During last two decades, Robotics applications have received increasing attention in manufacturing industries and transportation systems. In industries many applications have been proposed, however most of them are still under investigation or in the development stage. Most of the researches are based on the non-renewable sources to control the robot. Since non-renewable sources are in scarce today, as a different approach the project is based on control of robot using renewable sources, the renewable source is employed in this paper is solar energy.
Since solar energy is the most available energy at all times. This project MICRO CONTROLLER BASED AUTOMATED SOLAR VEHICLE is done for the transportation of loads in industries by employing mankind and also automatic process.
INTRODUCTION
1.1 GENERAL
Robots have been increasingly used to develop more efficient schemes for the industrial operation, control and management. The applications are mainly for controllers; however there are also exist many other areas such as prediction, diagnosis, optimization and planning. In this paper how the vehicle is operated by mankind using solar energy is clearly explained and how the solar vehicle is operate automatically employing micro controller is also explained in clear cut manner. This paper reveals the usage of solar energy and robot for industrial purpose.
The mechanical design of the vehicle involves two front wheels and two back wheels. The driving force for this vehicle is obtained from the motor rotates the back wheel moves, which in turn drives the vehicle. The whole mechanical construction of our solar vehicle is made in plastic in order to reduce the weight.
BLOCK DIAGRAM
2.1 SOLAR PANELThe above block diagram fig (2.1) illustrates the blocks of our project. At first solar panel. A number of solar cell modules connected together to form an assembly called a solar panel. In this, a number of solar cells are connected in series or parallel to obtain a desired voltage and current rating respectively.
2.2 CHARGE CONTROLLER
The solar panel gives a DC output, this DC output is not always a constant, there is a variation in this output and cannot be given to the battery as it may reduce the life of the battery. So in order to get constant DC output and also to avoid the reverse flow of current to the panel the charge controller is connected. It also acts as a blocking diode which lets the array generated power flow only towards the battery or grid. With out the blocking diode the battery would discharge back through the solar array during times of no insulation.
2.3 MICRO CONTROLLER
Micro controller is an electronic chip that incorporates the software written for the specific task. The microprocessor, which has been combined with Read only Memory (ROM), Read Access Memory (RAM) and input, output facilities on a single chip, is commonly referred to as micro controller. The highest performance of Real Time Control (RTC) application have employed 16 and 32 bit microns together with interrupt handles chip, programmable timer chip, read access memory and read only memory to achieve what can now be achieved in a single of the art micro controller chip. In our project micro controller used for given the time delay and change the current direction of the DC motor.
2.4 ENERGY CONVERTER
The energy converter device, which we are using in our project, is DC series motor. The motor has high starting torque. The weight of the vehicle acts as load to the motor initially. So this leads to necessity of high starting torque which replaced other DC motors from DC series motor. Cutting of the supply unit does the braking system for the DC motor manually.
2.5 STORAGE DEVICE
Batteries are used for the storage of excess solar energy converted into electrical energy. To be economically attractive the storage of solar electrical requires a battery with a particular combination of properties such as low cost, long life, high reliability, high efficiency, low discharge, and minimum maintenance. In our project uses Lead-Acid battery for the storage of the electrical power. This type has longer life and higher efficiency in power systems.
CHAPTER 3
SOLAR PANEL
3.1 GENERAL
A number of solar cell modules connected together to form an assembly called as a solar panel. In this a number of solar cells are connected in series or parallel to obtain a desired voltage and current rating. When sunlight is incident on solar panel the solar radiation is converted to D.C electricity without thermodynamic form. This works on the principle of photovoltaic effect. This project incorporates the use of a flat plate solar collector for receiving the solar radiation. Photovoltaic conversion has been receiving greater priority nowadays since they are not dependent on fossil fuels and are non-polluting.
3.2 SOLAR COLLECTORS
A solar collector is a device designed to absorb incident solar radiation and to transfer the energy to a fluid passing in contact with it. Utilization of solar energy requires solar collectors. There are two general types.
Ø Flat plate collector
Ø Focusing collector
Solar collectors may be classified according to their collecting characteristics, the way in which they are mounted and the type of transfer fluid they employ.
3.3 CHARACTERISTICS OF SOLAR COLLECTORS
3.3.1 Collecting Characteristics
A non-concentrating or ‘flat-plate’ collector is one in which the absorbing surface for solar radiation is essentially flat with no means for concentrating the incoming solar radiation. A concentrating or ‘focusing collector is one which usually contains reflectors or employs other optical means to concentrate the energy falling on the aperture on to a heat exchanger of surface area smaller than the aperture.
3.3.2 Mounting
A collector can be mounted to remain stationary, be adjustable as to tilt angle to follow the change in solar declination or be designed to track the sun. Employing either an equatorial mounting or an altazimuth mounting, for the purpose of increasing the absorption of the daily solar irradiation does tracking.
3.3.3 Types of fluid
A collector will usually use either a liquid or a gas as the transfer fluid. The most common liquids are water or a water-ethylene glycol solution. The most common gas is air.
3.4 FLAT-PLATE COLLECTORS
Flat plate solar collector is used in out project. It may be divided into two main Classifications based on the type of heat transfer fluid used.
1) Liquid heating collectors
2) Air or Gas heating collectors
3.4.1 Liquid Heating Collector
It basically consists of a flat surface with high absorption for solar radiation, called the absorbing surface. Typically a metal plate, usually of copper, steel, or a aluminium material with tubing of copper in thermal contact with the plates, are the most commonly used materials. The absorber plate is usually made from a metal sheet 1 to 2 mm in thickness, while the tubes, which are also of metal, range in diameter from 1 to 1.5cm. They are soldered, brazed or clamped to the bottom of the absorber plate with the pitch ranging from 5 to 15cm. In some designs, the tubes are also in line and integral with the absorber plate.
