordination objective by exchanging data over a shared cloud repository. The repository is accessed asychronously by different agents, and direct inter-agent commuication is not possible. This model is motivated by the problem of coordinating a fleet of autonomous underwater vehicles, with the aim to avoid the use of expensive and power-hungry modems for underwater communication. For the case of agents with integrator dynamics, a control law and a rule for scheduling the cloud access are formally defined and proven to achieve the desired coordination. A numerical simulation corroborate the theoretical results.

  • 24.
    Adaldo, Antonio
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Liuzza, Davide
    Dimarogonas, Dimos V.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl H.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Multi-Agent Trajectory Tracking with Self-Triggered Cloud Access2016In: 2016 IEEE 55th Conference on Decision and Control, CDC 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 2207-2214, article id 7798591Conference paper (Refereed)
    Abstract [en]

    This paper presents a cloud-supported control algorithm for coordinated trajectory tracking of networked autonomous agents. The motivating application is the coordinated control of Autonomous Underwater Vehicles. The control objective is to have the vehicles track a reference trajectory while keeping an assigned formation. Rather than relying on inter-agent communication, which is interdicted underwater, coordination is achieved by letting the agents intermittently access a shared information repository hosted on a cloud. An event-based law is proposed to schedule the accesses of each agent to the cloud. We show that, with the proposed scheduling of the cloud accesses, the agents achieve the required coordination objective. Numerical simulations corroborate the theoretical results.

  • 25.
    Adaldo, Antonio
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Liuzza, Davide
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Dimarogonas, Dimos V.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Control of Multi-Agent Systems with Event-Triggered Cloud Access2015In: Proceedings of the 14th annual European Control Conference, 2015Conference paper (Refereed)
  • 26.
    Adaldo, Antonio
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Mansouri, S. S.
    Kanellakis, C.
    Dimarogonas, Dimos V.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Johansson, Karl H.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Nikolakopoulos, G.
    Cooperative coverage for surveillance of 3D structures2017In: 2017 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 1838-1845Conference paper (Refereed)
    Abstract [en]

    In this article, we propose a planning algorithm for coverage of complex structures with a network of robotic sensing agents, with multi-robot surveillance missions as our main motivating application. The sensors are deployed to monitor the external surface of a 3D structure. The algorithm controls the motion of each sensor so that a measure of the collective coverage attained by the network is nondecreasing, while the sensors converge to an equilibrium configuration. A modified version of the algorithm is also provided to introduce collision avoidance properties. The effectiveness of the algorithm is demonstrated in a simulation and validated experimentally by executing the planned paths on an aerial robot.

  • 27.
    Adaldo, Antonio
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Mansouri, Sina Sharif
    Lulea Univ Technol, Dept Comp Elect & Space Engn, Control Engn Div, Robot Grp, SE-97187 Lulea, Sweden..
    Kanellakis, Christoforos
    Lulea Univ Technol, Dept Comp Elect & Space Engn, Control Engn Div, Robot Grp, SE-97187 Lulea, Sweden..
    Dimarogonas, Dimos V.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Johansson, Karl H.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Nikolakopoulos, George
    Lulea Univ Technol, Dept Comp Elect & Space Engn, Control Engn Div, Robot Grp, SE-97187 Lulea, Sweden..
    Cooperative coverage for surveillance of 3D structures2017In: 2017 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS) / [ed] Bicchi, A Okamura, A, IEEE , 2017, p. 1838-1845Conference paper (Refereed)
    Abstract [en]

    In this article, we propose a planning algorithm for coverage of complex structures with a network of robotic sensing agents, with multi-robot surveillance missions as our main motivating application. The sensors are deployed to monitor the external surface of a 3D structure. The algorithm controls the motion of each sensor so that a measure of the collective coverage attained by the network is nondecreasing, while the sensors converge to an equilibrium configuration. A modified version of the algorithm is also provided to introduce collision avoidance properties. The effectiveness of the algorithm is demonstrated in a simulation and validated experimentally by executing the planned paths on an aerial robot.

  • 28.
    Aglert, Johan
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Digital feedback control of the frequency response of a conventional loudspeaker2004Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Automatic control design and Hi-Fi loudspeakers are two areas that not very often are combined. In 1976 Karl Erik Ståhl performed a master thesis project at KTH where he, with analog circuits, made a positive feedback loop to manipulate the mechanical parameters of a loudspeaker. That project introduced the idea to use control design when constructing loudspeakers. In this project this idea is pursued.

