The document discusses vehicle suspension systems and their components. It explains that suspension systems are responsible for driving comfort and safety by carrying the vehicle body and transmitting forces between the body and road. Semi-active or active components can be introduced to improve these properties and allow the suspension to adapt to different driving conditions. Adding a variable damper and/or spring can considerably improve comfort and safety compared to fixed suspension setups.

1. UNIT5
5.1Suspension Systems
Introduction
– The vehicle suspension system is responsible for driving comfort and safety as the
suspension caries the vehicle body and transmits all forces between the body and the
road.
– In order to positively influence these properties, semiactive and/or active components
are introduced. These enable the suspension system to adapt to various driving
conditions.
– By adding a variable damper and/or spring, driving comfort and safety are
considerably improved compared to suspension setups with fixed properties.
--This strategy requires that the control behavior of these components is known and
that laws on how to adapt the free parameters depending on the driving excitations are
known.
– This also requires the identification and fault detection of the involved components
resulting in a mechatronic design.
• Vehicle Suspension System
– The vehicle suspension system consists of wishbones, the spring, and the shock
absorber to transmit and also filter all forces between the body and road.
– The spring carries the body mass and isolates the body from road disturbances and
thus contributes to drive comfort.
– The damper contributes to both driving safety and comfort. Its task is the damping of
body and wheel oscillations, where the avoidance of wheel oscillations directly refers to
drive safety, as a non-bouncing wheel is the condition for transferring road-contact
forces.

2. – Driving Safety
• Driving safety is the result of a harmonious suspension design in terms of wheel
suspension, springing, steering, and braking, and is reflected in an optimal dynamic
behavior of the vehicle. Tire load variation is an indicator for the road contact and can
be used for determining a quantitative value for safety.
– Driving Comfort
• Driving comfort results from keeping the physiological stress that the vehicle
occupants are subjected to by vibrations, noise, and climatic conditions down to as low
a level as possible. The acceleration of the body is an obvious quantity for the motion
and vibration of the car body and can be used for determining a quantitative value for
driving comfort.
– In order to improve the ride quality, it is necessary to isolate the body, also called the
sprung mass, from the road disturbances and to decrease the resonance peak of the
sprung mass near 1 Hz, which is known to be a sensitive frequency to the human body.
– In order to improve the ride stability, it is important to keep the tire in contact with the
road surface and therefore to decrease the resonance peak near 10 Hz, which is the
resonance frequency of the wheel, also called the unsprung mass.
– For a given suspension spring, the better isolation of the sprung mass from road
disturbances can be achieved with a soft damping by allowing a larger suspension
deflection.
Electromagnetic Linear Actuators in Suspension Systems
– The use of electromagnetic linear actuators in automobile suspensions is under
development.
– The reliability of electrical drives and the unconstrained integration with electronic
control systems are factors that justify their use.
One-Dimensional
Vertical Vehicle
Representation:
The Quarter-Car Model

3. – Rotational electromagnetic actuators have been proposed, however, their use requires
a gearbox to convert the rotational movement into linear movement and to increase the
force value. Linear actuators do not require a gearbox.
– The main objective of ground vehicle suspension systems is to isolate the vehicle body
from road irregularities in order to maximize passenger ride comfort and to produce
continuous road-wheel contact, improving the vehicle handling quality.
– Today, three types of vehicle suspensions are used: passive, semi-active, and active.
All systems implemented in automobiles today are based on hydraulic or pneumatic
operation. However, these solutions do not satisfactorily solve the vehicle oscillation
problem, or they are very expensive and increase the vehicle’s energy consumption.
– Significant improvement of suspension performance is achieved by active systems,
however, they are expensive and complex.
Hydraulic Single-Wheel Active Suspension

