PROJECT REPORT ON SEGWAYPERSONAL TRANSPORTER
Submitted in partial fulfillment of the requirement for the award of the Degree Of Bachelor of Technology In Mechanical Engineering
Under the supervision of
Mr. SURENDER KUMAR (HOD MECHENICAL, SRCEM)
SUBMITTED BY: Vinod Ch Chauhan
(83053)
SHRI RAM COLLEGE OF ENGINEERING &MANAGEMAENT NH2, AURANGABAD (PALWAL).
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PROJECT TOPIC
SEGWAY -
PERSONAL TRANSPORTER
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PROJECT TOPIC
SEGWAY -
PERSONAL TRANSPORTER
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TABLE OF CONTENTS CONTENTS CANDIDATE DECLARATION CERTIFICATE ACKNOWLEDGEMENT CHAPTER 1…………………………… 1………………………………………………………… ………………………………… …… INTRODUCTION 1.1 1.1 OVER OVERVI VIEW EW 1.2 LIMITATIO LIMITATION N OF EXISTING EXISTING SYSTEM 1.3 ADVANT ADVANTAGE AGES S OF SEGWA SEGWAY Y 1.4 PROPOS PROPOSED ED SYSTEM SYSTEM 1.5 SCOPE SCOPE OF PROPO PROPOSED SED SYSTE SYSTEM M
7
CHAPTER 2…………………………… 2………………………………………………………… …………………………………… ……… 17
TECHNICAL DETAILS AND CONSTRUCTION DC GEARED MOTORS DC BATTERY FRAME STEERING SYSTEM (bearing assembly) A CHARGER
CHAPTER 3…………………………… 3………………………………………………………… ……………………………………… ………… 32
FURUTE SCOPE
REFRENCES…………………………………………………………………….34
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SHRI RAM COLLEGE OF ENGINEERING AND MANAGEMENT
(AFFILIATED TO MAHARSHI DAYANAND UNIVERSITY, ROHTAK) NH2, AURANGABAD (PALWAL), HARYANA.
CANDIDATE DECLARATION We the students of Bachelor Of Technology in Mechanical discipline, Session: 2008–12, Faculty of Engineering and Technology(SRCEM); hereby declare that the work presented in
this dissertation entitled “Segway- a Personal Transporter” is the outcome of our work, is bonafide and correct to the best of our knowledge and this work has been carried out taking care of engineering ethics. The work presented does not infringe any patented work and has not been submitted to any other university or anywhere else for the award of any degree or any professional diploma.
Chirag Gupta
(83009)
Mohit Chaudhary
(83026)
Pawan Malik
(83033)
Sachin Sharma
(83041)
Vinod Chauhan
(83053)
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CERTIFICATE
This is to certify that Mr. Vinod Chauhan student of B.Tech (Mechanical) from SHRI RAM COLLEGE OF ENGINEERING AND MANAGEMENT, Maharishi Dayanand University, Rohtak, have completed his project as per partial fulfillment of the requirement for the award of
the Degree of Bachelor Of Engineering (ME) of M.D. University in a record of bonafied work carried out under the guidance of Mr. Surender Kumar.
The project work entitled “SEGWAY- A PERSONAL TRANSPORTER ” embodies the original work done by him during his final year. He have successfully completed the project work up to our full satisfaction. We wish him success in his future life.
Mr. Surender Kumar
Dr. D.S. Sharma
Professor & Head of Department
(Dean, Mech.)
Mech. Department
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ACKNOWLEDGMENT
I would like to express my gratitude to Mr. Surender Kumar (Professor & HOD), Department Mechanical who was instrumental in the formulation of the project. I am very grateful to him for his encouragement and dedication in making this project a successful one.
I express my sincere regards to other staff of the college for their constant support and suggestions during the making of this project and for all the facilities provided.
I extend my thanks to all my friends and well wishers for their instant and efficient co-operation whose efforts resulted in the timely development of the project. I also thank the technical staff of the computer labs who provided the facilities required during development.
Finally I am indebted to my parents who have constantly provided us the opportunity and support to rise to higher levels in life.
