15 Different Types of Robots | Explained

AI and Robotics are undoubtedly two of the most promising fields of study right now. These two will certainly define the future of humanity. At present, we have ultra-modern machines with sleek designs, agile and highly capable bodies, which are capable of doing almost any kind of work with efficiency. We also have machine intelligence, which is literally revolutionizing the way we do most of our work.

While AI is always an interesting subject to talk about, as we did countless times here on our website, let’s talk about robots today. As you might know, there are many different ways in which one could differentiate robots. I am sure that you know at least some of them, but there is always more.

Basically, robots are divided into two broad categories: based on their applications and the second is based on kinematics or locomotion. Below, we have only classified robots based on kinematics. Why is it so? Well, the application of any subject, especially robots’, vaguely describes its characteristics. For instance, two different types of robots can perform the same job, yielding the same result.

We have only mentioned major robotic types, and they are further subdivided based on kinematics. 

Robotic Arms or Stationary Robots

1. Cartesian Robots

Cartesian robotImage Courtesy: Florian Schäffer/ An implementation of the cartesian robot

Cartesian robots are perhaps the most common type of robot used for both industrial and commercial purposes. Sometimes known as gantry robots, they have three linear axes, i.e., they can only move in straight lines rather than rotating and are mounted at right angles. The mechanical arrangement of cartesian robots is far simpler than most of the other stationary robots.

2. Cylindrical Robot


cylindrical robot

Cylindrical robots are generally used for assembly purposes, spot welding, and machine die castings. Although these types of robots are relatively rare these days, they can still be useful. As the name suggests, it forms a cylindrical coordinate working system.

As you can see in the diagram above, a cylindrical robot has three axes of movements. On the Z axis, it rotates and moves vertically; and on the Y axis, it moves along in a linear motion. Sometimes these cylindrical robots are mistakenly regarded as SCARA robots or vice versa. Even though their work envelope is almost similar, both their structures and field of application are poles apart.

3. SCARA robots


SCARA rightGif Source: Wikimedia Commons

SCARA or Selective Compliance Assembly/Articulated Robot Arm is more commonly used for assembly purposes all over the world due to its easy and unobstructed mounting.

SCARA Robots generally have what we know as the serial architecture, where one base motor has to carry all the other installed motors. One of the downsides of these types of robots is that they are extremely expensive compared to rather inexpensive Cartesian robots. Also, they need high level and complex software to operate.

4. Parallel robots

Stewart's platform

Parallel robots are more commonly known as Parallel manipulator, in which a bunch of machine-controlled robotic chains supports the end effector or simply the end platform. One of the best examples of this type of robot is flight simulators, which military and commercial pilots use to enhance their flight abilities by simulating real-life situations.

The word ‘parallel’ should not be misunderstood as it’s not implying a geometric setting, but rather a unique characteristic of the robot type in computer science. Here parallel means that the endpoint of each individual linkages is completely different from others.

The parallel robot is specially designed to remain rigid and resist all the unwanted disturbances and movements, which is contrary to serial manipulator robots. Even though each actuator works with a degree of freedom, their flexibility is eventually constrained by the other actuators. Its rigidity and stiffness separate parallel manipulators from serial chain robots.

5. Articulated robots

articulated robots

When someone talks about industrial robots, there is a good chance that they are referring to articulated robots. These robots are extremely versatile and well suited for industrial works, unlike most other types of robots we showed above. This agility and versatility come from their extra axes, which are generally four to six but can also reach as high as 10. Their major applications are material handling, dispensing, welding, etc.

6. Spherical robots

spherical robotImage Courtesy: Seelio.com

Based on the level of sophistication, spherical robots are somewhere in between Cartesian or cylindrical robots and those ultra sophisticated articulated robots. Basically, a spherical robot is a mid-sized robot inside a spherical ball, which moves with the help of an IDU (Internal Driving Unit). These mobile spherical robots are extremely efficient in surveillance and monitoring missions and can also be used underwater.

Wheeled and Legged Robots

7. Single Wheel Robots

We all have ridden a bicycle or motorcycle at least once, but how many of you have actually ridden a unicycle? Well, I tried it once, couldn’t even get seated properly. The problem is that unicycles are not stable like bicycles, so it’s difficult to balance, and one would fall instantly without proper support.

Making a single-wheeled robot possesses a difficult challenge for engineers as they have to make it dynamically stable as well as efficient. One such example of a single wheel robot is MURATA GIRL.

Murata girl or Murata Seiko-chan is a unicycle robot manufactured by the Japanese electronics company Murata. According to the company, she has advanced gyro sensors that allow her to maintain balance, a Bluetooth device for communication, and an ultrasonic sensor for target detection. These types of compact robots can come in handy in crowded areas.

8. Two-Wheel Robots

two wheeled robotImage Courtesy: David P. Anderson 

Do you want to make your own robots? If yes, then small two-wheel robots are perhaps the right way for you to start. Their simple and effective design is the reason why two-wheeled robots are prevalent nowadays. All you need is a couple of motors and two wheels to move around.

