CONTROL SYSTEMS LABORATORY #EXPERIMENT 4 OPEN-LOOP vs. CLOSED-LOOP CONTROL SYSTEMS PDF

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CONTROL SYSTEMS LABORATORY #EXPERIMENT 4 OPEN-LOOP vs. CLOSED-LOOP CONTROL SYSTEMS Introduction The main purpose of experiment introduce to open-loop and closed-loop control system. We have tried to learn how to use MATLAB scripts to create mathematical model of a DC motor by open loop and closed lo...

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CONTROL SYSTEMS LABORATORY #EXPERIMENT 4 OPEN-LOOP vs. CLOSED-LOOP CONTROL SYSTEMS Introduction The main purpose of experiment introduce to open-loop and closed-loop control system. We have tried to learn how to use MATLAB scripts to create mathematical model of a DC motor by open loop and closed loop control systems . We have observed outputs and discussed differences and similarities between open loop and closed loop control systems. Open-Loop Control System

Its operation is very simple, when an input signal directs the control element to respond, an output will be produced. Examples of the open loop control systems include washing machines, light switches. Closed-Loop Control System

The output signal is feedback to the input to produce a new output. A well-designed feedback system can often increase the accuracy of the output. Differences between open-loop and closed-loop systems

Closed-loop control :can counteract against disturbances and can become unstable, the controlled variable does not fade away, but grows to an infinite value. Open-loop control : An open-loop controller, also called a non-feedback controller, is a type of controller that computes its input into a system using only the current state and its model of the system. can only counteract against disturbances, for which it has been designed; other disturbances cannot be removed and cannot become unstable - as long as the controlled object is stable. Summarising these properties we can define: Systems in the output quantity has no effect upon the process input quantity are called open-loop control systems.

Systems in the output has an effect upon the process input quantity in such a manner as to maintain the desired output value are called closed-loop control systems.

Torque Equations:

Transfer Functions:

=5000/(s^2+1020s+20500)

=5000/(s^3+1020s^2+20000)

In the first part of experiment;

Secondly, we have applied unit step function to input of the motor, for open-loop speed control operation and observed output;

DİSCUSS and COMMENTS We understand that the value of the poles of the system is stable. The values of the left pole system is stable.if the rigth pole is not stable. The middle pole values are sometimes stable(MARJİNAL.) open-loop system is constantly increasing(integrator). The closed-loop controlled system. The open-loop response of the system is not even stable. The pole at the origin behaves like an integrator. Therefore, when the system is given a step input its output continues to grow to infinity in the same manner that an integral of a constant would grow to infinity as the upper limit of the integral is made larger. for example; the car's speed increases continuously in open loop but the closed-loop speed can be controlled. Finally we have used proportional controller with K=100 and unity feedback path and observed the unit step response of this system

step response 0,375 sn

Conclusion In summary, we have discussed open-loop and closed-loop control system. We have created open and closed loop systems by using MATLAB scripts we observed output of created systems. We have learned creating open loop and closed loop control systems and determined differences between the systems....