Vinod Chauhan
(83053)
Semester – VIII B.Tech. (Mechanical) SRCEM,AURANGABAD(PALWAL)
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CHAPTER 1 INTRODUCTION
1.1 OVERVIEW A Segway is simply a light electric transportation device which is meant for personal transportation. It is a kind of vehicle which does not produce any kind of pollution because it runs on electricity. Basically it is a three wheel indoor scooter with two driving wheel and one supporting wheel. It consist of two DC geared motor and two Lead acid battery(12 volt 7 Ah). The Segway PT can take you places that a car or bicycle can't - including inside many stores, office buildings, businesses, airports, elevators, and trains. Although they're ideal for short jaunts, Segway PTs can travel as far as 8 km on a single battery charge, depending on terrain, payload, and riding style. The device is light and cheap and eco friendly at the same time. It can be used at places where other modes of transportation can’t be used such as inside malls, universities, golf courses and other big buildings. The device we have is a very initial step in this field as we have tried to develop an idea. We made this device by using components from toys. For example the wheel are taken from a children car, the accerlation device is also taken from the same. The basic components of this device are Two DC batteries (12v 7Ah) Two DC motors (12v 150 rpm) Simple steering mechanism (bearing) Basic structure A Charger
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1.2 LIMITATIONS OF EXISTING SYSTEM Before we talk about the limitations of the existing system, let us make it clear that through this device we are only aiming the travel of single person for short range of distances. So now, let us talk about the existing systems one by one. LIMITATIONS OF USING CAR IF A PERSON HAS TO TRAVEL SHORT RANGE OF DISTANCE. What if a person has to go to market. Will it be possible to take the car inside the market? - The answer in most of the cases will be NO due the congestion. He will not get any space to park his car, and soon he will regret his decision. - For a work that would have been completed in 20 minutes, it may take more than an hour if he uses car. Traffic Jams - This is another major problem - If there is a traffic jam and you are in car then for sure you are a part of jam. - You cannot turn your car at zero turning radius of carry in from there( which is simply possible with segway.
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POLLUTION This is other major problem which is increasing day by day Cars produce majorly 2 types of pollution i.e. air pollution, noise pollution. Air pollution - Air pollution occurs when the air contains gases, dust, fumes or odour in harmful amounts. That is, amounts which could be harmful to the health or comfort of humans and animals or which could cause damage to plants and materials. The substances that cause air pollution are called pollutants. Pollutants that are pumped into our atmosphere and directly pollute the air are called primary pollutants. Primary pollutant examples include carbon monoxide from car exhausts and sulfur dioxide from the combustion of coal Noise pollution - Noise pollution can become big environmental problem in some areas. It is not only stressful to many animals but can also cause the problems in predator/prey relation and detection, and even lead to different reproduction problems. More serious noise can even significantly reduce usable habitats for many sound-sensible animals, and can in the end even result in extinction of some species.
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COST The initial and travelling cost a as compared to this segway is much higher. It is not feasible to buy a car for a child who has to go for tution classes 3 kms from home. For him, the segway will be the best option.
LIMITATIONS OF USING BIKE/SCOOTER FOR SHORT RANGE DISTANCES The very first thing which comes in mind if one is giving a bike to his children is safety. The bikes can run at high speed and thus they are unsafe. Unfortunately if it meets an accident, it can result in serious injuries or even prove fatel. But the segway runs on very low speed so it can be controlled easily and chances of accident are very less. Other limitation of using bike/scooter is that to use these one should learn how to ride and they should be confident enough that that they can ride. Otherwise they should not ride bikes/scooter. It has been observed that for children and old age people it is not easy to ride bikes and scooters On the other hand, riding segway is very easy. One just has to get on it and press the accerlator. Weather it is children or old men, it is simple and safe to ride a segway.
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You will never fall from a segway like this.
