Different Control Sensors
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Introduction
Ricki Lambert Control Technology Assignment 1 Task 2 In this assignment I shall be giving an outline to the different types of control sensors we get in control systems. There are many types but I shall be explaining a selected few, they are the control systems found within; a. Linear and Angular position control b. Pressure/force control. c. Temperature, light, humidity control d. Digital devices e.g. switches, relays etc Pressure Sensors The idea of a pressure sensor is to ultimately measure and monitor the pressure of either gasses or liquids. But, what is pressure? Well, pressure ultimately is an expression used to describe the process of the force that is used when restraining a gas or a liquid from expanding. It has a certain measurement normally in the force per unit area. When the pressure is measured it can be monitored in a number of ways, but, most typically it is done with an electrical signal. We can see many examples of pressure monitors/switches in appliances all over the world today. Pressure sensors are found in items such as cars and lifts. For example, a person walks up to a door and they wish for it to be opened on arrival, with a pressure switch located in the ...read more.
Middle
It is often used to determine and control the temperature; however, it can also be used for radiation purposes. The word pyrometer is derives from the Greek word for fire, "???" and the Greek word for measure, which is "meter". As previously said, pyrometers are optical aids and although now days there are many forms of pyrometer as the need for more specific, demanding control systems are required the most basic still works on the principle below; On the previous page we can see how a basic optical pyrometer works, the only problem being that it can display temperatures that are high (up to around 700oC, but is inefficient for very low temperatures. As temperature inside the work place/furnace increases, so does the filament inside the pyrometer giving off a red colour, indicating the heat capacity. Using digital readouts the user can use the pyrometer to calculate the temperature of the material and also use the pyrometer to heat the material or furnace, or wherever the control system is placed to whatever they require. Thermocouples A thermocouple is a very simple heat/temperature sensor and comprises of two components. One end is joined tightly and the other end is separated. ...read more.
Conclusion
The thermistor would act as the thermostat. Therefore, when the thermostat is changed, we can change the output of the heating system accordingly. The thermistor is widely used and often unknown to the untrained eye. Linear Limit Switches The theory behind the linear limit switch is very straight forward. Basically the linear limit switch is a button, that when activated starts a process. In relation to computing it's like an event drive operation. For the linear limit switch to be activated it must be pressed. For example, in a lift, how do we get the lift to stop going up, or, stop going down, or stop on the right floor. It would be of my opinion that a linear limit switch is implemented, so that when the lift reaches the required floor, a switch is activated and the lift stops and the doors open. However, its not limited to lifts, the linear switch is a very common device. In the picture on the left we can see a clear example of a linear limit switch. The operation needed to be performed is for that of the swimming pool cover, when the cover reaches the end of the pool the switch is pressed and the motor stops working, this then stops the problem of the cover falling off of the reel. ...read more.
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