A robotic arm consists of linked segments connected by movable joints, similar to a human arm. The end of the kinematic chain that can grip or otherwise interact with its environment is called the end effector. The range of reachable positions for the end effector is defined as the robot's workspace. Proper selection of motors at each joint is important to ensure the arm can handle expected torques without failing. Common types of robot grippers include vacuum, hydraulic, pneumatic, and magnetic options, each with strengths for different applications.

2.  A robotic arm is a type of mechanical arm,
usually programmable, with similar functions to a
human arm; the arm may be the sum total of the
mechanism or may be part of a more complex robot.
 The links of such a manipulator are connected by joints
allowing either rotational motion (such as in an articulated
robot) or translational (linear) displacement.
 The links of the manipulator can be considered to form
a kinematic chain. The terminus of the kinematic chain of
the manipulator is called the end effectors and it is
analogous to the human hand.

3.  A degree of freedom is a joint on the arm, a place where it
can bend or rotate or translate. We can typically identify
the number of degrees of freedom by the number of
actuators on the robot arm(in case of serial arms). so for
simplicity it is treated as separate subsystem in basic robot
arm design.

4.  The robot workspace (sometimes
known as reachable space) is a
collection of points that the end
effector (gripper) can reach. The
workspace is dependent on the DOF
angle/translation limitations, the arm
link lengths, the angle at which
something must be picked up at, etc.
The workspace is highly dependent on
the robot configuration. The figure
given below describes the workspace
for our serial arm.

7.  To estimate the torque required at each joint, we must
choose the worst case scenario
 As arm is rotated clockwise, L, the perpendicular distance
decreases from L3 to L1 (L1=0). Therefore the greatest
torque is at L3 (F does not change) and torque is zero at L1.
 Motors are subjected to the highest torque when the arm
is stretched out horizontally

8.  If your arm has multiple points, you must determine the torque around
each joint to select the appropriate motor
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9. 1. Robotic arm (gripper) to hold
and release object
2. Lead screw assembly to move
the arm up and down
3. Electronic circuits for the
controls

11. • vacuum grippers
• pneumatic grippers
• hydraulic grippers
• servo-electric grippers
• Magnetic grippers

12.  The vacuum gripper has been the standard in
manufacturing because of its high level of flexibility. This
type of robot gripper uses a rubber or polyurethane suction
cup to pick up items. Some vacuum grippers use a closed-
cell foam rubber layer, rather than suction cups, to
complete the application.

13.  The hydraulic gripper provides the most strength and is
often used for applications that require significant amounts
of force. These robotic grippers generate their strength
from pumps that can provide up to 2000psi. Although they
are strong, hydraulic grippers are messier than other
grippers due to the oil used in the pumps. They also may
need more maintenance due the gripper being damaged
because of the force used during the application.

14.  The pneumatic gripper is popular due to its compact size
and light weight. It can easily be incorporated into tight
spaces, which can be helpful in the manufacturing
industry. Pneumatic robot grippers can either be opened or
closed, earning them the nickname “bang bang” actuators,
because of the noise created when the metal-on-
metal gripper operates.

15.  The servo-electric gripper appears more and more in
industrial settings, due to the fact that it is easy to
control. Electronic motors control the movement of
the gripper jaws. These grippers are highly flexible and
allow for different material tolerances
when handling parts. Servo-electric grippers are also
cost effective because they are clean and have no air
lines.

16.  Electromagnets
 Permanent magnets

17.  Electromagnetic grippers include a controller unit and
a DC power for handling the materials. This type of
grippers is easy to control, and very effective in releasing
the part at the end of the operation than the permanent
magnets. If the work part gripped is to be released, the
polarity level is minimized by the controller unit before the
electromagnet is turned off. This process will certainly help
in removing the magnetism on the work parts. As a result, a
best way of releasing the materials is possible in this
gripper.

18.  The permanent magnets do not require any sort of external
power as like the electromagnets for handling the
materials. After this gripper grasps a work part, an
additional device called asstripper push – off pin will be
required to separate the work part from the magnet. This
device is incorporated at the sides of the gripper.
 The advantage of this permanent magnet gripper is that it
can be used in hazardous applications like explosion-proof
apparatus because of no electrical circuit. Moreover, there
is no possibility of spark production as well.

19.  In constructing the arm, we made use of five servo motors (including
gripper) since our structure allows movement in all three dimensions.
There is a servo motor at the base, which allows for angular movement
of the whole structure; other two at the shoulder and elbow to allow the
upward and downward movement of the arm; one for the movement of
the wrist while the last servo motor at the end effector allows for the
gripping of objects.
 The serial arm is a four degree of freedom system. Three DOF control
the position of the arm in the Cartesian pace, one for wrist orientation
and one additional servo for actuating gripper.

23.  Industrial robots have various axis
configurations. The vast majority
of articulated robots,
however, feature six axes, also
called six degrees of freedom. Six
axis robots allow for greater
flexibility and can perform a
wider variety of applications than
robots with fewer axes.

