Comprehensive Guide to Robot Arms: Structure, Types, and Industrial Applications

07-12 2024

The robot arm is the most widely applied automated mechanical device in the field of robotics technology. It is a crucial component of actuators, responsible for transporting the grasped workpiece to a given position. A robot arm is characterized as a high-precision, multi-input multi-output, highly nonlinear, and strongly coupled complex system. Due to its unique operational flexibility, it has been extensively used in fields such as industrial assembly and safety explosion-proof operations.

Structure of the robot arm

A robot arm is composed of several parts: moving elements, guiding devices, and the arm itself. The structure, working range, flexibility, load capacity, and positioning accuracy of the arm directly influence the performance of the robot arm.

Standard Three-Axis Joint Type Mechanical Arm

A horizontally articulated robot arm generally has three main degrees of freedom: Z1 rotation, Z2 rotation, and Z movement. By adding X rotation and Y rotation at the execution terminal, it can reach any coordinate point in space.

Three-axis articulated robotic arm

Classification of robot arms

Currently, most robots are primarily in the form of robot arms, which vary in shape and size. Common types include linear arms, SCARA arms, and articulated multi-axis robot arms. For industrial applications, sometimes it is not necessary for a robot arm to have a full six degrees of freedom, but only one or a few degrees of freedom.
Articulated Robots are the most mainstream type of industrial robot today, generally having six joint axes, each consisting of rotational and swiveling degrees of freedom. They mimic the structure of the human arm: the lower arm is formed by the 1-2 axes, and the upper arm by the 3-6 axes. Most industrial robot products launched by major manufacturers on the market today are of this type, known for their wide working range, flexible movements, and extensive applications.

ABB Industrial Robots

SCARA Robots, mainly used for material handling and assembly applications, generally have four joint axes, composed of three rotational axes and one vertical moving joint axis. They are characterized by flexible movements, simple structure, high speed, and high positioning accuracy.

ABB industrial robots

Movement Forms of robot arms

Typically, a robot arm has 3 degrees of freedom: extension and retraction, left and right rotation, and pitching (or tilting) movement. The arm's rotation and lifting movements are achieved through the base's column, with the column's lateral movement constituting the arm's horizontal displacement. Various movements of the arm are usually realized by drive mechanisms and various transmission mechanisms, bearing not only the weight of the grasped workpiece but also the weight of the end effector, arm, and wrist itself.

History of robot arm Development

In 1921, Czech science fiction writer Karel Čapek's play "R.U.R." first mentioned robots named Robota. In 1954, George Devol applied for the first robot patent, and in 1956, Joseph Engelberger, based on Devol's patent, invented the first robot arm for industrial production.

In 1963, Japan's Fuji Conveyor Industrial Corporation manufactured a dedicated handling tool for pallet use. In 1973, Germany's KUKA Robotics developed the first six-axis robot arm with electromechanical drive.

Six-Axis robot arm

robot arms have extensive applications in industrial automation, primarily used for tasks that are impossible or time-consuming for humans. In terms of precision and durability, robot arms can reduce unpredictable human-related issues.

robot arms are widely applied automated mechanical devices in the field of robotics technology, visible in industrial manufacturing, medical treatment, entertainment services, military, semiconductor manufacturing, and space exploration. Despite their varying forms, they share a common feature: the ability to accept commands and precisely position themselves at a specific point in three-dimensional (or two-dimensional) space for operations.

Six-Axis robot arm

History of Industrial Robot Development

Industrial robots are multi-jointed manipulators or multi-degree-of-freedom machine devices aimed at the industrial sector. They can automatically execute tasks, relying on their own power and control capabilities to perform various functions. They can follow human commands or operate according to pre-arranged programs. Modern industrial robots can also act based on principles established by artificial intelligence technology.

Modern robotic research began in the mid-20th century, rooted in the development of computers and automation, as well as the exploitation and use of atomic energy. The urgent need for mass production spurred advancements in automation technology, resulting in the birth of the numerical control machine tool in 1952. Related control and mechanical part research laid the foundation for robot development.

On the other hand, the harsh environment of atomic energy laboratories required certain mechanical operations to replace humans in handling radioactive materials. Against this background, the Argonne National Laboratory of the U.S. Atomic Energy Commission developed the remote manipulator in 1947 and the mechanical master-slave manipulator in 1948.

Automotive robot arm

ABB Industrial Robots

In 1954, American Devol first proposed the concept of an industrial robot and applied for a patent. The patent's key point was controlling the robot's joints through servo technology, using human hand guidance to teach the robot movements, allowing for the recording and reproduction of actions. Almost all existing robots use this control method.

In 1965, MIT's "Robots" demonstrated the first robot system with vision sensors, capable of identifying and positioning simple blocks. In 1980, industrial robots truly became widespread in Japan, hence this year is called the "Year of the Robot." Germany ranks third in the world in the number of industrial robots, following Japan and the United States, with its intelligent robot research and applications leading globally.

Chinese industrial robots started in the early 1970s, with their development process roughly divided into three stages: the budding stage in the 1970s, the development stage in the 1980s, and the practical application stage in the 1990s. After years of development, it has now taken shape. Currently, China has produced some key components of robots and developed industrial robots for arc welding, spot welding, stacking, assembly, handling, injection molding, stamping, and painting. Some key technologies have reached or are close to the world's advanced level.