| 1. |
- Gunnarsson, Johan, et al.
(author)
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Automatic Synthesis for Simultaneous Supervision and Control - a First Example
- 1995
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In: Proceedings of the 1995 American Control Conference. - 0780324455 ; , s. 3157-3162 vol.5
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Conference paper (peer-reviewed)abstract
- We investigate whether it is possible to synthesize the control law for a discrete event dynamic system, using a polynomial representation of the system and controller. By working through a relatively simple example we propose a synthesis method based on the polynomial representation and repeated Grobner basis computations. The supervisor objective is given in terms of forbidden states and the controller should actively be able to avoid these. We reduce the manifold of solutions by imposing a weighting function on the state space and by proposing a priority among the actuators. In this way we can improve the computational performance and we can also control the system towards a desired state, which is our control objective. The computational load lies in the design phase where we use Grobner bases. The resulting controller description is suited for red time applications since the computations needed are evaluations of a limited number of polynomials. During the design phase we also obtain a polynomial describing where in the state space the computed control law is valid. This makes it possible to examine controllability and supervisability of the system.
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| 2. |
- Hillerström, Gunnar
(author)
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Adaptive suppression of vibrations : a repetitive control approach
- 1995
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In: Proceedings of the 1995 American Control Conference. - Piscataway, NJ : IEEE Communications Society. - 0780324455 - 0780324463 ; , s. 3820-3824
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Conference paper (peer-reviewed)abstract
- The aim of this paper is to present an adaptive solution to suppression of vibrations. Adaptation is appropriate whenever the fundamental frequency is unknown or drifting, e.g. when the vibration is caused by a rotational machine with unknown rotational speed. The approach presented here has its roots in repetitive control based on models of isolated frequencies rather than the commonly used delay model. The relationship between different modeled frequencies is fixed by the model structure, and the fundamental frequency is obtained by gradient descent. To show the feasibility of this approach, it was used to reduce vibrations on a lever that were caused by a motor with imbalance in its rotation. As actuator, a standard loudspeaker was used, and the vibration was sensed by an accelerometer.
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| 3. |
- Hjalmarsson, Håkan, 1962-, et al.
(author)
-
Optimality and sub-optimality of iterative identification and control design schemes
- 1995
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In: Proceedings of the American Control Conference. - Seattle, WA, USA : Linköping University. - 0780324455 ; , s. 2559-2563
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Conference paper (peer-reviewed)abstract
- We demonstrate that some recently proposed iterative identification and control design schemes do not necessarily converge to a local minimum of the design objective in the case of a restricted complexity model. There is, however, a link between these approaches and a recently proposed iterative optimization based control design procedure based on experimental data. We show that if the achieved and the desired output responses are perfectly matched, the schemes are (essentially) equivalent under noise free conditions.
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