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LIMITATION OF CYCLES •
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Bicycles are highly unstable except when chained to a lamp post They will not stand up on their own Due to their inherent instability, the direction of the rider is highly unpredictable to anyone in the vicinity They do not protect the rider in any way, neither from unsafe conditions nor from the weather They are not a satisfactory means for most people to cover long distances Their capacity for carrying things is strictly limited, innovativeness of far eastern populations using three-wheelers or mini-trailers notwithstanding Six bicycles take up about as much room as a car for six Bike owners tend to occupy pedestrian sidewalks Except for tandems, they are individualistic and hence unfriendly, and tandems are only suitable for people who like snuggling close. Even then the potential is very limited. Modern bikes are capable of speeds lethal to the rider and are operated at these lethal speeds more frequently than cars Cable actuated caliper brakes are not a robust mechanism for speed control, and bicycle tires wear out quickly Anyone who has tried to cross the street at quitting time in an eastern city where bicycles are the norm will know that it is like trying to cross a twelve-lane highway – next to impossible Modern bikes tend to be worse than earlier models because they don't have mudguards and so make the back of the rider unconscionably mucky, to say nothing of anyone who happens to stand too close They require a lot of personal effort to operate resulting in the operatives giving the impression of being superior and distant when they are really sweaty and uncomfortable
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1.3 ADVANTAGES OF SEGWAY 1. Segway is fun Fun is important to the adoption of new technology. Never underestimate its importance. People are more likely to find uses for things they like. 2. The Segway lets you be social The Segway allows you to be much more sociable with others while moving than many other forms of personal transportation. When two people ride bicycles or motor scooters near each other, there is always the likely danger of handlebars touching and a resulting crash. The Segway has no such problems it seems (while riding you can push each other with no worse effect than when walking). The Segway takes up about as much area as a person walking, so you can travel in groups much as you would with walking, with all the social advantages. 3. The Segway is a tool to improved cities The chaotic flow of not-too-long city blocks is crucial. Automobiles, because of their need for streets, ramps, parking, etc., break up this crucial world. Enter the Segway. You can envision how it enables all sorts of city designs that would better serve our needs. 4. The Segway PT can take you places that a car or bicycle can't - including inside many stores, office buildings, businesses, airports, elevators, and trains 5. A wide range of people can successfully use the Segway, including people for whom walking a distance is a challenge.
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1.4PROPOSED SYSTEM We have proposed a personal transporter and named it as Segway. This Segway has two DC motors which are connected to DC batteries through a circuit. It accerelates through a paddle which is placed under the foot of the rider, so he can press it and move the Segway whenever he wants. The segway is steered by simple steering system. The handle bar of the Segway is directly attached to front wheel through a bearing. So the rider can ride it in any direction while riding. Through this simple steering arrangement, this Segway can be steered in a turning radius of zero. The DC motors and batteries are of 12v each.
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Dimesnsions of the system are:Overall length -
60 cm
Overall width -
50 cm
Overall height -
117 cm
Wheelbase
-
42 cm
Wheel track -
42 cm
Ground clearance -
5 cm
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Rear wheel dia. -
23 cm
Front wheel dia. -
6.5 cm
Weight of device -
14.5 kgs
Battery
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12v 7 Ah
Motor
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12v 150 rpm
1.5_SCOPE OF PROPOSED SYSTEM A two wheeled, self-balancing transportation machine is designed and developed to change the scope of personal transportation. Segway is also on the leading edge of green forms of transportation. The Segway PT can take you places that a car or bicycle can't - including inside many stores, office buildings, businesses, airports, elevators, and trains. Although they're ideal for short jaunts, Segway PTs can travel as far as 8 km on a single battery charge, depending on terrain, payload, and riding style. The device is light and cheap and eco friendly at the same time. It can be used at places where other modes of transportation can’t be used such as inside malls, universities, golf courses and other big buildings.
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There is great scope for this device due to the following reasons :-
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Limataions of bicycles, cars, bikes in several places as discussed earlier.
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Segway is fun Fun is important to the adoption of new technology. Never underestimate its importance. People are more likely to find uses for things they like.
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The Segway lets you be social The Segway allows you to be much more sociable with others while moving than many other forms of personal transportation. When two people ride bicycles or motor scooters near each other, there is always the likely danger of handlebars touching and a resulting crash. The Segway has no such problems it seems (while riding you can push each other with no worse effect than when walking). The Segway takes up about as much area as a person walking, so you can travel in groups much as you would with walking, with all the social advantages.
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The Segway is a tool to improved cities The chaotic flow of not-too-long city blocks is crucial. Automobiles, because of their need for streets, ramps, parking, etc., break up this crucial world. Enter the Segway. You can envision how it enables all sorts of city designs that would better serve our needs.
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The Segway PT can take you places that a car or bicycle can't - including inside many stores, office buildings, businesses, airports, elevators, and trains
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A wide range of people can successfully use the Segway, including people for whom walking a distance is a challenge.
