TREE CLIMBING ROBOT
Submitted in the partial fulfillment of the requirement for the award of
IN MECHANICAL ENGINEERING ”
1. G.K. MANIGANDAN
2. B. KARTHIKEYAN
3. P. BALASUBRAMANI
4. J. DHANAJEYAN
5. D. DURAIVEL
6. L. PRABHU
Under guidance of
DEPARTMENT OF MECHANICAL ENGINEERING
SRI DURGA DEVI POLYTECHNIC COLLEGE
KAVERIPETTAI, CHENNAI – 600053
SRI DURGA DEVI POLYTECHNIC COLLEGE
KAVERIPETTAI, CHENNAI – 600053
This is to certify that this Project work on
submitted by …………………… ……………. Reg. No. ……………
in partial fulfillment for the award of
DIPLOMA IN MECHANICAL ENGINEERING
This is the bonafide record of work carried out by him under
our supervision during the year 2014
Submitted for the Viva-voce exam held on ……………..
HEAD OF THE DEPARTMENT
At the outset, we would like to emphasize our sincere thanks to the
encouragement and valuable advice.
we thank our Esquired Head of Department Mr MEGANATHAN, M.E.,
for presenting his felicitations on us.
We are grateful on our Entourages Mr. SABARINATHAN , M.E.,
for guiding in various aspects of the project making it a grand success.
We also owe our sincere thanks to all staff members of the
Mechanical Engineering Department.
Ultimately, we extend our thanks to all who had rendered their cooperation for the success of the project.
This is a self – assessment test on the part of the students to assess his
competency in creativity.
During the course of study, the student is put on a sound theoretical
foundation of various mechanical engineering subjects and of course, to a
satisfactory extent. Opportunities are made available to him to work on
different kinds of machines, so that he is exposed to various kinds of
As a students learn more and more his hold on production technology
becomes stronger. He attains a stage of perfection, when he himself is able
to design and fabricate a device.
This is the project work. That is the testimony for the strenuous
training, which the student had in the institute. This assures that he is no
more a student, he is an engineer.
This report discuses the necessity of the project and various aspects of
planning , design, selection of materials, fabrication, erection, estimation and
From centuries humans have been climbing trees and poles for various
jobs. This thing we have inherited from our ancestors. Evidently, this skill
has evolved from the need of protection from animals or collecting food
from trees. In the present world climbing poles is used in other fields of
technology as well.
With time the needs have increased. The requirement to carry load on and
off the trees and poles has shifted man’s focus on building machines to do
This “Tree Climber” is built to solve the problems man faced with climbing.
The robot works on two sub-mechanisms:
The machine could take load on and off the tree and pole whenever required.
The robot is autonomous.
The speed of climbing depends on the pitches of the ball screws placed for
movements of arms and the top and bottom gripper assembly.
The movement of the machine is like an ape climbing the tree.
First, the upper pair of arms grip the tree then the body moves up then the
lower pair of arms grip the tree then the upper pair leaves the contact and the
body moves up.
To build a Tree climbing machine which can bear a loading up to 2
@ Initial Problem Statement:
The machine should be able to climb straight poles and trees to fulfill all
It is difficult to build a heavy machine in the students’ lab.
Trees and poles have different friction coefficient values and different
built structures so the devised mechanism should be such that it works
equally good for both kind of surfaces.
LIMITATIONS OF DESIGN:
The robot is built for branchless trees.
The load carrying capacity could be maximized only to 3 kgs
HARD WARE CIRCUIT REQUIREMENTS
The hardware circuit requirements details consists of
1. Micro controller system
2. Power supply –BATTERY 7.5AH /12 V DC)2 NOS
3. 5VDC TO 12VDC DRIVE CARD
REMOTE CONTROL CIRCUIT
5. MOTOR FORWARD AND REVERSE CONTROL RELAY
6. 24DC MOTOR WIYH BUILT IN GEAR BOX
MICRO CONTROLLER SYSTEM:
This system monitors the engine condition by using PIC 16F870 (28
pin IC Package) micro controller. The pin details of micro controller are
shown in figure.