    For a subwoofer, the interesting thing from a control perspective is that it is the low frequency range that has to be controlled as opposed to the high frequency range which is normally the case in disturbance and servo problems. This master thesis project will present a solution to this problem where a digital signal processor is used to handle the feed back information. The IMC controller implemented in the processor is based on models derived from data, measured in the tailor made laboratory set-up that was built for the project. In order to satisfy the sampling rate requirements, the complexity of the control algorithm had to be restricted. Despite this limitation in the equipment, the frequency response of the loudspeaker was improved significantly at low frequencies.

  • 29.
    Agüero, Juan C.
    et al.
    The University of Newcastle, Australia.
    Rojas, Cristian R.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Goodwin, Graham C.
    The University of Newcastle, Australia.
    Fundamental Limitations on the Accuracy of MIMO Linear Models Obtained by PEM for Systems Operating in Open Loop2009In: Proceedings of the Joint 48th IEEE Conference on Decision and Control (CDC’09) and 28th Chinese Control Conference (CCC’09), 2009, p. 482-487Conference paper (Refereed)
    Abstract [en]

    In this paper we show that the variance of estimated parametric models for open loopMultiple-Input Multiple-Output (MIMO) systems obtained by the prediction error method (PEM) satisfies a fundamental integral limitation. The fundamental limitation gives rise to a multivariable 'water-bed' effect.

  • 30.
    Agüero, Juan C.
    et al.
    The University of Newcastle, Australia.
    Rojas, Cristian R.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Hjalmarsson, Håkan
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Goodwin, Graham C.
    The University of Newcastle, Australia.
    Accuracy of linear multiple-input multiple-output (MIMO) models obtained by maximum likelihood estimation2012In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 48, no 4, p. 632-637Article in journal (Refereed)
    Abstract [en]

    In this paper, we study the accuracy of linear multiple-input multiple-output (MIMO) models obtained by maximum likelihood estimation. We present a frequency-domain representation for the information matrix for general linear MIMO models. We show that the variance of estimated parametric models for linear MIMO systems satisfies a fundamental integral trade-off. This trade-off is expressed as a multivariable 'water-bed' effect. An extension to spectral estimation is also discussed.

  • 31.
    Ahmadi, Seyed Alireza
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Shames, Iman
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Scotton, Francesco
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Huang, Lirong
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Sandberg, Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Wahlberg, Bo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Towards more efficient building energy management systems2012In: Proceedings - 2012 7th International Conference on Knowledge, Information and Creativity Support Systems, KICSS 2012, IEEE , 2012, p. 118-125Conference paper (Refereed)
    Abstract [en]

    As a first step towards developing efficient building energy management techniques, in this paper, we first study the energy consumption patterns of heating, ventilation and cooling (HVAC) systems across the KTH Royal Institute of Technology campus and we identify some possible areas where energy consumption can be made less wasteful. Later, we describe a test-bed where wireless sensor networks are used to collect data and eventually control the HVAC system in a distributed way. We present some of the data, temperature, humidity, and CO2 measurements, that are collected by the aforementioned network and compare them with the measurements collected by the legacy sensors already in place. In the end we present a preliminary result on modelling the dynamics of the temperature, humidity, and CO2 using the data gather by the sensor network. We check the validity of the model via comparing the out put of the system with measured data. As a future work we identify the possibility of using the models obtained here for model based control, and fault detection and isolation techniques.

  • 32. Akbarzadeh, Sara
    et al.
    Combes, Richard
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Altman, Zwi
    Self-organizing femtocell offloading at the flow level2013In: International Journal of Network Management, ISSN 1055-7148, E-ISSN 1099-1190, Vol. 23, no 4, p. 259-271Article in journal (Refereed)
    Abstract [en]

    Femtocell technology is expected to be fully self-managed, empowered by self-organizing network functionalities. This paper proposes a solution for self-optimized offloading of macrocell traffic towards open/hybrid-access femtocells. A heterogeneous network comprising macro- and femtocells is modeled as parallel queues. The coverage area of the femtocells is self-optimized by dynamically adapting their pilot powers. A simple update equation for the pilot power is given and its convergence is studied using stochastic approximation techniques. The algorithm balances the load among the cells to improve network capacity. Simulation results illustrate the important performance gains brought about by the proposed scheme, using a dynamic network simulator.