3.4.2 Air Collector
Flat plate collector where an air stream is heated by the backside of the collector plate. Fins attached to the plate increase the contact surface. The backside of the collector is heavily insulated with mineral wool or some other material. The most favourable orientation, of a collector, for heating only, is facing due south at an inclination angle to the horizontal equal to the latitude plus 15 degree.
3.5 ADVANTAGES OF FLAT PLATE COLLECTORS
· No complicated tracking mechanisms are involved.
· Construction is relatively simple.
· They are easily manufactured.
3.6 FOCUSING COLLECTORS
Focusing collector is a device to collect solar energy with high intensity of solar radiation on the energy-absorbing surface. Such collectors use optical system in the form of reflectors or refractors
3.7 ADVANTAGES OF FOCUSING COLLECTORS
· Reflecting surfaces requires less material.
· The insolation intensity is greater than flat plate collector.
· The initial installation cost of the system can be regained.
· Little or no antifreeze is required.
3.8 DISADVANTAGES OF FOCUSING COLLECTORS
· Out of the beam and diffuse solar radiation, components, only beam component is collected in case of focusing collectors because diffuse component cannot be reflected and is thus lost.
· Costly orienting systems have to be used to track the sun.
· Additional requirements of maintenance particularly to retain the quality of reflecting surface against dirt, weather, oxidation etc.
· Additional optical losses.
· Non-uniform flux on the absorber whereas flux in flat-plate collectors is uniform.
3.9 ESTIMATION OF DIRECT AND DIFFUSED RADIATION
The solar radiation is not always constant. It varies in different columns. According to the clouds we have different solar radiation that is
Ø During days with no clouds
Ø During cloudy days
3.9.1 During Days with No Clouds
When solar radiation enters the atmosphere some of it is absorbed, some is scattered and the rest penetrates the atmosphere. The penetrated rays are called direct radiation while that part of the scattered rays that reach the earth is called diffused radiation. The term diffused radiation means the relatively short wavelength radiation coming from the sky and not from atmospheric thermal radiation, which has much longer wavelengths than the scattered sky radiation, which has much longer wavelengths than the scattered sky radiation. Both types of radiation are affected by the atmospheric ozone content, water vapour content, dust content and the solar altitude and other radiation depleting agents also affect them. Liu and Jordon found in 1960, that in dust free localities and with minimum water vapour content in the atmosphere the diffuse and the direct radiation varied with each other in a linear way and both of them are functions of the air mass. He have suggested the following formulae, for cloudless and dust free localities.
td =0.2710 –0.2939tD
td =0.3840 –0.4160tT
Where td Is the transmission coefficient for diffuse radiation
tD Is the ratio of direct radiation to extra terrestrial intensity of solar Radiation.
3.9.2 During cloudy days
Sharma and Pal proposed the following formula for the calculation of direct and diffuse solar radiation on horizontal surface
Where
H total solar radiation
a Solar altitude in degrees
CN clearance numbers
0.0 to 0.5 for cloudy and overcast atmosphere
0.5 to 0.7 for hazy atmosphere
0.7 to 1.1 for clear atmosphere
1.1 to 1.3 for very clear atmosphere
K & A are constants. It’s values are shown in table (3.1).
Measurements of solar radiation are important because of the increasing number of solar heating and cooling applications, and the need for accurate solar irradiation data to predict performance. Solar radiation data are available in several forms and should include the following in formations.
Ø Whether they are instantaneous measurement or values integrated over some period of time (usually hour or day)
Ø The time or time period of the measurements
Ø Whether the measurements are of beam, diffuse or total radiation, and the instrument used
Ø The receiving surface orientation (usually horizontal, it may be inclined at a fixed slope or normal)
Ø If averaged, the period over which they are averaged (e.g., monthly average of daily radiation)
The principal characteristics of the sun are
Ø Mass M= (1.991 + 0.002) * 1030 kg
Ø Radius R= (6.960 + 0.001) * 108 m
Ø Average density r= 1.410 + 0.002 g/cm3
Ø Temperature T= 5762 + 50o K
Ø Average solar energy = 5 KW/m2 per day
3.11 OPERATION OF SOLAR CELL
A solar cell consists of a semiconductor device that takes advantage of the Photovoltaic effect. The Photovoltaic effect can be described easily for p-n junction in a semiconductor. In an intrinsic semiconductor such as silicon, each one of the four valence electrons of the material atom is tied in a chemical bond, and there are no free electrons at absolute zero. If a piece of such a material is doped on one side by a five valence electron material, such as arsenic of phosphorus, there will be an excess of electrons in that side, becoming an n-type semi-conductor. The excess electrons will be practically free to move in the semi conductor lattice.
3.10 SOLAR RADIATION DATA
Measurements of solar radiation are important because of the increasing number of solar heating and cooling applications, and the need for accurate solar irradiation data to predict performance. Solar radiation data are available in several forms and should include the following in formations.
Ø Whether they are instantaneous measurement or values integrated over some period of time (usually hour or day)
Ø The time or time period of the measurements
Ø Whether the measurements are of beam, diffuse or total radiation, and the instrument used
Ø The receiving surface orientation (usually horizontal, it may be inclined at a fixed slope or normal)
Ø If averaged, the period over which they are averaged (e.g., monthly average of daily radiation)
The principal characteristics of the sun are
Ø Mass M= (1.991 + 0.002) * 1030 kg
Ø Radius R= (6.960 + 0.001) * 108 m
Ø Average density r= 1.410 + 0.002 g/cm3
Ø Temperature T= 5762 + 50o K
Ø Average solar energy = 5 KW/m2 per day
3.11 OPERATION OF SOLAR CELL
A solar cell consists of a semiconductor device that takes advantage of the Photovoltaic effect. The Photovoltaic effect can be described easily for p-n junction in a semiconductor. In an intrinsic semiconductor such as silicon, each one of the four valence electrons of the material atom is tied in a chemical bond, and there are no free electrons at absolute zero. If a piece of such a material is doped on one side by a five valence electron material, such as arsenic of phosphorus, there will be an excess of electrons in that side, becoming an n-type semi-conductor. The excess electrons will be practically free to move in the semi conductor lattice.
