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PERSONAL UTILITY VEHICLE

Department of Mechanical Engineering, Dr. AIT Page 1

1. INTRODUCTION

The ever-growing travel expenses associated with Single Occupancy Vehicles (SOV), in

terms of time, money, and emotional stress, created a need for better, easier, and

environmental friendly transportation modes. A wide range of responses to such needs have

emerged to the market in recent years such as, smaller and energy efficient cars, community

bound golf carts and electric cars in the motorized category and Inline skates, bicycles, and

scooters considered under the non-motorized category. Technologically advanced Segway

Human Transport is a new addition to the existing transportation modes, unveiled at the end

of year 2001. Since its introduction, Segway HT has caused a good stir in the transportation

community and general public. Therefore a number of transportation professionals and

advocates are carrying out the debate on why it should be treated as non-motorized device

and should it be operated on sidewalks.

As claimed by its developer and manufacturer, Segway HT is a self- balancing, personal

transportation device that’s designed to operate in any pedestrian environment. Segway

derived from the word “Segue” means “to transition smoothly from one state to another”.

Segway HT can travel three times faster than the average walker, empowering the pedestrian

with speed and a comfortable ride. Majority of people who have tried Segway HT, express

that Segway HT was easy to learn and to maneuver in the traffic.

The device is a combination of durable mechanical system controlled by electrical

system. As seen in the figure, the basic structure consists of handle bar, adjustable controlling

shaft and a standing platform. The entire unit balances intuitively on two wheels. The unit

moves forward if the rider leans forward, moves backwards if leaned backwards. Straighten

up to gently stop the device. With the slight twist of handles rider can maneuver to right or

left. The technology behind this is known as “Dynamic stabilization”. Segway HT equipped

with five specially designed gyroscopes and tilt sensors that detects the change in the rider’s

center of gravity one hundred times a second. Ten microprocessors in the controlling board

sends commands to powerful electric motors to keep the Segway HT balanced to provide a

smooth ride. To ensure safety and security of the riders, Segway makes use of redundant

sensors and electrical systems that share the load. If problem arises in any one system the

other maintains the balance and slows down before powering off. As claimed by the Segway

HT developers, the device balances are not affected by the travel velocities or loading factors.

That is, unit remains balanced whether traveling at its top speed, with full loading capacity, or



slowly maneuvering in crowded streets. As the very first Segway accident is reported in

Atlanta, which is discussed later in the paper, raise doubts about limitations to intuitive

balancing of the device. Segway HT operates in a wide range of environmental conditions.

Electronics and other components are sealed and protected and have been tested to with stand

vibrations, temperatures, and exposure to moisture. Segway HT is designed to ride on a

variety of terrains. With proper training and experience, it can be used wherever pedestrian

can walk. It can even maneuver on snow and ice with the addition of snow tires.

i series and e series Segway HT models are designed for commercial

purposes. These models are capable of traveling 11-17 miles on a single charge of Nickel

Metal Hydride (NiMH) battery. The standing platform is 19 x 25 inches with ground

clearance of 8 inches. The turning radius is zero, meaning the device can turn without

impacting the people nearby. Segway HT i series weigh 83 lbs and carry a person weighing

up to 250 lbs. The e series with a self-weight of 95 lbs can carry 75 lbs of cargo, addition to

250 lbs of passenger load. With the cargo carry bags attached, e series is designed to carry

cargo. The e series is equipped with an electronic stand, which keeps the unit balanced while

loading and unloading of cargo. The accessories can be customized to suit the commercial

needs.

Segway HT requires an intelligent key to start and to make mode selection such as- Learning

Mode, Sidewalk Mode, and Free Environment Mode, which will restrict the Segway HT

maximum speed to 6 mph, 9 mph and 12.5 mph respectively. With its unique 64-bit encoded

security ID, the device is protected against theft. Still the company recommends storing it in

a safe place, securing it to an immovable object. Cable and bicycle locks can be used for this

purpose.

Personal utility vehicle is a three wheeled battery powered vehicle. It is designed on

the idea of Segway, a two wheeled self-balancing vehicle. It is one of the low speed

transportation devices, used to travel on sidewalks, roadways etc. It is a clean and green

vehicle. The electric vehicles are a revolution in the field of green transportation. The

personal utility vehicle is both an effective and efficient device allowing the user to travel

further, faster and carry more than would be possible on foot. The device is simple,

technologically sound and easy to use when controlled in the correct manner.

The front wheel is a castor wheel and the rear wheels are driven by 2 DC motors

whose speed is controlled by a DC motor drive controller, an electronic device. The direction



is controlled by the handle attached to the front wheel. The motion is controlled by brake

mechanism.

