Knowledge Base

Classification of Robots


Robotics evolved as part of the third industrial revolution. Robots – in the form of manipulators - were used in automotive assemblies to speed up the production process of automobiles. Since that time, robots are being used in all sectors – industrial, healthcare, manufacturing, and elsewhere. Since a robot executes one or more tasks automatically with speed, precision and repeatability, their use has increased manifold. Robots are used in space programs, for underwater exploration of oil and gas structures, for military surveillance purposes, in environmental monitoring, in archaeology, for plant maintenance, medical treatment, and varied other sectors.

Classification of Robots
Defining robots is complex. There are many definitions that attempt to separate a robot from automation. Classifying them is not easy either. There are many ways to classify robots. They can be classified on the basis of how they perform tasks, on the basis of their application, on the basis of how they move and so on. For the purpose of this article, we will stick to the classification of robots based on the most popular ways to do so – by their application, or by their locomotion / kinematics. Before we proceed, let us make it clear that this classification is very broad, and we will not cover all robot types under it. Also, some types of classifications may overlap. For example, an industrial robot can be classified as a Cartesian robot as well. Or an airborne drone can also be classified as a defence robot. This overlap will be clear as you go through the article.

Classifying Robots by their Application
One of the most popular way of classifying robots – and one of the simplest – is by what they actually do. Based on this classification, there are two broad ways of categorising robots.

  • Industrial Robots: These were one of the first robots to be used commercially. In a factory assembly line, these are usually in the form of articulated arms specifically developed for such applications as welding, material handling, painting and others. They can be further subdivided as manufacturing robots and logistics robots. Manufacturing robots are designed to move materials, as well as perform a variety of programmed tasks in manufacturing and production settings. They are often used to perform duties that are dangerous or unsuitable for human workers. Logistics robots are mobile automated guided vehicles primarily used in warehouses and storage facilities to transport goods.
  • Service robots: The International Organization for Standardization defines a service robot as ‘a robot that performs useful tasks for humans.’ They can be further subdivided as medical robots, home robots, defence robots, entertainment robots, agricultural robots, educational robots, and other types of robots. Medical robots are professional service robots that are used in and out of hospital settings to improve the level of patient care. These robots reduce the workload of the medical staff, which allows them to spend more time caring directly for patients. Mobile medical robots are used for the delivery of medication and other sensitive materials in a hospital. Home robots automate tasks like cleaning and disinfecting. The primary purpose of education robots is to make kids aware of their potential, utility, and help kids build their own robots using readymade kits. Educational robots are used extensively in schools, both in classrooms and in extracurricular activities. One of the most important uses of robots in defence is to ensure the safety of soldiers and civilians. For example, remotely operated vehicles (ROVs) are used to carry out dangerous tasks or activities in hazardous environments, drones are used for surveillance, and so on. Agricultural robots sense weather pattern and can adjust the watering of crop as needed, can be used for sowing, de-weeding, and harvesting crops.

Classifying Robots by their Kinematics or Locomotion
Robots can also be classified according to how they move – or not move.

Stationary Robots:
They can be further subdivided as:

  • Cartesian Robots: these are perhaps the most common types of robots. They have three axes which are linear i.e, they can only move in straight lines rather than rotating and are mounted at right angles to each other. Because of their rigid structure, this type of robots usually can offer good levels of precision and repeatability. Cartesian robots are mostly used in the industrial and the manufacturing sector.
  • Cylindrical robots: The body of this type of robot is such that the robotic arm can move up and down along a vertical member. The arm can rotate about that vertical axis and the arm can also extend or contract. This construction makes the manipulator able to work in a cylindrical space. They are used for assembly operations, spot welding and for die casting machines.
  • Spherical Robots: This type of robot works in a spherical system. It can move in a bi-angular and single linear direction. SCARA Robots: SCARA stands for Selective Compliance Arm for Robotic Assembly. This type of robot has two parallel revolute joints. They are used for assembly purposes all over the world.
  • Articulated Robots: These are robots with a wide range of movements that include forward, backward, upward and downward motion. Because of their large work envelope, articulated robots can be used for several different applications like assembly, arc welding, material handling, machine tending, and packaging.
  • Parallel Robots: These are closed-loop systems to support a single platform where both accuracy and dynamic response are needed. An example of this kind of robot would be those used for drilling and milling.
  • Wheeled Robots and legged Robots: These are robots having wheels, and can be further be categorized as: single wheel robots, two-wheel robots, three and more wheel robots, bipedal robots (humanoid robots), tri-pedal robots, quadra-pedal robots and hexapod robots..
  • Airborne Robots: these robots can fly through the air. Drones are an extremely popular example of flying robots.
  • Aquatic Robots: These robots can work on or under water. They are mostly used for underwater exploration of oil, gas or minerals.

The Future of Robotics
Irrespective of their classification, the use of robots provides several advantages in manufacturing like reduced labour costs, increased production, high precision and flexibility. Fully autonomous robotic systems are able to operate completely independent of humans, using a variety of sensors and communication systems to assess the situation and make decisions and changes during operation. With high end software programming platform, it is possible to program robots with varying levels of autonomy ranging from constant repetition of a predefined motion to systems that are able to detect objects, avoid obstacles, map its surroundings, learn based on previous experience, etc.

Robots have assumed special importance in smart manufacturing and Industry 4.0 scenario. While Robots automate a lot of functions, with Industrial IoT, companies can take their smart manufacturing initiatives to another level. IIoT can help companies monitor and manage manufacturing operations digitally and hence remotely. It can red flag issues and hence help companies remain ahead of the problems. It can significantly improve manufacturing, productivity & efficiency. PTC IIoT ThingWorx solutions are considered amongst the best, that can help companies digitalise manufacturing operations management and AR (Augmented Reality) clubbed with IIoT can help companies achieve Digital Transformation.

Indeed, the future of industry in India, Singapore and other developing nations will be shaped by robotics.