The definition and classification of a robot:
According to ISO 8373, a robot is defined as an industrial automation device whose position can be fixed or moved, can be automatically controlled, can be reprogrammed, multi-functional, and the position of the end operator can be programmed in 3 or more degrees of freedom. Here the freedom refers to the axis that can be moved or rotated. Industrial robots are mainly classified into articulated robots, mobile robots, underwater robots, and Cartesian robots according to their structural forms and programmed coordinate systems. According to the main functional features and applications, it is divided into mobile robots, underwater robots, clean robots, rectangular coordinate robots, welding robots, surgical robots, and military robots. Robotics involves many aspects such as robot structure, robot vision, robot motion planning, robot sensors, robot communication and artificial intelligence. Robots with different uses are involved in different disciplines. The following is a brief introduction to the structure and application of these robots:
Two-joint robot The joint robot's structure is similar to the human's arm and consists of six to seven degrees of freedom, including several rotation axes, swing axes, and grippers. Manufacturers mainly include Germany Manutec, Germany KUKA, Germany REIS, Japan Motorman, Japan Yaskawa and Shenyang Xinsong. The rotary axis and the swing axis of an articulated robot are mainly driven by a servomotor or a precision speed reducer or a direct-drive torque motor with almost no backlash, and its control system is also very difficult. The joint robots of various manufacturers have the same structure and the main differences are in the technical parameters. The following is an example of the joint robot of the German Manutec company.
Figure 1 is Manutec's model r15-30 6-degree-of-freedom universal joint robot with a rated load of 30 kilograms, a maximum reach of 75 kilograms, a working radius of 1.3 meters, a repeatability of less than 0.04 mm, and a point-to-point maximum operating speed of 5.9 m/s, acceleration up to 23 m/s2 and working life of 20 years. It can be installed vertically. It can be installed off-hook, or it can be installed obliquely with a horizontal plane of less than 30 degrees without affecting its technical specifications. R15 can be fitted with explosion-proof, but also can be equipped with a clean type.
The main features of r15-30 are its high strength and rigidity, and its high repeatability. The main application areas are those where the joint robots of other manufacturers cannot be applied due to lack of rigidity and precision, and the use of 5-axis machining centers is too costly or incompetent. . Such as grinding teeth, special-shaped milling, shell (cavity) internal milling, grinding, polishing, cutting and welding.
Force sensors can be fitted at the end of the gripper to machine contoured surfaces (such as milling, grinding and polishing). A robot can also coordinate synchronous movement with the dual table and various dual rotary axes. It may also be that the two robots work in coordination and synchronization, such as a robot picking up a workpiece, and a robot performs processing on the workpiece. The two robots synchronously perform a specific machining trajectory.
Joint robots of other manufacturers are mainly used in tasks such as automobile welding and assembly. The advantage of articulated robots is that they can work from different angles and different orientations, and they are fast and work efficiently. However, the main disadvantages are the small working radius, small load, high price, difficulty in application and high maintenance costs.
The simplified robot SCARA as an articulated robot is two swing axes and one up and down movement axis. Its features are simple, economical, suitable for small working space, small load, and high speed handling. However, its price is higher than that of Cartesian robots, and its application industry and quantity are very small.
