| 1. |
- Andersson, Alina, et al.
(författare)
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Robustness of the Moore-Greitzer Compressor Model's Surge Subsystem with New Dynamic Output Feedback Controllers
- 2014. - 3
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Ingår i: 19th IFAC World Congress. - : Elsevier. - 2405-8963. - 9783902823625 ; 47, s. 3690-3695
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Konferensbidrag (refereegranskat)abstract
- This work presents an extension of a design procedure for dynamic output feedback design for systems with nonlinearities satisfying quadratic constraints. In this work we used an axial gas compressor model described by the 3-state Moore-Greitzer compressor model (MG) that has some challenges for output feedback control design (Planovsky and Nikolaev 1990), (Rubanova 2013). The more general constraints for the investigation of the robustness with respect to parametric uncertainties and measurement noise are shown.
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| 2. |
- Andersson, Ingemar, 1969, et al.
(författare)
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Detection of Combustion Properties in a Diesel Engine using Block Mounted Accelerometers
- 2014
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - : Elsevier BV. - 1474-6670. - 9783902823625 ; 19, s. 11866-11871
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Konferensbidrag (refereegranskat)abstract
- Engine block mounted accelerometers was used for estimating combustion phasing parameters for a heavy duty diesel engine. Several sensor locations were evaluated for its sensitivity to combustion related vibrations and mechanical noise.One sensor-cylinder combination was selected for the evaluation of a simple algorithm to detect 10% and 50% burned mass fraction. The algorithm uses the accumulated accelerometer vibration energy as a base for extracting the 10% and 50% points respectively.The results show that the angular positions for 10% and 50% burned mass fraction can be estimated with precisions of 1.5 and 3 CAD respectively. It is also concluded that the early part of the accelerometer signal has a significant influence from a mechanical noise source related to the start of injection.
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| 3. |
- Axelsson, Patrik, 1985-, et al.
(författare)
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H∞-Controller Design Methods Applied to One Joint of a Flexible Industrial Manipulator
- 2014
-
Ingår i: Proceedings of the 19th IFAC World Congress, 2014. - : International Federation of Automatic Control. - 9783902823625 ; , s. 210-216
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Konferensbidrag (refereegranskat)abstract
- Control of a flexible joint of an industrial manipulator using H∞ design methods is presented. The considered design methods are i) mixed-H∞ design, and ii) H∞ loop shaping design. Two different controller configurations are examined: one uses only the actuator position, while the other uses the actuator position and the acceleration of end-effector. The four resulting controllers are compared to a standard PID controller where only the actuator position is measured. The choices of the weighting functions are discussed in details. For the loop shaping design method, the acceleration measurement is required to improve the performance compared to the PID controller. For the mixed-H∞ method it is enough to have only the actuator position to get an improved performance. Model order reduction of the controllers is briefly discussed, which is important for implementation of the controllers in the robot control system.
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| 4. |
- Axelsson, Patrik, 1985-, et al.
(författare)
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H∞ Synthesis Method for Control of Non-linear Flexible Joint Models
- 2014
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Ingår i: Proceedings of the 19th IFAC World Congress, 2014. - : International Federation of Automatic Control. - 9783902823625 ; , s. 8372-8377
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Konferensbidrag (refereegranskat)abstract
- An H∞ synthesis method for control of a flexible joint, with non-linear spring characteristic, is proposed. The first step of the synthesis method is to extend the joint model with an uncertainty description of the stiffness parameter. In the second step, a non-linear optimisation problem, based on nominal performance and robust stability requirements, has to be solved. Using the Lyapunov shaping paradigm and a change of variables, the non-linear optimisation problem can be rewritten as a convex, yet conservative, LMI problem. The method is motivated by the assumption that the joint operates in a specific stiffness region of the non-linear spring most of the time, hence the performance requirements are only valid in that region. However, the controller must stabilise the system in all stiffness regions. The method is validated in simulations on a non-linear flexible joint model originating from an industrial robot.
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| 5. |
- Bonafilia, Brian, et al.
(författare)
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Robust manual control of a manufacturing system using supervisory control theory
- 2014
-
Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - : Elsevier BV. - 1474-6670. - 9783902823625 ; 19, s. 748-753
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Konferensbidrag (refereegranskat)abstract
- There are many situations where manual intervention in automated systems, such as flexible manufacturing systems, is inevitable. Commonly the control of a manufacturing system is implemented in terms of operations, and sequences thereof, and these operations can typically be run manually. However, running the operations in arbitrary order may lead to situations such as blocking or collisions, from which it its hard or even impossible to recover or to resume automatic execution. This paper describes an implementation of an operator interface for robust manual control of a manufacturing system, where the operator is aided not to manually drive the system into a state that breaches the system requirements. Hence, blocking and collisions are avoided, and automatic mode can always be resumed. From a model of the manufacturing system based on self-contained operations, each of which is identified in terms of events with preconditions, a supervisor is calculated by use of the Supervisory Control Theory framework. From this supervisor additional preconditions are extracted for each operation. The operations with the extended preconditions are then ported to an operator interface which allows manual control of the production cell by dynamically guiding the operator to only those operations for which the extended preconditions are satisfied.
