IB Comp Sci - Topic 7

Control Systems

Manages, commands, directs or regulates the **behaviour of other devices or systems**.

It can range from a home heating controller using a thermostat controlling a domestic boiler to large industrial systems which are used for controlling processes or machines.

Sensors

A device which reacts to different inputs from the **external physical environment**. It produces **analogue signals** which are sent to the ADC to be converted to **digital signals** which can be processed by the **microprocessor**.

Microprocessor

• Flexible processor used for intensive computing such as in laptops, mobile phones etc.

• Consists of just a CPU

• Uses external bus to interface with RAM, ROM and peripherals

Microcontroller

• It is used where the task is fixed and predefined, generally embedded systems.

• Consists of a CPU, RAM and I/O interface all integrated into one chip

• Uses an internal bus to interface with its own RAM and ROM

Actuators

A component of a machine that is responsible for moving or controlling a mechanism or system.

It turns **digital data** into **physical movement**.

Centralised System

A system that is **located, stored, and maintained in a single location**. If the location is compromised, the **entire** system is affected.

Decentralised System

A system in which **components located on networked computers** communicate and coordinate their actions by **passing messages**. The components interact with each other in order to achieve a **common goal**.

Transducer

A sensor that **changes energy from one form to another**. More technically converts a **physical parameter into another form**.

Can be used at the **input** (a microphone) or the **output** (a speaker) of a system. It receives a control signal from the **microprocessor** and extra power to produce a **physical effect**.

ADC

Analogue to digital converter (Sensor -\> Processor)

DAC

Digital to analogue converter (Processor -\> transducer)

Processor

The **logic circuitry** that respond to and process the **basic instructions** that drive a computer

Output transducer

A device that converts **input energy** of one form to **output energy** of another

Autonomous agents

They are **self-governing** computer programs which **sense and read the environment and reach individually**.

They sometimes **cooperate to achieve their aims** and usually **run on their own agenda**.

Input

Sensors capture **analog data**

Analog to digital converter

Coverts **analog data into digital** so it can be read by the CPU

Feedback

It occurs when **a system changes the value that it senses**. Value has to be kept within a range or threshold. Feedback regulates the variable to ensure that it remains within the specified range of values. Because the output changes the variable, inputs must repeatedly be taken.

If the variable exceeds the threshold, something will happen. If variable is below threshold, another thing will happen.

Distributed system

A system that is comprised of **multiple autonomous computers** which communicate and coordinate their actions using messages, as such they appear to be a single integrated computing system.

Distributed database

A database that does not reside on one computer but **multiple computers** which **update each other asynchronously**.

Embedded system

It is a dedicated, **single-purpose computer system** forming part of a **larger mechanical device**.

Input devices

This is a **peripheral device** used to provide **data and control signals** to an information processing system such as a computer.

Centrally controlled system

It is a **device or a set of devices** to manage, command, direct, or regulate **all elements of a system**.

Device driver

It is **a program that controls a particular type of device** that is attached to your computer and are many times built into devices such as printers, displays, CD-ROM readers, and diskette drivers.

Process control

An engineering discipline that deals with architectures, mechanisms, and algorithms for **maintaining the output of a specific process within a desired range**.