INDEX
CONTENTS
1. Abbreviations 2. Figures locations 3. Abstract 4. Introduction 5. Block Diagram6. Block Diagram Description 7. Schematic 8. Schematic Description 9. Hardware Components 10. Circuit Description 11. Software components Embedded ‘C’
12. KEIL procedure description 13. Conclusion (or) Synopsis 14. Future Aspects
ABBREVATIONS: Microcontroller:
Symbol Name
ACC Accumulator B B register
PSW Program status word SP Stack pointer
DPTR Data pointer 2 bytes DPL Low byte DPH High byte P0 Port0 P1 Port1 P2 Port2 P3 Port3
IP Interrupt priority control IE Interrupt enable control TMOD Timer/counter mode control TCON Timer/counter control T2CON Timer/counter 2 control T2MOD Timer/counter mode2 control TH0 Timer/counter 0high byte TL0 Timer/counter 0 low byte TH1 Timer/counter 1 high byte TL1 Timer/counter 1 low byte TH2 Timer/counter 2 high byte TL2 Timer/counter 2 low byte SCON Serial control
SBUF Serial data buffer PCON Power control
Landmine Detecting Robot
ABSTRACT
The robotics mainly aims at reduction of man-power by designing automated systems. In the present scenario of increase in wars and terrorist activities,
landmine detecting robot is one such automated unmanned system used for detecting landmines.
The microcontroller forms the heart of the system with landmine sensor, drivers and motors connected to it. These are used for moving the robot in desired direction and detecting landmines present if any. The sensor detects the metal (conductor) by using metal detector.
The system uses a battery for power supply. The buzzer is interfaced with the microcontroller which goes on immediately on detection of metal by metal detector. In stand-by mode the robot just moves in different directions.
This project finds its application for military purposes and policing purposes.
1. INTRODUCTION
EMBEDDED SYSTEMS
Embedded systems are designed to do some specific task rather than be a general-purpose computer for multiple tasks. Some also has real time performance constraints that must be met, for reason such as safety and usability; others may have
low or no performance requirements, allowing the system hardware to be simplified to reduce costs.
An embedded system is not always a separate block - very often it is physically built-in to the device it is controlling.
The software written for embedded systems is often called firmware, and is stored in read-only memory or flash convector chips rather than a disk drive. It often runs with limited computer hardware resources: small or no keyboard, screen, and little memory.
ROBOTICS
Robotics is the science and technology of robots, their design, manufacture, and application. Robotics requires a working knowledge of electronics, mechanics and software, and is usually accompanied by a large working knowledge of many subjects. A person working in the field is a robotics.
Although the appearance and capabilities of robots vary vastly, all robots share the features of a mechanical, movable structure under some form of autonomous control. The structure of a robot is usually mostly mechanical and can be called a kinematic chain (its functionality being akin to the skeleton of the human body). The chain is formed of links (its bones), actuators (its muscles) and joints which can allow one or more degrees of freedom. Most contemporary robots use open serial chains in which each link connects the one before to the one after it. These robots are called serial robots and often resemble the human arm. Some robots, such as the Stewart platform, use closed parallel kinematic chains. Other structures, such as those that mimic the mechanical structure of humans, various animals and insects, are comparatively rare. However, the development and use of such structures in robots is an active area of research (e.g. biomechanics). Robots used as manipulators have an end effector mounted on the last link. This end effector can be anything from a welding device to a mechanical hand used to manipulate the environment.
A re-programmable, multifunctional manipulator designed to move material, parts, tools, or specialized devices through various programmed motions for the performance of a variety of tasks.
BLOCK DIAGRAM:
BLOCK DIAGRAM EXPLANATION:
In this section we will be discussing about the complete block diagram and functional description of it.
Power supply:
In this system we are using 5V power supply for microcontroller of both Transmitter section as well as receiver section. We use rectifiers for converting the A.C. into D.C and a step down transformer to step down the voltage. The full description of the Power supply section is given in this documentation in the following sections i.e. hardware components.
Microcontroller (8051):
MICRO CONTROLLER
UNIT
Land Mine Sensor
BUZZER Battery
Motors Drivers
In this project the microcontroller plays a major role in transmitting data to RF transmitter and here the data is transmitted using RF communication. In transmitter side microcontroller directs the data obtained from PC and at the receiver side microcontroller receives the data from the RF receiver and is given to robot.
