| 1. |
- Axsäter, Sven
(författare)
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Control theory concepts in production and inventory control
- 1985
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Ingår i: International Journal of Systems Science. - : Informa UK Limited. - 0020-7721 .- 1464-5319. ; 16:2, s. 161-169
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Tidskriftsartikel (refereegranskat)abstract
- The use of efficient production and inventory control systems is of great importance for industry. Therefore this area could be expected to provide many fruitful applications of control theory techniques. However, control theory has traditionally been aimed at applications in other fields, and results have only limited applicability in production and inventory control. This paper gives an overview of earlier research concerning control theory applications in production and inventory control. Areas given special emphasis are those in which control theory seems to have a stronger potential for practical application
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| 2. |
- Gharaee, Zahra, et al.
(författare)
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Attention control learning in the decision space using state estimation
- 2014
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Ingår i: International Journal of Systems Science. - : Informa UK Limited. - 0020-7721 .- 1464-5319. ; 47:7, s. 1659-1674
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Tidskriftsartikel (refereegranskat)abstract
- The main goal of this paper is modelling attention while using it in efficient path planning of mobile robots. The key challenge in concurrently aiming these two goals is how to make an optimal, or near-optimal, decision in spite of time and processing power limitations, which inherently exist in a typical multi-sensor real-world robotic application. To efficiently recognise the environment under these two limitations, attention of an intelligent agent is controlled by employing the reinforcement learning framework. We propose an estimation method using estimated mixture-of-experts task and attention learning in perceptual space. An agent learns how to employ its sensory resources, and when to stop observing, by estimating its perceptual space. In this paper, static estimation of the state space in a learning task problem, which is examined in the WebotsTM simulator, is performed. Simulation results show that a robot learns how to achieve an optimal policy with a controlled cost by estimating the state space instead of continually updating sensory information.
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| 3. |
- Hultqvist, Daniel, et al.
(författare)
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Optimization of the raw material procurement at pulp or paper mills : The influence of weather-related risks
- 2006
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Ingår i: International Journal of Systems Science. - : Informa UK Limited. - 0020-7721 .- 1464-5319. ; 37:4, s. 253-269
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Tidskriftsartikel (refereegranskat)abstract
- There are usually many sources for the supply of raw material to a pulp or paper mill in Sweden. Optimization of this supply is therefore a challenging task, and can only be managed properly if all aspects of risk are considered. In our study, these risks are related to when the weather reduces the load-bearing capacity of the ground or the roads. A stochastic and a deterministic model have been formulated, and they have been solved with mixed-integer quadratic programming and tested with data from a Swedish forest company. The results of this study show that the option value is greater than zero and that both the optimal policy and the option value change whenever the storage cost is altered. This shows that the optimal planning policy obtained from the stochastic model differs from the solution of the deterministic model.
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| 4. |
- Meza-Sanchez, Iliana M, et al.
(författare)
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Periodic motion planning and nonlinear H-infinity tracking control of a 3-DOF underactuated helicopter
- 2011
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Ingår i: International Journal of Systems Science. - : Informa UK Limited. - 0020-7721 .- 1464-5319. ; 42:5, s. 829-838
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Tidskriftsartikel (refereegranskat)abstract
- Nonlinear H-infinity synthesis is developed to solve the tracking control problem into a 3-DOF helicopter prototype. Planning of periodic motions under a virtual constraints approach is considered prior the controller design in order to achieve our goal. A local H-infinity controller is derived by means of a certain perturbation of the differential Riccati equations that appear while solving the corresponding H-infinity control problem for the linearised system. Stabilisability and detectability properties of the control system are thus ensured by the existence of the proper solutions of the unperturbed differential Riccati equations, and hence the proposed synthesis procedure obviates an extra verification work of these properties. Due to the nature of the approach, the resulting controller additionally yields the desired robustness properties against unknown but bounded external disturbances. Convergence and robustness of the proposed design are supported by simulation results.
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| 5. |
- Paul, Satyam, 1981-, et al.
(författare)
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Bidirectional active control of structures with type-2 fuzzy PD and PID
- 2018
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Ingår i: International Journal of Systems Science. - : Taylor & Francis. - 0020-7721 .- 1464-5319. ; 49:4, s. 766-782
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Tidskriftsartikel (refereegranskat)abstract
- Proportional-derivative and proportional-integral-derivative (PD/PID) controllers are popular algorithms in structure vibration control. In order to maintain minimum regulation error, the PD/PID control require big proportional and derivative gains. The control performances are not satisfied because of the big uncertainties in the buildings. In this paper, type-2 fuzzy system is applied to compensate the unknown uncertainties, and is combined with the PD/PID control. We prove the stability of these fuzzy PD and PID controllers. The sufficient conditions can be used for choosing the gains of PD/PID. The theory results are verified by a two-storey building prototype. The experimental results validate our analysis.
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| 6. |
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