4. Electromagnetic Single-Wheel Automobile Active Suspension

5. 5.2 MICROMECHANICAL SYSTEMS
1. Introduction
Over the past 20 years we have witnessed a revolution in the miniaturization of
electronic components from the dimensions of inches to microns. Now we have the
potential to accomplish a similar revolution with many mechanical components [1].
Moreover, as we shrink various devices, fundamental scaling properties enhance the
performance of these small systems. In this paper we shall examine what happens as
we scale the dimensions of motors and other mechanical systems into the micro
domain. (An excellent overview of the micro field is given in an NSF report on
microdynamics [2].)
There are several reasons for developing micro systems. Systems with small
dimensions have advantages in handling small parts, advantages that include speed,
accuracy and gentleness. Intellectually, one is also drawn to this extensive and relatively
unexplored domain. Benefits will probably accrue in such areas as electronics assembly,
medicine and space exploration. Micro systems potentially have numerous advantages in
performing micro tasks that are at, or even beyond, the limits of human manipulation
and patience.
The actuators we use in the macro world often depend upon magnetic forces. As we
shall see, these magnetic forces scale poorly into the micro domain. Fortunately, several
other forces scale well. Scaling theory shows that electrostatics, pneumatics, surface
tension and biological forces are all strong enough to be useful in the small domain.
This paper explores the field of microrobotic and micromechanical systems. The first
portion of the paper examines the advantages, extent and applicability of micro systems.
The second portion analyzes what type of forces will be useful to power these
micromechanical systems. `Microrobotic' is used to refer to small, automated systems;
`micro teleoperator' refers to a small system that is remotely controlled by a human; and
`micromechanical systems' refers to all small mechanical systems.
2. Advantages of micromechanical systems
This Section discusses what sizes of mechanical systems are appropriate to handle
small objects. For example, what sized tooling is appropriate for assembling optical
fibers, lasers and light detectors used in fiber optic communication. There are
advantages in using micro tooling that is more commensurate in size with these small
parts than the macro tooling presently used. These advantages include:
(a) Higher throughput. The time for an operation scales with the system's linear

6. dimension raised to roughly the first power, s1. That is, a system one-tenth the size of
the original has the potential of performing the task ten times faster. (Later in the
analysis, it will be shown that the exponent ranges from 0.5 to 1.5 for most force laws.)
(b) Higher accuracy. Problems due to phenomena such as the temperature
coefficient of expansion, deflection and vibration become less trouble-some as the size of
the system decreases. Despite these advantages, it is curious that people generally
consider smaller mechanical systems to be less accurate, indeed often toys. This need
not be the case; the precision with which small machines can be made may ultimately
be limited by atomic dimensions [31.
(c) Gentleness. The small forces and masses associated with small systems make
them more gentle.
(d) Improved performance. Because the cost of materials scales as s3 (the
volume), a small system can be built with very expensive materials that have desirable
properties. This freedom to use exotic materials often allows the designer to improve
performance.
(e) Floor space. An important consideration in manufacturing plants is the cost
of floor space. Small systems reduce this cost and may also enable an operator to tend
more machines because of their proximity.
Well-made mechanical systems tend to have an accuracy (deviation from the ideal)
and resolution (least motion increment) of a part in 105, give or take an order of
magnitude or two. To obtain the precision movements usually needed to handle small
parts, macro designers resort to devices such as massive granite tables and temperature
controls. Not only do these massive mechanical systems need to be made with extreme
precision, but they also tend to be slow. In contrast, a centimeter-sized system with a
similar part in 10' resolution has an incremental motion of a tenth of a micron, and it is
potentially faster handling millimeter-sized components.
Electronics exemplifies a field where numerous advantages have accrued from
miniaturization. The small size of VLSI electronic circuits, for example, allows designers
to use exotic and expensive materials having desirable properties. A case in point: while
one can use gold for interconnecting VLSI components, it would be prohibitively
expensive for discrete components. Another advantage is convenience: if the word
processor I am using were made of vacuum tubes, it would fill my office instead of a
corner of my desk. There are also speed advantages in moving the electronic
components closer together. Thus, I believe that the advantages in micro structures,
which now seem so obvious in electronics, will someday be obvious in micromechanical
systems as well.
5.3 COMPUTER PRINTER
Printer glossary pg.156
A printer is an output device that produces text and graphics on a physical medium
such as paper. Printed information is often called hard copy because the information
exists physically and is a more permanent form of output than that presented on a VDU
(Monitor). Printers can be grouped into impact and non-impact printers.
_ An impact printer forms characters and graphics on a piece of paper by striking a
mechanism against an ink ribbon that physically contacts the paper.