When the other side of the same piece is dopped by a three valence electron material, such as boron, there will be deficiency of electrons leading to a p-type semiconductor this is shown in fig (3.1). This deficiency is expressed in terms of excess of holes free to move in the lattice. Such a piece of semi conductor, with one side of the p type and other of the n-type is called a p-n junction. In this junction after the photons are absorbed, the free electrons of the n side will tend to flow to the p-side, and the holes of the p-side will tend to flow to the n-region to compensate for their respective deficiencies. This diffusion will create an electric field Ef from the n-region to the p-region. This field will increase until it reaches equilibrium for Ve, the sum of the diffusion potentials for holes and electrons.
If electrical contacts are made with the two semiconductor materials and the contacts are connected through an external electrical conductor, the free electrons will flow from the n-type material through the conductor to the p-type material. Here the free electrons will enter the holes and become bound electrons: thus both free electrons and holes will be removed. The flow of electrons through the external conductor constitutes an electric current, which will continue as long as more free electrons and holes are being formed by the solar radiation. This is the basis of Photovoltaic conversion that is, the conversion of solar energy into electrical energy. The combination of n-type and p-type semiconductors thus constitutes a Photo voltaic cell or solar cell. All such cells generate direct current, which can be converted into alternating current if desired.
3.12 APPLICATION OF SOLAR SYSTEM
· Water pumping
· Radio beacons for ship navigations at ports
· Community radio and television sets
· Cathodic protection of oil pipe lines
· Weather monitoring
· Railway signaling equipment
· Battery charging
· Street lighting
· Battery car
3.13 ADVANTAGES OF PHOTO VOLTAIC SOLAR ENERGY
CONVERSION
· Direct room temperature conversion of light to electricity through a simple solid-state device.
· Absence of moving parts.
· Ability to function unattended for long periods as evidence in space programmed.
· Modular nature in which desired currents, voltages and power levels can be achieved by mere integration.
· Maintenance cost is low as they are easy to operate.
· They do not create pollution.
· They have a long effective life.
· They are highly reliable.
· They consume no fuel to operate, as the sun’s energy is free.
· They have rapid response in output to input radiation changes; no long time constant is involved, as on thermal systems, before steady state is reached.
· They have wide power handling capabilities from microwatts when modules are combined into large area arrays. Solar cells can be used in combination with power conditioning circuitry to feed power into utility grid.
· They can be used with or without sun tracking, making possible a wide range of application possibilities.
3.14 DISADVANTGES
Following are the main disadvantages of photovoltaic solar energy conversion.
· Distributed nature of solar energy
· Absence of energy storage
· Relatively high capital cost.
CHAPTER 4
CHARGE CONTROLLER
4.1 GENERAL
The solar panel gives a D.C output, this D.C output is not always a constant, there is a variation in this output and cannot be given to the battery as it may reduce the life of the battery. So in order to get constant D.C output and also to avoid the reverse flow of current to the panel the charge controller is connected. A 24V D.C to the battery and also it acts as a blocking diode. Which lets the array generated power flow only towards the battery or grid. Without a blocking diode the battery would discharge back through the solar array during times of no insolation.
4.2 OPERATION OF CHARGE CONTROLLER
A charge controller when fully charged has a voltage of 14.5v. When a controller is being charged there is no LED indication. When the battery is over charged then the LED marked HIGH glows and this automatically stops further charging of the battery and thus stops the battery from getting over charged. When the battery is undercharged then the LED marked as LOW glows and the controller disconnects the battery from the load and thus prevents it from getting deeply discharged. To prevent the discharge of the discharge of the battery through SPV panel during overcast days a blocking diode is provided. The blocking diode is an ordinary diode only if its ford were biased thus it allows only one flow. Only from the DC panel to the battery if the charge tries to flow from battery to panel then it is reverse biased and hence does not conduct.
CHAPTER 5
BATTERIES
5.1 GENERAL
In isolated systems away from the grid, batteries are used for the storage of excess solar energy converted into electric energy. The only exceptions are isolated sunshine load such as irrigation pumps or drinking water supplies for storage. In fact for small units with output less than one kilowatt. Batteries seem to be the only technically and economically available storage means. Since both the photovoltaic systems and batteries are high in capital costs. It is necessary that the overall system to be optimized with respect to available energy and local demand pattern.
Ø Low cost
Ø Long life
Ø High reliability
Ø High overall efficiency
Ø Low discharge
Ø Minimum maintenance
· Ampere hour efficiency
· Watt hour efficiency
We use lead acid battery for storing the electrical energy from the solar panel. Lead acid cells are explained below.
5.2 LEAD ACID WET CELL
Where high values of load current are necessary, the lead acid cell is the type most commonly used. The electrolyte is a dilute solution of sulphuric acid (H2SO4). In the application of battery power to start the engine in an automobile, for example, the load current to the starter motor is typically 200 to 400A.
One cell has a nominal output of 2.1V, but lead acid cells are often used in a series combination of three for a 6V battery and six for a 12V battery. The lead acid cell type is a secondary cell or storage cell, which can be recharged. The charge and discharge can be repeated many times to restore the output voltage, as long as the cell is in good physical condition. However, heat with excessive charge and discharge currents shorten the useful life to about 3 to 5 years for an automobile battery. Of the different types of secondary cells, the lead acid type has the highest output voltage, which allows fewer for a specified battery voltage.