But like any other robot, they also have their own flaws. Two-wheeled robots have poor balance since they use just two wheels on either side, and they always have to be in motion to maintain the upright position. To make it more stable, batteries are mounted directly below their bodies.

9. Three Wheel Robots

three wheel robots

Three-wheel robots are generally of two types, based on the nature of steered wheels. In the first type, two wheels are separately powered while the third wheel rotates freely for balance (differentially steered). In the second type, two wheels are powered by one source while the third wheel is powered by another source.

For differentially steered three-wheel robots, the direction at which the robot is going at a given time can be altered by changing the relative rate at which the two powered wheels are rotating. When two wheels have the same rate of rotation and same direction, the robot continues to go straight.

10. Humanoid Robots

humainoid robotTOPIO, a humanoid robot, played T.T at IREX, Tokio

As the name suggests, a humanoid robot is a type of robot that replicates the human body. The design of Humanoid robots is what makes them fairly distinct from the other types of mobile robots. A typical humanoid robot consists of a head, two arms, a torso, and two legs just like a human, but many of those robots are only based on some part of the human body, like from waist up or something like that.

Read: 12 Advanced Robotic Animals That Are Transforming Scientific Research

One of the main components of a humanoid robot is sensors, as they play a pivotal role in robotic paradigms. There are two types of sensors Proprioceptive and Exteroceptive sensors. The proprioceptive sensors sense the robot’s orientation, position, and other motor skills, while Exteroceptive includes visionary and sound sensors.

11. Tripedal and Quadrupedal robots

Quadrupedal robotsBoston Dynamics’ WildCat

Tripedal or three-legged robots are not so common; however, a robotics and mechanism laboratory in Virginia has developed a radical three-legged robot named STriDER. It uses a fairly new concept of passive dynamic locomotion to walk dynamically and be highly efficient, which can also be guided with minimal control.

In contrast to tripedal robots, four-legged robots are more popular. The four-legged robots, also known as quadrupedal robots, have more stability, especially when they are not in motion. Many quadrupedal robots use the alternating technique (in pairs) to walk. Some of the best examples of quadrupedal robots are WildCat, Cheetah, and Big Dog.

12. Hexapod Robots

hexa robots

In geometry, Hexagon implies a six-sided polygon, so a hexapod would mean a robot with six legs, right? Yes, that is the case here. Now since, a robot can be perfectly stable on just three legs, the remaining legs of a hexapod robot provide a great deal of flexibility and increases its capabilities.

Many, if not all, hexapod designs are inspired by the locomotion of Hexapoda (Greek for 6 legged) family of insects. They are also used to test various biological theories about insect locomotion and motor control. These hexapods deploy various types of gaits to make a move. The most common are:

  • Alternating tripod: Out of possible six, only 3 legs stay at the ground at a time, and
  • Crawl: only one leg stays on the ground at a time, giving the impression of crawling.

13. Hybrid Robot

We had robots with legs and robots with wheels, but Boston Dynamics, a robotics company, launched a research robot named Handle, which can stand tall up to 6.5 feet and travel in short distances at a speed of 9 mph. It can also jump vertically up to 4 ft.

Although it has all the basic working principles found in a quadruped robot, i.e., balance and mobile manipulation, it only uses 10 actuated joints, so it’s far simpler than other walking robots. With wheels, efficient on flat turfs and legs on rather rough terrain, ‘Handle’ can actually handle anything thrown at him.

14. Flying Robots

flying robotImage Courtesy: Ted Talks

How badly were you waiting for this? I was eager to write this too. Without a shadow of a doubt, flying robots are the most popular Robo types. Right now, some big multinational companies are planning to incorporate those automated flying machines into their day to day business. These robots aren’t just cool; they are also strong and aerodynamically sound.

In some areas, Amazon has started shipping products through flying drones. These fully electric and autonomous drones can fly up to 15 miles and deliver packages weighing at most 5 pounds to customers in less than 30 minutes.

Read: 14 Unique Early Experimental Flying Planes

15. Swimming Robots

swimming robot

Read: 17 Different Car Engine Types

And why flying robots should get all the limelight, why not swimming robots. Yes, they are as cool as the flying robots; the only difference is that instead of flying, they can swim. These robots can take the form of insects, fish, or big slithering snake; you just name it.

Written by
Varun Kumar

Varun Kumar is a professional science and technology journalist and a big fan of AI, machines, and space exploration. He received a Master's degree in computer science from GGSIPU University. To find out about his latest projects, feel free to directly email him at [email protected] 

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  • This is great. I am researching on the types of robots that are used in the motor vehicle manufacturing companies. Am I right to say that most of them are stationary robots?

  • this site is so helpful i used this a lot on my project for school if you look at the commets then i say i reccomend this to you it will help you so much with work and or school if you like doning robotics or you are a robo engenier

  • dear sir im in market and looking for a robot who can put any sort of flat pack kit together . let me know when you programed one.