Robots are the most typical electromechanical digital devices, possessing high added value and wide applications. As a supporting technology for advanced manufacturing and the information society, they play an increasingly important role in future production and social development. Since the second half of the 20th century, the global robotics industry has maintained steady growth. Based on the industrial development and modernization process of developed countries, and the trend of industrial robot commercialization, the Chinese robot market capacity was approximately 100,000 units by 2015. What are the structure and working principles of industrial robots?
1. Working principle of industrial robots
An industrial robot is a type of production equipment whose primary function is to ensure the movement and power required for work. Its main working principle is to automatically realize the operational functions and technical requirements of a workpiece through the movement of its robotic arm's moving parts. Therefore, in terms of basic functions and working principles, industrial robots and machine tools share similar characteristics: their end effectors require positional changes, which are achieved through coordinate motion. Of course, robots also have their own unique requirements, primarily in their articulated joints. Robots need high flexibility, while rigidity and precision requirements are relatively lower.
2. Industrial Robot Design System
A robot's functions can be divided into four parts: operator, end effector, sensor system, and controller. Operator: Composed of a base, hand and wrist, transmission mechanism, drive system, etc. Its function is to change the workspace on the wrist and adjust the wrist so that the end effector meets the operational requirements. End Effector: Also known as an industrial robot hand, it is an industrial robot component mounted on the wrist, allowing direct grasping or manipulation of workpieces. Sensor System: Indicates whether the robot can perform work as efficiently as a human. Sensory functions should assess external sensory capabilities. Tactics are often related to robot control. Vision is used to detect the presence of objects, their approximate location, position, and other states. On the other hand, touch helps you see clearly. It can detect the fine state of objects. Controller: The robot control system is the brain of the robot and is the main factor determining the robot's functions and performance. It mainly controls the industrial robot's movement position, location and trajectory in the workspace, work sequence, and operation time. It features simple programming, software menu operation, user-friendly human-machine interface, and quick and convenient online operation. Control systems used by robots include: point and contour; synchronous and asynchronous; digital and analog. Specific control system schemes can be selected according to the robot's technical and economic requirements and the characteristics of the process task.
3.1 Determination of wrist structure
The wrist connects the hand and the end effector. Its task is to realize three positions of the hand and seat end effector within the workspace, and four positions (or directions) of the end effector within the workspace, i.e., three rotational degrees of freedom. It connects to and supports the end effector via a mechanical interface. The degrees of freedom are determined according to the robot's performance requirements.
3.2 Selection of Harmonic Gears
Harmonic gear reducers are a new type of mechanical transmission mechanism. Compared with traditional gearboxes, they are smaller, lighter, and simpler in structure. Compared with traditional reducers with equivalent transmission, their parts are reduced by 50%. Volume and weight are reduced by approximately 1/3 or more. They offer a wide transmission ratio range (single-stage ratio 40–350, multi-stage ratio up to 16000–10000), high transmission efficiency (single-stage efficiency ≥85%), high transmission accuracy, and strong load-bearing capacity. Based on the selected engine, the SGMAH-OIA model is chosen. It features a rated power of 100W, a rated speed of 3000 rpm, and a drain-pole AC servo motor. Select now. XL1 Harmonic Reducer.
4. Robot bearing design
Ball bearings are the most commonly used bearings in robots and mechanical mechanisms. They can withstand radial and axial loads. They have low friction. Robot-specific bearings feature a four-point contact design and high-precision machining. This type of bearing is 25 times lighter than traditional four-point contact bearings. Its inner ring (or outer ring) consists of exactly two semi-rings. The radius of curvature of the grooves throughout the outer ring (or inner ring) is very small, so the balls contact the inner and outer rings at four "points". This not only increases radial load capacity but also enables it to withstand axial loads in both directions in a compact size, and provides good axial confinement in both directions due to its relatively small shaft clearance. It also features a large contact angle (typically 35 degrees). Thin-walled four-point contact ball bearings for industrial robots typically have seals, but without them (see Figure 4). It consists of a...
