What Is a Robot Manipulator?

Robot manipulator is the robot's execution system. It is the mechanical part of the robot that holds the workpiece or tool and completes various movements and operation tasks. It generally consists of four parts: the fuselage, arm, wrist, and hand. There are 4 types: rectangular coordinate type manipulator, cylindrical coordinate type manipulator, spherical coordinate type manipulator, and joint type manipulator. Regarding the degrees of freedom, the number of degrees of freedom of the robot is equal to the sum of the degrees of freedom of the components in the manipulator.

The word robot comes from the Slovak language and its original meaning is "serf". In modern science and technology, the word robot is defined as "a machine that can perform different tasks by programming under automatic control." It may not have similarities with human appearance, but it can emulate human motion and intelligent functions to a certain extent.

Essentially, the robot system consists of four parts:

The manipulator is the execution system of the robot, and it is the mechanical part of the robot that holds the workpiece or tool and completes various motions and operation tasks. Generally consists of the following parts:

So-called operator

The characteristics of the manipulator structure coordinate system can be divided into the following categories:

Robot manipulator rectangular type

The Cartesian coordinate type is also known as the straight-moving type. Its three basic joints are all moving joints, that is, the arm only has telescopic, lifting, and translational movements, and its motion pattern can be a straight line, a rectangle, or a cuboid.

(1) Advantages: The structure of this manipulator is simple, the movement is intuitive, and it is easy to achieve high precision.

(2) Disadvantage: It takes up a large space and the corresponding working range is small.

According to literature statistics, such robots account for about 14% of the total robot production. ^[1]

Robot manipulator cylindrical coordinate type

Cylindrical coordinate type is also known as transformation. Among its three basic joints, two are moving joints and one is a rotating joint. In addition to the telescopic and lifting degrees of freedom, the arm has a horizontal degree of freedom of rotation. Its motion graphics can be a circular arc, a fan-shaped plane, a cylindrical surface, or a hollow cylinder.

(1) Advantages: Compared with the Cartesian coordinate type manipulator, the cylindrical coordinate type manipulator has the advantages of keeping the movement intuitive and strong, and also has the characteristics of occupying less space, compact structure and large working range.

(2) Disadvantages: Due to the limitation of the lifting mechanism, the workpiece on the ground or lower position cannot generally be lifted.

According to literature statistics, this robot accounts for about 47% of the total robot production. ^[1]

Robot manipulator ball coordinate type

The spherical coordinate type is also known as the pitch type. Among its three basic joints, two are rotary joints and one is a mobile joint. That is to say, the arm has a degree of freedom of pitching motion in addition to telescopic and horizontal rotation degrees of freedom. For a hollow sphere.

(1) Advantages: Compared with the cylindrical coordinate type manipulator, this manipulator has a larger working range while occupying the same space. Because it has pitch freedom, it can also extend the arm to the ground to complete the operation. The task of extracting parts from the ground.

(2) Disadvantages: The movement is not intuitive and the structure is more complicated. The position error of the arm end will be enlarged with the elongation of the arm.

According to literature statistics, such robots account for about 13% of the total robot production. ^[1]

Robot manipulator type

The arm of the articulated manipulator is composed of a forearm and a forearm, the elbow joint is connected between the forearm and the forearm, and the shoulder joint is connected between the forearm and the fuselage. The boom has two degrees of freedom of horizontal rotation and pitch, and the forearm makes flexion and extension movements relative to the forearm. Therefore, this manipulator is also called flexion and extension type. Its motion graphic is a sphere.

(1) Advantages: The articulated manipulator has certain characteristics of a human arm. Compared with other types of manipulators, it occupies the smallest space and has the largest working range. In addition, it can also extract and transport workpieces around obstacles. Therefore, it has received widespread attention in recent years.

(2) Disadvantages: The motion is less intuitive and the drive control is more complicated.

According to literature statistics, this robot accounts for about 25% of the total robot production.

In addition to the above-mentioned four basic coordinate-type operators, there are various composite coordinate-type operators. ^[1]