| 1. |
- Andersson, Alina, et al.
(author)
-
Analytic Parameterization of Stabilizing Controllers for the Surge Subsystem of the Moore-Greitzer Compressor Model
- 2013
-
In: Proc. 2013 American Control Conference (ACC2013). - 0743-1619. - 9781479901777 ; , s. 5257-5262
-
Conference paper (peer-reviewed)abstract
- This paper is based on a new procedure for dynamic output feedback design for systems with nonlinearities satisfying quadratic constraints. The new procedure is motivated by the challenges of output feedback control design for the 3-state Moore-Greitzer compressor model. First, we use conditions for stability of a transformed system and the associated matching conditions to find the data of the stabilizing controllers for the surge subsystem. Second, using the set of stabilizing controllers satisfying the given constraints for the closed-loop system with the dynamic output feedback controller we made optimization over the parameter set. We present the data of the stabilizing controllers and the new constraints for the corresponding parameters. The contributions in this paper are simplified conditions for the synthesis and optimization over the control parameter set.
|
|
| 2. |
- Berntorp, Karl, et al.
(author)
-
Models and Methodology for Optimal Vehicle Maneuvers Applied to a Hairpin Turn
- 2013
-
In: 2013 American Control Conference. - 0743-1619. - 9781479901777 ; , s. 2139-2146
-
Conference paper (peer-reviewed)abstract
- There is currently a strongly growing interest in obtaining optimal control solutions for vehicle maneuvers, both in order to understand optimal vehicle behavior and to devise improved safety systems, either by direct deployment of the solutions or by including mimicked driving techniques of professional drivers. However, it is nontrivial to find the right mix of models, formulations, and optimization tools to get useful results for the above purposes. Here, a platform is developed based on a state-of-the-art optimization tool together with adoption of existing vehicle models, where especially the tire models are in focus. A minimum-time formulation is chosen to the purpose of gaining insight in at-the-limit maneuvers, with the overall aim of possibly finding improved principles for future active safety systems. We present optimal maneuvers for different tire models with a common vehicle motion model, and the results are analyzed and discussed. Our main result is that a few-state single-track model combined with different tire models is able to replicate the behavior of experienced drivers. Further, we show that the different tire models give quantitatively different behavior in the optimal control of the vehicle in the maneuver.
|
|
| 3. |
- Durr, H. -B, et al.
(author)
-
Obstacle avoidance for an extremum seeking system using a navigation function
- 2013
-
In: Proceedings of the American Control Conference 2013. - : AACC American Automatic Control Council. - 9781479901777 ; , s. 4062-4067
-
Conference paper (peer-reviewed)abstract
- The problem of autonomously steering a vehicle to a destination point, while avoiding obstacles, is considered. The vehicle is modeled as a single-integrator in the plane and it is assumed that the obstacles are unknown a priori. The control law is an extremum seeking algorithm, which steers the vehicle to the minimum of a navigation function. In this framework, obstacle avoidance and practical uniform convergence to a destination point for almost all initial conditions is proven. The theoretic results are illustrated using numerical examples.
|
|
| 4. |
- Farokhi, Farhad, 1987-, et al.
(author)
-
Complexity Reduction for Parameter-Dependent Linear Systems
- 2013
-
In: 2013 American Control Conference (ACC). - : American Automatic Control Council. - 9781479901777 ; , s. 2624-2630
-
Conference paper (peer-reviewed)abstract
- We present a complexity reduction algorithm for a family of parameter-dependent linear systems when the system parameters belong to a compact semi-algebraic set. This algorithm potentially describes the underlying dynamical system with fewer parameters or state variables. To do so, it minimizes the distance (i.e., $H_\infty$-norm of the difference) between the original system and its reduced version. We present a sub-optimal solution to this problem using sum-of-squares optimization methods. We present the results for both continuous-time and discrete-time systems. Lastly, we illustrate the applicability of our proposed algorithm on numerical examples.
|
|
| 5. |
- Grip, H. F., et al.
(author)
-
Output synchronization for heterogeneous networks of non-introspective, non-right-invertible agents
- 2013
-
In: Proceedings of the American Control Conference 2013. - : American Automatic Control Council. - 9781479901777 ; , s. 5791-5796
-
Conference paper (peer-reviewed)abstract
- We consider the output synchronization problem for a heterogeneous network of linear agents. The agents are non-introspective, meaning that they do not have access to their own state or output; the only information available to each agent comes from the network, in the form of a linear combination of its output relative to that of neighboring agents. The basis for our study is a design previously presented by the authors, which was based on an additional assumption requiring the agents to be right-invertible. Here we dispense with the assumption of right-invertibility and instead introduce a new assumption based on solvability of a particular set of regulator equations.
|
|
| 6. |
- Ishizaki, T., et al.
