Topic 7) Control

A device, or set of devices that control, manage, command, direct or regulate the behaviour of other devics or systems.

Computers can respond much more quickly than humans Control systems can run without breaks (24 hours, 365/366 days a year) Control Systems are less error prone than humans Control systems can be planed in an environment hazardous to humans

Technical Malfunctions can occur Cannot react to unexpected events Relies on a consistent supply of electricity Could be more expensive than a human solution

Microprocessors Sensors Actuators

An integrated circuit that contains all the functions of a computer’s CPU Performs calculations and data processing

A device which detects or measures a physical property and records, indicates or otherwise responds to it

Heat Humidity Infrared Light pH Pressure Smoke Sound Tilt Touch

Part of a device or machine that helps it to achieve physical movements by converting energy A device that moves or controls a mechanism.

Opening doors on a bus. Opening a car window. Locking the car doors

Converts one form of energy into another

True!

Analog-to-Digital converters. They convert analog data from sensors into digital data, which can be read by computers.

Input-Process-Output Model. 1) Sensors take in analog input and convert them into digital 2) Digital data is processed by the microprocessor, to output different digital data 3) Transducers turn this digital data into a form of physical motion

If either the output, or some form of it is utilised as part of the system input, then it is known as feedback.

Open Loop System Closed Loop System Negative Feedback Loop Positive Feedback Loop

Doesn’t take feedback into account, repeats the same action over and over again based on an input. ie, TV Remote Control, Light Bulb, Coffee Machine, Toaster

Takes feedback into account, including output and possible other factors that are external to the system Corrects errors by using feedback loop to alter subsequent inputs ie, Home Thermostat, Airplane Autopilot

A system in which feedback is given in order to reduce fluctuation in subsequent output Tries to move the output closer to the ‘target value’ ie, internal body temperature regulation

Enhances or amplified changes in output to move a system further away from the ‘target value’. ie, global warming

All components within the system are controlled by a central processing unit.

Easier to maintain and troubleshoot More control

If main sensor/controller/actuator fails, the whole system fails Less power Less flexibility

Different components are controlled by a number of different processing units located throughout the system- all working towards a common goal

Shared processing load More reliability Flexibility