The circuit diagram for this micro controller board is shown below,
MOTHER BOARD CIRCUIT DETAILS
the reset switch is connected to PORTA (i.e)pin no 1, The start switch is
connected to PORT B, 7 and MOTOR is connected to PORT C, The power
supply is connected to Pin 19 & 20.The ARIEL CIRCUIT is connected to
PORTB ,6.and PORTB ,7
A 12 –0 v step down transformer is used to step down 230V AC to
12V AC .This 12V AC supply is converted to 12V DC using four rectifier
diodes. The voltage from the rectifier section is regulated to 12V DC using
7812 IC .This voltage is used for supply for the DC motor. From 12V DC
the 7805 IC is used for
regulating 5V DC for the
microcontroller. The power supply circuit is shown in fig.
power supply of
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 can be shown as below
Block Diagram of a Regulated Power Supply System
Similarly, 12v regulated supply can also be produced by
suitable selection of the individual elements. Each of the blocks is
described in detail below and the power supplies made from these
blocks are described below with a circuit diagram and a graph of their
A transformer steps down high voltage AC mains to low voltage AC.
Here we are using a center-tap transformer whose output will be sinusoidal
with 36volts peak to peak value.
The low voltage AC output is suitable for lamps, heaters and special AC
motors. It is not suitable for electronic circuits unless they include a rectifier
and a smoothing capacitor. The transformer output is given to the rectifier
A rectifier converts AC to DC, but the DC output is varying. There
are several types of rectifiers; here we use a bridge rectifier.
The Bridge rectifier is a circuit, which converts an ac voltage to dc
voltage using both half cycles of the input ac voltage. The Bridge rectifier
circuit is shown in the figure. The circuit has four diodes connected to form
a bridge. The ac input voltage is applied to the diagonally opposite ends of
the bridge. The load resistance is connected between the other two ends of
For the positive half cycle of the input ac voltage, diodes D1 and D3
conduct, whereas diodes D2 and D4 remain in the OFF state. The
conducting diodes will be in series with the load resistance R L and hence the
load current flows through RL.
For the negative half cycle of the input ac voltage, diodes D2 and D4
conduct whereas, D1 and D3 remain OFF. The conducting diodes D2 and
D4 will be in series with the load resistance R L and hence the current flows
through RL in the same direction as in the previous half cycle. Thus a bidirectional wave is converted into unidirectional.
Output of the Rectifier
The varying DC output is suitable for lamps, heaters and standard
motors. It is not suitable for lamps, heaters and standard motors. It is not
suitable for electronic circuits unless they include a smoothing capacitor.
Smoothing or filtering:
The smoothing block smoothes the DC from varying greatly to a
small ripple and the ripple voltage is defined as the deviation of the load
voltage from its DC value. Smoothing is also named as filtering.
Filtering is frequently effected by shunting the load with a
capacitor. The action of this system depends on the fact that the capacitor
stores energy during the conduction period and delivers this energy to the
loads during the no conducting period. In this way, the time during which
the current passes through the load is prolonging Ted, and the ripple is
considerably decreased. The action of the capacitor is shown with the help of
Waveform of the rectified output smoothing
Regulator eliminates ripple by setting DC output to a fixed voltage.
Voltage regulator ICs are available with fixed (typically 5V, 12V and 15V)
or variable output voltages. Negative voltage regulators are also available
Many of the fixed voltage regulator ICs has 3 leads (input, output
and high impedance). They include a hole for attaching a heat sink if
necessary. Zener diode is an example of fixed regulator which is shown
Transformer + Rectifier + Smoothing + Regulator:
which is used to operate the two different voltages.
SPECIFICATION OF RELAY:
a) Nature of supply: 12v dc to 230 v ac
b) Coil voltage: 12v
c) No of NO and NC contacts: 1, 1
d) No of poles: single pole double throw
e) Shape of contact point: flat
f) Contact point material: silver or silver alloy
g) Type of relay: electro mechanical
5 TO 24 V DC DRIVE CARD
Here we have to drive the 12V DC load. The 5V signal from
the PIC 16F870 micro-controller is fed into the input of interface
circuit. SL100 transistor is used here for high speed switching
purpose and IRF 540N MOSFET is connected to the motor to
handle the larger current drawn by the MOTOR.
A Resistor is a heat-dissipating element and in the electronic circuits it is
mostly used for either controlling the current in the circuit or developing a voltage
drop across it, which could be utilized for many applications. There are various
types of resistors, which can be classified according to a number of factors
Material used for fabrication
Wattage and physical size
Ambient temperature rating
Basically the resistor can be split in to the following four parts from the
construction view point.
(2) Resistance element
(4) Protective means.
