a. Draw a block diagram of a closed-loop control system.
This design example will demonstrate how the Hypersignal Block Diagram or Hypersignal RIDE application can be used to implement a closed-loop control system.
A closed-loop control system can be represented by the general block diagram shown below:
b. Use the block diagram to describe how the system works.
In this configuration a feedback component is applied together with the input R. The difference between the input and feedback signals is applied to the controller. In responding to this difference, the controller acts on the process forcing C to change in the direction that will reduce the difference between the input signal and the feedback component. This, in turn, will reduce the input to the process and result in a smaller change in C. This chain of events continues until a time is reached when C approximately equals R.
A closed-loop system is able to regulate itself in the presence of disturbance or variations in its own characteristics. In this respect, a closed-loop system has a distinct advantage over an open-loop system.
c. What is the advantage of this system over an open-loop system?
Advantages of Closed Loop control - stability and repeatability
within the closed loop system the difference between the output and input will be fed into the control system.
Closed loop control, with the appropriate sensor, provides much greater stability.
If the magnetic field is controlled by setting the current of the power supply, then as the magnet or supply temperature changes the current can vary - so the field will deviate from its desired setting. If you are measuring the field directly then you can hold the field constant, despite external influences.
4. Identify the following as open- or closed-loop control.
a. Controlling the water height in a toilet tank
b. Actuation of street lights at 6 P.M.
c. Stopping a clothes dryer when the clothes are dry