  • 33.
    Al Alam, Assad
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Optimally Fuel Ecient Speed Adaptation2008Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An optimal velocity trajectory for a heavy duty vehicle, obtained with the aid of modern GPS and digital map devices, depends on several variables. Curvature speed limitations, road grade, and posted road speed are common constraints imposed by the road travelled. This thesis presents a method for modelling and analysing a switching controller through the use of the former mentioned constraints. A non-linear model for the heavy duty vehicle is derived, enabling suitable control methods to be applied. Pontryagin’s Principal and LQR are discussed to get a profound understanding of how the controller should be designed. It is discovered that a switching controller based on optimal control and engineering experience is most favourable for the problem at hand. The controller is designed to address the main objectives set in this paper of minimising fuel consumption, travelling time, and brake wear.

    Gauss-Newtons’s algorithm for non-linear equations is used to estimate curve radii. Other input parameters are presumed to be available. GPS data error is discussed to perform a sensitivity analysis. An electronic horizon is produced on three road segments, entailed with data of the future road topology. Finally the switching controller is applied to the road segments. Experimental results show that the controller produces a velocity trajectory, which reduces fuel consumption by 5-15% and brake wear by 15-35%, while the travelling time is only increased by 1-2%.

  • 34.
    Al Alam, Assad
    et al.
    Scania CV AB.
    Gattami, Ather
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    An experimental study on the fuel reduction potential of heavy duty vehicle platooning2010In: 13th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2010, IEEE , 2010, p. 306-311Conference paper (Refereed)
    Abstract [en]

    Vehicle platooning has become important for the vehicle industry. Yet conclusive results with respect to the fuel reduction possibilities of platooning remain unclear. The focus in this study is the fuel reduction that heavy duty vehicle platooning enables and the analysis with respect to the influence of a commercial adaptive cruise control on the fuel consumption. Experimental results show that by using preview information of the road ahead from the lead vehicle, the adaptive cruise controller can reduce the fuel consumption. A study is undertaken for various masses of the lead vehicle. The results show that the best choice with respect to a heavier or lighter lead vehicle depends on the desired time gap. A maximum fuel reduction of 4.7-7.7% depending on the time gap, at a set speed of 70 km/h, can be obtained with two identical trucks. If the lead vehicle is 10 t lighter a corresponding 3.8-7.4% fuel reduction can be obtained depending on the time gap. Similarly if the lead vehicle is 10 t heavier a 4.3-6.9% fuel reduction can be obtained. All results indicate that a maximum fuel reduction can be achieved at a short relative distance, due to both air drag reduction and suitable control.

  • 35.
    Al Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Gattami, Ather
    Electrical Engineering and Computer Sciences, UC Berkeley, Berkeley CA, 94720-1770, United States .
    Johansson, Karl Henrik
    Electrical Engineering and Computer Sciences, UC Berkeley, Berkeley CA, 94720-1770, United States .
    Tomlin, Claire Jennifer
    Scania CV AB, Södertälje, Sweden.
    Establishing safety for heavy duty vehicle platooning: a game theoretical approach2011In: IFAC Proceedings Volumes (IFAC-PapersOnline), 2011, p. 3818-3823Conference paper (Refereed)
    Abstract [en]

    It is fuel efficient to minimize the relative distance between vehicles to achievea maximum reduction in air drag. However, the relative distance can only be reduced to acertain extent without endangering a collision. Factors such as the vehicle velocity, the relativevelocity, and the characteristics of the vehicle ahead has a strong impact on what minimumrelative distance can be obtained. In this paper, we utilize optimal control and game theory toestablish safety criteria for heavy duty vehicle platooning applications. The derived results showthat a minimum relative distance of 1.2m can be obtained for two identical vehicles withoutendangering a collision, assuming that there is no delay present in the feedback system. If aworst case delay is present in the system, a minimum relative distance is deduced based uponthe vehicle’s maximum deceleration ability. The relative distance can be reduced if the followervehicle has a greater overall braking capability, which suggests that vehicle heterogeneity andorder has substantial impact. The findings are verified by simulations and the main conclusion isthat the relative distance utilized in commercial applications today can be reduced significantlywith a suitable advanced cruise control system.