CHAPTER – 2 TECHNICAL DETAILS & CONSTRUCTION. The Segway is transportation device meant for personal transportation. It takes power from DC batteries which can be charged again and again. So in this way it does not produces any pollution and its cost of running is also very cheap. Now, to study the technology used in this device, lets us take a look at the components it is made up of. This device is made by assembling the following components DC GEARED MOTORS (2, 12v each) DC BATTERY (2, 12v each)
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ACCERLATION PEDDLE FRAME STEERING SYSTEM (bearing assembly) A CHARGER
DC GEARED MOTOR
DC GEARED MOTOR
A gear motor is a type of electrical motor like all electrical motor. It uses the magnetism induced by an electrical current to rotate to a rotor that is connected to a shaft. The energy transferred from the rotor to the shaft is used to power a connecting device in a gear motor. The energy output used to turn a series of gears in an integrated train. It result in greatly increase the amount of torque the motor is capable of producing while simultaneously slowing down the motor output speed.
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A DC motor is an electric motor that runs on direct current (DC) electricity. DC motors were used to run machinery, often eliminating the need for a local steam engine or internal combustion engine. DC motors can operate directly from rechargeable batteries, providing the motive power for the first electric vehicles. Today DC motors are still found in applications as small as toys and disk drives, or in large sizes to operate steel rolling mills and paper machines. Modern DC motors are nearly always operated in conjunction with power electronic devices. Two important performance parameters of DC motors are the motor constants, K v and K m. Brush The brushed DC electric motor generates torque directly from DC power supplied to the motor by using internal commutation, stationary magnets (permanent or electromagnets), and rotating electrical magnets. Like all electric motors or generators, torque is produced by the principle of Lorentz force, which states that any current-carrying conductor placed within an external magnetic field experiences a torque or force known as Lorentz force. Advantages of a brushed DC motor include low initial cost, high reliability, and simple control of motor speed. Disadvantages are high maintenance and low life-span for high intensity uses. Maintenance involves regularly replacing the brushes and springs which carry the electric current, as well as cleaning or replacing the commuter. These components are necessary for transferring electrical power from outside the motor to the spinning wire windings of the rotor inside the motor.
Brushless Brushless DC motors use a rotating permanent magnet or soft magnetic core in the rotor, and stationary electrical magnets on the motor housing. A motor controller converts DC to AC. This design is simpler than that of brushed motors because it eliminates the complication of transferring power from outside the motor to the spinning rotor. Advantages of brushless motors include long life span, little or no maintenance, and high efficiency. Disadvantages include high initial cost, and more complicated motor speed controllers. Some such brushless motors are sometimes referred to as "synchronous motors" although they have no external power supply to be synchronized with, as would be the case with normal AC synchronous motors.
Un-commutated
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Other types of DC motors require no commutation. Homo-polar motor– A homopolar motor has a magnetic field along the axis of rotation and an electric current that at some point is not parallel to the magnetic field. The name homopolar refers to the absence of polarity change. Homopolar motors necessarily have a single-turn coil, which limits them to very low voltages. This has restricted the practical application of this type o f motor. •
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Ball bearing motor – A ball bearing motor is an unusual electric motor that consists of two ball bearing-type bearings, with the inner races mounted on a common conductive shaft, and the outer races connected to a high current, low voltage power supply. An alternative construction fits the outer races inside a metal tube, while the inner races are mounted on a shaft with a non-conductive section (e.g. two sleeves on an insulating rod). This method has the advantage that the tube will act as a flywheel. The direction of rotation is determined by the initial spin which is usually required to get it going.
Connection types There are three types of connections used for DC electric motors: series, shunt and compound. These types of connections configure how the motor's field and armature windings are connected together. The type of connection is significant because it determines the characteristics of the motor and is selected for speed/torque requirements of the load. Series connection A series DC motor connects the armature and field windings in series with a common D.C. power source. This motor has poor speed regulation since its speed varies approximately inversely to load. However, a series DC motor has very high starting torque and is commonly used for starting high inertia loads, such as trains, elevators or hoists. With no mechanical load on the series motor, the current is low, the magnetic field produced by the field winding is weak, and so the armature must turn faster to produce sufficient counterEMF to balance the supply voltage (and internal voltage drops). For some types of motor, the speed may be higher than can be safely sustained by the motor. In a no-load condition, the motor may increase its speed until the motor mechanically destroys itself. This is called a runaway condition. The speed/torque characteristic is also useful in applications such as dragline excavators, where the digging tool moves rapidly when unloaded but slowly when carrying a heavy load.
