Comprehensive Analysis of Industrial Robot Technology

1. Background of Industrial Robot Development

The term ROBOT was first introduced by Czech playwright Karel Čapek in his science fiction play “R.U.R. (Rossum’s Universal Robots)” in 1920, and it quickly became synonymous with machines designed to perform tasks. In March 1938, The Meccano Magazine reported on a model of a handling robot designed by Griffith P. Taylor in 1935, marking the earliest mention of robots aimed at industrial applications. By 1954, G.C. Devol in the United States developed the first electronic programmable industrial robot. In 1960, the AMF Corporation produced the Versatran robot, the world’s first robot used in industrial production, capable of point and trajectory control. Cincinnati Milacron successfully developed multi-joint robots in 1974, and in 1979, Unimation introduced the PUMA robot, a multi-joint, fully electric, multi-CPU controlled robot that utilized a specialized programming language called VAL, and could be equipped with visual, tactile, and force sensors, making it the most advanced industrial robot of its time. Modern industrial robots are largely based on these early designs. Robots from this era were primarily of the Teach-in/Playback type, possessing only memory and storage capabilities to repeat tasks according to pre-set programs, lacking any environmental perception or feedback control.

As we entered the 1980s, advancements in sensor technology, including visual and non-visual sensors, as well as information processing technologies, led to the emergence of the second generation of robots—sensory robots. These robots could gather partial information about their operational environment and objects, allowing them to perform real-time processing to guide their operations. The second generation of robots has since seen widespread application in industrial production. Currently, research is focused on developing intelligent robots that not only possess superior environmental perception capabilities compared to their predecessors but also exhibit logical thinking, judgment, and decision-making abilities, enabling them to work autonomously based on operational requirements and environmental information.

2. Application Scenarios of Industrial Robots

Since the creation of the first industrial robot in the early 1960s, robots have demonstrated their remarkable potential. In just over 50 years, robot technology has rapidly evolved, with the automotive and auto parts manufacturing industry being the most prominent sector for industrial robot applications. These robots are also expanding into other fields such as machining, electronics, plastics, food processing, and furniture manufacturing. In industrial production, various types of robots, including welding robots, polishing robots, laser processing robots, painting robots, handling robots, and vacuum robots, have been extensively adopted. Below is an overview of the applications and technical characteristics of industrial robots.

3. Current State of Industrial Robots

With the rise of industrial robots, the trend of automation is becoming more pronounced. Previously, Foxconn announced its plan to purchase one million robots within three years, aiming to establish the “world’s largest automated robot production base” in Jincheng, Shanxi by 2016. The automotive, electronics, food, chemical, rubber and plastics, and metal products industries are currently viewed as the main sectors applying industrial robots. Forecasts suggest a future demand of 1 to 2 million units annually, which would account for approximately 70% of China’s industrial robot market demand. As of September of this year, there are nearly 420 robot companies in China, with more than 30 robot industrial parks under construction nationwide. The rapid emergence of industrial robots in the Chinese market can be attributed to several factors: robotics typically represents only a quarter of labor costs; robots can add substantial value in terms of quality, efficiency, and management. Consequently, driven by rapid advancements in technology, significant price reductions, labor shortages, and rising labor costs, China’s industrial robot industry is experiencing explosive growth.

4. Key Technologies of Industrial Robots

1. Basic System Composition of Robots

Industrial robots consist of three main components and six subsystems. The three main components are the mechanical part, sensing part, and control part. The six subsystems include the mechanical structure system, drive system, perception system, robot-environment interaction system, human-machine interaction system, and control system.

1. Mechanical Structure System: This includes the base, arm, and end effector. Each major component contains several degrees of freedom. If the base has a mobility mechanism, it forms a mobile robot; if not, it consists of a single robotic arm. The arm typically comprises an upper arm, lower arm, and wrist. The end effector is a crucial component attached to the wrist, which can be a gripper with two or more fingers, or various tools such as spray guns or welding equipment.
2. Drive System: This system enables the robot’s operation by placing drive mechanisms at each joint, corresponding to each degree of freedom. The drive system can be hydraulic, pneumatic, or electric, and can employ a combination of these methods for optimized performance.
3. Perception System: Comprising internal and external sensor modules, this system gathers meaningful information about both the internal state of the robot and the external environment. The use of intelligent sensors enhances the robot’s maneuverability, adaptability, and intelligence.
4. Robot Environment Interaction System: This system integrates the industrial robot with external equipment, creating functional units for tasks such as processing, welding, or assembly. This can also include multiple robots, machine tools, or storage devices working together to perform complex tasks.
5. Human-Machine Interaction System: This allows operators to control and interact with the robot through devices like standard computer terminals, control consoles, and information displays. This system includes both command input devices and information display devices.
6. Control System: The brain of the robot, determining its functions and performance. The control system’s task is to manage the robot’s actuators based on task directives and feedback signals from sensors. Robots without feedback capabilities operate on an open-loop system, while those with feedback operate on a closed-loop system. Control systems can be categorized into program control systems, adaptive control systems, and artificial intelligence control systems.

