What are Articulated Robots? Anatomy, Control Systems, Advantages, Selection Criteria, and Applications

Articulated robots are highly versatile industrial robots that have been used in various industries to perform a wide range of tasks. These robots are designed with a series of interconnected segments, known as links, which are attached through movable joints. This design allows them to move with a high degree of flexibility and dexterity, making them ideal for performing complex tasks requiring high precision.

In this article, we will delve deeper into the specifics of articulated robots, explore the various control systems that they use, discuss their advantages and limitations, and examine their applications across different industries. We will also look at the challenges of operating articulated robots and discuss future trends and developments in this field.

Introduction

The history of articulated robots dates back to the 1950s, when they were first introduced for use in manufacturing processes. Since then, they have evolved significantly and become integral to many industries, including automotive, aerospace, healthcare, and research.

The importance of articulated robots lies in their ability to improve efficiency, accuracy, and safety in various operations. These robots are designed to perform repetitive and dangerous tasks that are often too difficult or hazardous for humans to undertake. As a result, they have helped to increase productivity and reduce the risk of workplace accidents.

Suggested Reading: 7 Types of Industrial Robots: Advantages, Disadvantages, Applications, and More

Anatomy of Articulated Robots

Articulated robots comprise several interconnected segments called links, which are connected through joints. These joints are designed to allow the robot to move with a high degree of flexibility, precision, and dexterity. The links of articulated robots can range from two to six or more, with each link providing a degree of freedom (DOF) that enables the robot to move in various directions.

The joints used in articulated robots can be classified into two types: revolute and prismatic. Revolute joints are rotary joints that allow the robot to rotate along an axis. Prismatic joints, on the other hand, are linear joints that enable the robot to move in a straight line.

Articulated robots are designed to have multiple degrees of freedom (DOF), which is the number of independent parameters that determine the robot's position and orientation. This allows the robot to move in a wide range of directions and positions, making it highly versatile. The DOF of articulated robots can range from two to six or more, with each DOF representing a degree of movement or rotation.

The most common DOF configurations for articulated robots are 4-DOF and 6-DOF. 4-DOF robots typically have three revolute joints and one prismatic joint, while 6-DOF robots have three revolute joints and three prismatic joints. The additional degrees of freedom in 6-DOF robots allow for greater flexibility and precision in their movements.

In addition to the links and joints, articulated robots also have end-effectors, which are the devices attached to the articulated robot arm that allow it to perform specific tasks. End-effectors can include grippers, suction cups, and other specialized tools that are designed to manipulate objects with precision and accuracy.

Suggested Reading: What are End Effectors in Robotics? Types of End Effectors, Applications, Future

Control Systems of Articulated Robots

The control systems of articulated robots are crucial in determining the robot's movements, actions, and overall performance. The robot control systems are responsible for monitoring the robot's position, speed, and orientation and making adjustments as needed to ensure that the robot moves accurately and precisely.

There are two main types of control systems used in articulated robots: open-loop and closed-loop control systems. Open-loop control systems are used in simple, repetitive tasks where the robot's movement can be pre-programmed and does not require real-time feedback. Closed-loop control systems, on the other hand, use sensors to monitor the robot's movements and make adjustments in real-time to ensure precise and accurate movements.

Sensors are an essential component of the control systems in articulated robots. They are used to monitor the robot's movements, track its position and orientation, and detect any errors or deviations from the intended path. Common sensors used in articulated robots include encoders, accelerometers, and proximity sensors.

A video showcasing articulated robot application on a production line. Notice how the robot displays a wide range of motions in the workspace.

Actuators are another critical component of the control systems in articulated robots. Actuators are responsible for moving the robot's joints and links, enabling it to move with precision and accuracy. The most commonly used actuators in articulated robots are electric motors (such as the servo motor), hydraulic cylinders, and pneumatic cylinders.