(author)
-
Structured model reduction of interconnected linear systems based on singular perturbation
- 2013
-
In: Proceedings of the American Control Conference 2013. - : American Automatic Control Council. - 9781479901777 ; , s. 5524-5529
-
Conference paper (peer-reviewed)abstract
- This paper proposes a singular perturbation approximation that preserves system passivity and an interconnection topology among subsystems. In the first half of this paper, we develop a singular perturbation approximation valid for stable linear systems. Using the relation between the singular perturbation and the reciprocal transformation, we derive a tractable expression of the error system in the Laplace domain, which provides a novel insight to regulate the approximating quality of reduced models. Then in the second half, we develop a structured singular perturbation approximation that focuses on a class of interconnected systems. This structured approximation provides a reduced model that not only possesses fine approximating quality, but also preserves the original interconnection topology and system passivity.
|
|
| 7. |
|
|
| 8. |
- Katselis, Dimitrios, et al.
(author)
-
Efficient OOK/DS-CDMA Detection Threshold Selection
- 2013
-
In: 2013 American Control Conference (ACC). - : American Automatic Control Council. - 9781479901777 ; , s. 3523-3528
-
Conference paper (peer-reviewed)abstract
- A major constraint in deployments of wireless sensor networks (WSNs) is the energy consumption related to the battery lifetime of the network nodes. To this end, power efficient digital modulation techniques such as On-Off keying (OOK) are highly attractive. However, the OOK detection thresholds, namely the thresholds against which the received signals are compared to detect which bit is transmitted, must be carefully selected to minimize the bit error rate. This is challenging to accomplish in resource-limited nodes with constrained computational capabilities. In this paper, the system scenario considers simultaneously transmitting nodes in Rayleigh fading conditions. Various iterative algorithms to numerically select the detection thresholds are established. Convergence analysis accompanies these algorithms. Numerical simulations are provided to support the derived results and to compare the proposed algorithms. It is concluded that OOK modulation is beneficial in resource constrained WSNs provided that efficient optimization algorithms are employed for the threshold selection.
|
|
| 9. |
- Larsson, Christian, et al.
(author)
-
Generation of excitation signals with prescribed autocorrelation for input and output constrained systems
- 2013
-
In: 2013 American Control Conference (ACC). - : American Automatic Control Council. - 9781479901777 ; , s. 3918-3923
-
Conference paper (peer-reviewed)abstract
- This paper considers the problem of realizing an input signal with a desired autocorrelation sequence satisfying both input and output constraints for the system it is to be applied to. This is a important problem in system identification. Firstly, the properties of the identified model are highly dependent on the used excitation signal during the experiment and secondly, on real processes, due to actuator saturation and safety considerations, it is important to constrain the inputs and outputs of the process. The proposed method is formulated as a nonlinear model predictive control problem. In general this corresponds to solving a non-convex optimization problem. Here we show how this can be solved in one particular case. For this special case convergence is established for generation of pseudo-white noise. The performance of the algorithm is successfully verified by simulations for a few different autocorrelation sequences, with and without input and output constraints.
|
|
| 10. |
- Luspay, T., et al.
(author)
-
Mean-square optimal control of Linear Parameter Varying systems
- 2013
-
In: American Control Conference. - 0743-1619. - 9781479901777 ; , s. 6084 - 6089
-
Conference paper (peer-reviewed)abstract
- The problem of designing parameter-dependent output feedback controllers by using inaccurate knowledge of the scheduling parameter is addressed in the paper. Discrete time Linear Parameter Varying (LPV) systems are considered with external scheduling variables corrupted by measurement noise. The paper investigates the optimal control of such LPV class in the quadratic mean-square sense. The solution of the controller design problem is obtained as a standard optimization problem subject to Linear Matrix Inequality (LMI) constraints. A comparative simulation example is given to illustrate the proposed methodology and underline the importance of embedding stochastic information in the LPV control design procedure.
|
|
| 11. |
- Oomen, T., et al.