5.3 CONSTRUCTION
Inside a lead acid battery, the positive and negative electrodes consist of a group of plates welded to a connecting strap. The plates are immersed in the electrolyte, consisting of 8 parts of water to 3 parts of concentrated sulphuric acid. Each plate is a grid or framework, made of a lead-antimony alloy. This construction enables the active material, which is lead oxide, to be pasted into the grid. In manufacture of the cell, a forming charge produces the positive and negative electrodes. In the forming process, the active material in the positive plate is changed to lead peroxide (Pbo2). The negative electrode is spongy lead (Pb).
Automobiles batteries are usually shipped dry from the manufacturer. The electrolyte is put in at the time of installation, then the battery is charged to form the plates. With maintenance-free batteries, little or no water need be added in normal service. Some types are sealed, except for a pressure vent, without provision for adding water.
5.4 CHEMICAL ACTION
Sulphuric acid is combination of hydrogen and sulphate ions. When the cell discharges, lead peroxide from the positive electrode combines with H2 ions to form water and with sulfate ions also produces the sulfate. Therefore, the net result of discharge is to produce more water, which dilutes the electrolyte, and to form lead sulfate on the plates.
As the discharge continues, the sulfate fills the pores of the grids, retarding circulation of acid in the active material. Lead sulfate is the powder after seen on the outside terminals of old batteries. When the combination of weak electrolyte and sulfating on the plate lowers the output of the battery, charging is necessary.
On charge, the external D.C source reverses the current in the battery. The reversed direction of ions flows in the electrolyte result in a reversal of the chemical reactions. Now the lead sulfates on the positive plate reactive with the water and sulfate ions to produce lead peroxide and sulphuric acid. This action re-forms the positive plates and makes the electrolyte stronger by adding sulphuric acid. At the time, charging enables the lead sulfate on the negative plate to react with hydrogen ions; this also forms sulphuric acid while reforming lead on the negative electrode. As a result, the charging current can restore the cell to full output, with lead peroxide on the positive plates, spongy lead on the negative plate, and the required concentration of sulphuric acid in the electrolyte. The chemical equation for the lead-acid cell is
Charge
Pb+PbO2+2H2SO4 2PbSO4+2H2O
Discharge
On discharge, the Pb and PbO2combine with the so4 ions at the left side of equation to form lead sulfate (Pbso4) and water (H20) at the right of the equation. One battery consists of 3 cells, each have an output voltage of 2.1V, which are connected in series to get a voltage of 6V and the same 6V battery is connected in series, to get a 12V battery. They are placed in the waterproof iron casing box.
5.5 CHARGING THE LEAD ACID BATTERY
An external D.C voltage source is necessary to produce current in one direction. Also, the charging voltage must be more than the battery emf. Approximately 2.5 per cell are enough to over the cell emf so that the charging voltage can produce current opposite to the direction of discharge current.
Note that the reversal of current is obtained just by connecting the battery VB and charging source VG with + to + and – to -. The charging current is reversed because the battery effectively becomes a load resistance for VG when it higher than VB. A commercial charger for automobile batteries is essentially a D.C. power supply, rectifying input from the AC power line to provide D.C output for charging batteries.
Float charging refers to a method in which the charger and the battery are always connected to each other for supplying current to the load. The charger provides current for the load and current necessary to keep the battery fully charged. The battery here is an auxiliary source for D.C power.
CHAPTER 6
THE 8051 MICROCONTROLLER
6.1 GENERAL
Intel Corporation introduced 8051 micro controllers in the year 1981.It is an 8-bit micro controller with Harvard Architecture manufactured by advanced CMOS processes. It has 128 bytes of on chip RAM, 4k bytes of on chip ROM, two 16-bit timers/counters, four 8-bit ports of which one is a serial port, etc. There are 6 interrupt sources also.
Since this is an 8-bit micro controller, the CPU can work on only 8 bits of data at a time. Data larger than 8 bits has to be broken down to 8 bit pieces. Though it has an addressing capability of 64kbytes, only 4k bytes have been provided on chip.
8051 is available in different memory types, such as UV-EPROM, FLASH, and NV-RAM. The UV-EPROM version of 8051 is the 8751. This chip has only 4k bytes of on chip UV-EPROM. To use this chip for development requires access to a PROM burner, as well as a UV-EPROM inside the 8751 chips before you can program it again. It takes about 20 minutes to erase the 8751 before it can be programmed again. This led to introduce FLASH and NV-RAM version of 8051.
Philips Corporation’s P89c51Rd2 is a low-power, high performance CMOS 8-bit microcomputer with 4k bytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Phillips high-density nonvolatile memory technology and is compatible with the industry-standard MCS-51 instruction set and pin out. 89C51 is used in place of 8751 to eliminate the waiting time needed to erase the chip and thereby speed up the development time the development system requires a ROM burner that supports flash memory. The entire contents of ROM should be erased in order to program it again; the PROM burner itself does this. The 89C51 Flash reliably stores memory contents even after 10,000 erase and program cycles. AT89C51 is a popular chip of this category from Philips Corporation.
Another popular version of 8051 is DS5000 chip from Dallas Semiconductor. The on chip ROM is in the form of NV-RAM. The read/write capability of NV-RAM allows the program to be loaded into the on chip ROM while in the system. This can be done via a serial port of a PC. Another advantage of NV-RAM is the ability to change the ROM contents one byte at a time. The entire ROM must be erased before programmed again in the case of UV-EPROM and flash memory.