  • 36.
    Alam, Assad
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Fuel-Efficient Heavy-Duty Vehicle Platooning2014Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The freight transport industry faces big challenges as the demand for transport and fuel prices are steadily increasing, whereas the environmental impact needs to be significantly reduced. Heavy-duty vehicle (HDV) platooning is a promising technology for a sustainable transportation system. By semi-autonomously governing each platooning vehicle at small inter-vehicle spacing, we can effectively reduce fuel consumption, emissions, and congestion, and relieve driver tension. Yet, it is not evident how to synthesise such a platoon control system and how constraints imposed by the road topography affect the safety or fuel-saving potential in practice.

    This thesis presents contributions to a framework for the design, implementation, and evaluation of HDV platooning. The focus lies mainly on establishing fuel-efficient platooning control and evaluating the fuel-saving potential in practice. A vehicle platoon model is developed together with a system architecture that divides the control problem into manageable subsystems. Presented results show that a significant fuel reduction potential exists for HDV platooning and it is favorable to operate the vehicles at a small inter-vehicle spacing. We address the problem of finding the minimum distance between HDVs in a platoon without compromising safety, by setting up the problem in a game theoretical framework. Thereby, we determine criteria for which collisions can be avoided in a worst-case scenario and establish the minimum safe distance to a vehicle ahead. A systematic design methodology for decentralized inter-vehicle distance control based on linear quadratic regulators is presented. It takes dynamic coupling and engine response delays into consideration, and the structure of the controller feedback matrix can be tailored to the locally available state information. The results show that a decentralized controller gives good tracking performance and attenuates disturbances downstream in the platoon for dynamic scenarios that commonly occur on highways. We also consider the problem of finding a fuel-efficient controller for HDV platooning based on road grade preview information under road and vehicle parameter uncertainties. We present two model predictive control policies and derive their fuel-saving potential. The thesis finally evaluates the fuel savings in practice. Experimental results show that a fuel reduction of 3.9–6.5 % can be obtained on average for a heterogenous platoon of HDVs on a Swedish highway. It is demonstrated how the savings depend on the vehicle position in the platoon, the behavior of the preceding vehicles, and the road topography. With the results obtained in this thesis, it is argued that a significant fuel reduction potential exists for HDV platooning.

  • 37.
    Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Asplund, Fredrik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Behere, Sagar
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Björk, Mattias
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Garcia Alonso, Liliana
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Khaksari, Farzad
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Khan, Altamash
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Kjellberg, Joakim
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Liang, Kuo-Yun
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Lyberger, Rickard
    Scania CV AB.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Nilsson, John-Olof
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Pettersson, Henrik
    Scania CV AB.
    Pettersson, Simon
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Stålklinga, Elin
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Sundman, Dennis
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Zachariah, Dave
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Cooperative driving according to Scoop2011Report (Other academic)
    Abstract [en]

    KTH Royal Institute of Technology and Scania are entering the GCDC 2011 under the name Scoop –Stockholm Cooperative Driving. This paper is an introduction to their team and to the technical approach theyare using in their prototype system for GCDC 2011.

  • 38. Alam, Assad
    et al.
    Besselink, Bart
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Turri, Valerio
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Heavy-Duty Vehicle Platooning for Sustainable Freight Transportation A COOPERATIVE METHOD TO ENHANCE SAFETY AND EFFICIENCY2015In: IEEE CONTROL SYSTEMS MAGAZINE, ISSN 1066-033X, Vol. 35, no 6, p. 34-56Article in journal (Refereed)
    Abstract [en]