The following characteristics are inherent in all resistors and may be
controlled by design considerations and choice of material i.e. Temperature co–
efficient of resistance, Voltage co–efficient of resistance, high frequency
characteristics, power rating, tolerance & voltage rating of resistors. Resistors
may be classified as
(2) Semi variable
(3) Variable resistor.
The fundamental relation for the capacitance between two flat plates
separated by a dielectric material is given by:C=0.08854KA/D
Where: C= capacitance in pf.
K= dielectric constant
A=Area per plate in square cm.
D=Distance between two plates in cm
Design of capacitor depends on the proper dielectric material with
particular type of application. The dielectric material used for capacitors may be
grouped in various classes like Mica, Glass, air, ceramic, paper, Aluminum,
electrolyte etc. The value of capacitance never remains constant. It changes with
temperature, frequency and aging. The capacitance value marked on the
capacitor strictly applies only at specified temperature and at low frequencies.
LED (Light Emitting Diodes):
As its name implies it is a diode, which emits light when forward biased.
Charge carrier recombination takes place when electrons from the N-side cross
the junction and recombine with the holes on the P side. Electrons are in the
higher conduction band on the N side whereas holes are in the lower valence
band on the P side. During recombination, some of the energy is given up in the
form of heat and light. In the case of semiconductor materials like Gallium
arsenide (GaAs), Gallium phoshide (Gap) and Gallium arsenide phoshide
(GaAsP) a greater percentage of energy is released during recombination and is
given out in the form of light. LED emits no light when junction is reverse biased.
A relay is an electrically operated switch. Many relays use an electromagnet
to operate a switching mechanism mechanically, but other operating
principles are also used. Relays are used where it is necessary to control a
circuit by a low-power signal (with complete electrical isolation between
control and controlled circuits), or where several circuits must be controlled
by one signal. The first relays were used in long distance telegraph circuits,
repeating the signal coming in from one circuit and re-transmitting it to
another. Relays were used extensively in telephone exchanges and early
computers to perform logical operations.
A type of relay that can handle the high power required to directly control an
electric motor is called a contactor. Solid-state relays control power circuits
with no moving parts, instead using a semiconductor device to perform
switching. Relays with calibrated operating characteristics and sometimes
multiple operating coils are used to protect electrical circuits from overload
or faults; in modern electric power systems these functions are performed by
digital instruments still called "protective relays".
3.b Basic design and operation:
A simple electromagnetic relay consists of a coil of wire surrounding soft
iron core, an iron yoke which provides a low reluctance path for magnetic
flux, a movable iron armature, and one or more sets of contacts (there are
two in the relay pictured). The armature is hinged to the yoke and
mechanically linked to one or more sets of moving contacts. It is held in
place by a spring so that when the relay is de-energized there is an air gap in
the magnetic circuit. In this condition, one of the two sets of contacts in the
relay pictured is closed, and the other set is open. Other relays may have
more or fewer sets of contacts depending on their function. The relay in the
picture also has a wire connecting the armature to the yoke. This ensures
continuity of the circuit between the moving contacts on the armature, and
the circuit track on the printed circuit board (PCB) via the yoke, which is
soldered to the PCB.
When an electric current is passed through the coil it generates a magnetic
field that attracts the armature and the consequent movement of the movable
contact either makes or breaks (depending upon construction) a connection
with a fixed contact. If the set of contacts was closed when the relay was deenergized, then the movement opens the contacts and breaks the connection,
and vice versa if the contacts were open. When the current to the coil is
switched off, the armature is returned by a force, approximately half as
strong as the magnetic force, to its relaxed position. Usually this force is
provided by a spring, but gravity is also used commonly in industrial motor
starters. Most relays are manufactured to operate quickly. In a low-voltage
application this reduces noise; in a high voltage or current application it
When the coil is energized with direct current, a diode is often placed across
the coil to dissipate the energy from the collapsing magnetic field at
deactivation, which would otherwise generate a voltage spike dangerous to
semiconductor circuit components. Some automotive relays include a diode
inside the relay case. Alternatively, a contact protection network consisting
of a capacitor and resistor in series (snubber circuit) may absorb the surge. If
the coil is designed to be energized with alternating current (AC), a small
copper "shading ring" can be crimped to the end of the solenoid, creating a
small out-of-phase current which increases the minimum pull on the
armature during the AC cycle.
A solid-state relay uses a thyristor or other solid-state switching device,
activated by the control signal, to switch the controlled load, instead of a
solenoid. An optocoupler (a light-emitting diode (LED) coupled with a
photo transistor) can be used to isolate control and controlled circuits.
