Sensors in monitoring and Control Applications
Sensor:A sensor is an input device that records data about the surrounding physical environment. The sensor inputs this data into a computer system to be processed. Once the data has been processed, if necessary, an output can be triggered as a response.
Sensors can automatically, enter data into a computer system, removing the need for a human to manually enter the data. They can be very beneficial as it can increase the accuracy of the data by removing the possibility of human error.
Using sensors can also be very beneficial in environments that could be harmful and dangerous for a human, for example in a nuclear plant to detect radiation levels, or inside an active volcano to detect changes in activity.
Monitoring and control! technologies make use of many different sensors. Monitoring technologies use sensors to monitor an environment, often collecting data about the environment.
Control technologies use sensors to automatically control elements of a system, or a whole system, by using the data from them to trigger an action or event.
The basic concept behind most monitoring and control systems is very similar. They will normally go through the following steps:
•The sensor will constantly monitor the surrounding environment
•The data readings from the sensor will normally be analogue. Therefore, they will be converted to a digital signal for a computer system to process. This is done by an analogue to digital converter
•The digital signal is then sent to a microprocessor. The microprocessor processes the value and compares it to a pre-set value or range of values
•If the value is outside the acceptable range, the microprocessor will send a signal to an actuator to trigger any action that needs to be taken.
A real-life example of a control technology in operation would be an automated street light. This may include the following stages:
- A light sensor will constantly monitor the level of light present in the surrounding environment.
- The analogue data from the reading will be converted to a digital value by an analogue to digital converter.
- The digital signal is sent to a microprocessor and the microprocessor will compare the value to a pre-set range.
- If the value is outside the pre-set range, the microprocessor sends a signal to an actuator that will trigger the action to turn the street light on or off.
- The whole process will then be repeated.
We can represent this as a flowchart:
This is an example of a control system at work. It is a control system as an action is triggered to control an element of the system as a result of the monitoring that is taking place. A monitoring system outputs results in a different way. Rather than an action being triggered, the results of the readings taken from the monitoring can be output in the form of graphs or charts. This allows the readings to be compared and any patterns or trends to be identified. This information can then be used to inform any future decision making.
Monitoring systems can be used in scientific experiments. The experiments are often left to run for periods of time, with a monitoring system taking readings at regular intervals. The readings are then output and can be analysed. This kind of technology removes then need for a human to regularly take the readings. This means that the readings can be taken over long periods of time and can often be more accurate if taken by a system.
There are a range of different sensors that we need to be able to define. We also need to describe how they are used in monitoring and control technologies and evaluate using these technologies in our everyday lives.
Light sensors
Light sensors monitor and measure light. There are
different types of light sensor and they measure light in different ways The most common type of light sensor is a photoresistor. This type of light sensor will change
its resistance when light shines on and is normally used to measure the intensity of light. This is important indevices such as digital cameras or street lights. The camera can adjust the level of flash needed depending on the level of light currently detected by the light sensor. A street light can detect when it gets dark enough to need to switch the light on.
Light sensors can be used in many different devices including barcode scanners, display screens, automated lighting systems and smartphones.
Sensors are used in a wide variety of monitoring and control systems. These systems are part of our everyday lives, from helping us cross the road safely, to making sure our clothes are washed properly. The use of sensors in computer systems can benefit us greatly. This remove the need for a human to monitor and measure an environment as this can be done continuously by the sensor. This can leave us to get on with other tasks that we need to complete It can also mean that the monitoring and measuring is more accurate.
For a human to complete a repeated action, for example taking a reading over and over for long periods of time, can be very arduous and it may prove difficult to maintain accuracy. A computer system that has a sensor that
can perform this role is able to run for long periods of time, with a high level of accuracy. This level of accuracy.
can make a system more reliable than one operated by humans.
By using a sensor or a number of sensors in a monitoring or control system, multiple readings can be taken in quick succession. It would require people to perform the same function, and so these people can be made available to perform other tasks. The computer system will make decisions based on the data it is given. It will act logically on these decisions in the way it has been programmed. This can be beneficial as the decisions made and actions taken will be consistent. If a human performed the same decision-making process, external factors may affect the decision they make, for example how tired they are. This could cause inconsistency in the decision-making process and actions taken. This can sometimes be a disadvantage and a computer system may not be able to react to an unexpected event that
a human would be able to assess and make a decision about.
Remember a computer system using sensors can operate 24 hours a day, 365 days a year, meaning that monitoring can be done on a continual basis. It can also remove the possibility of human error in the measurements.
Sensors are also extremely beneficial for use in environments that are dangerous to humans. This means that we can be kept safe yet dangerous environments can still be monitored. Also, computers can process data much more quickly and respond faster to any necessary actions than a human, so a dangerous environment can be monitored and controlled more effectively.
There is always a risk involved in using computer systems in monitoring and control. The system is electronic and if a power failure occurs, the system
will not operate. If the system is controlling a crucial process, this could have a detrimental effect. This could also happen with a simple system malfunction.
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Find out how pressure sensors are used in traffic control systems.