2. Drive System of Robots

The drive systems of industrial robots can be classified into three main types: hydraulic, pneumatic, and electric. These basic types can also be combined into hybrid drive systems.

1. Hydraulic Drive System: This mature technology offers high power, significant force-to-inertia ratios, rapid response times, and ease of direct drive implementation. It is suitable for robots operating in high-load, high-inertia, and harsh environments. However, hydraulic systems require energy conversion (from electrical to hydraulic), and speed control often relies on throttling, resulting in lower efficiency compared to electric systems.
2. Pneumatic Drive: This system is known for its speed, simple structure, ease of maintenance, and low cost. However, it has limitations in precise positioning and is generally used for driving end effectors like pneumatic grippers and suction cups.
3. Electric Drive: This is the mainstream drive method for modern industrial robots, which can be categorized into four types: DC servomotors, AC servomotors, stepper motors, and linear motors. Electric drives typically use closed-loop control for high precision and speed applications.

3. Perception System of Robots

The perception system of robots transforms various internal state information and environmental data into understandable and applicable formats. It requires the capacity to sense mechanical quantities such as displacement, speed, acceleration, force, and torque, with visual perception technology being a critical aspect. Visual servo systems use visual data as feedback for adjusting the robot’s position and orientation, which is especially prevalent in semiconductor and electronics industries. Visual systems are also widely applied in quality inspection, object recognition, food sorting, and packaging tasks.

Visual servo control can be categorized as position-based or image-based. The former utilizes camera parameters to establish a mapping relationship between image information and the position/orientation of the robot’s end effector, achieving closed-loop control. The latter compares features in images captured by the camera to given images, generating error signals to adjust the robot’s operation accordingly.

4. Key Fundamental Components of Robots

Robots consist of four main components: the body (22% of costs), servo system (24%), gearbox (36%), and controller (12%). These key components significantly influence robot performance and are characterized by modularity and general applicability:

1. Gearbox: Two main types of gearboxes are used: harmonic gearboxes and RV gearboxes. The harmonic drive, invented by C. Walt Musser in the 1950s, consists of a wave generator, flexible gear, and rigid gear. It provides high reduction ratios and compact sizes, reducing torque output by two-thirds for the same output torque. RV gearboxes, developed by TEIJIN in the 1980s, combine planetary and cycloidal gear mechanisms, offering superior accuracy and reliability.
2. Servo Motors: European robot drive components are mainly supplied by companies like Lenze, Bosch Rexroth, and others, known for their dynamic response and broad compatibility. Japanese brands like Yaskawa, Panasonic, and Mitsubishi provide more affordable components, albeit with some trade-offs in performance.
3. Controllers: Most mainstream robot manufacturers design controllers based on general multi-axis motion control platforms, which can vary widely in features and capabilities.

5. Robot Operating Systems

The Robot Operating System (ROS) is a standardized platform designed for robot software development, allowing designers to use a common operating system. This promotes independence between hardware and software, fostering rapid advancements in the field. Various institutions, including Stanford University and MIT, have developed different ROS systems, enhancing collaborative development in robotics.

6. Motion Planning for Robots

Effective motion planning is essential for enhancing operational efficiency and enabling robots to complete tasks in the shortest time possible. Motion planning can be divided into path planning and trajectory planning. Path planning aims to maximize the distance from obstacles while minimizing the path length. In contrast, trajectory planning incorporates timing information to optimize speed and acceleration, ensuring smooth and controllable movements.

7. Classification of Industrial Robots

Industrial robots can be classified based on various criteria:

1. Mechanical Structure: Robots are categorized into serial robots and parallel robots. Serial robots feature interconnected axes, where the motion of one axis affects the others, while parallel robots operate independently, providing greater stability and load capacity.
2. Coordinate System Type: This refers to the reference coordinate system used by the robot’s arm during operation. Coordinate types include Cartesian, cylindrical, spherical, multi-joint, and planar robots, each with unique advantages and limitations.
3. Input Method: Robots can be classified based on programming input, either through pre-written programs transferred to the robot’s controller or through a teaching method where an operator manually guides the robot’s movements.

8. Performance Evaluation Indicators for Industrial Robots

Key parameters for evaluating robot performance include workspace, degrees of freedom, effective payload, motion accuracy, motion characteristics, and dynamic properties. Understanding these indicators is crucial for selecting and deploying robots effectively in various industrial applications.

9. Challenges Facing Industrial Robots

Despite the flourishing market for robots, the Chinese robot industry faces significant challenges. The foreign market dominates, with Japanese and European companies holding a substantial market share. The high entry barriers to the robot industry hinder domestic manufacturers, and many components remain reliant on imports, limiting competitive development.

To address these challenges, experts suggest strengthening research on international robot technologies, establishing a roadmap for technological development, enhancing industry collaboration, and promoting the growth of domestic robot enterprises and brands.