Mechatronics & Robotics : Robotics

By Apoorbo Roy|Updated : July 13th, 2021

Introduction

Over the last few decades, use of industrial robots can be seen worldwide and has
significantly increased with a faster increasingly trend. Mostly these are being used for
material handling, welding, painting, assembling of parts, packaging, handling
hazardous materials, undersea operations, etc. Robot manipulator implicates an
electromechanical device that requires human dexterity to perform a variety of tasks. 

Introduction

Over the last few decades, use of industrial robots can be seen worldwide and has
significantly increased with a faster increasingly trend. Mostly these are being used for
material handling, welding, painting, assembling of parts, packaging, handling
hazardous materials, undersea operations, etc. Robot manipulator implicates an
electromechanical device that requires human dexterity to perform a variety of tasks. An important part of industrial robot manipulators is to achieve desired position and
orientation of end effector or tool so as to complete the pre-specified task. To achieve
the above stated goal one should have the sound knowledge of inverse kinematic
problem. The problem of getting inverse kinematic solution has been on the outline of
various researchers and is deliberated as thorough researched and mature problem.
There are many fields of applications of robot manipulators to execute the given tasks
such as material handling, pick-n-place, planetary and undersea explorations, space
manipulation, and hazardous field etc. Moreover, medical field robotics catches
applications in rehabilitation and surgery that involve kinematic, dynamic and control
operations. Therefore, industrial robot manipulators are required to have proper
knowledge of its joint variables as well as understanding of kinematic parameters.
The Three Laws of Robotics
The following Three Laws are a set of rules devised by the science fiction author Isaac Asimov in
1942.
1. A robot may not injure a human being or, through inaction, allow a human being to come
to harm.
2. A robot must obey the orders given to it by human beings, except where such orders
would conflict with the First Law.
3. A robot must protect its own existence as long as such protection does not conflict with
the First or Second Law.
Robots do not inherently obey the Three Laws; if the rules are to be obeyed their human creators
must choose to program them in.

Evolution of robot manipulators


The concept of the robot was evidently recognized by the Czech playwright Karel
Capek during the twentieth century in his play ―Rossum‘s Universal Robots (R.U.R.)‖.
The term ―robot‖ is derived from ―robota‖ which means subordinate labour in Slave
languages. In 1940, the ethics of the interaction between robots and humans was
envisioned to be governed by the well-known three fundamental laws of Isaac Asimov,
the Russian science-fiction writer in his novel ―Run-around‖.
The middle of the twentieth century brought the first explorations of the connection
between human intelligence and machines, marking the beginning of an era of fertile
research in the field of artificial intelligence (AI). Around that time, the first robots
were realized. They benefited from advances in the different technologies of mechanics,
controls, computers and electronics. As always, new designs motivate new research and
discoveries, which, in turn, lead to enhanced solutions and thus to novel concepts. This
virtuous circle over time produced that knowledge and understanding that gave birth to
the field of robotics, properly referred to as the science and technology of robots.

Some of the landmark
developments in industrial robots are:

1947 –The first servo controlled electric tele-operator launched
1948 –Introduction of force feedback in tele-operator
1954 –First programmable design from George Devol
1956 –Foundation of Unimation company by Josh Engelberger the Unimation
Company
1961 –General Motors implementation of Unimate robot in New Jersey
1963 –First vision system developed for robots
1973 - Stanford University developed robot arm
1974 –First computer controlled manipulator introduced the MilacronT3
1978 –Development of PUMA 6 axis robot
1979 –First assembly line SCARA robot designed by Japanese
1981 - Mellon University developed first direct drive manipulator
1989- Hi-tech chess playing robot
1996 - Concept of Honda's P2 humanoid robot
1997 - Mars space exploration robot sojourner rover
2001 - Canadarm2 was implemented into ISS
2002- Introduction of humanoid robot ASIMO
2004 - Cornell University exposed a robot skilled of self-replication
2005- Development of wireless operated and computer controlled HUBO robot by
KIST
2006- Starfish 4-legged robot developed by Cornell University
2007- Japanese company introduced entertainment robot TOMY
2013-to present- Kuka Robotics LBR iiwa, a lightweight robot Rob coaster for
entertainment

Classification by mechanism


Typically a robot manipulator may be either a serial one having open loop or a parallel
one having closed loop structure. In industrial robot manipulators the joint type may be
either prismatic (P) or revolute (R) whereas the link type may be either rigid or flexible.
Moreover, there can be hybrid structure that consists of both open and closed loop
mechanical chains.

Classification by degree of freedom and related components


The specific motion of links related to any mechanism or machine can be defined as the
degree of freedom. To execute specific task degree of freedom will always play the
main role. The total number of dof will always equal the number of independent
displacement of links. As we know that 6-dof robot manipulator is the basis to execute
the specific task in 3-dimentional space. On the other hand, mathematical definition of
degrees of freedom will be a minimum number of independent joint parameters of any
mechanism that exclusively describe the spatial position and orientation of
system/body. On the other hand, no. of dof in any mechanism can be obtained by
summation of the available dof of moving links that would be then λN. Examples of serial manipulators are PUMA, SCARA, KUKA, DENSO etc., Gough
platform, Delta robot, 3−RPR planar parallel robot etc., are parallel manipulators and
Fanuc S-9000W is an example of hybrid manipulator. Robotics and living organisms resemble the
serial/parallel or hybrid mechanism.

SCARA (Selective Compliance Assembly Robot Arm) robot manipulator is
basically designed for assembly tasks as it provides vertical axis rigidity and
compliance in the horizontal axis. It mainly contains three revolute (3-dof
revolute) and one prismatic (P) joints altogether known as RRRP manipulator. In this type of robot first three joints are parallel to each other and having downward direction gravity. This manipulator is used mainly in aeroplane parts and electronic parts assemblies. Adept one and SCARA ARi350 is the example of this robot configuration.

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