Cobots, short for collaborative robots are designed to assist human workers with various tasks in the manufacturing plants including machine tending, processing, and quality inspection. There is a huge demand for these across the world as they are affordable, easily trained, and can boost productivity (reduced human idle time by 85% according to a human-machine study by MIT).
What Are the Four Key Types of Collaborative Robots?
Here is the thing – collaborative robots have been here for a while. But the rapid growth in the industry has facilitated the definition of the four major types of collaborative robots.
ISO 10218 Robots and robotics devices—an international standard dealing with robot safety—defines these four types of robots as Safety Monitored Step, Speed, and Separation Monitoring, Power and Force Limiting and Hand Guiding.
ISO 10218 bases these definitions on the safety and programming features inherent in each collaborative robot. Essentially, how do these collaborative robots avoid harming human workers when working hand in hand with them?
1. Safety Monitored Step
Safety Monitored Step is a type of cobot that combines industrial robots with a safety device such as a large scanner. The scanner scans for the entrance of a human worker in the designated robot zone, and once it detects one in the vicinity, the robot automatically stops working.
The human employee will thus perform any necessary operations, and when leaving, he/she will press a button, and the robot will resume operations. These kinds of robots are ideal for working spaces where the interaction between employees and the robot are minimal.
2. Speed and Separation Monitoring
Similar to the Safety Monitored Step, this type of collaborative robot also uses industrial robots. However, the key difference is that manufacturers designed this robot for environments where human employees frequently interact with the robot.
As a result, the robots that fall under this category combine industrial robots with an extremely powerful vision system. The vision system is constantly monitoring and if it detects a human employee in the “warning zone” it automatically slows down to a safe speed.
Once the human employee proceeds to the “stop zone,” the robot pauses to allow the employee to accomplish his/her mission. When the employee leaves, the robot automatically resumes operations.
3. Power and Force Limiting
Robots under this category are the most collaborative in that they can work alongside humans without needing an extra safety device or process interruption. That is because they are loaded with sensors that can sense forces and react to avoid causing injury.
Power and Force Limiting robots are further divided into four categories: Joint Sensing, Force Sensor Base, Skin Sensing and Inherently Safe
Joint Sensing
A joint sensing robot uses its joints to keep track of the forces exerted on the robot’s body. Examples include Universal Robots industrial robot arm (UR3, UR5, UR10).
Force Sensor Base
Cobots in this category monitor the various forces via a sizeable force-torque sensor located at the bottom of the robot.
To fully visualize how these robots work, consider a Force Sensor Base robot that is set to move in a certain direction. If, for instance, the robot comes across an obstacle, it will recognize the foreign force vector and stop.
Skin Sensing
Skin Sensing robots are not that popular yet, but research is ongoing to improve their performance. These robots use tactile sensing to detect impact and react accordingly.
Inherently Safe
Inherently Safe robots can use any of the sensors mentioned above or even all of them. What distinguishes them from the rest is that under no circumstances can they hurt you.
Consider a situation where a cobot has a payload of 0.5kg. While the cobot might not have many uses due to the low payload, the advantage is that even if something goes awry, the robot cannot hurt you.
4. Hand Guiding
The final type of collaborative robot includes robots that allow a programmer to teach them new paths and positions by simply moving the robot arm with their hand and placing it in the desired position.
These kinds of robots are perfect for situations where the robot needs to be reprogrammed quickly and on the fly.
Final Words
As seen above, each collaborative robot in existence today has different methods of maintaining a safe operating environment.
Understanding each type of robot is vital because it helps define the working environments in which the cobot will excel. In turn, that makes it easy for you to determine which kind of robot best suits your business.