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| 6. |
- Bottegal, Giulio, et al.
(författare)
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Analysis and identification of complex stochastic systems admitting a flocking structure
- 2014
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - : Elsevier BV. - 1474-6670. - 9783902823625 ; , s. 2323-2328
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Konferensbidrag (refereegranskat)abstract
- We discuss a new modeling paradigm for large dimensional aggregates of stochastic systems by Generalized Factor Analysis (GFA) models. These models describe the data as the sum of a flocking plus an uncorrelated idiosyncratic component. The flocking component describes a sort of collective orderly motion which admits a much simpler mathematical description than the whole ensemble while the idiosyncratic component describes weakly correlated noise. The extraction of the dynamic flocking component is discussed for time-stationary systems.
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| 7. |
- Bottegal, Giulio, et al.
(författare)
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Outlier robust system identification : A Bayesian kernel-based approach
- 2014
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - : IFAC Papers Online. - 9783902823625 ; , s. 1073-1078
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Konferensbidrag (refereegranskat)abstract
- In this paper, we propose an outlier-robust regularized kernel-based method for linear system identification. The unknown impulse response is modeled as a zero-mean Gaussian process whose covariance (kernel) is given by the recently proposed stable spline kernel, which encodes information on regularity and exponential stability. To build robustness to outliers, we model the measurement noise as realizations of independent Laplacian random variables. The identification problem is cast in a Bayesian framework, and solved by a new Markov Chain Monte Carlo (MCMC) scheme. In particular, exploiting the representation of the Laplacian random variables as scale mixtures of Gaussians, we design a Gibbs sampler which quickly converges to the target distribution. Numerical simulations show a substantial improvement in the accuracy of the estimates over state-of-the-art kernel-based methods.
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| 8. |
- Broomhead, Timothy James, et al.
(författare)
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A Robust Model Predictive Control Framework for Diesel Generators
- 2014
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Ingår i: Proceedings of 19th IFAC World Congress. - : International Federation of Automatic Control (IFAC). - 9783902823625 ; , s. 11848-11853
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Konferensbidrag (refereegranskat)abstract
- A constraint tightened linear-time-varying MPC framework is proposed with applications in power tracking for variable and fixed speed generators. Current constraint tightening approaches are extended to allow for practical applications where future system representations are unknown. The resulting control structure is shown to be robustly feasible under given conditions. Knowledge about the geometry of system constraints is exploited to obtain a computationally efficient method of computing tightened sets online. A simulation study is presented demonstrating the ability of the controller to handle modelling error and demonstrate tracking of a commanded power profile.
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| 9. |
- Cao, Ming, et al.
(författare)
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Focused First-Followers Accelerate Aligning Followers with the Leader in Reaching Network Consensus
- 2014
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Ingår i: 19th IFAC World Congress 2014. - : Elsevier BV. - 9781634394567 - 9783902823625 ; , s. 7819-
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Konferensbidrag (refereegranskat)abstract
- This paper proposes and analyzes a new strategy to accelerate the process of reaching consensus in leader-follower networks. By removing or weakening specific directed couplings pointing to the first followers from the other followers, we prove that all the followers' states converge faster to that of the leader. This result is in sharp contrast to the well known fact that when the followers are coupled together through undirected links, removing or weakening links always decelerate the converging process. Simulation results are provided to illustrate this subtle, yet somewhat surprising, provably correct result.
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| 10. |
- Dabiri, Azita, 1984, et al.
(författare)
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Incident parameter scheduled freeway traffic control - A ramp meter approach
- 2014
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - : Elsevier BV. - 1474-6670. - 9783902823625 ; 19, s. 11338-11343
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Konferensbidrag (refereegranskat)abstract
- A novel model based local ramp metering method is presented in the paper by means of incident scheduled freeway traffic control solution. First, second order macroscopic freeway model is used with appropriate incident parametrization to describe eventual and unattended traffic variation caused by off-nominal traffic conditions (e.g. accidents). These traffic anomalies are captured by adequate model parameters, i.e. incident parameters that can be on-line estimated. The paper is motivated by incident scheduled ramp-meter solution to encounter real-time incident parameter information. The main idea is to use local freeway control solution triggered by available incident parameter values. The proposed approach is local in the sense of considering only non-coordinated ramp meter solution, first. Furthermore, we apply locally optimal (linearized) control solution to satisfy throughput maximization objective. The formal controller synthesis involves parameters to correct, compensate the effect of incidents. The proposed method is evaluated and compared to other existing approach by using simulation environment.
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