H-Bridge:
Each H-Bridge having two inputs. Micro controller gives input to H-Bridge to control the direction of the robot. Based on the given inputs to the H-Bridge, the motor will be rotates either in clock-wise or in anti-clock wise direction. So that the movement of the robot will be controlled
Land mine sensor:
Land mine sensor block is used to find landmines located in the path of the robot. It will search for landmine and if it finds, it gives logic high to microcontroller. Metal detector is used for this purpose.
Buzzer:
Buzzer in generally used to alert the humans by giving sound. In this project, if the robot detects any landmine in the path, it will give the buzzer.
SCHEMATIC EXPLANATION: Power supply:
The main aim of this power supply is to convert the 230V AC into 5V DC in order to give supply for the TTL or CMOS devices. In this process we are using a step down transformer, a bridge rectifier, a smoothing circuit and the RPS.
At the primary of the transformer we are giving the 230V AC supply. The secondary is connected to the opposite terminals of the Bridge rectifier as the input. From other set of opposite terminals we are taking the output to the rectifier.
The bridge rectifier converts the AC coming from the secondary of the transformer into pulsating DC. The output of this rectifier is further given to the smoother circuit which is capacitor in our project. The smoothing circuit eliminates the ripples from the pulsating DC and gives the pure DC to the RPS to get a constant output DC voltage. The RPS regulates the voltage as per our requirement.
The microcontroller AT89S51 with Pull up resistors at Port0 and crystal oscillator of 11.0592 MHz crystal in conjunction with couple of capacitors of is placed at 18th & 19th pins of 89S51 to make it work (execute) properly
H – Bridge motor:
This module is output to the microcontroller. The circuit for this motor is designed in hybrid model with 4 transistors. And its two input pins are connected to the pin1 and pin2(port 1.0 and 1.1) of the microcontroller. In this we are using two motors. The other motor pins are connected to the pin3 and pin4(port 1.2 and 1.3) of the microcontroller.
And the supply connections to these motors are given from the Power supply output 7805 to the VCC and VSS pins.
Land mine sensor:
Land mine sensor is an input device, It is connected to 24 pin(port 2.3).It comprises of sensor to sense electromagnetic pulses, its output is connected to base of the transistor in amplifier circuit. Sensed data is given to microcontroller to which it is connected Buzzer:
Buzzer is an output device. It is connected to 39th pin (port 0.0) of microcontroller.
MICRO CONTROLLER (AT89S51)
Introduction
A Micro controller consists of a powerful CPU tightly coupled with memory, various I/O interfaces such as serial port, parallel port timer or counter, interrupt controller, data acquisition interfaces-Analog to Digital converter, Digital to Analog converter, integrated on to a single silicon chip.
If a system is developed with a microprocessor, the designer has to go for external memory such as RAM, ROM, EPROM and peripherals. But controller is provided all these facilities on a single chip. Development of a Micro controller reduces PCB size and cost of design.
One of the major differences between a Microprocessor and a Micro controller is that a controller often deals with bits not bytes as in the real world application. Intel has introduced a family of Micro controllers called the MCS-51.
Figure: micro controller
FEATURES:
• Compatible with MCS-51® Products
• 4K Bytes of In-System Programmable (ISP) Flash Memory – Endurance: 1000 Write/Erase Cycles
• 4.0V to 5.5V Operating Range
• Fully Static Operation: 0 Hz to 33 MHz • Three-level Program Memory Lock • 128 x 8-bit Internal RAM
• 32 Programmable I/O Lines • Two 16-bit Timer/Counters • Six Interrupt Sources
• Full Duplex UART Serial Channel • Low-power Idle and Power-down Modes
DESCRIPTION:
The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller with 4K bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry- standard 80C51 instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the Atmel AT89S51 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications.
BLOCK DIAGRAM:
PIN DIAGRAM:
Figure: pin diagram of micro controller
PIN DESCRIPTION:
VCC - Supply voltage. GND - Ground.
Port 0:
Port 0 is an 8-bit open drain bidirectional I/O port. As an output port, each pin can
sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-impedance inputs. Port 0 can also be configured to be the multiplexed low-order address/data bus during accesses to external program and data memory. In this mode, P0 has internal pull-ups. Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. External pull-ups are required
Port 1:
Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. Port 1 also receives the low-order address bytes during Flash programming and verification.
Port 2:
Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. Port 2 also receives the high-order address bits and some control signals during Flash programming and verification.
Port 3:
Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull-ups. Port 3 receives some control signals for Flash programming and verification. Port 3 also serves the functions of various special features of the AT89S51, as shown in the following table.