The vehicle runs on flat surfaces, and the rider has to manage speed, maneuver the

device, pass a variety of objects and stop in response to environmental stimuli like people,

traffic, signals, curbs and obstructions such as poles , park benches etc.



2. LITERARY SURVEY

2.1 Batteries – Lead-acid batteries.

Fig 2.1 – Lead-Acid Battery

Specifications: Voltage - 12V

Current rating – 7.5 ampere hour/20 hour

Type - Lead acid

Dimensions- 5.94 L x 2.56 W x 3.7 H Inches

Lead-acid is the oldest rechargeable battery in existence. Invented by the French physician

Gaston Planté in 1859, lead-acid was the first rechargeable battery for commercial use. 150

years later, we still have no cost-effective alternatives for cars, wheelchairs, scooters, golf

carts and UPS systems. During the mid-1970s, researchers developed a maintenance-free

lead-acid battery that can operate in any position. The liquid electrolyte is gelled into

moistened separators and the enclosure is sealed. Safety valves allow venting during charge,

discharge and atmospheric pressure changes. Driven by different market needs, two lead-acid

systems emerged: The small sealed lead-acid (SLA), also known under the brand name of

Gel cell, and the larger Valve-regulated-lead-acid (VRLA). Both batteries are similar.

Finding the ideal charge voltage limit is critical. A high voltage (above 2.40V/cell) produces

good battery performance but shortens the service life due to grid corrosion on the positive

plate. A low voltage limit is subject to salvation on the negative plate. Leaving the battery on

float charge for a prolonged time does not cause damage.



Table 2.1- Lead-Acid Battery Characteristics

The optimum operating temperature for the lead-acid battery is 25*C (77*F). Elevated

temperature reduces longevity. As a guideline, every 8°C (15°F) rise in temperature cuts the

battery life in half. A VRLA, which would last for 10 years at 25°C (77°F), would only be

good for 5 years if operated at 33°C (92°F). The same battery would desist after 2½ years if

kept at a constant desert temperature of 41°C (106°F). The sealed lead-acid battery is rated at

a 5-hour (0.2) and 20-hour (0.05C) discharge. Longer discharge times produce higher

capacity readings because of lower losses. The lead-acid performs well on high load currents.

Lead-Acid battery is used as the power source for the PUV. Two 12V-DC

batteries are used in PUV. The batteries are connected in series. Battery supplies power to the

motors to drive the wheels. The batteries are rechargeable. Charging a lead acid battery is

simple but the correct voltage limits must be observed.

Overcharging with high charging voltages generates oxygen and hydrogen gas by electrolysis

of water, which is lost to the cell. Periodic maintenance of lead-acid batteries requires

inspection of the electrolyte level and replacement of any water that has been lost. Due to

the freezing-point depression of the electrolyte, as the battery discharges and the

concentration of sulfuric acid decreases, the electrolyte is more likely to freeze during winter

weather when discharged.

The advantages of using Lead-Acid batteries are

Inexpensive.

Mature, reliable and well-understood technology - when used correctly, lead-acid

is durable and provides dependable service.

The self-discharge is among the lowest of rechargeable battery systems.

Capable of high discharge rates.

Type Voltage Regulation Initial Current

Stand by use 13.5 - 13.8 Less than 2.6A

Cycle use 14.4 - 15 Less than 2.6A



2.2 Motors – 12V DC motors.

Fig 2.2- DC Motor

Specifications: Speed - 1500 RPM

Power - 0.2 HP

Voltage - 12V

A DC motor is any of a class of electrical machines that converts direct current electrical

power into mechanical power. The most common types rely on the forces produced by

magnetic fields.

Nearly all types of DC motors have some internal mechanism, either electromechanical or

electronic; to periodically change the direction of current flow in part of the motor. Most

types produce rotary motion; a linear motor directly produces force and motion in a straight

line. C motors were the first type widely used, since they could be powered from existing

direct-current lighting power distribution systems. A DC motor's speed can be controlled over

a wide range, using either a variable supply voltage or by changing the strength of current in

its field windings. Small DC motors are used in tools, toys, and appliances. Larger DC

motors are used in propulsion of electric vehicles, elevator and hoists, or in drives for steel

rolling mills.



Motors are fixed to the chassis through screwed bolt and it is the main source of

power which is to drive the vehicle. There are two motors, each for one wheel. Each motor is

driven by a separate 12v battery.

2.3 Wheels.

Wheels are basic components of Personal Utility Vehicle for the motion of vehicle. Two

types of wheels are used in front end and rear end of PUV.

Quantity - 3

Front wheel - Castor wheel (1)

Rear wheels – Rubber wheels (2)

2.3.1 Rear Wheels.

Fig 2.3.1 - Rear wheel

Wheels are attached to motor spindle through bearings. It is driven by 12V DC motors. Two

Rubber wheels with bearings are used as rear end wheels.