There is also OTP (One Time Programmable) version of the 8051 available from different sources. Flash and NV-RAM version are typically used for product development. When a product is designed and finalized, the OTP version of the 8051 is used for mass production since it is much cheaper in terms of price per unit.
There are two other members in the 8051 families of micro controllers. They are the 8052 and the 8031. 8031 is often referred to as ROM-less 8051 since it has 0k bytes of on chip ROM. To use this chip we must add external ROM to it. The ROM containing the program attached to the 8031 can be as large as 64k bytes. For adding external ROM two ports are needed out of 4 ports, leaving only 2 ports for I/O operations. To solve this, external I/O ports like 8255 can be added to 8031.
6.2 GENERAL INSTRUCTION FOR PROJECT IN 8951
Four port (P0, P1, P2 & P3) are used for communicate the external world, entire ports are used for either input or output it is your choice. For simple application that is no interrupt, no serial communication don’t care about multifunctional pins.
Biasing voltage of the Micro controller is 5v. For that purpose IC7805regulator is connected to 40th pin and grounded by 20th pin.
User programming area is 4Kbyte from origin. Without any interrupt you can use entire 4Kbyte otherwise the interrupt area is segmented. Flash memory is not enough of your project you can add the external memory. The external and internal memory is desired by the 31st pin (EA) if 31st pin is high the internal program is executed otherwise the external program is executed.
Speed of operation is depends on clock frequency, which is external controlled. The interaction between micro controller speed and user is making by 18th & 19th pin (XTAL2 & XTAL1). The 2 pins are connected through the crystal oscillator and grounded by capacitors. The general rating of the crystal oscillator is 12MHZ and capacitor is 33PF.
Rest switch is connected to the 9th pin in 89C51.When you need rest the program just press the switch. No connection for simple without external memory interface circuit in 29th and 30th pin. Because for external memory interface the address latch is needed one, when ALE pin is high the address latched after one T cycle the data is transferred. Response of the ALE is connected to output enable in the latch IC’s. So simple application there is no need to utilities ALE pin features.
6.3 80C51 8-BIT FLASH MICRO CONTROLLER FAMILY
The P89C51RB2/RC2/RD2 device contains a non-volatile 16KB/32KB/64KB Flash program memories that are both parallel programmable and serial In-System and In-Application Programmable. In-System Programming (ISP) allows the user to download new code while the micro controller sits in the application
In-Application Programming (IAP) means that the micro controller fetches new program code and reprograms itself while in the system. This allows for remote programming over a modem link.
A default serial loader (boot loader) program in ROM allows serial In-System programming of the Flash memory via the UART without the need for a loader in the Flash code. For In-Application Programming, the user program erases and reprograms the Flash memory by use of standard routines contained in ROM. This device executes one machine cycle in 6 clock cycles, hence providing twice the speed of a conventional 80C51. An OTP configuration bit lets the user select conventional 12-clock timing if desired. This device is a single-chip 8-bit micro controller manufactured in advanced CMOS process and is a derivative of the 80C51 micro controller family. The instruction set is 100% compatible with the 80C51 instruction set.
The device also has four 8-bit I/O ports, three 16-bit timer/event counter, a multi-source, and four-priority-level, nested interrupt structure, an enhanced UART and on-chip oscillator and timing circuits. The added features of the P89C51RB2/RC2/RD2 makes it a powerful micro controller for application that require pulse width modulation, high-speed I/O and up/down counting capabilities such as motor control.
6.4 FEATURES
Ø 80C51 Central Processing Unit
Ø On-chip Flash Program Memory with In-System
Ø Programming (ISP) and In-Application Programming (IAP) Capability
Ø Boot ROM contains low level Flash Programming routines for downloading via the UART
Ø Can be programmed by the end-user application (IAP)
Ø Parallel programming with 87C51 compatible hardware Interface to programmer
Ø 6 clocks per machine cycle operation (standard)
Ø 12 clocks per machine cycle operation (optional)
Ø Speed up to 20 MHZ with 6 clocks cycles per machine cycle
Ø Speed up to 33 MHZ with 12 clocks per machine cycle
Ø Fully static operation
Ø RAM expandable externally to 64 Kbytes
Ø 4 level priority interrupt
Ø 7 interrupt sources
Ø Four 8-bit I/O ports
Ø Full-duplex enhanced UART
Ø Framing error detection
Ø Automatic address recognition
Ø Power control modes
6.5 IN-SYSTEM PROGRAMMING (ISP)
The In-System Programming (ISP) is performed without removing the micro controller from the system. The In-system Programming (ISP) facility consists of a series of internal hardware resources coupled with internal firmware to facilitate remote programming of the 89C51Rx+ through the serial port. This firmware is provided by Philips and embedded within each 89C51Rx+ device.
The Philips In-System Programming (ISP) facility has made in-circuit programming in an embedded application possible with a minimum of additional expense in components and circuit board area. The ISP function uses five pins: TxD, RxD, VSS, VCC, and VPP. Only a small connector needs to be available to interface your application to an external circuit in order to use this feature. The VPP supply should be adequately and VPP not allowed exceeding datasheet limits.
6.6 DIFFERENT TYPES OF MICRO CONTROLLER
There are two different types of micro controller that is
Ø Embedded Micro controllers
Ø External Memory Micro controllers
6.6.1 Embedded Micro controllers
When all the hardware required running the application is provided on the chip, it is referred to as an embedded micro controller. All that is typically required to operate the device is power, reset, and a clock. Digital I/O pins are provided to allow interfacing with external devices.
6.6.2 External Memory Micro controllers
Sometimes, the program memory is insufficient for an application or, during debug, a separate ROM would make the work easier. Some micro controllers allow the connection of external memory. An external memory micro controller seems to primarily differ from a microprocessor in the areas of built-in peripheral features. These features could include memory device selection, timers, interrupt controllers, DMA, and I/O devices like serial ports.