Three special robot mobile robots are electric vehicles that can move independently or go up and down the stairs. They are mainly used for the production of on-site cargoes for autonomous transport and depot operations, or for sampling and surveillance in polluted and radioactive environments. There are also some mobile robots that imitate some animals. Walking robots that walk on their legs and claws, such as American military dogs, are still in the applicable stage. Underwater robots and submarines can submerge themselves underwater to complete video recording and monitoring of underwater construction of offshore drilling platforms, submerged gates of power stations, and submarine salvage. Clean-type robots are mainly articulated robots that wear protective clothing to make them have a good seal, do not bring dust into the work site, and do not generate dust themselves. They are mainly used in the production of electronic devices, foods, and pharmaceuticals. in. International has a clear definition of the cleanliness of clean robots. Military robots are mainly small mobile vehicles, remote-controlled aircraft or electronic dogs, etc. They complete some operations in hazardous areas, such as mine clearance, minelaying, on-site monitoring, and shooting to destroy specific targets. Although the current service robots are mainly toy-type self-propelled electric vehicles, devices such as vision and ultrasound are mounted on them to make it possible to move without collision at home, take pictures at different locations, use for theft prevention, detect coal vapor leakage, and wirelessly send Information and receiving instructions, transportation of goods and so on. However, the function of service robots will continue to increase in the future, and it will continue to penetrate into every aspect of people’s daily life. There are also special robots such as surgical robots, aerospace robots, milking robots, and robots for nuclear power plants.
Four rectangular coordinate robots are the most widely used Cartesian robots in all walks of life. They are mainly based on the linear motion axis. Each motion axis usually corresponds to the X axis, Y axis, and Z axis in the rectangular coordinate system, and the general X axis. The Y axis is the horizontal axis of motion, and the Z axis is the vertical axis. In some applications there is a rotation axis on the Z axis, or an oscillation axis and a rotation axis. In most cases, the angle between each linear motion axis of the Cartesian robot is a right angle.
4.1 Composition of Cartesian Robots Figure 2 is a typical 3D Cartesian robot consisting of an X-axis, a Y-axis, a Z-axis, and a drive motor. In addition, a complete robotic system also requires a control system and hands, which are described separately below:
4.1.1 Linear Motion Axis: It is also called a linear motion unit. It is an independent motion axis. It is mainly composed of aluminum profiles or steel profiles that support carriers and linear guides, motion sliders, and driven sliders installed inside the profiles. High-speed motion of the timing belt.
4.1.2 The drive system of the motion axis Cartesian coordinate The drive of the robot mainly drives the movement of the timing belt through the rotation of the drive motor, and the timing belt drives the slider movement on the linear guide. When the maximum speed of the drive shaft is less than 600 rpm, the stepping motor is usually selected; otherwise, the AC servo motor is used.
4.1.3 Control System for Cartesian Robots Robots perform certain tasks within a certain period of time, such as completing a task every 10 seconds. In the completion of the grab, accelerated movement, high-speed movement, deceleration movement, release the workpiece, etc., but also with the relevant equipment through communication or I / O port to achieve some of the time synchronization coordination. In addition, on the application of glue, each axis of motion must complete the linear and arc interpolation motion. Therefore, the numerical control system should select the number of control axes, the number of I/O ports and software functions according to the specific application requirements. Usually choose the numerical control system, the PLC, the industrial control machine adds the motion control card and the drive motor with the axis card function and the I/O mouth to do the control system.
4.1.4 Cartesian robot end-effector - the gripper system According to its specific application, the gripper system may be a pneumatic sucker, a pneumatic gripper grip, an electric gripper gripper, an electromagnetic gripper gripper, a welding torch, a glue gun, Special tools and testing instruments. In many situations it is possible to grab multiple workpieces at a time.
Many manufacturers have developed some standard linear motion units and their combinations. The technical data and applications of Cartesian coordinate robots are described below in connection with the products of German Bagela.
4.2 Introduction to German Cartesian Cartesian Coordinate Robots The German Bagra is one of the world's most famous suppliers of Cartesian robots, producing a wide range of linear motion units, stepper motors, AC servo motors, linear motors and multi-axis CNCs. system. Based on this, we can provide linear guides of various specifications, 2D and 3D standard robots, and user-specific robots and production lines in a short time. These robots can be equipped with welding torches, various universal grippers or special tools. They are positioned reliably, precisely and quickly within the defined 3D space as required, interpolating motion along straight lines or circular arcs. Finished welding, handling and loading and unloading, packaging, palletizing, demolition, inspection, classification, assembly, labeling, coding, coding, (soft copy) spraying and a series of work. As all parts are produced by themselves, the overall performance of the robot is even better.