26.  Servos are a special type of DC motors with built in gearing and
feedback control loop circuitry and they don’t require motor
controllers. These motors are mainly developed for making robots,
toys, etc. that are mainly used for education and not for industrial
applications.
 Servos are becoming extremely popular with robot, RC plane, and RC
boat builders. Most servo motors can rotate about 90 to 180 degrees.
Some rotate through a full 360 degrees or more. However, servos are
unable to continually rotate, meaning they can't be used for driving
wheels (unless modified), but their precision positioning makes them
ideal for robot arms and legs, rack and pinion steering, and sensor
scanners to name a few. Since servos are fully self contained, the
velocity and angle control loops are very easy to implement. To use a
servo, we connect the black wire to ground, the red to a 4.8-6V source,
and the yellow/white wire to a signal source (such as from your
microcontroller). Vary the square wave pulse width from 1-2ms and the
servo is now position/velocity controlled.

27. Servo Wiring:
 All servos have three
wires:
 Black or Brown is for
ground.
 Red is for power (~4.8-
6V).
 Yellow, Orange, or White
is the signal wire (3-5V).
Servo Voltage (Red and
Black/Brown wires):
 Servos can operate under a
range of voltages. Typical
operation is from 4.8V to 6V.
There are a
 few micro sized servos that can
operate at less, and now a few
Hitec servos that operate at
much
 more.

28.  While the black and red wires provide power to the motor, the signal
wire is what we use to command the servo. The general concept is to
simply send an ordinary logic square wave to your servo at a specific
wave length (50Hz), and the servo goes to a particular angle. The
wavelength directly maps to servo angle. In our case Arduino Mega
takes input from the PC and generates
 the corresponding square wave, which in turn controls the angular
position of the servo motor.
 The standard time vs. angle is represented in this chart:

29.  Overview
 An Arduino is a single-board microcontroller and a software suite for
programming. It is designed for an Atmel AVR processor and features
on-board I/O support. The software consists of a standard
programming language and the boot loader that runs on the board.
 We are using Arduino Mega microcontroller board based on the
ATmega1280.
 It has 54 digital input/output pins (of which 14 can be used as PWM
outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz
crystal oscillator, a USB connection, a power jack, an ICSP header, and
a reset button.
 It contains everything needed to support the microcontroller; simply
connect it to a computer with a USB cable or power it with an AC-to-DC
adapter or battery to get started.

31. •POWER: The Arduino Mega can be powered via the USB connection or with
an external
•power supply: The power source is selected automatically.
•The power pins are as follows:
•VIN: The input voltage to the Arduino board when it's using an external power
source.
•5V: The regulated power supply used to power the microcontroller and other
components on the board.
•3V3: 3.3 volt supply generated by the on-board FTDI chip. Maximum current
draw is 50 mA.
•GND: Ground pins.
•MEMORY: The ATMEGA 1280 has 128 KB of flash memory for storing
code.
•COMMUNICATION: The Arduino software includes a serial monitor
which allows simple textual data to be sent to and from the Arduino board. The RX
and TX LEDs on the board will flash when data is being transmitted via the FTDI
chip and USB connection to the computer (but not for serial communication on
pins 0 and 1. It has a number of facilities for communication with a computer,
another Arduino, or other microcontrollers.

32. In this tutorial, we assume you're using an Arduino Mega.
The Arduino is a simple board that contains everything you need to start working
with electronics and microcontroller programming. This diagram illustrates the
major components of an Arduino Mega.
You also need a standard USB cable (A plug to B plug): the kind you would connect
to a USB
printer, for example.

33. 7805 is a 5V fixed three terminal positive voltage regulator IC. The IC has features
such as safe operating area protection, thermal shut down, internal current limiting
which makes the IC very rugged. Output currents up to 1A can be drawn from the IC
provided that there is a proper heat sink. A 9V transformer steps down the main
voltage, 1A bridge rectifies it and capacitor C1 filters it and 7805 regulates it to
produce a steady 5Volt DC. The circuit schematic is given below.
Circuit diagram with Parts list.

35. Servomotors are special position motors. They are
often used in RC airplanes, RC cars and robots,
where a precise position is required. You can easily
find them in a RC specialized store.
A typical servomotor consists in a DC motor
connected with a control circuit and a gear box. The
gear box converts the DC motor into torque. The
control circuit has a potentiometer for feedback, so it
can read the current position and adjust
it automatically. A servomotor can't do a complete
turn, they go up to 90 or 180 degress.
A servomotor has 3 wires: red (V+), black (GND) and
white or yellow (SIGNAL). The red and black are the
power supply wires and the third is for control.
To control a servomotor, power it with 5V and supply
the control wire with a voltage from 0 to V+, the
position will be proportional to the Signal voltage. To
test it, connect it like this: