What are the components and classifications of industrial robots?
The industrial robot consists of three major parts and six subsystems. The three parts are: the mechanical body, the sensor part and the control part. The six subsystems are: drive system, mechanical structure system, perception system, robot -environment interaction system, human-computer interaction system and control system.
I. The composition of industrial robots:
To make the robot run, it is necessary to install a transmission device for each joint, that is, each degree of freedom of movement, which is the drive system. The drive system can be hydraulic, pneumatic, or electric, or a comprehensive system combining them, or it can be driven directly or indirectly through mechanical transmission mechanisms such as timing belts, chains, gear trains, and harmonic gears.
2.Mechanical structure system
The mechanical structure system of the industrial robot is composed of three major parts: the fuselage, the arm, and the end effector, as shown in Figure 1.6. Each large piece requires several degrees of freedom to form a multi-degree-of-freedom mechanical system. If the fuselage has a walking mechanism, it constitutes a walking robot; if the fuselage does not have a walking and waist rotation mechanism, it constitutes a single robot arm. The arm generally consists of an upper arm, a lower arm, and a wrist. The end effector is an important component attached to the wrist. It can be a two-finger or multi-finger claw.
3. Perception system
The sensing system is composed of internal sensors and external sensors, and its role is to obtain the internal and external environmental information of the robot and feed back this information to the control system. Internal state sensors are used to detect variables such as the position and speed of each joint, and provide feedback to the closed-loop servo control system. External sensors are used to detect some state variables between the robot and its surroundings, such as distance, proximity, and contact, etc., and are used to guide the robot so that it can identify objects and make corresponding processing. External sensors make the robot more accurately obtain the surrounding environment, on the other hand, it can also play a role in error correction.
The task of the control system is to obtain feedback signals from the sensors according to the robot's work instructions, and control the robot's actuators to complete prescribed movements and functions. If the robot does not have the information feedback feature, the control system is called an open-loop control system; if the robot has the information feedback feature, the control system is called a closed-loop control system. This part is mainly composed of computer hardware and software. The software is mainly composed of a human-computer interaction system and a control algorithm.
Classification of industrial robots:
Industrial robots are divided into three parts: mechanical body, sensor part and control part.
1. Material handling robot
The handling robot has a wide range of uses. Generally, only point control is required, that is, the workpiece being moved does not have strict motion trajectory requirements, and only the starting position and the end position must be accurate.
The earliest handling robots appeared in the United States in I960, and Versatran and Unimate robots were first used for handling operations. The handling operation refers to holding a workpiece with one type of equipment and moving it from one processing position to another. The handling robot can be equipped with different end effectors to complete workpieces of various shapes and states, reducing human heavy manual labor. At present, there are more than 100,000 handling robots in the world, which are widely used in automatic loading and unloading of machine tools, automatic production lines for punching machines, automatic assembly lines, palletizing, and containers. Some developed countries have formulated corresponding standards that stipulate the maximum limit for manual handling, and those exceeding the limit must be completed by a handling robot.
2. Detection robot
Inspection in the manufacturing process of parts and inspection of finished products are the keys to ensuring product quality. The work of this type of robot is mainly to confirm whether the size of the part is within the allowable tolerance, or to control the parts to be classified according to quality.
For example, after the threading of the tubing joint is completed, the ring gauge is screwed into the pipe end, and the accuracy of the processing of the joint thread can be understood by measuring the amount of screwing or detecting the contact degree with the gasket. The tubing joint workpiece is heavy, and the quality of the ring gauge is generally more than 15kg. In order to complete the continuous automatic action of the thread testing task (automatic ring gauge disengagement, automatic screwing measurement, etc.), a tubing joint thread testing robot is required. The robot is a six-axis multi-joint robot, which is characterized in that the hand mechanism is a five-degree-of-freedom compliant threaded screwing mechanism. In addition, there is a jam detection mechanism, which can control the screwing motion.
3. Welding robot
This is currently the most widely used type of robot, which is divided into two types of electric welding and arc welding. Welding people have a large load, fast movement, and strict posture requirements. Generally, they have 6 degrees of freedom. The arc welding robot has a small load and low speed. Arc welding has strict requirements on the robot's motion trajectory, and continuous path control must be implemented, that is, each point of the motion trajectory must achieve predetermined position and attitude requirements.
Of the 6 degrees of freedom of the arc welding robot, generally 3 degrees of freedom are used to control the spatial trajectory of the welding tool following the weld seam, and the other 3 degrees of freedom maintain the correct attitude relationship between the welding tool and the workpiece surface, so as to ensure good welding Seam quality. At present, automobile manufacturers have widely used welding robots to weld bearing beams and bodywork.
The working object of the pipe joint thread detection robot is a steel pipe. Different pipe diameters or pipe bending can cause eccentricity of the positioning of the steel pipe. Therefore, a camera must be installed on the robot's hand to identify the position of the steel pipe, and then the center of the steel pipe is identified according to techniques such as image matching. line.
4. Assembly robot
The assembly robot is required to have high pose accuracy, and the wrist has greater flexibility, as shown in Figure 1.9. Because assembly is a complicated operation process, not only the errors in the assembly operation must be detected, but also such errors must be corrected. Therefore, the assembly robot uses many sensors, such as contact sensors, vision sensors, proximity sensors, and hearing sensors.
5. Spraying robot
The painting robot is mainly composed of a robot body, a computer and a corresponding control system. Hydraulically driven painting robots also include hydraulic oil sources such as oil pumps, tanks, and motors. Mostly adopt 5 or 6 degrees of freedom articulated structure, the arm has a large space for movement, and can do complex trajectory movements, and its wrist generally has 2 to 3 degrees of freedom, which can be flexibly moved. The wrist of the more advanced painting robot uses a flexible wrist, which can be bent in all directions and can be rotated. Its action is similar to that of a human wrist. It can easily reach into the workpiece through smaller holes and spray its inner surface. Paint spraying robots are generally driven by hydraulics. They have the characteristics of fast movement speed and good explosion-proof performance. They can be taught by hand teaching or point counting. Painting robots are widely used in automotive, instrumentation, electrical appliances, enamel and other process production departments.
This industrial robot is mostly used in spraying production lines, and the repeat positioning accuracy is not high. In addition, because paint mist is flammable, the drive must be flameproof and explosion-proof.
It has many advantages such as accurate spraying, long uptime, less paint consumption, short working cycle, and effective integration of coating equipment.
Other advantages include strong load capacity and high operational reliability. ABB's original integrated process system (IPS) has closed-loop adjustment and high-speed control for paint and air supply, which can minimize overspray and ensure uniform paint film.