    The current system of global trade is largely based on transportation and communication technology from the 20th century. Advances in technology have led to an increasingly interconnected global market and reduced the costs of moving goods, people, and technology around the world [1]. Transportation is crucial to society, and the demand for transportation is strongly linked to economic development. Specifically, road transportation is essential since about 60% of all surface freight transportation (which includes road and rail transport) is done on roads [2]. Despite the important role of road freight transportation in the economy, it is facing serious challenges, such as those posed by increasing fuel prices and the need to reduce greenhouse gas emissions. On the other hand, the integration of information and communication technologies to transportation systems-leading to intelligent transportation systems-enables the development of cooperative methods to enhance the safety and energy efficiency of transportation networks. This article focuses on one such cooperative approach, which is known as platooning. The formation of a group of heavy-duty vehicles (HDVs) at close intervehicular distances, known as a platoon (see Figure 1) increases the fuel efficiency of the group by reducing the overall air drag. The safe operation of such platoons requires the automatic control of the velocity of the platoon vehicles as well as their intervehicular distance. Existing work on platooning has focused on the design of controllers for these longitudinal dynamics, in which simple vehicle models are typically exploited and perfect environmental conditions, such as flat roads, are generally assumed. The broader perspective of how platooning can be effectively exploited in a freight transportation system has received less attention. Moreover, experimental validations of the fuel-saving potential offered by platooning have typically been performed by reproducing the perfect conditions as assumed in the design of the automatic controllers. This article focuses on these two aspects by addressing the following two objectives.

  • 39.
    Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Scania CV AB, SE-15187 Södertälje, Sweden.
    Gattami, Ather
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl H.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Tomlin, Claire J.
    UC Berkeley.
    Guaranteeing safety for heavy duty vehicle platooning: Safe set computations and experimental evaluations2014In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 24, no 1, p. 33-41Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the problem of finding a safety criteria between neighboring heavy duty vehicles traveling in a platoon. We present a possible framework for analyzing safety aspects of heavy duty vehicle platooning. A nonlinear underlying dynamical model is utilized, where the states of two neighboring vehicles are conveyed through radar information and wireless communication. Numerical safe sets are derived through the framework, under a worst-case scenario, and the minimum safe spacing is studied for heterogenous platoons. Real life experimental results are presented in an attempt to validate the theoretical results in practice. The findings show that a minimum relative distance of 1.2 m at maximum legal velocity on Swedish highways can be maintained for two identical vehicles without endangering a collision. The main conclusion is that the relative distance utilized in commercial applications today can be reduced significantly with a suitable automatic control system.

  • 40. Alam, Assad
    et al.
    Gattami, Ather
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Suboptimal Decentralized Controller Design for Chain Structures: Applications to Vehicle Formations2011In: IEEE 50th Annual Conference on Decision and Control and European Control Conference, Orlando, December, 2011, IEEE , 2011, p. 6894-6900Conference paper (Refereed)
    Abstract [en]

    We consider suboptimal decentralized controllerdesign for subsystems with interconnected dynamics and costfunctions. A systematic design methodology is presented overthe class of linear quadratic regulators (LQR) for chain graphs.The methodology is evaluated on heavy duty vehicle platooningwith physical constraints. A simulation and frequency analysisis performed. The results show that the decentralized controllergives good tracking performance and a robust system. We alsoshow that the design methodology produces a string stablesystem for an arbitrary number of vehicles in the platoon, ifthe vehicle configurations and the LQR weighting parametersare identical for the considered subsystems.

  • 41.
    Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Experimental evaluation of decentralized cooperative cruise control for heavy-duty vehicle platooning2015In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 38, p. 11-25Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the problem of finding decentralized controllers for heavy-duty vehicle (HDV) platooning by establishing empiric results for a qualitative verification of a control design methodology. We present a linear quadratic control framework for the design of a high-level cooperative platooning controller suitable for modern HDVs. A nonlinear low-level dynamical model is utilized, where realistic response delays in certain modes of operation are considered. The controller performance is evaluated through numerical and experimental studies. It is concluded that the proposed controller behaves well in the sense that experiments show that it allows for short time headways to achieve fuel efficiency, without compromising safety. Simulation results indicate that the model mimics real life behavior. Experiment results show that the dynamic behavior of the platooning vehicles depends strongly on the gear switching logic, which is confirmed by the simulation model. Both simulation and experiment results show that the third vehicle never displays a bigger undershoot than its preceding vehicle. The spacing errors stay bounded within 6.8. m in the simulation results and 7.2. m in the experiment results for varying transient responses. Furthermore, a minimum spacing of -0.6. m and -1.9. m during braking is observed in simulations and experiments, respectively. The results indicate that HDV platooning can be conducted at close spacings with standardized sensors and control units that are already present on commercial HDVs today.