RST:
Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. This pin drives High for 98 oscillator periods after the Watchdog times out. The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state of bit DISRTO, the RESET HIGH out feature is enabled.
ALE/PROG:
Address Latch Enable (ALE) is an output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming. In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external data memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.
PSEN:
Program Store Enable (PSEN) is the read strobe to external program memory. When the AT89S51 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory.
EA/VPP:
External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC for internal program executions. This pin also receives the 12-volt programming enable 12-voltage (VPP) during Flash programming.
XTAL1:
Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2:
Output from the inverting oscillator amplifier.
Oscillator Characteristics:
XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which can be configured for use as an on-chip oscillator, as shown in Figs 6.2.3. Either a quartz crystal or ceramic resonator may be used. To drive the device from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 6.2.4.There are no requirements on the duty cycle of the external clock signal, since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications must be observed.
Fig 6.2.3 Oscillator Connections Fig 6.2.4 External Clock Drive Configuration
POWER SUPPLY:
There are many types of power supply. Most are designed to convert high voltage AC mains electricity to a suitable low voltage supply for electronics circuits and other devices. A power supply can by broken down into a series of blocks, each of which performs a particular function.
For example a 5V regulated supply:
Description
A variable regulated power supply, also called a variable bench power supply, is one where you can continuously adjust the output voltage to your requirements. Varying the output of the power supply is the recommended way to test a project after having double checked parts placement against circuit drawings and the parts placement guide.
This type of regulation is ideal for having a simple variable bench power supply. Actually this is quite important because one of the first projects a hobbyist should undertake is the construction of a variable regulated power supply. While a dedicated supply
TRANSFORMER:
Transformers convert AC electricity from one voltage to another with little loss of power. Transformers work only with AC and this is one of the reasons why mains electricity is AC. Step-up transformers increase voltage, step-down transformers reduce voltage. Most power supplies use a step-down transformer to reduce the dangerously high mains voltage to a safer low voltage. The input coil is
called the primary and the output coil is called the secondary. There is no electrical connection between the two coils, instead they are linked by an alternating magnetic field created in the soft-iron core of the transformer. The two lines in the middle of the circuit symbol represent the core. Transformers waste very little power so the power out is (almost) equal to the power in. Note that as voltage is stepped down current is stepped up. The ratio of the number of turns on each coil, called the turns ratio, determines the ratio of the voltages. A step-down transformer has a large number of turns on its primary (input) coil which is connected to the high voltage mains supply, and a small number of turns on its secondary (output) coil to give a low output voltage.
Fig 6.1.2 An Electrical Transformer Turns ratio = Vp/VS = Np/NS
Power Out= Power In VS X IS=VP X IP
Vp = primary (input) voltage
Np = number of turns on primary coil
Ip = primary (input) current Full wave rectifier
Full wave rectifier circuit is shown in fig2(a). The transformer
secondary has a centre-tap and each half give voltage of Vm. In each half there is one diode i.e. D1 and D2.the load resistance Rl is common to both halves. This can be seen to comprise of two half-wave circuits. On the positive half cycle, when the point is positive w.r.t point B, the Diode D1 conducts and current i1 flows through Rl .
During this half cycle, the point C is negative w.r.t point B and hence the diode D2 does not conduct. Therefore i2=0.
On the negative half cycle the point C is positive w.r.t. point B. hence the diode
D2 conducts and current i2 flows through RL. During this half cycle. The point A is negative w.r.t point B and hence the diode D1 does not conduct. Therefore i1=0
Fig2(b) and Fig2(c) shows the waveforms of currents i1 and i2. Since both i1 and i2 flow through the load RL, the current i through RL is i= i1+i2, which is obtained by adding the two waveform and is shown in Fig2(d)
Advantages and disadvantages of full wave Rectifier:
(a) amount of ripple is much lower(r=0.482)as compared to half wave (r=1.21). (b) Rectification efficiency is high (n=0.812)
(c) T.U.F is better (= 0.693) then that of half wave (=0.287). (d) No problem of core saturation.
