Finite state machines (fsm, sequential machines): examples and applications
Illustration: Design a finite state controller to synchronize the traffic lights
Finite state-machines are the most general controllers of machines we use in everyday life. In the illustration described by the figure, the intersection of a main road with pedestrian crossing is controlled by two traffic lights. The traffic light for cars consists of 3 possible values: Red R, Yellow Y and Green G. The traffic light for pedestrians consists of 2 possible values: Red r and Green g. The task is to design a finite state controller which turns different lights on and off in a reasonable and safe way.
The controller responds to an input signal B which consists of 2 possible values, 1 (pressed) and 0 (not pressed), based on whether or not a pedestrian has pressed the button B in the prior time-interval. This signal is sampled at regular time intervals of, say 10 seconds, and the controller performs a transition once every 10 seconds. The time-interval of 10 seconds is supposed to be adequate to cross the road.
Whenever first confronted with the task of explaining the behavior of such a system, then most of the people resort to scenarios including time sequences: When the button is pressed, after 10 seconds, this or that occurs, and then .... This approach is uncontrollable for a realistic controller whose behavior based on a range of sensors, as the number of scenarios develops exponentially with the number of sensor readings. We require a static explanation which captures all the conceivable scenarios, in order to prove invariants that state some configurations or events should, or should not, occur. The concept of state space of the system is a standard method which compresses all the possible sequences of states (in general, infinitely numerous and of unbounded length) into an explanation of fixed size. Let us design a state space for controlling the traffic light system described above. There is no unique solution to this problem - various designs might contain different merits and demerits.
At first we list all the states which the traffic light system is potentially capable of signaling to an observer, and comment to the desirability and role of each these visible state. Among the six different visible states, namely: Rr, Rg, Yr, Yg, Gr, Gg, we can instantly rule out Gg, a killer, and Yg, as too hazardous. Rg and Gr are the two alternating states which assign the right way to one or the other participant. Rr may make sense when it never lasts very long, however is unnecessary as we introduced the signal Y, yellow, to provide cars time to break before pedestrians see green g. Therefore, we introduce a state Yr, as shown in figure below.
The answer at left (Try 1) has the problem that it rely on the courtesy of drivers to delay take-off till all pedestrians complete their crossing. When we try to utilize the delay state Yr in both phases (Try 2), in transition from Rg back to Gr as we did on the way from Gr to Rg, we run to a technical trouble: on both input values 0 and 1, transitions out of Yr have already been set to lead to the Rg. The solution beneath (Try 3) identifies the fact that the total state of system is not essentially limited to the visible state. Whenever the lights show Yr, we require an additional bit of memory to keep in mind whether the prior state was Gr or Rg. Therefore, we introduce 2 delay states that look similar to an observer, however are distinguished internally.
Latest technology based Theory of Computation Online Tutoring Assistance
Tutors, at the www.tutorsglobe.com, take pledge to provide full satisfaction and assurance in Theory of Computation help via online tutoring. Students are getting 100% satisfaction by online tutors across the globe. Here you can get homework help for Theory of Computation, project ideas and tutorials. We provide email based Theory of Computation help. You can join us to ask queries 24x7 with live, experienced and qualified online tutors specialized in Theory of Computation. Through Online Tutoring, you would be able to complete your homework or assignments at your home. Tutors at the TutorsGlobe are committed to provide the best quality online tutoring assistance for Theory of Computation Homework help and assignment help services. They use their experience, as they have solved thousands of the Theory of Computation assignments, which may help you to solve your complex issues of Theory of Computation. TutorsGlobe assure for the best quality compliance to your homework. Compromise with quality is not in our dictionary. If we feel that we are not able to provide the homework help as per the deadline or given instruction by the student, we refund the money of the student without any delay.
tutorsglobe.com sources of energy assignment help-homework help by online natural resources tutors
Vegetative Structure of Seed Plants-Leaf tutorial all along with the key concepts of Anatomy of Leaf, Epidermis, Mesophyll, Veins and Leaf morphology
tutorsglobe.com dual property of an electron assignment help-homework help by online atomic structure tutors
a propeller blade fan comprising two or more blades is directly driven through an electric motor. it might be a bracket mounted wall kitchen fan, table fan, or a portable table fan.
tutorsglobe.com islamic history and civilization assignment help-homework help by online history tutors
Having set out the major principles included in preparing an income statement, we required to consider some additional points.
tutorsglobe.com cytokinin assignment help-homework help by online phytohormones tutors
tutorsglobe.com chlamydia assignment help-homework help by online medical bacteriology tutors
www.tutorsglobe.com offers effective modular design heuristics homework help, assignment help, case study, writing homework help, online tutoring assistance by computer science tutors.
Presentation of Financial Statements requires listed companies to give a statement of comprehensive income that extends the conventional income statement to involve certain other gains and losses that influence equity of shareholders.
www.tutorsglobe.com offers Named Constants homework help, assignment help, case study, writing homework help, online tutoring assistance by computer science tutors.
www.tutorsglobe.com offers substituted cyclohexane compounds homework help, substituted cyclohexane compounds assignment help, online tutoring assistance, organic chemistry solutions by online qualified tutor's help.
basics of national income application - standard of living, use of gnp to measure standard of living, tutorsglobe offers assignment help - homework help in economics subject.
P-N Junction Diodes tutorial all along with the key concepts of Zero Bias, Zero Biased Junction Diode, Reverse Bias, Zener Diode, Forward Bias and Non-Rectifying Junctions
tutorsglobe.com significance of abscission assignment help-homework help by online abscission and senescence tutors
1942898
Questions Asked
3689
Tutors
1490974
Questions Answered
Start Excelling in your courses, Ask an Expert and get answers for your homework and assignments!!