6.7 INTERRUPTS
Interrupts are defined as requests because they can be refused (or masked). If they are not refused, then when an interrupt request is acknowledged (either by you or a computer), a special set of events or routines are followed to handle the interrupt. Interrupts are usually lumped into the category of things that are best left alone until expert status is attained.
This is very unfortunate because interrupts can be very useful in applications, allowing the code to respond much more quickly to input stimulus, and can make the code simpler as well as shorter than an application “polling” the inputs and responding when a change is detected. All of these attributes make using interrupts attractive for working in devices like the 8051, which has a limited amount of control store and will run at a set speed.
These special routines are known as interrupt handlers or interrupt service routines and are located at a special location in memory. The mainline code does not resume executing until the interrupt has finished being service and the processor indicates that the originally executing function can resume.
There are three different ways that you could respond, each one analogous to how interrupts are handled in a computer system.
· Handling the interrupt is to ignore it
· Responding to the interrupts
· Handling an interrupt is to process as it comes in
When an interrupt request is acknowledged by a computer system, the following actions are taken to service the interrupt.
· Save the context register information
· Reset the hardware requesting the interrupt
· Reset the interrupt controller
· Process the interrupt
· Restore the context information
· Return to the previously executing code (the mainline)
6.8 TIMERS
One of the most critical functions required by all computer systems is a timer. Along with providing real-time information interrupts to the processor, timers used in micro controllers also provide a number of other tasks helpful in the operation of the application. A basic computer timer consists of a counter that can be read from or written to by the processor and is driven by some constant frequency source. A typical enhancement is to provide an interrupt request from an overflow. The counter’s clock source is typically either the micro controller’s clock or an external source.
Fig (6.1)To measure pulse widths, an external control or gate input is used as shown in fig (6.1). It is to mask the clock source except when the pulse is active. When the gate becomes high, the counter’s clock source is allowed to increment the counter. When the pulse becomes inactive, the counter’s clock source is masked and an interrupt is requested to allow the application to read the counter value that is proportional to the width of the pulse. If the count overflows during the active pulse, the processor is also notified via an interrupt request, and it can increment a word counter used for sensing the pulse width. To determine the interval between overflows, the following formula is used:
CountMax is the overflow value of the counter
ClockFreq is the frequency
The 8051 have two 8/16-bit timers that can run in four different modes.
Ø Mode 0
Ø Mode 1
Ø Mode 2
Ø Mode 3
The clock source can either be the instruction clock or an external source. The timer registers can be read from or written to at any time, including when the timer is running. An interrupt request can be generated by the timer hardware when the timer overflows. Each of the two-timer’s operation is controlled by 4 bits devoted to it in the timer mode (TMOD) register at address 089h. The gate bit is used as a secondary execution-control bit. If the gate bit is reset, the timer is enabled to run at any time. The timer run control (TRn) bits are located in the TCON register (at address 088h) along with the overflow interrupts request pins.
Timer mode 0 and mode 1 are similar with the timer being configured as either a 13-bit or 16-bit counter. When the timer reaches the limit of the count, the appropriate overflow flag is set, and the counter is reset back to zero. Modes 0 and 1 can also be used to time external events. This is done by setting the gate bit of the TMOD register so that the INTn pin enables and disables the timer running. The timer will run when the INTn pin is high.
For mode 1 (the 16-bit counter), a specific time delay can be created by loading TLn and THn with values derived from the formula:
Init value =TLn + (256 * THn)
It is important to note that, after the overflow flag is set, the timer is loaded with zero and continues counting. To allow asynchronous serial communications to run stably, a programmable interval mode has been provided in the 8051’s timer. This is known as mode 2. In this mode, when TLn overflows, it is reloaded with the value set in THn. The delays between overflows can be calculated from:
Mode 2 works like modes 0 and 1 with software Initvalue reloads, but provides a hardware based reload that does not have any of the cycle uncertainty of implementing the reloads in software. The overflow of Timer 1, when in mode 2, will continue to be passed to the serial port even if the TF1 bit in software. This helps make the serial ports “set and forget”.
Mode 3, TH0 timer uses the Timer1 enable (TR1) and overflow flag (TF1). Because of this translation of timer resources, if Timer0 is in mode 3, then Timer1 is enabled to run all the time except when it is input into mode3. When Timer1 is put into mode3, it will not run. The purpose of implementing mode3 this way in the two timers is to allow Timer1 to be used as the data-rate generator for the serial without requiring any additional resources.
6.9 INDUSTRIAL AUTOMATION
6.9.1 Automation
Automation is technology concerned with the application of mechanical, electronic and computer based systems to operate and control. This technology includes
Ø Automatic positioning
Ø Automatic material handling
Ø Computer systems for data collection and decision making
Ø Feed back control and computer process control
Our project is limited to the field of automatic material handling. In this type of automation an 89C51 micro controller controls the operation. It is capable of interpreting with our robot.
6.9.2 Need for automation
Ø Increase in accuracy and precision
Ø Decrease in safety
Ø Decrease in cost
Ø Decrease in labour force
The purpose of automation is accomplished by using a robot and sensors.
6.9.3 Types of automation
Automation is a technology that is concerned with the use of mechanical, electronics, computer-base systems in the operation and control of industrial automation according to the product variety and production volume. They are
Ø Fixed automation
Ø Programmable automation
Ø Flexible automation
6.9.3.1 Fixed automation
Fixed automation is used when the volume of production is very high and it is therefore appropriate to design specialized equipment to process the produces very efficiently and at high rates.
6.9.3.2 Programmable automation
Programmable automation is used when the volume of production is relatively low and there is variety of products to be made. In this case, the production equipment is designed to be adaptable to variations in the product configuration.