2.3.2 Castor Wheel.

Fig 2.3.2 - Castor Wheel

Castor wheel is the front end wheel that passes through the chassis and is attached to PUV

handle. It is the guiding wheel and is used by rider to control the direction of vehicle.

2.4 Wooden box for assembly and support.

Fig 2.4 – Wooden Box

Wood used - Jungle wood

Capacity - up to 150 kg’s



Dimensions: Length - 425 mm

Width - 575 mm

Height - 275 mm

Chassis is made of wooden block and four wooden blocks are used to make the frame. To

make chassis to be balanced, four wooden blocks of equal weights are used. Jungle Wood is

the material used. It is engaged firmly with the help of stud. Stud is to connect the wooden

block together with the nut. Slots are provided in wooden box for two batteries and at rear

end two motors are fixed. At front end hole is provided for vehicle handle.

2.5 Handle for maneuvering the vehicle.

Fig 2.5 - Handle

PUV handle is made of mild steel of length 120cm and is cut to form a T joint. T joint is

formed by arc welding of two mild steel. Handle passes through the hole provided in front

end of wooden box and is connected to castor wheel. Handle is detachable as it is connected

to castor wheel through threaded nut. Brake for controlling the speed is attached to handle at

top, same as cycle brake.



2.6 Rim Braking System.

Rim brakes are so called because braking force is applied by friction pads to the rim of the

rotating wheel, thus slowing it and the bicycle. Brake pads can be made of leather, rubber or

cork and are mounted in metal "shoes". Rim brakes are typically actuated by the rider

squeezing a lever mounted on the handlebar.

Rim brakes are inexpensive, light, mechanically simple, easy to maintain, and powerful.

However, they perform relatively poorly when the rims are wet. This problem is less serious

with rims made of aluminium than on those with carbon fiber, steel or chromed rims.

Because the rims can carry debris from the ground to the brake pads, rim brakes are more

prone to clogging with mud or snow than disc brakes (where both braking surfaces are high

off the ground), particularly when riding on unpaved surfaces. The low price and ease of

maintenance of rim brakes makes them popular in low- to mid-price commuter bikes, where

the disadvantages are greatly alleviated by the unchallenging conditions. The light weight of

rim brakes also makes them desirable in road racing bicycles.

Rim brakes require regular maintenance. Brake pads wear down and have to be replaced.

Over longer time and use, rims become worn. Rims should be checked for wear periodically

as they can fail catastrophically if the braking surface becomes too worn. Wear is accelerated

by wet and muddy conditions. Some types of rim brake, e.g. dual pivot, require that the rim

be relatively straight; if the rim has a pronounced wobble, then either the brake pads rub

against it when the brakes are released, or apply insufficient or uneven pressure to the rim.

Fig 2.6 - Rim Brake



2.7 ELECTRONIC DC MOTOR SPEED CONTROLLER

Fig 2.7(a) – DC Motor Speed Controller

SPECIFICATIONS:

Power requirement: 10-50VDC

Rated current: 40A（Maximum output current）

Frequency: 12000HZ

Control Motor Power: 0.01-2000W,

12V:480W (max), 24V:960W (max)

36V:1440W (max), 50V:2000W (max)

Regulation range: 5-100%

PCB Size: 90x51mm (inch: 3.5"x2")

Plastic Case size: 105x55x40mm (inch:4"x2.2"x1.6")

Weight: 130g



DC motor speed controller is used to vary the speed of the DC motors by turning the

potentiometer knob. Since gear boxes are costly, the electronic component being less costlier

helps in easy regulation of the speed. The speed is varied by the method of pulse width

modulation (PWM). This type of controllers are used in electric scooters, golf buggies etc.

Fig 2.7(b) - Connection Details

The terminals of the motors and batteries are connected to the DC motor control drive. Just

turning the knob one can control the speed of the motors.

2.7.1 Individual Components of DC Motor Speed Controller

The DC motor speed controller circuit has different components. They are as follows

1)NE555 Timer IC

The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation,

and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and

as a flip-flop element. Derivatives provide up to four timing circuits in one package. The

NE555 is s monolithic timing circuit and is highly stable controller capable of producing

accurate time delays or oscillation. In the time delay mode of operation, the time is precisely

controlled by one external resistor and capacitor. For a stable operation as an oscillator, the

free running frequency and the duty cycle are both accurately controlled with two external

resistors and one capacitor.



Modes-

The IC 555 has three operating modes:

Monostable mode: In this mode, the 555 functions as a"one-shot" pulse generator.

Applications include timers, missing pulse detection, bounce free switches, and touch

switches, frequency divider, capacitance measurement, pulse-width modulation (PWM) and

so on.

