| 1. |
- Hjalmarsson, Håkan, et al.
(författare)
-
Identification of performance limitations in control
- 2001
-
Ingår i: 2001 European Control Conference, ECC 2001. - : IEEE conference proceedings. - 9783952417362 ; , s. 1446-1451
-
Konferensbidrag (refereegranskat)abstract
- Non-minimum phase zeros and poles of a process put upper and lower constraints on the bandwidth of a closed loop system. It is thus of great interest to be able to identify these quantities. In this contribution it is shown that non-minimum phase zeros and unstable poles can be identified using high order models without the standard o(n) (n is the model order) variance penalty for over modeling. An asymptotic, in the model order and the number of data, expression for the variance of non-minimum phase zeros is derived. This result shows that the problem of determining the performance limits of a system from experimental data is considerably easier than identifying the complete system. As a direct application of this an optimal experiment design problem for identification of performance limits is posed and solved.
|
|
| 2. |
- Hjalmarsson, Håkan, et al.
(författare)
-
Robust loopshaping using iterative feedback tuning
- 2001
-
Ingår i: 2001 European Control Conference, ECC 2001. - : IEEE conference proceedings. - 9783952417362 ; , s. 2046-2051
-
Konferensbidrag (refereegranskat)abstract
- Iterative Feedback Tuning (IFT) is a direct tuning method using closed loop experimental data. The method is based on numerical optimization and in each iteration an unbiased gradient estimate is used. In this contribution we show how to use IFT to do robust loopshaping. One method, based on the approach suggested by Glover and McFarlane [1], uses an approximate H∞ cost function and alternates between updating the loop gains and the robustness margins. In a second, H2 based method, a joint criterion of robustness and performance is optimized. The methods are illustrated on numerical examples.
|
|
| 3. |
- Holmberg, Ulf, 1959-, et al.
(författare)
-
A pneumatic loudspeaker for intensive sounds
- 2001
-
Ingår i: ECC : 2001 European Control Conference. - New York, NY : Institute of Electrical and Electronics Engineers (IEEE). - 9783952417362 ; , s. 2257-2260
-
Konferensbidrag (refereegranskat)abstract
- A pneumatic loudspeaker for intensive sounds is presented. It operates by modulation of air from over- and underpressure reservoirs, as opposed to siren-like loudspeakers that use compressed air only. The symmetric construction makes the behavior more linear both with respect to aperture amplitudes and frequency bandwidth. Therefore, it may be used as secondary source in industrial active noise control problems where generation of large volume velocities are necessary. It is also shown that a Hammerstein model can model the loudspeaker over a wide frequency band. © 2001 EUCA.
|
|
| 4. |
- Horch, A., et al.
(författare)
-
Detection of valve stiction in integrating processes
- 2001
-
Ingår i: 2001 European Control Conference, ECC 2001. - : IEEE conference proceedings. - 9783952417362 ; , s. 1327-1332
-
Konferensbidrag (refereegranskat)abstract
- A simple method for detection of static friction (stiction) in control valves was presented in [6]. However, that method cannot be used for control loops with integrating processes. This paper presents a new method to handle these cases. The main idea is to detect abrupt changes (which are typical in the case of stiction) in the loop output. This is done by considering the probability distribution of the second derivative. In the stiction case the distribution is close to Gaussian, otherwise it will have two peaks.
|
|
| 5. |
- Nagamune, Ryozo
(författare)
-
Closed-loop shaping by analytic functions with a bounded degree
- 2001
-
Ingår i: 2001 European Control Conference, ECC 2001. - : IEEE conference proceedings. - 9783952417362 ; , s. 722-726
-
Konferensbidrag (refereegranskat)abstract
- This paper proposes a new technique for frequency shaping of the closed-loop system. The technique does not involve any weighting function for shaping, which is often used in the conventional H∞ control theory, but selects a desirable analytic function from a set of H∞ suboptimal solutions with a bounded degree. The Nevanlinna-Pick interpolation theory with a degree bound plays a central role in deriving shaping strategies of the closed-loop frequency responses. One example illustrates the efficiency of the proposed method by comparing it with a conventional method in H∞ control.
|
|
| 6. |
- Reinelt, Wolfgang
(författare)
-
Control of Multivariable Systems with Hard Constraints
- 2001
-
Ingår i: Proceedings of the 2001 European Control Conference. - Linköping : IEEE. - 9783952417362 ; , s. 2576-2581
-
Konferensbidrag (refereegranskat)abstract
- A general framework for the design of multivariable control systems subject to hard constraints on each control channel is developed. The design procedure is an extension of the well-known H∞ Loop Shaping Design Procedure and is based on the calculation of the maximum possible control amplitude for a certain class of reference signals. Special attention is given to the adaption of the design weights in order to meet the prescribed bounds on the control signal. A multivariable simulation example, the control of the vertical dynamics of an aircraft, illustrates the suggested procedure.
|
|
| 7. |
- Reinelt, Wolfgang
(författare)
-
Design of Optimal Control Systems with Bounded Control Signals
- 2001
-
Ingår i: Proceedings of the 2001 European Control Conference. - Linköping : IEEE. - 9783952417362 ; , s. 348-353
-
Konferensbidrag (refereegranskat)abstract
- The design of optimal controllers for systems subject to hard bounds on the control signal is considered. Optimality refers to the fact that we achieve the smallest possible worst case error (i.e. difference between reference signal and plant output) during runtime. The external reference signal is bounded in amplitude and rate, which encounters for many practical situations. Moreover, a conservative design is avoided by these assumptions. The resulting constrained and infinite dimensional optimisation problem is re-casted to an unconstrained and finite dimensional one by applying the notion of Pareto-optimal solutions and Ritz approximation. Moreover, the presented framework allows to assess feasibility of the constraint control problem, and to display the tradeoff between the two objectives. A simulation example illustrates the developed theory.
|
|
| 8. |
- Simić, S. N., et al.
(författare)
-
Structural stability of hybrid systems1
- 2001
-
Ingår i: 2001 European Control Conference, ECC 2001. - : IEEE conference proceedings. - 9783952417362 ; , s. 3858-3863
-
Konferensbidrag (refereegranskat)abstract
- We study hybrid systems from a global geometric perspective as piecewise smooth dynamical systems. Based on an earlier work, we define the notion of the hybrifold as a single piece-wise smooth state space reflecting the dynamics of the original system. Structural stability for hybrid systems is introduced and analyzed in this framework. In particular, it is shown that a Zeno state is locally structurally stable and that a standard equilibrium on the boundary of a domain implies structural instability.
|
|