(e) Requires centre-tapped secondary of the transform
A
B
C
Vm
Vm
Ac
supply
D1
D2
RL
E
i1
i2
Comparison of rectifier circuits:
Parameter Type of Rectifier
Half wave full wave bridge
Number of diodes 1 2 3 PIV of diodes Vm 2Vm Vm Secondary voltage (rms) V V-0-V V Secondary voltage Vm V-0-V Vm D.C output voltage Vm/ 2Vm/ 2Vm/ Vdc,at no-load 0.318Vm 0.636Vm 0.636Vm Ripple factor 1.21 0.482 0.482 Ripple frequency f 2f 2f Rectification efficiency 0.406 0.812 0.812 Transformer Utilization Factor(TUF) 0.287 0.693 0.812 Capacitor Filter:
We have seen that the ripple content in the rectified output of half wave
rectifier is 121% or that of full-wave or bridge rectifier or bridge rectifier is 48% such high percentages of ripples is not acceptable for most of the applications. Ripples can be removed by one of the following methods of filtering:
(a) A capacitor, in parallel to the load, provides a easier by –pass for the ripples
voltage though it due to low impedance
(b) An inductor, in series with the load, prevents the passage of the ripple current (due
to high impedance at ripple frequency) while allowing the d.c (due to low resistance to d.c)
(c) Various combinations of capacitor and inductor, such as L-section filter
section filter, multiple section filter etc. which make use of both the properties mentioned in (a) and (b) Above.
Two cases of capacitor filter, one applied on half wave rectifier and another with full wave rectifier.
Full-wave Rectifier with capacitor filter:
Fig 4(a) shows the circuit diagram, with a full wave rectifier comprising of a
center-tapped secondary winding and two diodes. All the analysis given in this section are also valid for a bridge rectifier, which also gives full-wave rectification. The filter capacitor C is connected in parallel with load resistance RL.
In a manner similar to half-wave circuit with capacitor filter, in this circuit also the capacitor C will get charged during short periods and thereafter, discharge through the load resistance RL. One notable difference here is that the discharge duration is shorter, whereas in half-wave case the duration was longer due to the missing half – waves in between. As a result, the average value of output voltage is higher.
Bridge Rectifier A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-wave rectification. This is a widely used configuration, both with individual diodes wired as shown and with single component bridges where the diode bridge is wired internally.
A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-wave rectification. This is a widely used configuration, both with individual
diodes wired as shown and with single component bridges where the diode bridge is wired internally.
Fig 6.1.3 A Typical Bridge Rectifier Circuit Current Flow in the Bridge Rectifier
Fig 6.1.4 Current Flow in the Bridge Rectifier
For both positive and negative swings of the transformer, there is a forward path through the diode bridge. Both conduction paths cause current to flow in the same direction through the load resistor, accomplishing full-wave rectification. While one set of diodes is forward biased, the other set is reverse biased and effectively eliminated from the circuit.
Fig 6.1.5 Current Flow in the Bridge Rectifier
Smoothing:
Smoothing is performed by a large value electrolytic capacitor connected across the DC supply to act as a reservoir, supplying current to the output when the varying DC voltage from the rectifier is falling. The diagram shows the unsmoothed varying DC (dotted line) and the smoothed DC (solid line). The capacitor charges quickly near the peak of the varying DC, and then discharges as it supplies current to the output. Smoothing significantly increases the average DC voltage to almost the peak value (1.4 × RMS value). For example 6V RMS AC is rectified to full wave DC of about 4.6V RMS (1.4V is lost in the bridge rectifier), with smoothing this increases to almost the peak value giving 1.4 × 4.6 = 6.4V smooth DC. Smoothing is not perfect due to the capacitor voltage falling a little as it discharges, giving a small ripple voltage. For many circuits a ripple, which is 10% of the supply voltage, is satisfactory and the equation below gives the required value for the smoothing capacitor. A larger capacitor will give less ripple. The capacitor value must be doubled when smoothing half-wave DC.
Regulator:
Most digital logic circuits and processors need a 5-volt power supply. To use these parts we need to build a regulated 5-volt source. Usually you start with an unregulated power supply ranging from 9 volts to 24 volts DC (A 12 volt power supply is included
with the beginner kit and the Microcontroller. To make a 5 volt power supply, we use a LM7805 voltage regulator IC (Integrated Circuit). The IC is shown below.
FIG 7.1
The LM7805 is simple to use. You simply connect the positive lead of your unregulated DC power supply (anything from 9VDC to 24VDC) to the Input pin, connect the negative lead to the Common pin and then when you turn on the power, you get a 5 volt supply from the Output pin.