  • 42.
    Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Johansson, Karl H.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Automatic Control.
    Look-Ahead Cruise Control for Heavy Duty Vehicle Platooning2013In: Proceedings of the 16th International IEEE Annual Conference onIntelligent Transportation Systems (ITSC 2013), IEEE conference proceedings, 2013, p. 928-935Conference paper (Refereed)
    Abstract [en]

    Vehicle platooning has become important for thevehicle industry. Yet conclusive results with respect to thefuel reduction possibilities of platooning remain unclear, inparticular when considering constraints imposed by the topography.The focus of this study is to establish whether itis more fuel-efficient to maintain or to split a platoon that isfacing steep uphill and downhill segments. Two commercialcontrollers, an adaptive cruise controller and a look-aheadcruise controller, are evaluated and alternative novel controlstrategies are proposed. The results show that an improvedfuel-efficiency can be obtained by maintaining the platoonthroughout a hill. Hence, a cooperative control strategy basedon preview information is presented, which initiates the changein velocity at a specific point in the road for all vehiclesrather than simultaneously changing the velocity to maintainthe spacing. A fuel reduction of up to 14% can be obtainedover a steep downhill segment and a more subtle benefit of0.7% improvement over an uphill segment with the proposedcontroller, compared to the combination of the commerciallyavailable cruise controller and adaptive cruise controller thatcould be used for platooning. The findings show that it isboth fuel-efficient and desirable in practice to consider previewinformation of the topography in the control strategy.

  • 43.
    Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Sahlholm, Per
    KTH, School of Electrical Engineering (EES), Automatic Control.
    A Method for Determining an Economical Speed for Heavy Vehicles2008In: Proceedings of the 15th World Congress on Intelligent Transport Systems, World Congress on Intelligent Transport Systems (ITS), 2008Conference paper (Refereed)
  • 44.
    Alberer, Daniel
    et al.
    Johannes Kepler University.
    Hjalmarsson, HåkanKTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.del Re, LuigiJohannes Kepler University.
    Identification for Automotive Systems2012Collection (editor) (Refereed)
  • 45.
    Alberer, Daniel
    et al.
    Johannes Kepler University.
    Hjalmarsson, Håkan
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    del Re, Luigi
    Johannes Kepler University.
    System Identification for Automotive Systems: Opportunities and Challenges2012In: Identification for Automotive Systems / [ed] Daniel Alberer, Håkan Hjalmarsson, Luigi del Re, Springer London, 2012, p. 1-10Chapter in book (Refereed)
    Abstract [en]

    Without control many essential targets of the automotive industry could not be achieved. As control relies directly or indirectly on models and model quality directly influences the control performance, especially in feedforward structures as widely used in the automotive world, good models are needed. Good first principle models would be the first choice, and their determination is frequently difficult or even impossible. Against this background methods and tools developed by the system identification community could be used to obtain fast and reliably models, but a large gap seems to exist: neither these methods are sufficiently well known in the automotive community, nor enough attention is paid by the system identification community to the needs of the automotive industry. This introduction summarizes the state of the art and highlights possible critical issues for a future cooperation as they arose from an ACCM Workshop on Identification for Automotive Systems recently held in Linz, Austria.

  • 46.
    Alderisio, Francesco
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Pinning Control of Networks: an Event-Triggered Approach2013Student paper other, 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this master thesis we present an algorithm for distributed event-triggered pinning control of a network of nonlinear oscillators. In order to extend the concepts of connected, switching connected and slow switching topology to a pinning control scenario, we introduce the denitions of pinned, switching pinned and frequently pinned topology respectively. For each of these three topologies we try to identify the conditions under which the network achieves exponential convergence of the error norm, find a lower bound for the rate of convergence and prove that the trigger sequences do not exhibit Zeno behavior. Some numerical results are presented for each of the considered scenarios; further numerical results are presented for four elementary static topologies.

