-(f Will it be difficult to clearly relate the results of using the fuzzy controller to previous work in conventional control to definitively show that contributions are being made to the field of control? Yes 7. Is there always a formal model available for control design? No, but for most systems there is at least an approximate model available. This information is often valuable and should not be ignored 8. Does the use of fuzzy controllers limit the design methodology as compared to the use of more general expert controllers? Expert controllers use more general knowledge-representation schemes and inference strategies(see more details in Section 4.5.1), so for some plants it may be advantageous to use the expert controller. It is, however, not clear at this point what class of plants call for the use of expert control 4.2.2 Stability and Performance Analysis Next, we will discuss several issues related to the performance analysis of fuzzy control systems Is verification and certification of fuzzy control systems important? Yes, especially for safety-critical systems(e. g an aircraft). It may not be as important for certain applications(e.g, a washing machine with a fuzzy control system) 2. What are the roles of simulation and implementation in evaluating the performance of fuzzy control systems? They play exactly the same role as for conventional control systems 3. What are the roles of the following nonlinear analysis approaches in fuzzy control system design? (c) Stability analysis: Lyapunov's first and second methods; absolute stability; and the small gain theorem errors (e) Method of equivalent gains (f Cell-to-cell mapping approaches Several of these approaches may apply to the analysis of the behavior of the fuzzy control system you design. 4. What are the problems with utilizing mathematical analysis for fuzzy control system verification? The technique ake time to learn. The problems for which fuzzy control are particularly well suited, and where there is often very good motivation to use fuzzy rather than conventional control, are the control problems where the plant has complex nonlinear behavior and where a model is hard to derive due to inherent uncertainties. Each of these characteristics often makes the assumptions that are needed for the nonlinear analysis techniques invalid, so the theory often does not end up offering much when it is really needed 5. Does fuzzy control provide robust control"? If so, can this be demonstrated mathematically or experimentally? There has been a recent focus in research on stability analysis to show that fuzzy control does provide robust control. It is very difficult, of course, to show robustness via experimentation since by its very definition robustness verification requires extensive experimentation(e.g, you could not call the fuzzy controller for the rotational inverted pendulum case or"robust"when it was only shown to be successful for one disturbance condition 4.2.3 Implementation and General Issues Finally, we will discuss several issues related to implementation and the overall fuzzy controller design methodology 1. Are there computational advantages in using fuzzy control as compared to conventional control? Not always. PID control is simpler than fuzzy control; however, there are some types of conventional control that are very difficult to implement where a fuzzy controller can be simpler. It depends on the application and the methods you choose PDF文件使用" pdffactory Pro"试用版本创建ww. fineprint,com,cn¡ (f) Will it be difficult to clearly relate the results of using the fuzzy controller to previous work in conventional control to definitively show that contributions are being made to the field of control? Yes. 7. Is there always a formal model available for control design? No, but for most systems there is at least an approximate model available. This information is often valuable and should not be ignored. 8. Does the use of fuzzy controllers limit the design methodology as compared to the use of more general expert controllers? Expert controllers use more general knowledge-representation schemes and inference strategies (see more details in Section 4.5.1), so for some plants it may be advantageous to use the expert controller. It is, however, not clear at this point what class of plants call for the use of expert control. 4.2.2 Stability and Performance Analysis Next, we will discuss several issues related to the performance analysis of fuzzy control systems. 1. Is verification and certification of fuzzy control systems important? Yes, especially for safety-critical systems (e.g., an aircraft). It may not be as important for certain applications (e.g., a washing machine with a fuzzy control system). 2. What are the roles of simulation and implementation in evaluating the performance of fuzzy control systems? They play exactly the same role as for conventional control systems. 3. What are the roles of the following nonlinear analysis approaches in fuzzy control system design? ¡ (a) Phase plane analysis. ¡ (b) Describing function analysis. ¡ (c) Stability analysis: Lyapunov's first and second methods; absolute stability; and the small gain theorem. ¡ (d) Analysis of steady-state errors. ¡ (e) Method of equivalent gains. ¡ (f) Cell-to-cell mapping approaches. Several of these approaches may apply to the analysis of the behavior of the fuzzy control system you design. 4. What are the problems with utilizing mathematical analysis for fuzzy control system verification? The techniques take time to learn. The problems for which fuzzy control are particularly well suited, and where there is often very good motivation to use fuzzy rather than conventional control, are the control problems where the plant has complex nonlinear behavior, and where a model is hard to derive due to inherent uncertainties. Each of these characteristics often makes the assumptions that are needed for the nonlinear analysis techniques invalid, so the theory often does not end up offering much when it is really needed. 5. Does fuzzy control provide "robust control"? If so, can this be demonstrated mathematically or experimentally? There has been a recent focus in research on stability analysis to show that fuzzy control does provide robust control. It is very difficult, of course, to show robustness via experimentation since by its very definition robustness verification requires extensive experimentation (e.g., you could not call the fuzzy controller for the rotational inverted pendulum case or "robust" when it was only shown to be successful for one disturbance condition). 4.2.3 Implementation and General Issues Finally, we will discuss several issues related to implementation and the overall fuzzy controller design methodology. 1. Are there computational advantages in using fuzzy control as compared to conventional control? Not always. PID control is simpler than fuzzy control; however, there are some types of conventional control that are very difficult to implement where a fuzzy controller can be simpler. It depends on the application and the methods you choose. PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn