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9 Parameters for Choosing the Right Industrial Robot Model Type

"Robots" are often discussed by people. First of all, for the industrial automation industry, it has to be cleared that the "robot" used by the factory is absolutely not a similar robot like girlfriend robot in the movie.



For the experienced mechanical, electrical engineers in the automation industry, it is probably a simple job to choose the right robot. But for some automation designers or factories who need to purchase or import robots for the first time may be somewhat confused.



The following is about how to choose a suitable industrial robot concerning 9 professional parameters.


1. Application


First of all, the most important part is to evaluate what kind of applications and what kind of processes the robots are used for. The cooperative robot (Cobots) should be a good option if the application process needs to be for the usual man-machine closely mixed semi-automatic line, especially the situations which needs changing work position or shifting the line,or are combined with a new torque sensor.




If you are looking for a well-knit Pick& Place robot, you can choose a horizontal joint robot (Scara). Parallel (Delta) robots  are very suitable for situations in which they need to pick and place small objects quickly. Next, we will discuss the vertical joint multi axis robot (Multi-axis). This robot can adapt to a very wide range of applications. Choose the most suitable model.


2. Payload


The payload is the maximum load that a robot can carry in its work. For example, the payload can be from 3Kg to 1300Kg according to different model types. If you want the robot to carry the target workpiece from one working position to another, you need to add the weight of the workpiece and the weight of the robot's gripper to its estimated payload requirement.

It is also important to note that the load required by the robot is related to the distance of the end load. For example, you can check the load counting drawing method of SOOYEE Robot SYB1410B.

SYB1410B load counting drawing



3. Degree of Freedom (number of axes)


The number of axes configured by the robot is directly related to its degree of freedom. If it is for a simple straight-forward operation situation, such as taking from one belt line to another, a simple 4-axis robot is sufficient.However, if the application is in a small working space and the robot arm needs a lot of twisting and turning, a 6-axis or 7-axis robot will be good choice.


The number of axes generally depends on the application. It should be noted that more axises the robot has, the better flexibility is, provided that the cost permits. This facilitates the subsequent re-use of the revamping robot to another application process, which can adapt to more work tasks, rather than finding that the number of axes is not enough. Robot manufacturers tend to use differently named axes or joints. Basically, the first joint (J1) is the closest to the robot base.The following joints are called J2, J3, J4, and so on until they reach the end of the wrist. Other companie like Yaskawa Motoman  uses words name their robot axis.




4. Maximum Operating Range


When evaluating a targeting application, you should know the maximum distance the robot needs to reach. Choosing a robot is not solely based on its payload - it also requires a comprehensive consideration of the exact distance it reaches. Each company will give a map of the range of motion of the corresponding robot, from which it can be judged whether the robot is suitable for a particular application. About the horizontal movement range of the robot, please pay attention to a non-working area of the robot in the close and rear place .

The maximum vertical height of the robot is measured from the lowest point the robot can reach (usually below the base of the robot) to the maximum height (Y) the wrist can reach. The maximum horizontal movement distance is the distance (X) from the center of the robot base to the center of the furthest point that the wrist can reach horizontally.


5. Repeated Positioning Accuracy


This factor also depends on your application. Repeated Positioning Accuracy can be described as the robot's ability to complete routine work tasks each time they reach the same location. Generally between ±0.05mm and ±0.02mm, or even more accurate. For example, if you need your robot to assemble an electronic circuit board, you may need a super precise repeated positioning accuracy robot. If the application process is relatively rough, such as packaging, palletizing, etc., the industrial robots do not need to be so precise in repeated positioning.


On the other hand, the requirements for robot precision in assembly engineering are also related to the transmission and calculation of the dimensions and tolerances of each process in the assembly engineering, such as the positioning accuracy of the incoming materials and the repeated positioning accuracy of the workpiece itself in the fixture. This indicator is expressed as plus or minus '±' from 2D. In fact, since the robot's movement repetition point is not linear but moves in space 3D, the actual condition of this parameter can be anywhere within the spherical space within the tolerance radius.

Of course, the current motion compensation with machine vision technology will reduce the robot's requirements and dependence on the accuracy of incoming materials and improve the overall assembly accuracy.


6. Speed


This parameter is closely related to each user. In fact, it depends on the cycle time that the job needs to complete. The specification table shows the maximum speed of the model robot, but we should know that considering the acceleration and deceleration from one point to another, the actual speed will be between 0 and the maximum speed. This parameter is usually expressed in degrees/second. Some robot manufacturers also mark the maximum acceleration of the robot.




7. Body Weight


The robot body weight is an important factor when designing a robot cell. If an industrial robot must be mounted on a custom machine, even on a guide rail, you may need to know its weight to design the corresponding supporting structure.



8. Brake and Moment of Inertia


Basically every robot manufacturer provides information about their robotic braking system. Some robots have brakes on all axes. Other robot models do not have brakes on all axes. To ensure an accurate and repeatable position in the work area, you need a sufficient number of brakes. In another special case, when an accidental power outage occurs, the load-bearing robot shaft without brakes will not lock up, causing an accidental risk.

At the same time, some robot manufacturers also provide the robot's moment of inertia. In fact, this will be an additional guarantee for the safety of the design. You may also notice the applicable torque on different axes. For example, if your action requires a certain amount of torque to perform the job correctly, you need to check if the maximum torque applied on the shaft is correct. If the selection is incorrect, the robot may be shut down due to overload.



9. Protection level(IP)


According to the using environment of the robot, we will need to select a certain degree of protection (IP rating). Some manufacturers provide the same robots with different IP protection grades for different applications. If the robot is working with a food-related product, medicine, medical device, or in a flammable environment, the IP rating will vary accordingly.  For example, SOOYEE robot's IP is IP54.

Here is the explain on IP number.


First number (Protection against solid objects)

0 No protection
1 Protected against solids objects over 50mm (e.g. accidental touch by hands
2 Protected against solids objects over 12mm (e.g. fingers)
3 Protected against solids objects over 2.5mm (e.g. tools and wires)
4 Protected against solids objects over 1mm (e.g. tools, wires and small wires
5 Protected against dust - limited ingress (no harmful deposit)
6 Totally protected against dust

Second number (Protection against liquids)
0 No protection
1 Protected against vertically falling drops of water
2 Protected against direct sprays up to 15o from the vertical
3 Protected against direct sprays up to 60o from the vertical
4 Protected against sprays from all directions - limited ingress permitted
5 Protected against low pressure jets if water from all directions - limited ingress permitted
6 Protected against strong jets of water e.g. for use on shipdecks - limited ingress permitted
7 Protected against the effects of temporary immersion between 15cm and 1m. Duration of test 30 minutes

8 Protected against long periods of immersion under pressure




Image Credits:

Image#1: http://estoesiot.es/wp-content/uploads/2017/03/1928619fa80ccd8ec13304cd26f76789628b8674fb6247c22c8f88c94947d6f5.jpg

Image#6: http://img.directindustry.com/images_di/photo-g/17587-6825589.jpg

Image#9: https://www.visiononline.org/userAssets/aiaUploads/image/iStock-648248064.jpg

Image#11: https://www.mhlnews.com/sites/mhlnews.com/files/uploads/2017/02/automation-robot-revolution.gif

Image#12: https://www.robotics.org/userAssets/riaUploads/image/pick-and-place-robots.jpeg




WRITTEN BY

Sharon Xiao

Marketing Director of SOOYEE Robotics.







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