4.2.1 Gantry axis linear motion unit The linear motion unit and the drive motor are fixed, while the slider motion is mainly used for horizontal and vertical long-distance movements. There are standardized products PAS41, PAS42, PAS43 and PAS44. Corresponding cross-sectional dimensions are 40*40 mm, 60*60 mm, 80*80 mm and 110*110 mm, single standard length is 6000 mm, load is 10~200 kg, repetitive positioning accuracy is 0.05 mm, and maximum operating speed is 8 meters In seconds, the acceleration is 4 meters per second.
4.2.2 Gripping axis The linear motor unit drive motor and the slider are fixed on a plane. The linear motion unit body moves. The standard length of the guide rail is up to 2400 mm. Mainly enters the working space vertically or horizontally, used for grabbing and handling of goods. Its standardized products are LM-A001 to LM-A808, and the corresponding dimensions are 40*40 mm, 60*60 mm, 80*80 mm to 110*110 mm, the single maximum length is 3000 mm, and the load is 2~100 kg. The repeat positioning accuracy is 0.05mm, the maximum operating speed is 8m/s, and the acceleration is 4m/s.
4.2.3 Various structural forms of 2D and 3D Cartesian robots Using the standard gantry and gripping axis linear motion units The German Bagra company has successfully combined hundreds of structural forms, strokes and loads over the past 20 years. Ability to install robots in different ways. Among them, a variety of enhanced forms have been adopted to meet the requirements of different applications to ensure its strength, improve its deformability, reduce vibration and shaking, and increase its life span. Its common structural forms include gantry type, cantilever type, hanging arm type and drop type.
4.3 The main structural forms and main characteristics of Cartesian coordinate robots But for a variety of different applications, in fact can be quickly and easily combined into different dimensions, a variety of trips and different carrying capacity of the wall, cantilever, gantry or inverted And other forms of Cartesian robots. From simple two-dimensional robots to complex five-dimensional robots, there are hundreds of successful examples of structural applications. From the motor to the automobile and other automated production lines in various walks of life, but also a variety of rectangular coordinate robots and other equipment strictly synchronous and coordinated work. It can be said that Cartesian robots are capable of almost all industrial automation tasks. Here are its main features:
4.3.1 Arbitrary combination into various styles: The maximum length of each linear motion axis is 6 meters, and its carrying capacity is from 10 kg to 200 kg. In practical applications, there are nearly 100 kinds of Cartesian coordinate robots, and these structures can also be arbitrarily combined into new structures.
4.3.2 Oversized travel: Because the length of a single gantry type linear motion unit is 6 meters, it can also be cascaded into multiple large and convenient strokes, so its working space is almost unlimited. It can be as small as a mobile phone dispenser and can be as large as 18 Meter long stroke cutting machine, 8 meters long stroke drilling and milling machine, 6 meters * 6 meters * 3 meters detection robot. When using large strokes, use linear guides and rack drives.
4.3.3 Strong load capacity: The load of a single linear motion unit is usually less than 200 kg. However, the load capacity can be increased by 5 to 10 times when using a dual-slider or multi-slide rigid coupling. When two or four linear motion units are used side by side, the load can be increased by 2 to 4 times. When using multiple multi-slider configurations, the load capacity can be increased to several tons.
4.3.4 High dynamic characteristics: At light loads, the maximum operating speed can reach 8 meters per second and the acceleration can reach 4 meters per second. To make it highly dynamic, work efficiency is very high, usually within a few seconds to complete a work cycle.
4.3.5 High Accuracy: According to the transmission mode and configuration, the repeat positioning accuracy can reach 0.05mm~0.01mm in the whole stroke.
4.3.6 Strong ability to expand: It is easy to change the structure or program to suit new applications.
4.3.7 Simple Economy: Compared with joint robots, Cartesian robots not only have intuitive appearance and low construction cost, they are similar to CNC milling machines in programming, and they are easy to train employees and maintain, making them very economical.
4.3.8 Competent and Complicated Tasks: The use of a 5-axis or 5-axis numerical control system with RTCP function can accomplish very complex tasks such as spraying, shot blasting, inspection, and processing.
4.3.9 Long life: The life of Cartesian robots is generally more than 10 years and can be maintained for up to 20 years.
4.3.10 Wide range of applications: It is easy to assemble multiple types and sizes of grippers. It can be used for many common tasks such as welding, cutting, handling, loading and unloading, packaging, palletizing, demolition, inspection, flaw detection, and classification. , assembly, labeling, coding, coding, and spraying tasks.
4.4 Cartesian Robot Selection and Maintenance
4.4.1 Selection: The shape of the robot must first be selected according to the size of the load, stroke, work cycle, and work space limitations. After selecting the structure, select the type and model of each axis according to the stroke and deformation amount. For large loads and high impact forces, you can choose to combine two or four motion axes into one compound motion axis. The assembly between the various axes of movement is also critical, not only to ensure its verticality, but also to have sufficient impact resistance and deformation in all directions. The robot must complete a beat of the sport in a few seconds. The drive motor selected must have sufficient driving force, which is usually 100% higher than the theoretical calculation. When the ratio of the moment of inertia of the load to the moment of inertia of the drive motor is greater than 12, a precision planetary reducer from Germany's Newcastle company is to be fitted.
In the case of very high dynamics and positioning accuracy requirements, linear motors can be used to drive. However, the installation and protection of the linear motor is difficult, the heat is large, the impact risk is high and the control is difficult, and the cost is also high, so it should be used with caution. However, the difficulty of protection and the large amount of heat are currently in the machine tool industry and it is a worldwide problem.
4.4.2 The mounting robot generates strong impact when accelerating and decelerating, and it usually works 24 hours a day, so the robot must be firmly mounted on the bracket. The robot's support must have sufficient impact resistance and have footings to ensure that there is no shaking under long-term high-speed and high-dynamic motion shocks. In addition, the parallelism, flatness, and perpendicularity between the axes of motion must be ensured during installation.
4.4.3 Maintenance items Usually, after each movement axis of the robot has passed a certain length of movement, the linear guides are periodically filled with lubricant through the oil filling holes of the slider. Depending on the environment in which the robot is used and the speed of the work, the cycle of oil injection varies. In industries such as food and glass cutting, it is necessary to use a movement axis with a dust-proof tape and shorten the oil injection cycle, and also shorten the oil injection cycle in the case of water spray.
V. Application and Prospect Each robot has its own particularities and advantages, which apply to a specific industry or job. There are also joint robots installed on large linear motion platforms to expand the work area and accomplish more tasks. In order to overcome the fact that Cartesian robots are not easy to work in deep and slender space regions, the German Bagra company has successfully assembled a cantilevered Cartesian robot with various structures and added a 500-mm swing axis and a vertical lifting axis to the Z-axis of the Cartesian robot. In addition, a rotary axis and a swing axis are sometimes added to the Z-axis to form a 5-axis robot, and a combination of Cartesian robots of different structural forms are combined into a variety of functions for capturing, carrying, processing, and finally grasping and transporting. Robotics work center. In Germany, there are more than 50 Cartesian robot manufacturers, large and small, and their 20-year efforts have made Cartesian robots more widely used than articulated robots. For example, it is widely used in Western developed countries to perform a series of work such as welding, handling, loading and unloading, packaging, palletizing, demolition, inspection, inspection, classification, assembly, labeling, marking, gluing, and cutting. Deeply praised by the packaging machinery, printing machinery, automotive industry, food production industry, pharmaceutical production industry, electronics industry, machine manufacturing and cosmetics production industries. With the increasing degree of automation, environmental protection requirements, health regulations, production efficiency, personnel quality and labor costs, rectangular coordinate robots will also be widely adopted in all walks of life in China.