Astable (free-running) mode: The 555 can operate as an oscillator. Uses include LED and

lamp flashers, pulse generation, logic clocks, tone generation, security alarms, pulse position

modulation and so on. The 555 can be used as a simple ADC, converting an analog value to

a pulse length.

Bistable mode or Schmitt trigger: The 555 can operate as a flip-flop, if the DIS pin is not

connected and no capacitor is used. Uses include bounce-free latched switches.

Fig 2.7.1(a) – NE555 Timer IC

Key features:

Low turn-off time

Maximum operating frequency greater than 500 kHz

Timing from microseconds to hours

Operates in both astable and monostable modes

Output can source or sink up to 200 mA

Adjustable duty cycle

TTL compatible

Temperature stability of 0.005% per °C



The pin diagram and the functions of the pins are as follows:

Fig 2.7.1(b) - Pin diagram NE555

PIN

NAME

PURPOSE

1 GND Ground reference voltage, low level (0 V)

2

TRIG

The OUT pin goes high and a timing interval starts when this input falls

below 1/2 of CTRL voltage .

3 OUT This output is driven to approximately 1.7 V below +VCC, or to GND.

4

RESET

A timing interval may be reset by driving this input to GND, but the

timing does not begin again until RESET rises above approximately 0.7

volts

5

CTRL

Provides "control" access to the internal voltage divider (by default, 2/3

VCC).

6

THR

The timing (OUT high) interval ends when the voltage at THR

("threshold") is greater than that at CTRL

7

DIS

Open collector output which may discharge a capacitor between

intervals. In phase with output.

8

VCC

Positive supply voltage, which is usually between 3 and 15 V depending

on the variation.

Table 2.7.1(a) - NE555 Pin Details



2)MOSFET

The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET)

is a type of transistor used for amplifying or switching electronic signals.

Fig 2.7.1(c)- MOSFET

Although the MOSFET is a four-terminal device with source (S), gate (G), drain (D), and

body (B) terminals, the body (or substrate) of the MOSFET is often connected to the source

terminal, making it a three-terminal device like other field-effect transistors. Because these

two terminals are normally connected to each other (short-circuited) internally, only three

terminals appear in electrical diagrams. The MOSFET is by far the most common transistor

in both digital and analog circuits, though the bipolar junction transistor was at one time

much more common.

The main advantage of a MOSFET over a regular transistor is that it requires very little

current to turn on (less than 1mA), while delivering a much higher current to a load (10 to

50A or more). However, the MOSFET requires a higher gate voltage (3-4V) to turn on.

In enhancement mode MOSFETs, a voltage drop across the oxide induces a

conducting channel between the source and drain contacts via the field effect. The term

"enhancement mode" refers to the increase of conductivity with increase in oxide field that

adds carriers to the channel, also referred to as the inversion layer. The channel can contain

electrons (called an nMOSFET or nMOS), or holes (called a pMOSFET or pMOS ), opposite

in type to the substrate, so nMOS is made with a p-type substrate, and pMOS with an n-type

substrate (see article on semiconductor devices).

In the less common depletion mode MOSFET, detailed later on, the channel consists of

carriers in a surface impurity layer of opposite type to the substrate, and conductivity is

decreased by application of a field that depletes carriers from this surface layer.



The "metal" in the name MOSFET is now often a misnomer because the previously

metal gate material is now often a layer of polysilicon (polycrystalline silicon). Aluminum

had been the gate material until the mid-1970s, when polysilicon became dominant, due to its

capability to form self-aligned gates. Metallic gates are regaining popularity, since it is

difficult to increase the speed of operation of transistors without metal gates.

Likewise, the "oxide" in the name can be a misnomer, as different dielectric

materials are used with the aim of obtaining strong channels with smaller applied voltages.

3) Heat Sink

In electronic systems, a heat sink is a passive heat exchanger that cools a device by

dissipating heat into the surrounding medium. In computers, heat sinks are used to cool

central processing units or graphics processors. Heat sinks are used with high-power

semiconductor devices such as power transistors and optoelectronics such as lasers and light

emitting diodes (LEDs), where the heat dissipation ability of the basic device is insufficient

to moderate its temperature.

Fig 2.7.1(d) - Heat Sink

A heat sink is designed to maximize its surface area in contact with the cooling medium

surrounding it, such as the air. Air velocity, choice of material, protrusion design and surface

treatment are factors that affect the performance of a heat sink. Heat sink attachment methods

and thermal interface materials also affect the die temperature of the integrated circuit.

Thermal adhesive or thermal grease improve the heat sink's performance by filling air gaps

between the heat sink and the heat spreader on the device. The most common heat sink

materials are aluminium alloys. Aluminium alloy 1050A has one of the higher thermal

conductivity values at 229 W/m•K but is mechanically soft. Aluminium alloys 6061 and 6063



are commonly used, with thermal conductivity values of 166 and 201 W/m•K, respectively.

