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© Boardworks Ltd 20051 of 19

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Product Design Control Components


Learning objectives


Lea

rnin

g o

bje

ctiv

es To be able to identify common electronic and mechanical components.

To understand the functions and uses of common electronic and mechanical components.


Any system depends on a number of components to make it work.

In the majority of cases, these components are electronic or mechanical.

In many systems, electronic components provide control over mechanical devices and they work in conjunction with each other to perform tasks, e.g. a production line.

Components can also link into a system via a computer. In this case, components are plugged into an interface unit so that the PC can interpret the signals and use them in a program.

What are control components?


Inputs, processes and outputs


Different types of control components


PICs are programmable ICs which can accept information from a range of input sensors.

They are also able to process and store information in order to drive an output.

The ‘processing’ part is usually worked out using a computer with specialist software; the whole program is then ‘burnt’ onto the chip so that it becomes a stand-alone chip, specifically programmed to work for a particular task.

PIC chips can be used over and over again and will process both analogue and digital sensors.

Programmable integrated circuits (PICS)


Mechanisms are concerned with movement and force in a system.

Motion can also be converted from one form to another via different mechanisms.

There are 4 types of motion:

linear

rotary

reciprocating

and oscillating.

What are mechanisms?


Linear motion is the most basic of all the motions. If an object is moving in linear motion, it is travelling in a straight line.

A good example of a object that moves in a linear motion is a train.

What is linear motion?


Rotary motion moves in circles.

Rotary motion is fairly common and can be found in a number of objects…

…for example, in a wheel.

What is rotary motion?


Reciprocating motion is the motion of an object when it moves backwards and forwards.

An example of reciprocating motion is the action a person would make when using a hand bike pump.

What is reciprocating motion?


Oscillating motion is a motion that is a cross between linear motion and reciprocating motion. It involves backwards and forwards motion, but in an arc rather than a straight line.

Pendulums and metronomes move in an oscillating motion.

What is oscillating motion?


Gears play a major role in mechanisms. They are discs with toothed edges, which rotate around a central axle. They come in a variety of sizes and are used to change the direction and speed of motion. However, the motion always remains rotary in nature.

A worm gear can change the rotary motion by 90 degrees, as well as affecting the speed.

What are gears?


Gears test


Levers are an essential part of many mechanisms. They can be used to change the strength and direction of movement.

Levers magnify the strength of forces. The longer the lever, the more the force is magnified.

The fixed point of a lever is known as the fulcrum.

Two common examples of everyday levers are a pair of scissors and a seesaw.

What are levers?


Levers test


Cams are used to convert rotary motion into reciprocating motion.

The motion that is created can be simple and regular…

…or complex and irregular.

The cam follower follows the profile of the cam.

The cam must be well designed to produce the motion required.Cam

Cam follower

What are cams?


Pulleys Pulleys are used to transfer motion. They work under rotary motion. Motion is passed along a pulley belt causing more pulleys to turn.

The size of the pulley wheels determines the speed of motion – this can be altered accordingly.

You can twist the belt, causing the rotary motion to change direction.

Pulleys can also increase the strength of a force, and are useful for lifting heavy objects.

What are pulleys?


Pulleys test


Key points


Key

po

ints

LDRs are sensitive to light.

Thermistors are sensitive to heat.

A solenoid converts electromagnetic energy into reciprocating movement.

LEDs are used for visual signals. They only use small amounts of current and so a resistor is placed in series with the LED to protect it.

PIC chips store information about inputs and outputs and can be re-used. They accept both digital and analogue signals.

Mechanisms are concerned with movement.

A lever provides mechanical advantage.

© Boardworks Ltd 2005 1 of 19 These icons indicate that teacher’s notes or useful web addresses...

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