6.9.3.3 Flexible automation
The third category known as the flexible automation is between the fixed automation and the programmable automation. This is also known as “Flexible manufacturing automation” or computer-integrated manufacturing systems. This type of automation has some features of both the fixed automation and programmable automation.
CHAPTER 7 RELAY
7.1 GENERAL
Relays are electromagnetic switches used as protective devices, indicating devices and as transmitting devices. Protective relay protect good component from the effects of the circuit components that have failed. Transmission relay are used in communication systems. Indicating relay may be used to identify a component, which has failed. Transmission relay may be used to identify a component, which has failed.
The relay is one of the most widely used components in industrial electronic. In combination with transistors, electron tubes and other circuit’s elements, this electromagnetic device performs countless tasks. Relays are electro magnetically operated remote controlled switches with one or more sets of contacts. When energized, the relay operates to open or close its contacts or to open some contacts and close others. Contacts, which are opened and close others. Contacts, which are opened when energized, are called “Normally Open” (NO) or simply open contacts. Contacts, which are closed when energized, are called “Normally Closed” (NC) or simply open contacts. Normally open contacts are referred to as “a” contacts. Normally closed contacts are sometimes referred to as “b” contacts.
There are certain terms associated with relays. The relay is said to “pick up” when it is energized and trips, and this “pick up” value is the smallest value of the fluctuating current required to close “a” contact or open “b” contact “b” contact is said to “reset” or “dropout”.
Relay contacts are held in their normal position by either springs or by some gravity-activated mechanism. An adjustment or adjustments are usually provided to set the restraining force to cause the relay to operate within predetermined conditions.
7.2 OPERATION
Relay operate on one of the two different principles namely,
Ø Electromagnetic attraction
Ø Electromagnetic induction
In this project electromagnetic attraction type relays are used which may be either be AC or DC actuated consists of an electromagnet having a core and winding. The core, the armature and plunger are made of magnetic materials such as iron, silicon steel or perrnalloy (an alloy of nickel and steel). The movable contact is fixed on the armature. A spring, whose tension is adjustable, retains the armature closing the stationary and movable contact.
When the electric current is supplied, an electromagnet is formed, and armature is attracted to the core. If there is sufficient current to overcome the restraining force of the spring the relay contact close. The armature will be attracted whether the poles of the electromagnet adjacent to the armature is the north or south. The AC attraction type relay is different from a DC relay in manner that it has a shading ring, whereas the DC relay does not. The shading ring is a non-magnetic device, which is inserted in to a slot cut in the coil and minimizes the tendency of the relay contact to chatter under the influence of the alternation magnetic field.
7.3 AC OPERATION TYPE
For the operation of AC relays, the power source is almost always a commercial frequency (50 or 60Hz) with standard voltages 8,115, and 240VAC. Because of this, when the voltage is other than the standard voltage, the product is a special order item, and the factors of price, delivery, and stability of characteristics may create inconveniences. To the extent that it is possible, the standard voltages should be selected.
Also, in the AC type, shading coil resistance loss, magnetic circuit eddy current loss, and hysteresis loss exit, and because of lower coil efficiency, it is normal for the temperature rise to be greater than that for the DC type. Further more, because humming occurs when below the pick-up voltage and when above the rated voltage, care is required with regard to power source voltage fluctuations .For example, in the case of motor starting, if the power source voltage drops, and during the humming of the relay, if it reverts to the restored condition, the contacts suffer a burn damage and welding, with the occurrence of a false operation self-maintaining condition.
For the AC type, there is an inrush current during the operation time (for these paraded condition of the armature, the impedance is low and a current better than rated current flows; for the adhered condition of the armature, the impedance is high and the rated value of current flows), and because of this, for the case of several relays being used in parallel connection, it is necessary to give consideration to power consumption.
7.4 DC OPERATION TYPE
For the operation of DC relays, standards exist for power source voltage and current, with DC voltage standards set at 5, 6, 12, 24, 48, and 100V, but with regard to current, the values as expressed in Catalogs n milliamperes of pick-up current. However, because this value of pick-up current is nothing more than a guarantee of just barely moving the armature, the variation in energizing voltage and resistance values, and the increase in coil resistance due to temperature rise, must be given consideration for the worst possible condition of relay operation, scary to consider the current value as 1.5 to 2 times the pick-up current.
Also, because of the extensive use of relays as limit devices in place of meters for both voltage and current, and because of the gradual increase or decrease of current impressed on the coil causing possible delay in movement of the contacts, there is the possibility that the designated control capacity may not be satisfied. Thus it is necessary to exercise care. The DC type relay coil resistance varies due to ambient temperature as well as to its own heat generation to the extent of about 0.4%, and accordingly, if the temperature increases, because of the increase in pick-up and drop-out voltages, care is required.
7.5 ENERGIZING VOLTAGE OF AC COIL
In order to have stable operation of the relay, the energizing voltage should be basically within the range of +10%/-15%of the rated voltage. However, it is necessary that the waveform of the voltage impressed on the coil be a sine wave. There is no problem if the power source is commercially provided power, but when a stabilized AC power source is used, there is a waveform distortion due to that equipment, and there is the possibility of abnormal overheating.
By means of a shading coil for the AC coil, humming is stopped, but with a distorted waveform, that function is not displayed below shows an example of waveform distortion. If the power source for the relay operating circuit is connected to the same line as motors, solenoids, transformers, another loads, when these loads operate, the line voltage drops, and because of this the relay contacts suffer the effect of vibration and subsequent burn damage.