The values depend on the temper of the alloy.

4) Potentiometer

The DC motor speed controller consists of a 50K potentiometer. A potentiometer, informally

a pot, is a three-terminal resistor with a sliding or rotating contact that forms an adjustable

voltage divider. If only two terminals are used, one end and the wiper, it acts as a variable

resistor or rheostat.

Fig 2.7.1(e) – Potentiometer

The measuring instrument called a potentiometer is essentially a voltage divider used for

measuring electric potential (voltage); the component is an implementation of the same

principle, hence its name.

Potentiometers are commonly used to control electrical devices such as volume

controls on audio equipment. Potentiometers operated by a mechanism can be used as

position transducers, for example, in a joystick. Potentiometers are rarely used to directly

control significant power (more than a watt), since the power dissipated in the potentiometer

would be comparable to the power in the controlled load.



3. PROBLEM DEFINITION

Vehicular pollution has grown at an alarming rate due to growing urbanization. The air

pollution from vehicles in urban areas, particularly in big cities, has become a serious

problem. The pollution from vehicles has begun to tell through symptoms like cough,

headache, nausea, irritation of eyes, various bronchial and visibility problems. The other

factors of vehicular pollution in the urban areas are 2-stroke engines, poor fuel quality, old

vehicles, inadequate maintenance, congested traffic, poor road condition and old automotive

technologies and traffic management system.

Not only air pollution, noise pollution is also a major problem. In the city, the main sources

of traffic noise are the motors and exhaust system of autos, smaller trucks, buses, and

motorcycles. This type of noise can be augmented by narrow streets and tall buildings, which

produce a canyon in which traffic noise reverberate.

Fuel prices have risen; there is a greater awareness of the damage caused by carbon

dioxide and other greenhouse gas emissions and environmental and political forces have de-

stabilized the global petroleum supply. The PUV can help reduce dependence on foreign oil,

use the existing energy supply more efficiently, and reduce pollution. The PUV helps to

reduce the pollution by cutting down the oil usage, and by using the existing energy sources

more efficiently. The PUV do not produce any emission during the operation except for the

recharging of the batteries during which heat emission takes place.



4. MODELLING AND IMPLEMENTATION

4.1 Motor Control Using PWM

Pulse Width Modulation (PWM) uses digital signals to control power applications, as well as

being fairly easy to convert back to analog with a minimum of hardware. Analog systems,

such as linear power supplies, tend to generate a lot of heat since they are basically variable

resistors carrying a lot of current. Digital systems don't generally generate as much heat.

Almost all the heat generated by a switching device is during the transition (which is done

quickly), while the device is neither on nor off, but in between. This is because power follows

the following formula:

P = E I, or Watts = Voltage X Current

If either voltage or current is near zero then power will be near zero. PWM takes full

advantage of this fact.

PWM can have many of the characteristics of an analog control system, in that the digital

signal can be freewheeling. PWM does not have to capture data, although there are

exceptions to this with higher end controllers.

There are many different ways to control the speed of motors but one very simple and easy

way is to use Pulse Width Modulation. But before we start looking at the ins and outs of

pulse width modulation we need to understand a about how a DC motor works.

Next to stepper motors, the Permanent Magnet DC Motor (PMDC) is the most commonly

used type of small direct current motor available producing a continuous rotational speed that

can be easily controlled. Small DC motors ideal for use in applications were speed control is

required such as in small toys, models, robots and other such Electronics Circuits.

A DC motor consists basically of two parts, the stationary body of the motor called the

“Stator” and the inner part which rotates producing the movement called the “Rotor”. For

D.C. machines the rotor is commonly termed the “Armature”.

Generally in small light duty DC motors the stator consists of a pair of fixed permanent

magnets producing a uniform and stationary magnetic flux inside the motor giving these

types of motors their name of “permanent-magnet direct-current” (PMDC) motors.

The motors armature consists of individual electrical coils connected together in a circular

configuration around its metallic body producing a North-Pole then a South-Pole then a

North-Pole etc., type of field system configuration.

The current flowing within these rotor coils producing the necessary electromagnetic field.

The circular magnetic field produced by the armatures windings produces both north and



south poles around the armature which are repelled or attracted by the stator’s permanent

magnets producing rotational movement around the motors central axis as shown.

Fig 4.1(a) - DC Motor Working

As the armature rotates electrical current is passed from the motors terminals to the next set

of armature windings via carbon brushes located around the commutator producing another

magnetic field and each time the armature rotates a new set of armature windings are

energized forcing the armature to rotate more and more and so on.

