Understanding Smart Sensors - Nomads.usp

7Control TechniquesA machine is intelligent when it does the things of a common three year old.—Marvin Minsky, creator of the concept of artificial intelligence7.1 IntroductionDistributed control systems (DCS) have brought decision making to the sensor.The built-in intelligence for the smart sensor can take advantage of a varietyof existing and developing control techniques. The extent to which newcomputing paradigms will affect sensors depends on the need for control at thesensor and the cost effectiveness of using those new techniques. Existing controltechniques have grown from programmable logic controllers (PLCs) andPC-based instruments. Proportional-integral-derivative (PID) control and thestate machine are the basis of many control systems. However, the newest artificialintelligence approaches of fuzzy logic and neural networks will increasinglyaffect sensor-based systems. Fuzzy logic is already finding several applications inappliances and automobiles. Adaptive control techniques using the higher performingMCUs and DSPs will allow sensors to adjust to aging effects duringtheir operating life. Control strategies that implement computationally intensealgorithms will be able to shrink a proof-of-concept laboratory demonstrationinto a useful solution that can have popular applications based on the increasedcomputing capability of MCUs and DSPs.149