In particular, if a small type transformer is used and its capacity has no margin of safety, when there is long wiring, or in the case of household used or small sales shop use where the wiring is slender, it is necessary to take precautions because of the normal voltage fluctuations combined with these other factors. When trouble develops, a survey of the voltage situation should be made using a synchro scope or similar means, and the necessary counter-measures should be taken, and together with this determine whether a special relay with suitable excitation characteristics should be used, or make a change in the DC circuit in which a capacitor is inserted to absorb the voltage fluctuations. In particular, when a magnetic switch is being used, because the load becomes like that of a motor, depending upon the application, separation of the operating circuit and power circuit should be tried and investigated. Sine wave approximate keystone wave Waveform with an included CTR100V AC Switch 24V DC Relay coil.
7.6 RELAY DRIVE BY MEANS OF A TRANSISTOR
7.6.1 Connection method
The voltage impressed on the relay is always full rated voltage, and in the OFF time, the voltage is completely zero for avoidance of trouble
Collector connection (fig 7.1) is the most common connection, because operation is stable. Emitter connection (fig 7.2) when the circumstances make the use of this connection unavoidable, if the voltage is not completely impressed on the relay, the transistor does not conduct completely and operation is uncertain. Parallel connection (fig 7.3) when the power consumed by the complete circuit becomes large, consideration Of the relay voltage is necessary.
7.6.2 Counter measures for surge voltage of relay control transistor
If the coil current is suddenly interrupted, a sudden high voltage pulse is developed in the coil. If this voltage exceeds the voltage resistance of the transistor, the transistor will be degraded, and this will lead to damage. It is absolutely necessary to connect a diode in the circuit as a means of preventing damage from the counter emf. As suitable ratings for this diode, the current should be equivalent to the average rectified current to the coil, and the inverse blocking voltage should be about 3 times the value of the power source voltage.
CHAPTER 8
SAMPLE PROGRAM
MOV p1, #ooh
Mov p2, #00h
Mov p3, #ooh
Mov p0, #ooh
Setb p2.1
Clr p2.5
Acall delay
Setb p2.2
Mov R1, #17
Loop1 Mov R2, #FF
Loop2 acall delay
djnz R2, Loop2
djnz R1, Loop1
Mov p2, #00
Mov R2, #FF
Loop2 Acall delay 0023
djnz R2, Loop2
Setb p2.3
Acall delay
Setb p2.5
Mov R1, #17
Loop1 Mov R2, #FF
Loop2 acall delay
djnz R2, Loop2
djnz R1, Loop1
Mov p2, #00
Here: jump here
Delay:
Mov TMOD, #01
Mov TLO, #FD
Mov THO, #03
Setb TRO
Here:
JNB TFO here, 005B
Clr TRO
Clr TFO
RET
CHAPTER 9 CIRCUIT DIAGRAM
CIRCUIT DESCRIPTION
The photovoltaic cell in the solar panel produces electrical energy from sunlight with the help of photovoltaic effect. This energy is then stored in the lead-acid battery via charge controller. The solar panel gives a D.C output, this D.C output is not always a constant, there is a variation in this output and cannot be given to the battery as it may reduce the life of the battery. So in order to get constant D.C output and also to avoid the reverse flow of current to the panel the charge controller is connected and also it acts as a blocking diode. Which lets the array generated power flow only towards the battery or grid. Without a blocking diode the battery would discharge back through the solar array during times of no insolation. Hence the charge controller gives steady supply of 6V to the battery. The supply from the battery helps to run the D.C motor. The shaft of this motor is in turn connected to the shaft of the wheel. Based upon the motor rotation the wheel rotates either in forward or reverse direction. Thus by the operation of this D.C motor the solar vehicle operates.
In our project, we use 8051-microcontroller families. In this family, we use 89C51 because it has its specific importance over the other types of micro controller family. The stored energy in the battery helps to operate the micro controller chip 89C51. According to our program, this 8951 produces various pulses. This pulse is then given to ULN buffer. This micro controller chip has its control over the relay. The chip 89C51 has four ports. Each port has eight pins with it. To have its control over the relay we use the first four pins of the second port of the chip. The first pin of the second port of the chip 89C51 is connected to relay A, while that of second pin of this port is connected to relay B. This relay A & B are connected to the positive and negative direction of the D.C motor. The third pin of the second port is connected to the relay D, while that of fourth pin of this port is connected to relay C.
The various pulses produced by the micro controller chip operate the relay. The first pulse energizes relay A and B. Both this A and B relay helps in the forward direction of the solar vehicle in a predefined path. After traveling in this path the solar vehicle has it’s braking in the forward direction based upon the program stored in the micro controller chip.
After a certain time delay the opposite pulse ready to energies the relay C and D. Both this relay C and D helps in the reverse direction of the solar vehicle in the same predefined path. The vehicle as it’s braking the reverse direction same as that of the forward direction. Again after certain time delay the solar vehicle moves in the forward direction. Thus this forward and reverse process after certain time delay is continued.
CHAPTER 10
APPLICATIONS OF OUR PROJECT
· In Airport
· In Industry
· In Army
· In Railway Station
· In Library
CHAPTER 11
CONCLUSION
The world has seen great inventions right from small atoms to cursing missiles, rocket, and planes. But these inventions had indirectly affected the environment in one (or) more ways, apart from their glorious, unimaginable use to the environment. The pollutions of air were one of the most concern things in the world. Here the solar energy comes as a replacement for the other resources. Because of its non-pollution, simplicity, easy availability, less costs etc. Our vehicle, which is powered by solar energy, brings enormous amount of advantageous to the world. So we conclude that in the fast charging world where speed and accuracy remains a main concern apart from non-pollution of the environment, solar vehicle provides all the advantageous to create a clean, green and healthy environment. The next generation will have the atmosphere, which is free pollutants, and harmful substances, which make the world a joyous place to live.
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