In this blog post, we’ll explore the characteristics of robotics—which has evolved through the convergence of knowledge from various disciplines, including mechanical engineering—as well as the structure of robotic arms, their control principles, and their role in industrial settings.
When many people hear the term “mechanical engineering,” they likely think of cars, gears, or factories. In fact, if you search for “mechanical engineering” by image on a search engine, you’ll see many pictures of cars and gears. However, mechanical engineering encompasses many other fields as well, and here we’ll focus on robotics. In robotics, the primary focus is on studying robotic arms (manipulators). A robotic arm is a machine with functions similar to a human arm, designed to move objects. Humanoid robots—which attract a great deal of public interest and frequently appear in science fiction movies (robots that resemble humans and possess human-like cognitive and motor functions)—can also be considered an application based on robotic arms. Robotic arms are actually used in industrial settings, such as in automobile assembly lines. When I first entered university, during the College of Engineering orientation, Jin Dae-je, then Minister of Information and Communications, said, “Natural sciences are disciplines where you spend money to gain knowledge (‘make knowledge with money’), while engineering is a discipline where you apply knowledge to make money (‘make money with knowledge’).” Robotics, as a subfield of engineering, is meaningful only when it is applied in industrial settings to perform specific tasks. The reason I chose robotics as my major is that its significance lies in the fact that it is a field that requires the convergence of various subdisciplines within mechanical engineering. In other words, because it demands both deep knowledge of a specific field and a broad understanding of other fields, robotics can be described as a convergent science and technology. The “other fields” referred to here include not only other disciplines within mechanical engineering but also those from other departments. To major in mechanical engineering, one must study the so-called “four major branches of mechanics”: solid mechanics, thermodynamics, dynamics, and fluid mechanics. Among these, dynamics and solid mechanics are essential courses for studying robotics. Mechanics is a discipline that, based on dynamics and statics, examines the effects of forces on the motion of objects, studying an object’s path, velocity, acceleration, and other characteristics. In order for a robotic arm to perform a given task, an analysis of this process must be conducted beforehand. Furthermore, solid mechanics analyzes the loads and moments acting on structures; similarly, a robotic arm must be designed to perform its intended task effectively by analyzing the relationship between the forces and moments that may arise during the task. For example, if a robotic arm lifts an object and the beam bends so that it cannot reach the exact target position, it can be said that the arm was not designed properly. In addition to dynamics and solid mechanics, it is necessary to study joint control. Relevant courses include “Mechanical and Aerospace Systems Analysis” and “Systems Control Theory.” Proper control of the joints is essential for successfully accomplishing the task. For instance, suppose a joint needs to rotate 60 degrees and the appropriate time for this movement is 1 second. If control is mishandled and the joint rotates 60 degrees in just 0.1 seconds, the object could be dropped due to inertia, or fatigue could accumulate in the joint during the design phase, leading to failure sooner than expected. Finally, since robots use electricity as their power source, study of this subject is also required. As such, robotics requires knowledge spanning multiple disciplines. Consequently, graduate programs in convergent science and technology—which address fields requiring the integration of various disciplines—have been established. In this way, robotics is significant in that it drives the advancement of multiple academic fields.
I will now explain the robotic arm studied in robotics. A robotic arm is broadly composed of joints and an end-effector. Since a robotic arm is modeled after a human arm, the joints correspond to the shoulder, elbow, and wrist, while the end-effector corresponds to the hand. There are five main types of joints. These include the revolute joint, which performs rotational motion; the prismatic joint, which performs linear motion; the cylindrical joint, which combines both; the universal joint, which consists of two revolute joints; and finally, the ball joint (or spherical joint), which is similar to a human shoulder. Typical robotic arms include the PUMA-type open-chain arm, which has six revolute joints, and the Stanford arm, which consists of five revolute joints and one prismatic joint. Since the end-effector must function like a human hand, students study the number of contact points with the object, the force required to grasp it, and friction, among other factors. A thorough understanding of joints and end-effectors is essential for designing robotic arms that function properly. Robotics plays a very significant role in actual industrial settings. Productivity has greatly improved as various assembly processes have been automated using robotic arms. As such, robotics has become an essential element of modern industry. Furthermore, because it draws upon many different disciplines, I believe it is a crucial field that contributes to the advancement of mechanical engineering itself. If robotics continues to advance, we can look forward to a society where humans live alongside robots, much like what we see in science fiction movies and novels.