The control systems of articulated robots are typically operated through a computer interface. The operator can program the robot's movements, set its parameters, and monitor its performance through a graphical user interface (GUI). The GUI provides real-time feedback on the robot's movements, allowing the operator to make adjustments as needed to ensure that the robot moves accurately and precisely.

In recent years, there have been significant advancements in the control systems of articulated robots, with the integration of artificial intelligence (AI) and machine learning (ML) technologies. These technologies enable the robot to learn and adapt to its environment, improving its performance and increasing its flexibility in performing tasks.

Advantages and Limitations of Articulated Robots

Articulated robots offer several advantages over traditional industrial automation methods. Some of these advantages include:

1. Flexibility: Articulated robots have a high degree of flexibility and dexterity, enabling them to perform a wide range of tasks in various industries.

2. Precision: The use of advanced control systems, sensors, and actuators allows articulated robots to perform tasks with a high degree of precision and accuracy.

3. Efficiency: Articulated robots can perform tasks with greater speed and efficiency than human workers, resulting in increased productivity and reduced labor costs.

4. Safety: Articulated robots can perform tasks that are hazardous or dangerous for human workers, reducing the risk of workplace accidents and injuries.

However, there are also limitations to the use of articulated robots. Some of these limitations include the following:

1. Cost: Articulated robots can be expensive to purchase and maintain, making them less accessible to small and medium-sized businesses.

2. Complex Programming: Programming articulated robots can be complex and time-consuming, requiring specialized knowledge and expertise.

3. Maintenance: The maintenance of articulated robots can be challenging, requiring specialized skills and equipment.

4. Space requirements: Articulated robots require a significant amount of space to operate, which can be a limitation in smaller facilities.

5. Lack of adaptability: Articulated robots may struggle to perform tasks in constantly changing or unpredictable environments, as they are programmed to perform specific tasks in a set environment.

While articulated robots offer several advantages over traditional industrial automation methods, it is important to consider their limitations and potential challenges before implementing them in a business or manufacturing setting.

Applications of Articulated Robots

Articulated robots are used in a wide range of industries and applications, including manufacturing, healthcare, and entertainment. Here are some of the most common applications of articulated robots:

1. Manufacturing: Articulated robots are widely used in manufacturing industries for tasks such as assembly, welding, painting, packaging, and material handling. These robots can perform these tasks with high precision and speed, resulting in increased productivity and efficiency.

2. Healthcare: Articulated robots are increasingly being used in healthcare applications, such as surgery and rehabilitation. They can perform surgical procedures with greater precision and accuracy than human surgeons, reducing recovery times and improving patient outcomes.

3. Entertainment: Articulated robots are used in the entertainment industry for tasks such as animatronics, special effects, and puppetry. They can be programmed to perform complex movements and actions, resulting in lifelike performances and realistic special effects.

Fig. 1: Articulated robot used for pick and place application

4. Agriculture: Articulated robots are used in agriculture for tasks such as harvesting, planting, and spraying. By operating in difficult and dangerous environments, articulated robots reduce the risk of injury to human workers and improve the efficiency of the agricultural process.

5. Military and Defense: Articulated robots are used in military and defense applications for tasks such as bomb disposal and reconnaissance. These robots can operate in hazardous environments, reducing the risk of injury to military personnel and improving the safety and effectiveness of military operations.

6. Education: Articulated robots are increasingly being used in educational settings to teach students about robots and robotic automation. Robots are specifically programmed to perform a specific set of tasks, allowing students to learn about robotics in a hands-on, interactive way.

Selection Criteria for Articulated Robots

When it comes to selecting an industrial robot, there are a variety of factors to consider, including the application, payload capacity, reach, and repeatability required. In some cases, an articulated robot may be the best choice, while in others, a different type of robot, such as a Cartesian robot, a SCARA robot, or a Delta robot, may be more appropriate.

