Cartesian coordinate robot concept:
In industrial applications, a Cartesian coordinate robot is a versatile manipulator capable of automatic control, reprogrammability, multifunctionality, multiple degrees of freedom, and spatial Cartesian coordinate relationships between its degrees of freedom. It can move objects and manipulate tools to complete various tasks. The definition of a robot is constantly evolving with technological advancements, and the meaning of Cartesian coordinate robots, as a type of robot, is also continuously being refined.
Based on our analysis of this concept, we elaborate as follows:
I. Characteristics of Cartesian Coordinate Robots:
1. Multi-degree-of-freedom motion, where the spatial angle between each degree of freedom is a right angle.
2. Automatically controlled and reprogrammable, all movements are executed according to the program.
3. It generally consists of a control system, a drive system, a mechanical system, and operating tools.
4. Flexible and multifunctional, with different functions depending on the operating tools.
5. High reliability, high speed, and high precision.
6. It can be used in harsh environments, can work for a long time, and is easy to operate and maintain.
II. Applications of Cartesian Coordinate Robots:
Due to the variety of end-effector tools available, Cartesian robots can be easily used as various automated equipment to perform a range of tasks, including welding, handling, loading and unloading, packaging, palletizing, depalletizing, inspection, flaw detection, sorting, assembly, labeling, inkjet printing, coding, (soft-contour) painting, target tracking, and bomb disposal. They are particularly suitable for flexible operations involving multiple product varieties and large batches, playing a vital role in stabilizing and improving product quality, increasing labor productivity, improving working conditions, and facilitating rapid product updates.
III. Classification of Cartesian Coordinate Robots:
1. By application: welding robots, palletizing robots, gluing (dispensing) robots, inspection (monitoring) robots, sorting (classification) robots, assembly robots, bomb disposal robots, medical robots, special robots, etc.
2. Classified by structural form: wall-mounted (cantilever) robots, gantry robots, inverted robots, etc.
3. Classified by degrees of freedom: two-axis robot, three-axis robot, four-axis robot, five-axis robot, and six-axis robot.
There are other classification methods, which will not be introduced here.
IV. Core Component of Cartesian Robots – Linear Positioning Unit <br /> In order to reduce the cost of Cartesian robots, shorten the product development cycle, increase product reliability, and improve product performance, many countries in Europe and America have modularized Cartesian robots, and the linear positioning unit (system) is the most typical product of modularization.
A complete positioning unit (system) consists of several parts.
1. Positioning body profile: As the installation support part of the track, this profile is different from ordinary frame profiles. It requires very high straightness and flatness.
2. Motion Rail: Installed on the positioning profile, this rail directly supports the movement of the slider. A positioning profile (system) may have one or multiple motion rails installed. The characteristics and quantity of the rails directly affect the mechanical properties of the positioning unit (system). There are many types of rails that make up a positioning system; common types include linear ball bearing rails and linear cylindrical steel rails.
3. Motion slider: Composed of a load mounting plate, bearing bracket, roller assembly (ball bearing assembly), dust removal brush, lubrication chamber, and sealing cover. The motion slider is coupled to the track via rollers or balls to guide the motion.
4. Transmission components: Common transmission components include synchronous belts, toothed belts, lead screws/ball screws, racks, linear motors, etc.
7. Bearings and bearing housings: used to mount transmission components and drive units.
V. Cartesian Coordinate Robot Drive Components – Motor Drive System <br />The reason why the linear positioning unit (system) can achieve precise motion positioning is determined by the motor drive system.
Commonly used driver systems include:
AC/DC servo motor drive systems, stepper motor drive systems, and linear servo motor/linear stepper motor drive systems. Each drive system consists of two parts: a motor and a driver. The driver amplifies the weak electrical signal and applies it to the strong electrical circuit of the drive motor to drive the motor. The motor then converts the electrical signal into precise speed and angular displacement.
AC/DC servo motor systems are often used as drives in applications requiring high dynamics, high speed, and high power; stepper motor systems can be used in applications requiring low dynamics, low speed, and low power; and linear servo systems are used in applications requiring extremely high dynamics, high speed, and high positioning accuracy.
VI. The Soul of a Cartesian Robot—The Controller <br /> To achieve the robot's flexible and versatile movement functions and rapid response and processing functions, the robot must have a brain—the controller.
The controller functions as a command source, which can issue control commands, receive feedback signals, and process information in real time according to the numbered program.
Depending on their function, controllers can come in many forms:
1. Combination of industrial computer and motion control card: The motion control card borrows the resources of the computer and uses its own motion control function to achieve control.
2. Offline motion control card: The program is written using a computer and can be stored and run offline.
3. PLC - The program is written using a computer and can be stored and run offline.
4. Dedicated controller.
7. Terminal Equipment for Cartesian Robots – Operating Tools <br />The terminal equipment for Cartesian robots can be equipped with various operating tools depending on the intended use:
For example, the terminal operating tool of a welding robot is a welding gun; the terminal operating tool of a palletizing robot is a gripper; the terminal operating tool of a glue applicator (dispensing robot) is a glue gun; and the terminal operating tool of an inspection (monitoring) robot is a camera or laser.
Some complex tasks cannot be completed with a single tool and require two or more tools. For example, grasping objects that are not moving along a fixed trajectory requires not only a mechanical gripper but also a camera to continuously track and calculate the object's spatial position.
