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- Taylor, James H., et al.
(författare)
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Safe and Secure Wireless Networked Control Systems
- 2012
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Ingår i: Proc. IEEE Multiconference on Systems and Control. - : IEEE conference proceedings. - 9781467345040 - 9781467345033 ; , s. 871-878
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Konferensbidrag (refereegranskat)abstract
- Wireless technology has gained much interestin industrial automation due to its flexibility, mobility, easeof installation, and lower cost. Wireless systems, in general,require additional and different engineering and maintenancetasks, for example cryptographic key management for security.The pace of application in process control has been impeded,however, by concern about the risks involved in incorporatingwireless paths in feedback loops and making the accommoda-tions necessary for reliable control. The issue is that there areconflicts between maintaining control loop performance andthe usual objectives in managing a wireless sensor network.In this paper, we take a holistic approach that addressessafety, reliability and security in two primary aspects: com-munication and control; thus we hope to contribute a morecomplete roadmap for developing safe and secure wireless net-worked control systems. This proposed framework representsa synthesis of two formerly separate bodies of research, oneprimarily focussed on communication requirements for safetyand security and the other on safe and reliable controls.
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| 3. |
- Taylor, James H., et al.
(författare)
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A Nonlinear PID Autotuning Algorithm
- 1986
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Ingår i: Proceedings of the 1986 American Control Conference : Seattle Sheraton Hotel and Towers, Seattle, WA, June 18-20, 1986 - Seattle Sheraton Hotel and Towers, Seattle, WA, June 18-20, 1986. ; , s. 2118-2123
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Konferensbidrag (refereegranskat)abstract
- A nonlinear autotuning regulator algorithm is obtained via a direct combination of the Åström-Hägglund algorithm for the linear case [1] with the sinusoidal-input describing function (SIDEF) approach to nonlinear compensator synthesis of Taylor and Strobel [2]. The basic approach for linear autotuning proceeds as follows: a. install a relay with hysteresis in series with the unknown plant to be controlled; close a unitygain feedback loop around this combination; b. choose several values of hysteresis so that this system exhibits limit cycles; the frequencies and amplitudes of the oscillation at the output of the plant determine points on the plant Nyquist plot; and c. given points on the plant Nyquist plot, set the PID controller gains using an appropriate tuning algorithm (e.g., Ziegler-Nichols). This approach produces good results if the plant is liner or nearly so; however, if the plant behavior is strongly amplitude-dependent, there are likely to be problems with implementing this algorithm. The nonlinear autotuning regulator algorithm which extends the above approach to handle situations where the plant behavior is strongly amplitude-dependent is based on the SIDF approach. In essence, SIDF input/output (I/O) models of the compensated nonlinear system are exploited to directly synthesize a compensator nonlinearity that eliminates or reduces the amplitude dependence of the open-loop I/O relation. The nonlinear synthesis portion of this algorithm is reasonably simple to implement, has been shown to be effective [2], and should be of practical utility. An example application to a precision position control system is provided as an illustration.
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