Circuit features
Brief description of operation: Gives out well regulated +5V output, output current capability of 100 mA
Circuit protection: Built-in overheating protection shuts down output when regulator
IC gets too hot
Circuit complexity: Very simple and easy to build
Circuit performance: Very stable +5V output voltage, reliable operation
Availability of components: Easy to get, uses only very common basic components Design testing: Based on datasheet example circuit, I have used this circuit
successfully as part of many electronics projects
Applications: Part of electronics devices, small laboratory power supply Power supply voltage: Unregulated DC 8-18V power supply
Power supply current: Needed output current + 5 mA
Voltage regulator ICs is available with fixed (typically 5, 12 and 15V) or variable output voltages. The maximum current they can pass also rates them. Negative voltage regulators are available, mainly for use in dual supplies. Most regulators include some automatic protection from excessive current ('overload protection') and overheating ('thermal protection'). Many of the fixed voltage regulator ICs have 3 leads and look like power transistors, such as the 7805 +5V 1A regulator shown on the right.
Fig 6.1.6 A Three Terminal Voltage Regulator
LM787777777777XX7898
78XX:
The Bay Linear LM78XX is integrated linear positive regulator with three terminals. The LM78XX offer several fixed output voltages making them useful in wide range of applications. When used as a zener diode/resistor combination replacement, the LM78XX usually results in an effective output impedance improvement of two orders of magnitude, lower quiescent current.
The LM78XX is available in the TO-252, TO-220 & TO-263packages,
Features:
• Output Current of 1.5A
• Output Voltage Tolerance of 5% • Internal thermal overload protection • Internal Short-Circuit Limited • No External Component
• Output Voltage 5.0V, 6V, 8V, 9V, 10V,12V, 15V, 18V, 24V • Offer in plastic TO-252, TO-220 & TO-263
• Direct Replacement for LM78XX Applications:
• Post regulator for switching DC/DC converter • Bias supply for analog circuits
DC Motor
DC motors are configured in many types and sizes, including brush less, servo, and gear motor types. A motor consists of a rotor and a permanent magnetic field stator. The magnetic field is maintained using either permanent magnets or electromagnetic windings. DC motors are most commonly used in
variable speed and torque.
Motion and controls cover a wide range of components that in some way are used to generate and/or control motion. Areas within this category include bearings and bushings, clutches and brakes, controls and drives, drive components, encoders and resolves, Integrated motion control, limit switches, linear actuators, linear and rotary motion components, linear position sensing, motors (both AC and DC motors), orientation position sensing, pneumatics and pneumatic components, positioning stages, slides and guides, power transmission (mechanical), seals, slip
rings, solenoids, springs.
Motors are the devices that provide the actual speed and torque in a drive system. This family includes AC motor types (single and multiphase motors, universal, servo motors, induction, synchronous, and gear motor) and DC motors (brush less, servo motor, and gear motor) as well as linear, stepper and air motors, and motor contactors and starters.
In any electric motor, operation is based on simple electromagnetism. A current-carrying conductor generates a magnetic field; when this is then placed in an external magnetic field, it will experience a force proportional to the current in the conductor, and to the strength of the external magnetic field. As you are well aware of from playing with magnets as a kid, opposite (North and South) polarities attract, while like polarities (North and North, South and South) repel. The internal configuration of a DC motor is designed to harness the magnetic interaction between a current-carrying conductor and an external magnetic field to generate rotational motion.
Let's start by looking at a simple 2-pole DC electric motor (here red represents a magnet or winding with a "North" polarization, while green represents a magnet or winding with a "South" polarization).
Every DC motor has six basic parts -- axle, rotor (a.k.a., armature), stator, commutator, field magnet(s), and brushes. In most common DC motors (and all that Beamers will see), the external magnetic field is produced by high-strength permanent magnets1. The stator is the stationary part of the motor -- this includes the motor
casing, as well as two or more permanent magnet pole pieces. The rotor (together with the axle and attached commutator) rotates with respect to the stator. The rotor consists of windings (generally on a core), the windings being electrically connected to the commutator. The above diagram shows a common motor layout -- with the rotor inside the stator (field) magnets.
The geometry of the brushes, commutator contacts, and rotor windings are such that when power is applied, the polarities of the energized winding and the stator magnet(s) are misaligned, and the rotor will rotate until it is almost aligned with the stator's field magnets. As the rotor reaches alignment, the brushes move to the next
commutator contacts, and energize the next winding. Given our example two-pole motor, the rotation reverses the direction of current through the rotor winding, leading to a "flip" of the rotor's magnetic field, and driving it to continue rotating.
In real life, though, DC motors will always have more than two poles (three is a very common number). In particular, this avoids "dead spots" in the commutator. You can imagine how with our example two-pole motor, if the rotor is exactly at the middle of its rotation (perfectly aligned with the field magnets), it will get "stuck" there. Meanwhile, with a two-pole motor, there is a moment where the commutator shorts out the power supply (i.e., both brushes touch both commutator contacts simultaneously). This would be bad for the power supply, waste energy, and damage motor components as well. Yet another disadvantage of such a simple motor is that it would exhibit a high amount of torque” ripple" (the amount of torque it could produce is cyclic with the position of the rotor).
