Unit 24: Controlling Systems Using IT

Task 1

Control Systems: are sets of devices that monitor, control, influence and regulates the actions of other devices in order to achieve the best outcome.

Types of Control Systems

Command Systems: are a type of system that allows the consumer to operate a device. The consumer inputs what they want the device to do, and this input will be output to their particular device. An example could be a remote controlled RC car. As you push the joystick in a direction which you want the RC car to go. Another example could be TV remote controls as you press on a certain button (input) and the TV will do the certain task (output). Like increasing the volume for example.

Programmable Systems: are programmed to execute a specific task. In order to perform the task, the device will not have to be touched. An example could be a washing machine, as all you do is put the clothes in and the detergent, and set it to wash the certain clothes. And the washing machine will do the rest.

Sensing Systems: are made from sensors. They function according to the environment and whenever there is a change in the environment. The sensor will sense it and adjust the device it controls. An example of this could be thermostat, as if it set to make the room warm, and if it is already warm, then the thermostat will turn off the heaters if its needed.

Conditional Systems: base their actions on logic, if the required condition is met. For example, like in the previous example a thermostat will sense the temperature of the room and will only turn the heaters on or off if the temperature decreases or increases above a certain temperature.

Security Systems: is linked to sensing systems. Because for example, a security camera will most likely have sensors inside it, meaning that it can sense when an object or a person passes its field of observation. And when that happens the system will alert the house owner, as there is an intruder near the security camera.

Environmental control: provides a degree of independent control of various home devices to individuals with severe physical disabilities. Environmental control can be necessary if you are unable to manage the machinery around you because of difficulty in using your body parts. A device or machinery which you can control would be stuff like the lights, smartphones, TV’s and more.

TV remote controls: is linked to command systems, as a button on the TV remote has to be pressed (input) in order for the TV to do a certain task (output). For example, pressing the volume button (input) on the TV remote will increase the volume of the TV (output). I have mentioned this before in the “command systems”.

Gate sensors: is linked to sensing systems, which are made from sensors. They function according to the environment and whenever there is a change in the environment. The sensor will sense it and adjust the device it controls (mentioned this above). For example, an automated gate has sensors so that if there is and object in its field of observation, the gate will stop so that it wouldn’t hit that object. And if there isn’t any objects in its way then the gate will continue opening so that it could let the vehicle go through the gates.

Digital

Microcontroller device selection: processes the data via a control system. The key factors are power efficiency, temperature tolerance, memory, security and number of ports.

Basic System design: The control system controls, monitors, guides or regulates the actions of other devices or systems using control loops. For example, home heating controller utilising a thermostat controlling a boiler.

Speed: a microcontroller’s clock speed is around 300 MHz. It depends on how good and expensive the microcontroller is. The more expensive it is, usually the faster it is.

Memory requirements: Since they are easy to customise and reconfigure using software, they can be scaled to memory limitations.

Number of I/O ports needed: I/O ports (input and output ports) enable hardware connections. This hardware may be either internal or external. Ports are connected to copper circuits and memory ranges that enable the access of information between the CPU, RAM and the ports itself. And also other equipment like USB and fireWire.

Digital to analogue (DAC) devices: is a system that converts a digital signal from a device to an analogue signal, which can be used to operate electrical equipment.

Analogue

Signal conditioning: require any form of planning until it can be digitised. Signal conditioning is the processing of a signal in a fashion that strengthens it for the next stage of processing.

Noise filtering: Analog inputs may pick up sounds from the background as readings are taken. Noise filtering is a method in which these unnecessary signals are eliminated from the digital signal. This is the same as a microphone picking up background noises when recording or streaming.

Level-shifting: is needed to increase the voltage for the system. It’s the method through which the voltage of the analogue system meets the maximum level of the analogue to digital converter (ADC). As the operating voltage of the analogue system can be inconsistent from the operating voltage of the ADC.

Matching to sensors: is a clear case of obtaining the right frequencies for the converter in issue. Sensors must be used to help obtain the frequency of preference and match the converter to obtain and perceive the signal correctly.

Digital to analogue (DAC) devices: can be the sounds coming from a PC (output to analogue devices), a digital to analogue converter is used in this case. It reverses the pulse-code modulation process (PCM). Discrete digital steps are taken and converted into an analogue system.

Sensors

Choosing sensors: When choosing a sensor, look for the temperature, safety class, and whether the sensor needs a discrete or analogue input. Consider also the accuracy of the repeat sensor, the speed of the sensor response, and the range of the sensor.

Sensor type: The most common sensors type are temperature, light, linear position, shaft position/rotation speed and switch.

• Temperature sensor: Senses the temperature, it monitors the changes in temperature.
• Light sensor: is a device that senses the intensity of the light. Light sensors can identify various types of light, such as visible light, ultraviolet light and more.
• Linear position sensor: convert the position into a analogue or digital signal. Linear position sensors allow manufacturers to make compact designs that could be mounted internally.
• Rotation speed sensor: use different magnetic proximity adjustment rules to track system components at speeds between 0 and 30,000 rpm.
• Switch sensor: are ideal for any new service-sector room, from the smallest to the biggest. It’s made up of both motion and lighting sensors that control on/off loads.

Electrical characteristics of sensors:  include sensitivity, resolution, linearity and other. For example, sensitivity is a measure of the difference in the output of the sensor compared to the change in the input device.

Output devices

Liquid crystal display (LCD): operates by blocking the light. Specifically, the LCD consists of two bits of polarised glass that hold a liquid crystal material within them. The backlight creates light which passes through the first polarised glass.

Other output devices:

• Lamps: emit light as the electrical current flows through them. Have a thin wire filament that gets very warm and lights up as the current flows through it.

• Relays: convert a small electrical input into a high-current output. This is done to operate different standard appliances. Relays can be found in different electronics.

• Motors: is an electronic system that transforms electrical energy into mechanical energy. Many electric motors work by the interaction between the magnetic field of the motor and the electrical current in a wire winding to produce power in the form of a torque applied to the shaft of the motor. An example of a motor is a DC motor (used in electric cars).

• Solenoids: is a device that converts electrical energy to mechanical energy. The device generates a magnetic field from electrical current which the magnetic field uses to generate linear motion.

Interfacing to controller: is the transfer of data among microcontrollers and interfaces such as sensors, keypads and more. The microcontroller is linked to several external devices called interface devices to perform particular tasks. For example, consider a security device with a user-modifiable password project, where the keypad interface to the microcontroller is used to enter a password.