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Series motors called "universal motors" can be used on alternating current. Since the armature voltage and the field direction reverse at (substantially) the same time, torque continues to be produced in the same direction. Since the speed is not related to the line frequency, universal motors can develop higher-than-synchronous speeds, making them lighter than induction motors of the same rated mechanical output. This is a valuable characteristic for hand-held power tools. Universal motors for commercial power frequency are usually small, not more than about 1 kW output. However, much larger universal motors were used, fed by special low-frequency traction power networks to avoid problems with commutation under heavy and varying loads. Shunt connection A shunt DC motor connects the armature and field windings in parallel or shunt with a common D.C. power source. This type of motor has good speed regulation even as the load varies, but does not have as high of starting torque as a series DC motor. It is typically used for industrial, adjustable speed applications, such as machine tools, winding/unwinding machines and tensioners. Compound connection A compound DC motor connects the armature and fields windings in a shunt and a series combination to give it characteristics of both a shunt and a series DC motor. This motor is used when both a high starting torque and good speed regulation is needed. The motor can be connected in two arrangements: cumulatively or differentially. Cumulative compound motors connect the series field to aid the shunt field, which provides higher starting torque but less speed regulation. Differential compound DC motors have good speed regulation and are typically operated at constant speed. They are commonly used in elevators, air compressors, conveyors and punch presses.
DC BATTERY We have used to lead acid batteries in this system. These batteries are re-chargable.
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LEAD ACID BATTERY Lead–acid batteries, invented in 1859 by French physicist Gaston Planté, are the oldest type of rechargeable battery. Despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, their ability to supply high surge currents means that the cells maintain a relatively large power-to-weight ratio. These features, a long with their low cost, make them attractive for use in motor vehicles to provide the high current required by automobile starter motors.
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Fully Discharged: Two identical lead sulfate plates In the discharged state both the positive and negative plates become lead(II) sulfate (PbSO4) and the electrolyte loses much of its dissolved sulfuric acid and becomes primarily water. The discharge process is driven by the conduction of electrons from the positive plate back into the cell at the negative plate. Negative plate reaction: Pb(s) + HSO− 4(aq) → PbSO4(s) + H+(aq) + 2e Positive plate reaction: PbO2(s) + HSO− 4(aq) + 3H+(aq) + 2e → PbSO4(s) + 2H2O(l)
Charging
Fully Charged: Lead and Lead Oxide plates In the charged state, each cell contains negative plates of elemental lead (Pb) and positive plates of lead(IV) oxide (PbO2) in an electrolyte of approximately 33.5% v/v (4.2 Molar) sulfuric acid (H2SO4). The charging process is driven by the forcible removal of electrons from the negative plate and the forcible introduction of them to the positive plate. Negative plate reaction: PbSO4(s) + H+(aq) + 2e → Pb(s) + HSO− 4(aq) Positive plate reaction: PbSO4(s) + 2H2O(l) → PbO2(s) + HSO− 4(aq) + 3H+(aq) + 2E
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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 water, as the battery discharges and the concentration of sulfuric acid decreases, the electrolyte is more likely to freeze during winter weather. Construction Plates The lead–acid cell can be demonstrated using sheet lead plates for the two electrodes. However such a construction produces only around one ampere for roughly postcard sized plates, and for only a few minutes. Gaston Planté found a way to provide a much larger effective surface area. In Planté's design, the positive and negative plates were formed of two spirals of lead foil, separated with a sheet of cloth and coiled up. The cells initially had low capacity, so a slow process of "forming" was required to corrode the lead foils, creating lead dioxide on the plates and roughening them to increase surface area. Initially this process used electricity from primary batteries; when generators became available after 1870, the cost of production of batteries greatly declined. Planté plates are still used in some stationary applications, where the plates are mechanically grooved to increase their surface area. Faure pasted-plate construction is typical of automotive batteries. Each plate co nsists of a rectangular lead grid alloyed with antimony or calcium to improve the mechanical characteristics. The holes of the grid are filled with a paste of red lead and 33% dilute sulfuric acid. (Different manufacturers vary the mixture). The paste is pressed into the holes in the grid which are slightly tapered on both sides to better retain the paste. This porous paste allows the acid to react with the lead inside the plate, increasing the surface area many fold. Once dry, the plates are stacked with suitable separators and inserted in the battery container. An odd number of plates is usually used, with one more negative plate than positive. Each alternate plate is connected. The positive plates are the chocolate brown color of lead dioxide, and the negative are the slate gray of "spongy" lead at the time of manufacture. In this charged state the plates are called 'formed'. One of the problems with the plates is that the plates increase in size as the active material absorbs sulfate from the acid during discharge, and decrease as they give up the sulfate during charging. This causes the plates to gradually shed the paste. It is important that there is room underneath the plates to catch this shed material. If it reaches the plates, the cell short-circuits.