So since most small DC motors are of a three-pole design, let's tinker with the workings of one via an interactive animation (JavaScript required):
You'll notice a few things from this -- namely, one pole is fully energized at a time (but two others are "partially" energized). As each brush transitions from one commutator contact to the next, one coil's field will rapidly collapse, as the next coil's field will rapidly charge up (this occurs within a few microsecond). We'll see more
about the effects of this later, but in the meantime you can see that this is a direct result of the coil windings' series wiring:
There's probably no better way to see how an average dc motor is put together, than by just opening one up. Unfortunately this is tedious work, as well as requiring the destruction of a perfectly good motor. This is a basic 3-pole dc motor, with 2 brushes and three commutator contacts.
Land mine sensor or proximity sensor:
A proximity sensor detects an object when the object approaches within the detection boundary of the sensor. Proximity sensors are used in various facets of manufacturing for detecting the approach of metal objects. Various types of proximity sensors are used for detecting the presence or absence of an object. The design of a proximity sensor can be based on a number of principles of operation, some examples include: variable reluctance, eddy current loss, saturated core, and Hall Effect. Depending on the principle of operation, each type of sensor will have different performance levels for sensing different types of objects. Common types of non-contact proximity sensors include inductive proximity sensors, capacitive proximity sensors, ultrasonic proximity sensors, and photoelectric sensors.
Hall-effect sensors detect a change in a polarity of a magnetic field. Variable reluctance sensors typically include a U-type core and coils wound around the core legs. Inductive proximity sensors have a lossy resonant circuit (oscillator) at the input side whose loss resistance can be changed by the proximity of an electrically conductive medium. An electrical capacitance proximity sensor
converts a variation in electrostatic capacitance between a detecting electrode and a ground electrode caused by approaching the nearby object into a variation in an oscillation frequency, transforms or linearizes the oscillation frequency into a direct current voltage, and compares the direct current voltage with a predetermined threshold value to detect the nearby object.
Ultrasonic sensing systems provide a much more efficient and effective method of longer range detection. These sensors require the use of a transducer to produce ultrasonic signals. Eddy-current proximity sensors are well known and operate on the principle that the impedance of an ac-excited electrical coil is subject to change as the coil is brought in close proximity to a metallic object.
Proximity sensors often are employed in manufacturing industries in which the sensors are exposed to harsh environmental conditions. Inductive proximity sensors are used in automation engineering to define operating states in automating plants, production systems and process engineering plants. Magnetic proximity detectors are commonly used on ski lifts and tramways for detecting a drop condition of the steel cable used as a haul line or haul rope.
Proximity sensors are widely used in the automotive industry to automate the control of power accessories. For instance, proximity sensors are often used in power window controllers to detect the presence of obstructions in the window frame when the windowpane is being directed to the closed position.
In the project, our aim is to detect the land mines. So, to detect the land mines in the path, we insert the land mine sensor. Land mine sensor will detect the electromagnetic signals evolving from land mine. If it finds the land mine, it gives high pulse to microcontroller. Microcontroller will understand that land mine is present at that place and gives the high signal to buzzer in order to alert humans by sounding it.
Motors in the circuit are useful for the moment and directions of the robot., it moves right by making left side motor off and running right side motor and vice versa. This moment is to be programmed.
SOFTWARE Components
ABOUT SOFTWARE
Software used is:
*Keil software for C programming *Express PCB for lay out design *Express SCH for schematic design
KEIL µVision3
What's New in µVision3?
µVision3 adds many new features to the Editor like Text Templates, Quick Function Navigation, and Syntax Coloring with brace high lighting Configuration Wizard for dialog based startup and debugger setup. µVision3 is fully compatible to µVision2 and can be used in parallel with µVision2.
What is µVision3?
µVision3 is an IDE (Integrated Development Environment) that helps you write, compile, and debug embedded programs. It encapsulates the following components:
• A project manager.
• A make facility.
• Tool configuration.
• A powerful debugger.
Express PCB
Express PCB is a Circuit Design Software and PCB manufacturing service. One can learn almost everything you need to know about Express PCB from the help topics included with the programs given.
Details:
Express PCB, Version 5.6.0
Express SCH
The Express SCH schematic design program is very easy to use. This software enables the user to draw the Schematics with drag and drop options.