3.c Type of Relay:
Machine tool relay
Solid state contactor relay
Forced-guided contacts relay
Overload protection relay
Relays are used to and for:
Control a high-voltage circuit with a low-voltage signal, as in some
types of modems or audio amplifiers,
Control a high-current circuit with a low-current signal, as in the
startersolenoid of an automobile,
Detect and isolate faults on transmission and distribution lines by
opening and closing circuit breakers (protection relays),
A DPDT AC coil relay with "ice cube" packaging
Isolate the controlling circuit from the controlled circuit when the two
are at different potentials, for example when controlling a mains-powered
device from a low-voltage switch. The latter is often applied to control office
lighting as the low voltage wires are easily installed in partitions, which may
be often moved as needs change. They may also be controlled by room
occupancy detectors in an effort to conserve energy,
Logic functions. For example, the boolean AND function is realised
by connecting normally open relay contacts in series, the OR function by
connecting normally open contacts in parallel. The change-over or Form C
contacts perform the XOR (exclusive or) function. Similar functions for
NAND and NOR are accomplished using normally closed contacts. The
Ladder programming language is often used for designing relay logic
Early computing. Before vacuum tubes and transistors, relays were
used as logical elements in digital computers. See ARRA (computer),
Harvard Mark II, Zuse Z2, and Zuse Z3.
Safety-critical logic. Because relays are much more resistant than
semiconductors to nuclear radiation, they are widely used in safety-critical
logic, such as the control panels of radioactive waste-handling machinery.
Time delay functions. Relays can be modified to delay opening or
delay closing a set of contacts. A very short (a fraction of a second) delay
would use a copper disk between the armature and moving blade assembly.
Current flowing in the disk maintains magnetic field for a short time,
lengthening release time. For a slightly longer (up to a minute) delay, a
dashpot is used. A dashpot is a piston filled with fluid that is allowed to
escape slowly. The time period can be varied by increasing or decreasing the
flow rate. For longer time periods, a mechanical clockwork timer is
INTRODUCTION TO MICROCONTROLLER
PIC WITH RS-232
The PIC Microcontrollers are supported with a full range of Hardware
and software development tools. The used PIC16F870 device comes in 28
pin package. To communicate with the PIC we are using RS-232 standard
port of computer. In personal computer, data transfer takes place serially.
RS-232 standard is used for serial communication. PIC Microcontroller is
linked to PC through the RS-232 port. The PC displays the menu for
selecting the calibrating equipment and all the calibration results graphically
and in tabular form. The user can access the calibration reports, comparison
graphs etc at any time using the menu offered in the PC.
The PIC Microcontrollers are supported with a full range of hardware
and software development tools. The used PIC16F870 device comes in 28
pin package. To communicate with the PIC we are using RS-232 port of the
computer. So we have to initialize the port before using it. To initialize and
to communicate with the PIC, the file COM.C defines and uses several
functions. The functions and their definitions are given below.
ADC RELATED FUNCTIONS:
void Set Reference (int ref);
This function is used to set the INTERNAL or EXTERNAL reference for
The parameter ref can accept any one of the two values. They are,
Set Reference (INTERNAL_REF);
Float GetAdcCh(int Chno);
This function is used to get the specified channel’s (Chno) digital value
from ADC. The parameter Chno can accept a range of values from 0 to 9,
which is the channel number.
Var = GetAdcCh(5);
Void Initialize Port (char * str);
This function must be called before performing any digital input/output
Can be configured as
Configurable bits can be either zero or one according to the initialization. If
the particular bit is to be used as a input port then write ‘1’ to it else ‘0’ for
Initialize Port (“[1ffffffff]”);
Above statement mention all registers bits are act as input port.