7. _ A non-impact printer forms characters and graphics on a piece of paper without
actually striking the paper. The printing speed of a printer is usually expressed in pages
per minute (ppm). Printer resolution is often expressed in dpi (dots per inch). The larger
the number, the higher the resolution.
Advantages of printers include
_ Information produced is permanent.
Disadvantages of printers include
_ The time to get the printout is slow, when compared with display devices.
_ Paper is wasted for obtaining the output.
_ Printers are generally noisier than display devices.
The following types of printers will be considered in more detail;
1. Daisy wheel Printer
2. Dot-matrix printer
3. Line printer
4. Ink-jet printer
5. Laser printer
6. Plotter
General Structure of a Printing Engine
The main functional blocks of a printing engine are the following:
1. Printing block;
2. Paper-feeding system;
3. Control system;
4. Interface.
In addition to these blocks, other sub-assemblies might exist that are specific to various
types of printers.
The control system of complex printers may contain several processors Figure. The
control system of a complex printer.

8. Figure . The control system of a complex printer.
The control system of a printer may divide a physical page into several areas or logi-cal
pages. Each area may be smaller or equal to a physical page and the areas may overlap,
which allows to create complex pages. In addition to defining the boundaries and
position of each area within the page, some processing operations to be performed on
the areas may also be specified (e.g., a rotation).
Modern printers can be controlled with a command language. The command proces-sor
controls the data transfer between the computer and printer, interprets the commands,
pro-cesses the data that describe a page, and stores these data in the page memory. The
area pro-cessor performs the changes specified by the user upon the data in the page
memory and transfers them into the area buffer, and from here towards the image
processor, also referred to as Raster Image Processor (RIP). This processor defines the
status of each dot of the image that will appear on the paper, based on the data received
and the stored character formats.
The data prepared for printing are transferred into one of several accumulators. These
are high-capacity memories, containing the bitmap of the image to be transferred onto
the pa-per. To increase speed, several accumulators may be used. While one of the
accumulators is used for printing, the second (or the others) may be loaded with a new
page. Another proces-sor controls the printing block and the paper-feeding system. This
processor interprets the commands referring to the printing format, which will also
determine the paper movement.
5.4 VCR
videocassette recorder, also spelled video cassette recorder
(VCR), electromechanical device that records, stores, and plays back television
programs on a television set by means of a cassette of magnetic tape. A videocassette
recorder is commonly used to record television programs broadcast over the air or by
cable and to play back commercially recorded cassettes on a television set.