  • 47. Alesii, Roberto
    et al.
    Congiu, Roberto
    Santucci, Fortunato
    Di Marco, Piergiuseppe
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Architectures and protocols for fast identification in large-scale RFID systems2014In: ISCCSP 2014 - 2014 6th International Symposium on Communications, Control and Signal Processing, Proceedings, 2014, p. 243-246Conference paper (Refereed)
    Abstract [en]

    Passive tags based on backscattered signals yield low energy consumption for large-scale applications of RFIDs. In this paper, system architectures and protocol enhancements for fast identifications in ISO/IEC 18000-6C systems that integrate UWB technology are investigated. The anti-collision protocol is studied by considering various tag populations. A novel algorithm is proposed to adapt the UHF air interface parameters with the use of UWB ranging information. The results show that the proposed algorithm yields up to 25% potential performance improvement compared to the ISO/IEC 18000-6C standard.

  • 48. Alexandre, Seuret
    et al.
    Dimarogonas, Dimos V.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Automatic Control.
    Consensus of Double Integrator Multi-agents under Communication Delay2009In: IFAC Proceedings Volumes (IFAC-PapersOnline), 2009, p. 376-381Conference paper (Refereed)
    Abstract [en]

    This paper deals with the consensus problem under network induced communication delays. It is well-known that introducing a delay generally leads to a reduce of the performance or to instability. Thus, investigating the impact of time-delays in the consensus problem is an important issue. Another important issue is to obtain an estimate of the convergence rate, which is not straightforward when delays appear in the network. In this paper, the agents are modelled as double integrator systems. It is assumed that each agent receives instantaneously its own output information but receives the information from its neighbors after a constant delay. A stability criterion is provided based on Lyapunov-Krasovskii techniques and is expressed in terms of LMI. An expression of the consensus equilibrium which depends on the delay and on the initial conditions taken in an interval is derived. The results are supported through several simulations for different network symmetric communication schemes.

  • 49.
    Alfonsetti, Elisabetta
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Privacy preserving car-parking: adistributed approach2012Student paper other, 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There has been a substantial interest recently in privacy preserving problems in various application domains, including data publishing, data mining, classication, secret voting, private querying of database, playing mental poker, and many others. The main constraint is that entities involved in the system are unwilling to reveal the data they hold or make them public. However, they may want to collaborate and nd the solution of a bigger computational problem without revealing the privately held data. There are several approaches for addressing such issues, including cryptographic methods, transformation methods, and parallel and distributed computation techniques. In this thesis, these three methods are highlighted and a greater emphasis is placed on the last one. In particular, we discuss the theoretical backgrounds of optimization decomposition techniques. We further point out key literature associated with the privacy preserving problems and provide basic classications of their treatments. We focus to a particular interesting application, namely the car parking problem, or parking slot assignment problem. To solve the problem in a privacy preserving manner, a new parallel and distributed computation method is proposed. The goal is to allocate the parking slots to the cars, but without revealing anyone else the intended destinations. We apply decomposition techniques together with projected subgradient method to address this problem and the result is a decentralized privacy preserving car parking algorithm. We compare our algorithm with three other methods and numerically evaluate the performance of the proposed algorithm, in terms of optimality and as well as the computational speed. Despite the reduced computational complexity of the proposed algorithm, it provides close-to-optimal performance.

  • 50.
    Alfonsetti, Elisabetta
    et al.
    KTH, School of Electrical Engineering (EES).
    Weeraddana, P. C.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Min-max fair car-parking slot assignment2015In: Proceedings of the WoWMoM 2015: A World of Wireless Mobile and Multimedia Networks, IEEE conference proceedings, 2015Conference paper (Refereed)
    Abstract [en]

    Empirical studies show that cruising for car parking accounts for a non-negligible amount of the daily traffic, especially in central areas of large cities. Therefore, mechanisms for minimizing traffic from cruising directly affect the dynamics of traffic congestions. One way to minimizing cruising traffic is efficient car-parking-slot assignment. Usually, the related design problems are combinatorial and the worst-case complexity of optimal methods grows exponentially with the problem sizes. As a result, almost all existing methods for parking slot assignment are simple and greedy approaches, where each car or the user is assigned a free parking slot, which is closer to its destination. Moreover, no emphasis is placed to optimize any form of fairness among the users as the a social benefit. In this paper, the fairness as a metric for modeling the aggregate social benefit of the users is considered. An algorithm based on Lagrange duality is developed for car-parking-slot assignment. Numerical results illustrate the performance of the proposed algorithm compared to the optimal assignment and a greedy method.

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