Suggested Reading: What are Robot Gantries? Types, Applications, Advantages, Selection Criteria, and more

Articulated robots are often the preferred choice when a high degree of flexibility and maneuverability is required. These robots have multiple joints that can move independently, allowing them to reach a wide range of positions and orientations.

The ability of articulated robots to move in multiple directions makes them well-suited for applications that require complex movements. They are also capable of handling a variety of payloads, from small electronic components to heavy automotive parts.

In contrast, Cartesian robots are designed to move in a straight line along three axes, making them ideal for applications that require precise linear motion in a cubical work envelope. Another type of industrial robot is the SCARA robot, which is designed for tasks that require high-speed, precise movement in a horizontal plane.

When deciding whether to use an articulated robot or another type of industrial robot, it is important to consider the specific requirements of the application. Articulated robots are best suited for applications that require a high degree of flexibility and maneuverability, while Cartesian and SCARA robots are better suited for applications that require precise linear or horizontal movement.

Ultimately, the selection of an industrial robot will depend on the application's specific needs, as well as factors such as cost, ease of programming, and maintenance requirements. By carefully evaluating the application's requirements, it is possible to choose the right type of robot for the job and ensure maximum efficiency and productivity.

Future Developments in Articulated Robots

As technology continues to evolve, articulated robots are expected to become even more advanced and versatile. Here are some of the developments that we can expect to see in the future of articulated robotics:

1. Enhanced sensory capabilities: As sensor technology continues to improve, articulated robots will be able to sense and respond to their environment in more sophisticated ways. This will allow robots to adapt to changing environments and perform more complex tasks.

2. Improved mobility: Advances in mobility technology, such as the development of new types of actuators and locomotion systems, will allow articulated robots to move more efficiently and effectively in a wider range of environments.

3. Artificial intelligence: The integration of artificial intelligence and machine learning algorithms into articulated robots will enable them to learn and adapt to new tasks and environments more quickly and efficiently.

4. Collaborative robots: Collaborative robots, or "cobots," will become more prevalent in the future of articulated robotics. These robots are designed to work alongside human workers, performing tasks that are too dangerous, repetitive, or strenuous for humans to perform.

5. Miniaturization: Advances in miniaturization technology will allow for the development of smaller, more compact articulated robots that can perform tasks in tight spaces or delicate environments.

Conclusion

Articulated robots have revolutionized the field of industrial automation, offering greater flexibility, precision, and efficiency than traditional factory automation methods. These robots are used in various industries and applications, from manufacturing and healthcare to entertainment and agriculture.

While there are limitations to the use of articulated robots, such as cost and programming complexity, their advantages make them an attractive option for businesses looking to improve their productivity and efficiency.

Looking to the future, we can expect to see continued advancements in articulated robot technology, such as enhanced sensory capabilities, improved mobility, and the integration of artificial intelligence and machine learning algorithms. These developments will further increase the versatility and efficiency of articulated robots, allowing them to perform even more complex tasks in a wider range of environments.

The future of articulated robotics is promising, and businesses that embrace this technology will likely see significant benefits in increased productivity, efficiency, and safety.

References

[1] Siciliano B, Sciavicco L, Villani L, Oriolo G. Robotics: modelling, planning and control. 2nd ed. London: Springer; 2010.

[2] Minner M. 4 types of robots every manufacturer should know [Internet]. Gaithersburg: National Institute of Standards and Technology (NIST); 2019 Jul 11. Available from: https://www.nist.gov/blogs/manufacturing-innovation-blog/4-types-robots-every-manufacturer-should-know

[3] Spong MW, Hutchinson S, Vidyasagar M. Robot modeling and control. 2nd ed. Hoboken: Wiley; 2020.

[4] Nof SY. Handbook of industrial robotics. 2nd ed. Hoboken: Wiley; 1999.

[5] ISO. Robots and robotic devices — Safety requirements for industrial robots (ISO 10218-1:2011) [Internet]. Geneva: International Organization for Standardization; 2011. Available from: https://www.iso.org/standard/51330.html