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The paste contains carbon black, blanc fixe (barium sulfate) and lignosulfonate. The blanc fixe acts as a seed crystal for the lead–to–lead sulfate reaction. The blanc fixe must be fully dispersed in the paste in order for it to be effective. The lignosulfonate prevents the negative plate from forming a solid mass during the discharge cycle, instead enabling the formation of long needle–like crystals. The long crystals have more surface area and are easily converted back to the original state on charging. Carbon black counteracts the effect of inhibiting formation caused by the lignosulfonates. Sulfonated naphthalene conden sate dispersant is a more effective expander than lignosulfonate and speeds up formation. This dispersant improves dispersion of barium sulfate in the paste, reduces hydroset time, produces a more breakage-resistant plate, reduces fine lead particles and thereby improves handling and pasting characteristics. It extends battery life by increasing end–of–charge voltage. Sulfonated naphthalene requires about one-third to one-half the amount of lignosulfonate and is stable to higher temperatures. Practical cells are usually not made with pure lead but have small amounts of antimony, tin, calcium or selenium alloyed in the plate material to add strength and simplify manufacture. The alloying element has a great effect on the life of the batteries, with calcium-alloyed plates preferred over antimony for longer life and less water consumption on each charge/discharge cycle. About 60% of the weight of an automotive-type lead–acid battery rated around 60 Ah (8.7 kg of a 14.5 kg battery) is lead or internal parts made of lead; the balance is electrolyte, separators, and the case. Separators Separators between the positive and negative plates prevent short-circuit through physical contact, mostly through dendrites (‘treeing’), but also through shedding of the active material. Separators obstruct the flow of ions between the plates and increase the internal resistance of the cell. Wood, rubber, glass fiber mat, cellulose, and PVC or polyethylene plastic have been used to make separators. Wood was the original choice, but deteriorated in the acid electrolyte. Rubber separators were stable in the battery acid. An effective separator must possess a number of mechanical properties; such as permeability, porosity, pore size distribution, specific surface area, mechanical design and strength, electrical resistance, ionic conductivity, and chemical compatibility with the electrolyte. In service, the separator must have good resistance to acid and oxidation. The area of the separator must be a little larger than the area of the plates to prevent material shorting between the plates. The separators must remain stable over the battery's operating temperature range.
Applications
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Most of the world's lead–acid batteries are automobile starting, lighting and ignition (SLI) batteries, with an estimated 320 million units shipped in 1999. In 1992 about 3 million tons of lead were used in the manufacture of batteries. Wet cell stand-by (stationary) batteries designed for deep discharge are commonly used in large backup power supplies for telephone and computer centers, grid energy storage, and off-grid household electric power systems. Lead–acid batteries are used in emergency lighting in case of power failure. Traction (propulsion) batteries are used for in golf carts and other battery electric vehicles. Large lead–acid batteries are also used to power the electric motors in diesel-electric (conventional) submarines and are used on nuclear submarines as well. Valve-regulated lead acid batteries cannot spill their electrolyte. They are used in back-up power supplies for alarm and smaller computer systems (particularly in uninterruptible power supplies) and for electric scooters, electric wheelchairs, electrified bicycles, marine applications, battery electric vehicles or micro hybrid vehicles, and motorcycles. Lead–acid batteries were used to supply the filament (heater) voltage, with 2 V common in early vacuum tube (valve) radio receivers.
FRAME
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The frame of this Segway has been made by using a thin steel plate, a wooden piece of ply, iron rod and some nut and bolts.
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The iron rod is attached to the steering bearing at the lower end and at the upper end is given as the shape of handle bar. The length of this iron rod is 91 cms (above the bearing to handle). The floor of this Segway is made by thin steel plate whose dimensions are 38*32 cm(L*B). Further, a wooden ply piece is bolted to the steel plate in order to improve the strength and quality.
