What are a manipulator, wrist and end effectors for a robot?


 Manipulator is built as series chains or parallel chains or occasionally a combination of both. Links and joints (revolute and prismatic) are mostly used in manipulators. In spatial manipulators (open chains) adjacent axes are parallel or perpendicular to each other.
In robotics, a manipulator refers to the main body of the robot responsible for carrying out various tasks and movements. It typically consists of several linked segments, known as links, which are connected by joints. These joints allow the manipulator to articulate and move in different directions, enabling it to reach specific positions and orientations.

The manipulator is the core part of the robot responsible for carrying out various tasks. It consists of a series of interconnected links and joints that allow it to move in specific ways. The number of degrees of freedom (DOF) in a manipulator determines its range of motion. The simplest manipulators might have just a few DOFs, such as those used in robotic arms, while more complex robots, like humanoid robots, can have multiple DOFs in each joint, enabling them to mimic human movements more closely.

Manipulators can be designed for various applications, such as industrial tasks, medical procedures, underwater exploration, space missions, and many other fields where precise and repetitive actions are required.


Wrists roll, yaw and pitch. There are three motions and three actuators are required for motion.
The wrist is a specific part of the manipulator, located at the end of the arm. It is designed to provide additional degrees of freedom, allowing the end effector to rotate or tilt independently from the main arm movement. The wrist’s extra flexibility enhances the robot’s ability to reach more positions and manipulate objects with greater precision.

The wrist is a crucial part of the manipulator, situated at the end of the robot’s arm. Its primary purpose is to provide additional degrees of freedom, allowing the end effector to move independently of the main arm’s motion. This extra flexibility enables the robot to orient and align the end effector precisely, improving its dexterity and reach.

The wrist often consists of one or more rotational joints that permit pitch, yaw, and roll movements. By combining the movements of the arm and wrist, the robot can access more locations and achieve complex orientations needed to complete various tasks effectively.

 End effectors

Continuous path motion – painting application is an example when the end effectors have to move over a desired curve in space. The robot end effectors are required to reach the centre of circle the target point. The circle on extreme left shows the situation when the robot has poor accuracy and poor repeatability. The circle in the middle shows the EE had been repeatedly reaching positions which are closely together through way  from the target
An end effector, sometimes called an end-of-arm tool, is the final component attached to the wrist of the robot. It is the part that directly interacts with the objects or environment to perform specific tasks. End effectors can vary widely depending on the application, and they can be equipped with different tools, such as grippers, suction cups, welding tools, cutting tools, sensors, and more. The choice of end effector depends on the intended task, whether it’s picking up objects, welding materials, painting, or any other operation the robot is designed to perform. The end effector is crucial for the robot to effectively execute its designated functions.
The end effector is the “hand” of the robot, the component that directly interacts with the objects or environment to execute specific tasks. It comes in various shapes and designs, depending on the application and the task at hand. Some common types of end effectors include:
  • Grippers: Mechanisms used to grasp and hold objects. Grippers can be pneumatic, electric, or utilize other actuation methods.
  • Suction Cups: Used to create a vacuum seal on objects to pick them up or hold them securely.
  • Welding Tools: End effectors designed for performing welding operations in industrial applications.
  • Cutting Tools: Tools used for tasks like trimming, milling, or drilling.
  • Sensors: Some robots use specialized sensors as end effectors, such as cameras, 3D scanners, or tactile sensors, to gather information about their environment.

End effectors are often interchangeable, allowing a robot to adapt to different tasks by swapping out the tool at the end of its arm. This feature makes robots versatile and adaptable to a wide range of applications.

Overall, the combination of the manipulator, wrist, and end effector is what gives robots their ability to perform diverse tasks efficiently and effectively, making them valuable tools in various industries and research fields.

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