So the rotational speed of a DC motor depends upon the interaction between two magnetic

fields, one set up by the stator’s stationary permanent magnets and the other by the armatures

rotating electromagnets and by controlling this interaction we can control the speed of

rotation.

The magnetic field produced by the stator’s permanent magnets is fixed and therefore cannot

be changed but if we change the strength of the armatures electromagnetic field by

controlling the current flowing through the windings more or less magnetic flux will be

produced resulting in a stronger or weaker interaction and therefore a faster or slower speed.

Then the rotational speed of a DC motor (N) is proportional to the back emf (Vb) of the

motor divided by the magnetic flux (which for a permanent magnet is a constant) times and

electromechanical constant depending upon the nature of the armatures windings (Ke) giving

us the equation of: N ∝ V/Keϕ.

One simple and easy way to control the speed of a motor is to regulate the amount of

voltage across its terminals and this can be achieved using “Pulse Width Modulation” or

PWM.



As its name suggests, pulse width modulation speed control works by driving the motor with

a series of “ON-OFF” pulses and varying the duty cycle, the fraction of time that the output

voltage is “ON” compared to when it is “OFF”, of the pulses while keeping the frequency

constant. The power applied to the motor can be controlled by varying the width of these

applied pulses and thereby varying the average DC voltage applied to the motors terminals.

By changing or modulating the timing of these pulses the speed of the motor can be

controlled, ie, the longer the pulse is “ON”, the faster the motor will rotate and likewise, the

shorter the pulse is “ON” the slower the motor will rotate. In other words, the wider the pulse

width, the more average voltage applied to the motor terminals, the stronger the magnetic

flux inside the armature windings and the faster the motor will rotate and this is shown

below.

Fig 4.1(b) - PWM

The use of pulse width modulation to control a motor has the advantage in that the power loss

in the switching transistor is small because the transistor is either fully “ON” or fully “OFF”.

As a result the switching transistor has a much reduced power dissipation giving it a linear

type of control which results in better speed stability.



4.2 MODELLING

The modelling of the PUV is done using the modelling software CATIA.

Fig 4.2(a) - Wooden box with motors and wheels

Fig 4.2(b) - Model of PUV



5. SYSTEM ASSEMBLY AND TESTING

5.1 System Assembly

1. The motors are fixed at the back end of the chassis facing opposite.

2. Motor shaft is fitted to the wheel for free rotation of wheels.

3. Castor wheel is fixed at the front end of the wooden chassis.

4. Batteries are connected in series and then are connected to the motors.

5. Handle is fitted in the front side of the chassis.

6. Mechanical brakes are attached to handle at top.

Fig 5.1(a) – CATIA Model of System Assembly



Fig 5.1(b) - PUV Assembly

5.2 Testing

After the system assembly, the system is tested for various properties.

1. Speed - The speed of the vehicle is found to be varying from 6-10 kmph. It is also

found that the speed of the vehicle depends on the weight of the rider.

2. Torque - Initially the vehicle requires some external torque, later the vehicle runs

smoothly.

3. Load - The vehicle carries an average load of 60kgs and on increasing the load the

speed of the vehicle may vary and higher torque is expected to be given at the

beginning.

4. Battery life - The vehicle runs with greater speeds when the battery is in fully charged

state. As the battery drains the speed of the vehicle decreases. And the battery life is

about 30 minutes.



5.3 Advantages

A clean, green, eco-friendly machine (zero emission).

Low operating costs: no need for gas and inexpensive battery charging (A complete

cycle charge will take eight to ten hours)

More work can be done by using the product VS walking.

Reduces fatigue caused by walking.

Can be developed further for higher end applications.

Simplicity in building.

5.4 Disadvantages

The distance travelled by the vehicle and the speeds may vary with weight of the

rider.

Slow, having a max speed varying between 6 to 10 kmph.

Ground clearance is less.

Does not exactly say how far the Segway will go with riders of different masses.

Unlike bicycles, a drained Segway cannot be pedaled home or a charge.



6. OPPORTUNITIES FOR TRANSPORTATION

IMPROVEMENT

People from rural surroundings are drawn to urban developments for better social and

economic opportunities. However when population density increases, the urban problems

associated with higher population densities are multifold. A few easily identifiable examples

include congested roads and sidewalks, increased pollution, and reduced open spaces. A Part

of these problems can be explained by the massive pavement and vast size of parking lots and

garages in the urban areas. SOVs certainly created large expenses for urban dwellers along

with the comfort and convenience it brought to its users. Therefore, this section will address

the potential opportunities created by introduction of Personal Utility Vehicle as a potential

transportation mode to improve efficiency of transportation systems.

6.1 Relieve Congestion

Cities and traffic have developed hand-in-hand since the earliest large human settlements.