9. Prototypes of videocassette recorders were developed in the l960s, but the
first relatively convenient and low-cost VCR was introduced by the Sony Corporation in
1969. With the subsequent development of the Betamax format by Sony and
the VHS format by the Matsushita Corporation in the 1970s, videocassette recorders
became sufficiently inexpensive to be purchased by millions of families for use in the
home. Both the VHS and Betamax systems use videotape that is 0.5 inch (13 mm) wide,
but the two systems are mutually incompatible, and a cassette that is recorded on one
system cannot be played back on the other system. A third system using 0.3inch- (8-
millimetre-) wide tape was introduced in early 1985.
A videocassette recorder can have from two to as many as seven tape heads
that read and inscribe video and audio tracks on the magnetic tape. Most VCRs have
fast-forward and reverse controls and a timer that enables television programs to be
recorded automatically, and they can record a program on one television channel while
a viewer watches a program on another channel of the same television set.
Colour home movies can be made with the use of a camcorder system; this
consists of a videocassette recorder that is connected to a relatively light and
simple video camera. One camcorder system uses 8-millimetre videotape, and other
portable video systems are available for filming outside of the home or studio.
5.5 Fax Machine
Short for facsimile machine, a device that can send or receive pictures
and text over a telephone line. Fax machines work by digitizing an image -- dividing it
into a grid of dots. Each dot is either on or off, depending on whether it is black or
white. Electronically, each dot is represented by a bit that has a value of either 0 (off) or
1 (on). In this way, the fax machine translates a picture into a series of zeros and ones
(called a bit map) that can be transmitted like normal computer data. On the receiving
side, a fax machine reads the incoming data, translates the zeros and ones back into
dots, and reprints the picture.
The idea of fax machines has been around since 1842, when
Alexander Bain invented a machine capable of receiving signals from a telegraph wire
and translating them into images on paper. In 1850, a London inventor named F. C.
Blakewell received a patent for a similar machine, which he called a copying telegraph.
But while the idea of fax machines has existed since the 1800s, fax
machines did not become popular until the mid-1980s. The spark igniting the fax
revolution was the adoption in 1983 of a standard protocol for sendingfaxes at rates of
9,600 bps. The standard was created by the CCITT standards organization and is
known as theGroup 3standard. Now, faxes are commonplace in offices of all sizes. They
provide an inexpensive, fast, and reliable method for transmitting correspondence,
contracts, handwritten notes, and illustrations.

10. 5.6 NC machine
Controlling a machine tool by means of prepared program, which consists of blocks, or
series of numbers, is known as numerical control (NC). In manufacturing of more
complicated parts, the system has to calculate automatically additional data points,
which is done by means of an interpolator. Numerical Control (NC) refers to the method
of controlling the manufacturing operation by means of directly inserted coded
numerical instructions into the machine tool. It is important to realize that NC is not a
machining method; rather, it is a concept of machine control. Although the most
popular applications of NC are in machining, NC can be applied to many other
operations, including welding, sheet metalworking, riveting, etc.
NC machines are method of automation, where automation of medium and small
volume production is done by some controls under the instructions of a program.
Various definitions of NC are:
A system in which actions are controlled by direct insertion of
Numerical Data at some point. The system must automatically interpret at least
some portion of this data by Electronic Industries Association (EIA).
Numerical Control is defined as a form of software controlled automation, in
which the process is controlled by alphanumeric characters or symbols.
CNC Machines: According to these definitions, a programme is prepared which
consists of blocks, blocks consisting of combination of characters and numbers in
sequence describing the position of the tool and job, the cutting speed and feed. The
data converted into coded instructions which are called a Part Programme. As the job
changes, the instructions of part program are also changed. The other instructions
which can be included may be for tool changing or coolant on and off. It is easy to
encode a new programme than to change the machinery for flexibility, thus arising the
need of an NC machine tool.
Figure 1.1 : Numerical Control (NC) Machine Tool

11. Advantages of NC
The major advantages of NC over conventional methods of machine control are as
follows :
Higher Precision
NC machine tools are capable of machining at very close tolerances, in some operations
as small as 0.005 mm.
Better Quality
NC systems are capable of maintaining constant working conditions for all parts in a
batch thus ensuring less spread of quality characteristics.
Higher Productivity
NC machine tools reduce drastically the non machining time. Adjusting the machine
tool for a different product is as easy as changing the computer program and tool turret
with the new set of cutting tools required for the particular part.
Multi-operational Machining
Some NC machine tools, for example machine centers, are capable of accomplishing a
very high number of machining operations thus reducing significantly the number of
machine tools in the workshops.
Low Operator Qualification
The role of the operation of a NC machine is simply to upload the work piece and to
download the finished part. In some cases, industrial robots are employed for material
handling, thus eliminating the human operator.
Less Time
An easy adjustment of the machine, adjustment requires less time. 7 Introduction to NC
Machine Tools.
Types of NC System
Machine controls are divided into three groups:
(a) Traditional numerical control (NC);
(b) Computer numerical control (CNC);
(c) Distributed numerical control (DNC).