(author)
-
Iteratively learning the H∞-norm of multivariable systems applied to model-error-modeling of a vibration isolation system
- 2013
-
In: Proceedings of the American Control Conference 2013. - : American Automatic Control Council. - 9781479901777 ; , s. 6703-6708
-
Conference paper (peer-reviewed)abstract
- The aim of this paper is to develop a new data-driven approach for learning the H∞-norm of multivariable systems that can be used for model-error-modeling in robust feedback control. The proposed algorithm only requires iterative experiments on the system. Especially for the multivariable situation that is considered in this paper, these experiments have to be judiciously chosen. The proposed algorithm delivers an estimate of the H ∞-norm of an unknown multivariable system, without the need or explicit construction of a (parametric or non-parametric) model. The results are experimentally demonstrated on model-error-modeling of a multivariable industrial active vibration isolation system. Finally, connections to learning control algorithms are established.
|
|
| 12. |
- Shi, Guodong, et al.
(author)
-
Convergence of Distributed Averaging and Maximizing Algorithms : Part II: State-dependent Graphs
- 2013
-
In: 2013 American Control Conference. - : American Automatic Control Council. - 9781479901777 ; , s. 6859-6864
-
Conference paper (peer-reviewed)abstract
- In this paper, we formulate and investigate a generalized consensus algorithm which makes an attempt to unify distributed averaging and maximizing algorithms considered in the literature. Each node iteratively updates its state as a time-varying weighted average of its own state, the minimal state, and the maximal state of its neighbors. In Part I of the paper, time-dependent graphs are studied. This part of the paper focuses on state-dependent graphs. We use a μ-nearest-neighbor rule, where each node interacts with its μ nearest smaller neighbors and the μ nearest larger neighbors. It is shown that μ+1 is a critical threshold on the total number of nodes for the transit from finite-time to asymptotic convergence for averaging, in the absence of node self-confidence. The threshold is 2μ if each node chooses to connect only to neighbors with unique values. The results characterize some similarities and differences between distributed averaging and maximizing algorithms.
|
|
| 13. |
- Shi, Guodong, et al.
(author)
-
Convergence of distributed averaging and maximizing algorithms : Part I: Time-dependent graphs
- 2013
-
In: 2013 American Control Conference (ACC). - : American Automatic Control Council. - 9781479901777 ; , s. 6096-6101
-
Conference paper (peer-reviewed)abstract
- In this paper, we formulate and investigate a generalized consensus algorithm which makes an attempt to unify distributed averaging and maximizing algorithms considered in the literature. Each node iteratively updates its state as a time-varying weighted average of its own state, the minimal state, and the maximal state of its neighbors. This part of the paper focuses on time-dependent communication graphs. We prove that finite-time consensus is almost impossible for averaging under this uniform model. Then various necessary and/or sufficient conditions are presented on the consensus convergence. The results characterize some similarities and differences between distributed averaging and maximizing algorithms.
|
|
| 14. |
- Stotsky, Alexander, 1960, et al.
(author)
-
Control of wind turbines: A tutorial on proactive perspectives
- 2013
-
In: American Control Conference. - : IEEE. - 0743-1619. - 9781479901777 ; , s. 3429-3436
-
Conference paper (peer-reviewed)abstract
- Recent achievements in the proactive turbine control1, based on the upwind speed measurements are described in a unified tutorial fashion (as an extension of the tutorial [1]), that in turn represents a systematic view of the control activity carried out within the Swedish Wind Power Technology Center (SWPTC). A new turbine control problem statement with constraints on blade loads is reviewed. This problem statement allows the design of a new class of simultaneous speed and pitch control strategies based on the preview measurements and look-ahead calculations. A generation of a piecewise constant desired pitch angle profile which is calculated using the turbine load prediction is reviewed in this paper as one of the most promising approaches. This in turn allows the reduction of the pitch actuation and the design of the collective pitch control strategy with the maximum possible actuation rate.
|
|
| 15. |
- Yang, Tao, et al.
(author)
-
Output synchronization for heterogeneous networks of discrete-time introspective right-invertible agents with uniform constant communication delay
- 2013
-
In: 2013 American Control Conference (ACC). - : American Automatic Control Council. - 9781479901777 ; , s. 516-521
-
Conference paper (peer-reviewed)abstract
- In this paper, we consider synchronization problems for heterogeneous networks of introspective, right-invertible, discrete-time linear agents with uniform constant communication delay. We first design decentralized controllers for solving the output synchronization problem for a set of network topologies under arbitrary bounded delay. We then apply the proposed scheme to solve the formation problem with arbitrarily given formation vectors. Finally, we consider the output regulation problem, where the output of each agent has to track an a prior specified reference trajectory, generated by an exosystem. In this case, we assume that the common root agent has access to its own output relative to the reference trajectory. We then solve the problem for a set of network topologies with delay whose upper bound depends exosystem and some characteristic of network topologies.
|
|
