Types of Robots

An excerpt from Robotics for Software Engineers by Andreas Bihlmaier


The first fundamental type of robots are stationary manipulators. This category of robot includes the “classic” industrial robot arms that have shaped the commercial robotics industry since its beginning. Until recently they also made up the majority of robots in the world. The two important properties required for a robot to fall into the manipulator category are:

  • The robot’s purpose is to manipulate objects, i.e. to purposefully move objects through space.
  • The robot itself is stationary.
Figure 1. Examples of different robot manipulators.
Figure 2. The different parts making up a manipulator.
  • Joint: The moveable parts in the robot hardware. The most common joint types are those that can rotate, like a hinge, and those that can extend linearly, like a drawer slide or telescopic pole. Joints contain the actuators that make the robot move.
  • Link: A rigid mechanical part connecting the joints. The links give the manipulator its shape and make up the bulk of what is visible when looking at a robot.
  • Robot Base: The first link of the robot. The base attaches the robot to the environment.
  • End Effector (EE): The last link of the robot, i.e. the link farthest away when counting from the robot base.
  • Tool Flange: A standardized mounting plate that allows to fasten tools to the last link of the robot. The tool flange is often simply referred to as flange.
  • Tool: A device attached to the tool flange that enables the robot to perform the intended process. Another common term here is End Of Arm Tooling (EOAT). The most common robot tools are grippers. However, the variety of robot tools is as big as the applications performed by manipulators. Other examples of tools are welding equipment, tool changers, force-torque sensors, paint sprayers, material removal equipment and 3D printing nozzles.

Mobile Robots

Mobile robots move themselves through the environment. As discussed in the previous section, this contrasts with robot manipulators that move objects around, while the manipulator itself is stationary as it fixed to the environment.

Figure 3. Examples of different mobile robots.
Figure 4. Distinction between a sensor that (a) is part of the robot system and (b) is only a payload.

Mobile Manipulators

Since we have already discussed robot manipulators and mobile robots in the previous sections, it is straight forward to define mobile manipulators: A mobile manipulator is a manipulator mounted on a mobile robot. The assumption here of course is that the combined robot is still mobile and that the manipulator can still function.

Figure 5. Examples of mobile manipulators.
  1. Using a manipulator in different places. The mobile aspect removes the stationary property from the manipulator by transporting it. The focus is on manipulation.
  2. Enhancing the mobile robots payload transportation flexibility. The manipulator aspects allows loading and unloading of payloads. The focus is on transportation.
  3. Extending the manipulator workspace to infinity. The mobile and manipulation aspect are intimately linked by simultaneously using the motion capabilities of the manipulator with those of the mobile base. This is also known as whole-body control.
  • Independent successive
  • Coupled simultaneous



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