We have used nut and bolts to attach the steel plate and the wooden ply together. Electric arc welding has been used to join the frame together. Arc welding is a type of welding that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct (DC) or alternating (AC) current, and consumable or non-consumable electrodes. The welding region is usually protected by some type of shielding gas, vapor, and/or slag. 1 e g a P
STEERING SYSTEM The steering system of this device has been made very basic and simple. We have taken front wheel of diameter 6.5 cm and it is attached to a bearing which is fixed on the frame of the device. Actually, the housing of the bearing is welded to the frame of the device, while its shaft is connected to the iron bar which goes straight to handle of the device. As the rider moves the handle linearly, the front wheel moves respectively and thus the Segway turns.
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This steering system works along with the bearing, so to understand the detail working of this steering let us simply take a look at the bearing turning process. A bearing is any of various machine elements that constrain the relative motion between two or more parts to only the desired type of motion. This is typically to allow and promote free rotation around a fixed axis or free linear movement; it may also be to prevent any motion, such as by controlling the vectors of normal forces. Bearings may be classified broadly according to the motions they allow and according to their principle of operation, as well as by the directions of applied loads they can handle. By far, the most common bearing is the plain bearing, a bearing which uses surfaces in rubbing contact, often with a lubricant such as oil or graphite. A plain bearing may or may not be a discrete device. It may be nothing more than the bearing surface of a hole with a shaft passing through it, or of a planar surface that bears another (in these cases, not a discrete device); or it may be a layer of bearing metal either fused to the substrate (semidiscrete) or in the form of a separable sleeve (discrete). With suitable lubrication, plain bearings often give entirely acceptable accuracy, life, and friction at minimal cost. Therefore, they are very widely used. However, there are many applications where a more suitable bearing can improve efficiency, accuracy, service intervals, reliability, speed of operation, size, weight, and costs of purchasing and operating machinery. Thus, there are many types of bearings, with varying shape, material, lubrication, principle of operation, and so on.
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CHARGER As the lead acid batteries are re-chargeable, we have also provided a charger along with the device. We have used two lead acid batteries (12v 7Ah each). The charger is of 26 v and 26 Ah and it will charger both of the batteries in 3 hours connected together.
Lead acid charging uses a voltage-based algorithm that is similar to lithium-ion. The charge time of this sealed lead acid battery is 3hours. With higher charge currents and multi-stage charge methods, the charge time can be reduced. However, the topping charge may not be complete. Lead acid is sluggish and cannot be charged as quickly as other battery systems. Lead acid batteries should be charged in three stages, which are [1] constant-current charge, [2] topping charge and [3] float charge. The constant-current chargeapplies the bulk of the charge and takes up roughly half of the required charge time; the topping charge continues at a lower charge current and provides saturation, and the float charge compensates for the loss caused by self-discharge. Figure illustrates these three stages.
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Figure 4-4: Charge stages of a lead acid battery The battery is fully charged when the current drops to a pre-determined level or levels out in stage 2. The float voltage must be reduced at full charge.
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CHAPTER – 3 FUTURE SCOPE
We have represented a very basic idea in the field of segway, but there is great future scope for it. With new improvements and technology, it can be proved commercially successful in near future The use of computers and sensors can enhance the performance of this device upto a great extend. Computers and motors in the base of the device, can be used, to keep the Segway PT upright when powered on with balancing enabled. A user can command the Segway to go forward by shifting their weight forward on the platform, and backward by shifting their weight backward. The Segway notices, as it balances, the change in its center of mass, and first establishes and then maintains a corresponding speed, forward o r backward. Gyroscopic sensors and fluid-based leveling sensors are used to detect the shift of weight. To turn, the user can manipulate a control on the handlebar left or right. We hope that the Segway can go up to 12.5 miles per hour (20.1 km/h) by using better motor and sensors.
IN NEAR FUTURE….. The dynamics of the Segway will be similar to a classic control problem, the inverted pendulum. The Segway PT ( PT is an initialism for personal transporter while the old suffix HT was an initialism for human transporter ) has electric motors powered by Valence Technology phosphate-based lithium-ion batteries which can be charged from household current. It will balance with the help of dual computers running proprietary software, two tilt sensors, and some gyroscopic sensors. The servo drive motors rotate the wheels forwards or backwards as needed for balance or propulsion. The rider will be able to control forward and backward movement by leaning the Segway relative to the combined center of mass of the rider and Segway, by holding the control bar closer to or farther from their body. The Segway will be able to detect the change in the balance point, and adjust the speed at which it is balancing the rider accordingly. Newer models will be able to enable the use of tilting the handle bar to steer. 1 e g a P
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