A Quick Start Guide is provided by which the user can learn how to use it. Details:
Express SCH, Version 5.6.0
EMBEDDED C:
The programming Language used here in this project is an Embedded C Language. This Embedded C Language is different from the generic C language in few things like
a) Data types
b) Access over the architecture addresses.
The Embedded C Programming Language forms the user friendly language with access over Port addresses, SFR Register addresses etc.
Embedded C Data types:
Data Types Size in Bits Data Range/Usage
unsigned char 8-bit 0-255
signed char 8-bit -128 to +127 unsigned int 16-bit 0 to 65535
bit 1-bit RAM bit addressable only sfr 8-bit RAM addresses 80-FFH only
Signed char:
o Used to represent the – or + values.
o As a result, we have only 7 bits for the magnitude of the signed number, giving us values from -128 to +127.
CIRCUIT DESCRIPTION:
This project is basically aimed to build a system in which the controlling of robot is done based on the instructions given at PC and.There are two sections in this project one is transmitter section which contain PC, microcontroller , RF encoder and RF Transmitter and receiver section contain RF Decoder ,RF receiver, micro controller and Robot.
Transmitter section:
In transmitter section, PC is used for entering the instructions to control robot. Micro controller reads the instructions and directs the data to receiver by encoding data and transmitting wirelessly using RF transmitter.
Receiving section:
In receiver section, the control signals are taken by RF receiver from transmitter section. These control signals are read by micro controller and controls the robot based on the RF signals received.
SOFTWARE
µVision3
µVision3 is an IDE (Integrated Development Environment) that helps you write, compile, and debug embedded programs. It encapsulates the following components:
• A project manager.
• A make facility.
• Tool configuration.
• Editor.
• A powerful debugger.
To help you get started, several example programs (located in the \C51\Examples,
\C251\Examples, \C166\Examples, and \ARM\...\Examples) are provided.
HELLO is a simple program that prints the string "Hello World" using the
Serial Interface.
Building an Application in µVision2
To build (compile, assemble, and link) an application in µVision2, you must: 1. Select Project - (for example, 166\EXAMPLES\HELLO\HELLO.UV2). 2. Select Project - Rebuild all target files or Build target.
µVision2 compiles, assembles, and links the files in your project.
Creating Your Own Application in µVision2
To create a new project in µVision2, you must: 1. Select Project - New Project.
3. Select Project - Select Device and select an 8051, 251, or C16x/ST10 device from the Device Database™.
4. Create source files to add to the project.
5. Select Project - Targets, Groups, Files, Add/Files, select Source Group1, and add the source files to the project.
6. Select Project - Options and set the tool options. Note when you select the target device from the Device Database™ all special options are set automatically. You typically only need to configure the memory map of your target hardware. Default memory model settings are optimal for most applications.
7. Select Project - Rebuild all target files or Build target.
Debugging an Application in µVision2
To debug an application created using µVision2, you must: 1. Select Debug - Start/Stop Debug Session.
2. Use the Step toolbar buttons to single-step through your program. You may enter G, main in the Output Window to execute to the main C function.
3. Open the Serial Window using the Serial #1 button on the toolbar. Debug your program using standard options like Step, Go, Break, and so on.
Starting µVision2 and creating a Project
µVision2 is a standard Windows application and started by clicking on the program icon. To create a new project file select from the µVision2 menu
Project – New Project…. This opens a standard Windows dialog that asks you for the
new project file name.
We suggest that you use a separate folder for each project. You can simply use the icon Create New Folder in this dialog to get a new empty folder. Then select this folder and enter the file name for the new project, i.e. Project1.
µVision2 creates a new project file with the name PROJECT1.UV2 which contains a default target and file group name. You can see these names in the Project
Window – Files.
Now use from the menu Project – Select Device for Target and select a CPU for your project. The Select Device dialog box shows the µVision2 device database. Just select the microcontroller you use. We are using for our examples the Philips
80C51RD+ CPU. This selection sets necessary tool options for the 80C51RD+ device and simplifies in this way the tool Configuration
Building Projects and Creating a HEX Files
Typical, the tool settings under Options – Target are all you need to start a new application. You may translate all source files and line the application with a click on the Build Target toolbar icon. When you build an application with syntax errors, µVision2 will display errors and warning messages in the Output
Window – Build page. A double click on a message line opens the source file on the correct location in a µVision2 editor window.