The same forces that draw inhabitants to congregate in large urban areas also lead to

sometimes intolerable levels of traffic congestion on urban streets and thoroughfares.

Effective urban governance requires a careful balancing between the benefits of

agglomeration and the disadvantages of excessive congestion. Road traffic congestion poses a

challenge for all large and growing urban areas. Congestion involves queuing, slower speeds

and increased travel times, which impose costs on the economy and generate multiple

impacts on urban regions and their inhabitants. Congestion also has a range of indirect

impacts including the marginal environmental and resource impacts of congestion, impacts

on quality of life, stress, and safety as well as impacts on non-vehicular road space users such

as the users of sidewalks and road frontage properties.

On the other hand, the Personal Utility Vehicle only needs a lane width of 3

to 4 feet at the most. Taking into consideration of the lower speed of the vehicle, lanes can be

created for PUV’s and PUV’s could be used for short distance travelling which not only

reduces the traffic but also helps in cutting down pollution.



6.2 Reduce Gasoline Consumption and Air Pollution

Emission from the vehicles is the primary cause of air pollution throughout the nation. In

urban streets where vehicles are turned on and off a number of times, the pollution is more

compared to highways with higher speeds. This is because of cold start, a large amount of

pollutants are released when the automobiles are started and traveling at lower speeds than at

higher speeds. Carbon monoxide, hydrocarbons, nitrogen oxides and particulate matters are

major pollutants as a result of, improper fuel combustion and evaporation. Air toxics

produced by mobile sources, are suspected to cause serious health problems. Carbon dioxide,

methane and nitrous oxide are greenhouse gases contributing to global warming. It is

estimated that some 7 million premature deaths may be attributed to air pollution. India has

the highest death rate due to air pollution. India also has more deaths from asthma than any

other nation according to the World Health Organization. In December 2013 air pollution was

estimated to kill 500,000 people in China each year. There is a correlation between

pneumonia-related deaths and air pollution from motor vehicles.

Air pollution is estimated to reduce life expectancy by almost nine months across the

European Union. Causes of deaths include strokes, heart disease, COPD, lung cancer, and

lung infections.

The average trip speed on many Indian city roads is less than 20 kilometers per hour;

a 10 kilometer trip can take 30 minutes, or more. At such speeds, vehicles in India emit air

pollutants 4 to 8 times more than they would with less traffic congestion; Indian vehicles also

consume a lot more carbon footprint fuel per trip, than they would if the traffic congestion

was less. Emissions of particles and heavy metals increase over time because the growth of

the fleet and mileage outpaces the efforts to curb emissions.

Petrol is getting really ridiculously expensive these days and scientists say that if we don't

do something to reduce carbon emissions within 5 years, permanent climatic change would

have taken place. Gasoline is an extinguishable natural resource and its conservation is

essential. From the above paragraph it is clear that vehicles with low speed cause a lot of

emission. Instead of using bikes and cars for short trip purposes PUV can be used.



6.3 Increase Productivity

Personal Utility Vehicles increases the productivity in the sense more work can be done or

more load can be carried using the vehicle than by walk. It also saves a lot of time. PUVs can

be implemented in the fields where walking is mostly involved like

Postal Service

National Park Service

Street Patrolling

Distribution Centers etc.

Just like the Segway’s are already in use for the above purposes in the US, PUV

being cheaper than a Segway can also be used for the above purposes with some

technological improvisation,

6.4 Create Livable Communities

The planning and design of communities over the past decades precluded other options or

made them so inconvenient that few people walk, ride bike, or take public transportation. The

automobiles have negatively impacted even existing communities and older neighborhood

that had once been walkable and well served by mass transportation. Cars are required rather

than optional. While many people find convenient to drive cars to run mundane errands, but

often find themselves waiting in traffic jam. The automobile has its clear advantages in terms

of flexibility and comfort. In contrast, most transit systems have been operating on rigid

routes and schedules and limited geographic overages. For reasons of economic practicality,

some destinations simply can’t be served or serviced as frequently as others. A small number

of hardcore cyclists or roller-skaters may insist on using non-motorized modes. Limited or

non- existing dedicated non-motorized traffic lanes often make it unsafe for those riders.

If PUV is well accepted and adapted by the urban communities, congestion on

roads can be relieved greatly. Noise and air pollution can be reduced. The boundaries

between residential and commercial districts will fade, as people will start moving to multi-

use neighborhoods, leading to compact urban land use form.

6.5 As a Link in Intermodal Transportation

In the urban and sub urban areas with extensive mass transportation, accessibility from the

neighboring areas to the facility if often neglected. People who have to use transit for long

commute often have to drive from home to the transit station. Therefore the transit provider

usually will have to bear the construction and maintenance of parking lots or decks adjacent

to the stations.



