To study classification of Robots
Robots are devices that are programmed to move parts, or to do work with a tool. Robotics is a
multidisciplinary engineering field dedicated to the development of autonomous devices,
and mobile vehicles.
Robots can be classified as follows:
Classification Based on drive
Hydraulic drive: gives a robot great speed and strength. These systems can be designed to
actuate linear or rotational joints.
Advantages of hydraulic drive
are, they consume less
amount of power, good physical strength and provides good accuracy.
disadvantage of a hydraulic system is that it occupies floor space in addition to that
required by the robot.
Apart from that they are expensive and regula
r maintenance is
Electric drive: compared with a hydraulic system, an electric system provides a robot
with less speed and strength. Accordingly, electric drive systems are adopted for smaller
robots. However, robots supported by electric drive s
ystems are more accurate, exhibit
better repeatability, and are cleaner to use.
Pneumatic drive: are generally used for smaller robots. These robots, with fewer degrees
of freedom, carry out simple pick
place material handling operations.
of pneumatic drive robots include
difficult speed control and use of air accessories.
Classification based on m
point (PTP) control robot: is capable of moving from one point to another point.
The locations are recorded in the control memory. PTP robots do not control the path to
get from one point to the next point. Common applications include component in
spot welding, hole drilling, machine loading and unloading, and crude assembly
path (CP) control robot: with CP control, the robot can stop at any specified
point along the controlled path. All the points along the path mus
t be stored explicitly in
the robot’s control memory. Typical applications include spray painting, finishing,
gluing, and arc welding operations.
path robot: the control equipment can generate paths of different geometry
such as straight lines,
circles, and interpolated curves with a high degree of accuracy. All
path robots have a servo capability to correct their path.
These types of robots
commonly used for loading and unloading the objects.
Classification based on Physical con
/ Workspace Envelop
Four basic configurations are identified with most of the commercially available industrial robots
Cartesian configuration: A robot which is constructed around this configuration consists
of three orthogonal slides, as shown
in fig. the three slides are parallel to the x, y, and z
axes of the Cartesian coordinate system. By appropriate movements of these slides, the
robot is capable of moving its arm at any point within its three dimensional
spaced work space.
They have high resolution and greater accuracy and are easy to
t the disadvantages of them are
requirement of complex mechanical design for
performing linear displacement.
Cylindrical configuration: in this configuration, the robot body is a
vertical column that
swivels about a vertical axis. The arm consists of several orthogonal slides which allow
the arm to be moved up or down and in and out with respect to the body.
less complex design than
robot but they h
ave restrictions on
compatibility with other manipulators in workspace.
schematically in figure.
configuration: this configuration also goes by the name “spherical
coordinate” because the workspace within which
it can move its arm is a partial sphere as
shown in figure. The robot has a rotary base and a pivot that can be used to raise and
lower a telescoping arm.
They have good resolution but with spherical coordinates the
spatial relationship are more difficult
robot and cylindrical robot.
Articulated Configuration: An
is a robot with
). Articulated robots can range from simple two
res to systems with 10 or more interacting joints. They are powered by a variety of
These types of robots do
. They have ability to avoid
D workspace. But the disadvantages
are poor resolution and difficult to controls due to three
acronym stands for
Selective Compliance Assembly Robot
Articulated Robot Arm. By virtue of the SCARA's parallel
axis joint layout, the arm is slightly compliant in the X
Y direction but rigid in the ‘Z’
direction, hence the term: Selective Compliant. This is advantageous for many types of
i.e., inserting a round pin in a round hole without binding.
The second attribute of the SCARA is the jointed two
link arm layout similar to our
human arms, hence the often
used term, Articulated. This feature allows the arm to
extend into confined areas a
nd then retract or “fold up” out of the way. This is
advantageous for transferring parts from one cell to another or for loading/ unloading
process stations that are enclosed.
Classification based on intelligence
First generation robots are
characterized by fixed control programs, they are capable to
only repeat in a strict fashion operations previously programmed into them, they cannot
adapt to the environment so no external perturbations must exist. The program can be
changed to some extent
, but these robots are best suited in industrial environments
performing repetitive operations.
They have limited memory and
Robot arm is not much smooth.
Second generation robots are adaptive, they can operate in variable or partia
environments. The ability to adapt under the effect of external perturbations is enabled by
using sensors that measure various parameters of the environment. These robots execute
a series of predefined operations but can also take into account
changes in the
environment and alter their routine in order to accomplish their tasks.
They have good
amount of memory and offers a good flexibility. They are advance version of 1
generation robots. Second generation robots also offers
Third generations robots are intelligent, they have certain artificial intelligence abilities,
their degree of intelligence varies according to needs identified in the design phase. These
robots are capable of defining their instantaneous actio
ns taking into account information
gathered by tactile, visual or noise sensors, resolve particular issues and modify their
Industrial robots belong
Fourth generation robots have walking capability. Robots like android, humanoids,
biobots, macrobots falls under this category. They are very intelligent one have good
Robot classification based on their function and performance
Based on the fun
performed by the robot
, they can be classified as follows:
Manual manipulator: They are operated manually by the human beings.
Fixed sequence robots
They generally have a fixed sequence which cannot be changed
Variable sequence robots
Sequence of operations to do particular task can be varied.
In playback robot, first task is taught to the robot. During the teaching
memorizes the task, stores the taught instructions in memory and then
plays back the
taught by the user. Hence the name playback robot.
they operates on numbers.
Robots operated by remote control, extra terrestrial robot
MARS path finder), uses
Hence we studied classification of robots.