Once you have successfully generated your application you can start debugging. After you have tested your application, it is required to create an Intel HEX file to download the software into an EPROM programmer or simulator. µVision2 creates HEX files with each build process when Create HEX files under Options for Target – Output is enabled. You may start your PROM programming utility after the make process when you specify the program under the option Run User Program #1.
CPU Simulation
µVision2 simulates up to 16 Mbytes of memory from which areas can be mapped for read, write, or code execution access. The µVision2 simulator traps and reports illegal memory accesses being done.
In addition to memory mapping, the simulator also provides support for the integrated peripherals of the various 8051 derivatives. The on-chip peripherals of the CPU you have selected are configured from the Device
Database selection
You have made when you create your project target. Refer to page 58 for more Information about selecting a device. You may select and display the on-chip peripheral components using the Debug menu. You can also change the aspects of each peripheral using the controls in the dialog boxes.
µVision2 will load the application program and run the startup code µVision2 saves the editor screen layout and restores the screen layout of the last debug session. If the program execution stops, µVision2 opens an editor window with the source text or shows CPU instructions in the disassembly window. The next executable statement is marked with a yellow arrow. During debugging, most editor features are still available.
For example, you can use the find command or correct program errors. Program source text of your application is shown in the same windows. The µVision2 debug mode differs from the edit mode in the following aspects:
_ The “Debug Menu and Debug Commands” described on page 28 are Available. The additional debug windows are discussed in the following.
_ The project structure or tool parameters cannot be modified. All build Commands are disabled.
Disassembly Window
The Disassembly window shows your target program as mixed source and assembly program or just assembly code. A trace history of previously executed instructions may be displayed with Debug – View Trace Records. To enable the trace history, set Debug – Enable/Disable Trace Recording.
If you select the Disassembly Window as the active window all program step commands work on CPU instruction level rather than program source lines. You can select a text line and set or modify code breakpoints using toolbar buttons or the context menu commands.
You may use the dialog Debug – Inline Assembly… to modify the CPU instructions. That allows you to correct mistakes or to make temporary changes to the target program you are debugging.
SOURCE CODE:
1.
Click on the Keil uVision Icon on Desktop3.
Click on the Project menu from the title bar4.
Then Click on New Project5.
Save the Project by typing suitable project name with no extension in your own folder sited in either C:\ or D:\6.
Then Click on save button above.7.
Select the component for your project. i.e. Atmel……8.
Click on the + Symbol beside Atmel10.
Then Click on “OK”11.
The Following window will appear12.
Then Click either YES or NO………mostly “NO”13.
Now your project is ready to USE14.
Now double click on the Target1, you would get another option “Source group 1” as shown in next page.15.
Click on the file option from menu bar and select “new”16.
The next screen will be as shown in next page, and just maximize it by double clicking on its blue boarder.17.
Now start writing program in either in “C” or “ASM”18.
For a program written in Assembly, then save it with extension “. asm” and for “C” based program save it with extension “ .C”19.
Now right click on Source group 1 and click on “Add files to Group20.
Now you will get another window, on which by default “C” files will appear.21.
Now select as per your file extension given while saving the file22.
Click only one time on option “ADD”24.
If the file contains no error, then press Control+F5 simultaneously.25.
The new window is as follows26.
Then Click “OK”27.
Now Click on the Peripherals from menu bar, and check your required port as shown in fig below28.
Drag the port a side and click in the program file.29.
Now keep Pressing function key “F11” slowly and observe.30.
You are running your program successfullyCONCLUSION
The project “LAND MINE DETECTING ROBOT” has been successfully designed and tested. Integrating features of all the hardware components used have developed. Presence of every module has been reasoned out and placed carefully thus contributing to the best working of the unit.
Secondly, using highly advanced IC’s and with the help of growing technology the project has been successfully implemented.
FUTURE ASPECTS
In this project, the robot is connected with land mine detector and is self controlled and it will sound the buzzer when it finds the landmine. This project can be extended by making robot controlled by human; it can be by mobile i.e., GSM technology, or PC. And also can try to make the landmine disposed by robot using advanced technologies.
BIBLIOGRAPHY
NAME OF THE SITES1. WWW.MITEL.DATABOOK.COM
2. WWW.ATMEL.DATABOOK.COM
3. WWW.FRANKLIN.COM
4. WWW.KEIL.COM
REFERENCES
1. 8051-MICROCONTROLLER AND EMBEDDED SYSTEM. Mohd. Mazidi. 2. The 8051 Micro controller Architecture, Programming & Applications
-Kenneth J.Ayala 3. Micro processor Architecture, Programming & Applications