PUV can be a link in intermodal transportation by substituting these auto trips. Trains and

buses should be able to accommodate these units on board for the convenience of the

passengers. Further PUV rental stations can be provided close to the transit so that people can

easily rent and drop off at convenient locations near their destination.



7. CHALLENGES TO TRANSPORTATION SYSTEMS

It is certain numerous opportunities for PUV can be pointed out. However, it is also clear that

a large number of obstacles are lying ahead before PUV gain wide acceptance by general

public and transportation professional. Therefore, it is also imperative to point out a few

challenges created by such a device.

7.1 The Cost

PUV is very cheap when compared to Segway which costs more than a car in India. The cost

involved in fabricating the vehicle and the cost of the components involved in it are as shown

in the table below

COMPONENT

QUANTITY

COST( in Rupees)

DC Motor 2 5000

Lead-Acid Batteries 2 1500

Braking System 1 220

Wooden Box 1 2500

Wheels 3 1200

DC Motor Speed Controller 1 1000

Handle 1 300

Miscellaneous 600

Total 12,320

Table 7.1 (a) Cost Involved

PUV doesn’t involve the use of gyroscope which helps in reducing the cost to a great extent

compared to that of a Segway. Exclusion of the gyroscopic unit also decreases the effort of

programming. So a common user can also repair or service the vehicle when needed without

the help of a technician.



7.2 Charging the batteries

Anything above 2.15 volts per cell will charge a lead acid battery; this is the voltage of the

basic chemistry. This also means than nothing below 2.15 volts per cell will do any charging

(12.9V for a 12V battery) However, most of the time a higher voltage is used because it

forces the charging reaction at a higher rate. Charging at the minimum voltage will take a

long time. As you increase the voltage to get faster charging, the voltage to avoid is the

gassing voltage, which limits how high the voltage can go before undesirable chemical

reactions take place. The typical charging voltage is between 2.15 volts per cell (12.9 volts

for a 6 cell battery) and 2.35 volts per cell (14.1 volts for a 6 cell battery). These voltages are

appropriate to apply to a fully charged battery without overcharging or damage. If the battery

is not fully charged you can use much higher voltages without damage because the charging

reaction takes precedence over any over-charge chemical reactions until the battery is fully

charged. This is why a battery charger can operate at 14.4 to 15 volts during the bulk-charge

phase of the charge cycle.

Since the batteries are placed inside the wooden box, in order to avoid removing the

batteries again and again for charging, batteries are connected in series and two wires are

extended outside the box to which the connectors of the charger can be connected and the

charged.



8. CONCLUSION

The technology behind PUV operation is new and innovative. The PUV can transport a

person and some cargo with less electricity consumption. The range and speed is appropriate

for a short travel trip. Transportation planners can look at this as a possible link in intermodal

system of transportation to promote mass transportation. Use of such vehicles is viewed as an

opportunity in congestion management of urban roadways. Environmental benefits are

expected to follow, when congested roads are relieved.

Challenges to transportation system by PUV are important, as this involves safety of

PUV users as well as pedestrians sharing the sidewalks. Sidewalks shared by different age

groups with various activity and reaction levels are at a greater risk. Segway, which is three

times faster than a walker, increases the conflicts between pedestrians and Segway users.

Increased number of community advocates and doctors are concerned about the safety issues.

The requirements such as pavement condition, type are not know for smooth operation of

PUV. How PUV technology can negotiate pot- holes and uneven surfaces are causes of

concern.

After examining the PUV technology and related uses of non-motorized transportations, it is

believed that a long term solution is to establish dedicated non-motorized lanes in urban

environment, which will promote more energy efficient and environment friendly travel

means.



9. APPLICATIONS AND FUTURE ENHANCEMENTS

It is used in industries to move from one place to other.

It can be used in law enforcement/security purposes.

Helps military staff in various roles to travel throughout large bases and vast facilities

quickly.

It can be used for Robotics Mobility Platform.

It can be used even by consumers for campus use.

PUV racing can be organized.

Elevates the visibility, responsiveness and productivity of critical staff.

By using high capacity motors it can carry more loads.

By using high capacity batteries large distance can be travelled.

Attaching a seat, the vehicle can be used by the physically disabled.



10. REFERENCES

1) Reinventing the wheel: A story of genius, innovation and grand ambition by Steven

Kemper.

2) Cervero.R, Walk and ride, factors influencing pedestrian access to transit journal of

public transportation.

3) Segway TM, Potential opportunities and challenges for human transportation systems

by Ron fang Liu, Rohini Parthasarathy.

4) Role of Segway Personal Transporter in emission reduction and energy efficiency by

John David Heinzmann and B. Michael Taylor, Segway Inc.

5) Design and fabrication of failsafe Segway transporter by M Thompson, J.Beula

Juliette Mary.

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