MICROCONTROLLER CORE FEATURES:
High-performance RISC CPU
Only 35 single word instructions to learn
All single cycle instructions except for program branches which are
Operating speed: DC-20 MHz clock input DC – 200 ns instruction
4K x 14 words of Program Memory, 256 x 8 bytes of Data Memory
Interruput capability (upto 14 Internal / External interrupt sources)
Eight level deep hardware stack
Direct, indirect, and relative addressing modes
Power-on Reset (POR)
Power-up Timer (PWRT) and Oscillator Start-up Timer (OST)
Watchdog timer (WDT) with its own on-chip RC oscillator for
Power saving SLEEP mode
Selectable oscillator options
Low-power, high-speed CMOS EPROM technology
Fully static design
In-circuit Serial Programming (ISC)
Wide operating voltage range: 2.5V to 5.5V
High Sink / Source current 25/25 mA
Commercial and Industrial temperature ranges
Low power consumption
<2 mA at 5V, 4 MHz
22.5 mA typical at 3V, 32 KHz
<1 mA typical standby current
Timer 0: 8-bit timer / counter with 8-bit prescaler
Timer 1: 16 bit timer / counter with prescaler, can be incremented
during sleep via external crystal/clock
Timer 2: 8 bit timer / counter with 8 bit period register, prescaler and
Two capture, compare, PWM modules
Caputure is 16 bit, max. resolution is 12.5 ns
Compare is 16 bit, max. resolution is 200 ns,
PWM max. resolution is 10 bit
12 bit multi channel Analog-to Digital converter
On-chip absolute band gap voltage reference generator
Synchronous Serial Port (SSP) with SPI (Master Mode) and I 2 C
Universal Synchronous Asynchronous Receiver Transmitter, supports
high / low speeds and 9 bit address mode (USART/SCI)
Parallel Slave Port (PSP) 8 bits wide, with external RD, WR and CS
Programmable Brown out detection circuitry for Brownout Reset
Programmable Low-voltage detection circuitry
Each PIC16F870 instruction is a 14 bit word divided into an opcode
which specifies the instruction type and one or more operands which further
specify the operation of the instruction. The PIC16F870 instruction set
summary in Table lists byte oriented bit-oriented and literal and control
operations. Table shows the opcode field descriptions. For byteoriented
instructions, ‘f’ represents a file register designator and ‘d’ represents a
The file register designator specifies which file
register is to be used by the instruction. The destination designator specifies
where the result of the operation is to be placed. If ‘d’ is zero, the result is
placed in the W register. If ‘d’ is one, the result is placed in the file register
specified in the instruction. For bit-oriented instructions. ‘b’ represents a bit
field designator which selects the number of the bit affected by the
operation, while ‘f’ represents the number of the file in which the bit is
located. For literal and control operations, ‘k’ represents an eight or eleven
bit constant or literal value.
The instruction set is highly orthogonal and is grouped into three basic
Byte oriented operations
Literal and control operations
All instructions are executed within one single instruction cycle,
unless a conditional test is true or the program counter is changed as a result
of an instruction. In this case, the execution takes two instruction cycles
with the second cycle executed as a NOP. One instruction cycle consists of
four oscillator periods. Thus, for an oscillator frequency of 4 MHz, the
normal instruction execution time is 1 micro second. If a conditional test is
true or the program counter is changed as a result of an instruction, the
instruction execution time is 2 µs. All examples use the following format to
represent a Hexadecimal number : 0xhh, where h signifies a hexadecimal
GENERAL FORMAT FOR INSTRUCTIONS:
Register file address (0 x 00 to 0x7F)
Working register (accumulator)
Bit address within an 8-bit file register
Literal field, constant data or label
Don’t care location (=0 or 1)
16CXX has 35 instructions. All instructions are single cycle, except
for any program that branches.
This take two cycles since the fetch
instruction is flushed from the pipe line by changing the content of PC,
while the new instruction is being fetched and then executed.
instruction set is grouped into three basic categories.
# Byte Oriented operations
# Bit oriented operations
# Literal and control operations
For byte-oriented instructions, ‘f’ represents a file register designator
and ‘d’ represents destination designator.
The file register designator
specifies which file register is to be used by the instruction. For bit oriented
instructions ‘b’ represents a bit field designator which selects the number of
the bit affected by the operation, while ‘f’ represents the number of the file
in which the bit is located. For literal and control operation ‘k’ represents an
eight or eleven bit constant or literal value.
BIT ORIENTED FILE REGISTER OPERATIONS:
LITERAL AND CONTROL OPERATIONS:
It requires simple maintenance cares.
this project does not require any external transmission arrangements.
This add to the system leads safety for coconut tree climber
Easy to Handle.
We make this project entirely different from other projects. Since
concepts involved in our project is entirely different that a single unit is used
to various purpose which is not developed by any of other team members.
We have successfully complete this project work at our Institute.
By doing this project work we understood the working principle of
uses of various relays, switches, valves and cylinders.
Once again we express our sincere thanks to our staff members.