Since fuzzy control is a relatively new technology, it is often quite important to determine what value it has relative to conventional methods Unfortunately, few have performed detailed comparative analyses between conventional and intelligent control that have ta ken into account a wide array of available conventional methods (linear, nonlinear, adaptive, etc. ) fuzzy control methods(direct, adaptive, supervisory) theoretical, simulation, and experimental analyses: computational issues: and so on 26
26 Since fuzzy control is a relatively new technology, it is often quite important to determine what value it has relative to conventional methods. Unfortunately, few have performed detailed comparative analyses between conventional and intelligent control that have taken into account a wide array of available conventional methods (linear, nonlinear, adaptive, etc.); fuzzy control methods (direct, adaptive, supervisory); theoretical, simulation, and experimental analyses; computational issues; and so on
What should we pay attention in fuzzy controller aesign Moreover, most work in fuzzy control to date has focused only on its advantages and has not taken a critical look at what possible disadvantages there could be to using it (hence the reader should be cautioned about this when reading the literature). For example, the following questions are cause for concern when you employ a strategy of gathering heuristic control knowledge: 27
27 What should we pay attention in fuzzy controller design? Moreover, most work in fuzzy control to date has focused only on its advantages and has not taken a critical look at what possible disadvantagesthere could be to using it (hence the reader should be cautioned about this when reading the literature). For example, the following questions are cause for concern when you employ a strategy of gathering heuristic control knowledge:
will the behaviors that are observed by a human expert and used to construct the fuzzy controller include all situations that can occur due to disturbances, noise, or plant parameter variations? Can the human expert realistically and reliably foresee problems that could arise from closed- loop system instabilities or limit cycles? will the human expert be able to effectively incorporate stability criteria and performance objectives(e.g, rise-time, overshoot, and tracking specifications) into a rule-base to ensure that reliable operation can be obtained? 28
28 • Will the behaviors that are observed by a human expert and used to construct the fuzzy controller include all situations that can occur due to disturbances, noise, or plant parameter variations? • Can the human expert realistically and reliably foresee problems that could arise from closedloop system instabilities or limit cycles? • Will the human expert be able to effectively incorporate stability criteria and performance objectives (e.g., rise-time, overshoot, and tracking specifications) into a rule-base to ensure that reliable operation can be obtained?
These questions may seem even more troublesome (1)if the control problem involves a safety-critical environment where the failure of the control system to meet performance objectives could lead to loss of human life or an environmental disaster, or(2 )if the human expert's knowledge implemented in the fuzzy controller is somewhat inferior to that of the very experienced specialist we would expect to design the control system(different designers have different levels of expertise). Clearly, then, for some applications there is a need for a methodology to develop implement, and evaluate fuzzy controllers to ensure that they are reliable in meeting their performance specifications. This is the basic theme and focus of this book. 29
29 These questions may seem even more troublesome (1) if the control problem involves a safety-critical environment where the failure of the control system to meet performance objectives could lead to loss of human life or an environmental disaster, or (2) if the human expert's knowledge implemented in the fuzzy controller is somewhat inferior to that of the very experienced specialist we would expect to design the control system (different designers have different levels of expertise). Clearly, then, for some applications there is a need for a methodology to develop, implement, and evaluate fuzzy controllers to ensure that they are reliable in meeting their performance specifications. This is the basic theme and focus of this book
2.1.4 Application Areas Fuzzy systems have been used in a wide variety of applications in engineering, science, business, medicine, psychology, and other fields. For instance, in engineering some potential application areas include the following Aircraft/spacecraft: Flight control, engine control avionic systems, failure diagnosis, navigation, and satellite attitude control Automated highway systems: Automatic steering, braking, and throttle control for vehicles Automobiles: Brakes, transmission, suspension, and engine control Autonomous vehicles: ground and underwater. 30
30 Fuzzy systems have been used in a wide variety of applications in engineering, science, business, medicine, psychology, and other fields. For instance, in engineering some potential application areas include the following: • Aircraft/spacecraft: Flight control, engine control, avionic systems, failure diagnosis, navigation, and satellite attitude control. • Automated highway systems: Automatic steering, braking, and throttle control for vehicles. • Automobiles: Brakes, transmission, suspension, and engine control. • Autonomous vehicles: Ground and underwater. 2.1.4 Application Areas