Human-machine collaborative work
Within the same collaborative space, robots and operators are allowed to move simultaneously. However, to ensure the safety of operators, safety technologies are needed to detect the distance between them.
Based on the distance between the operator and the robot, the system adjusts the robot's speed accordingly, ultimately stopping the robot before a collision occurs. When the operator leaves, the robot system can manually or automatically resume its original path as needed, while maintaining a minimum distance.
Such speed and separation monitoring are considered one of the four types of human-machine collaborative safety applications in ISO/TS 15066.
Speed and separation monitoring diagram
Speed and Separation Monitoring Examples
To vividly demonstrate the monitoring of speed and separation, Pilz built a monitoring system based on SafetyEye to showcase this type of application.
This application demonstrates the following scenarios and processes:
When an operator enters the collaborative area, the safety system immediately detects the operator's entry, at which point the robot begins to decelerate and eventually comes to a stop.
After completing the operation, the operator triggered a button to manually reset the system.
Generally speaking, as long as the security features cannot be disabled, the system can be reset automatically without pressing a button.
safe distance
Because this application allows robots and operators to move simultaneously within the same collaborative space, the movement speeds of both the robot and the operator, as well as the corresponding minimum safety distance, should be limited by the system.
Referring to ISO 13855 regarding the positioning of safety devices related to human approach speed, the formula for calculating the minimum distance is:
S = (K × T )+ C
in:
S = Minimum distance (mm)
K = A parameter derived from the human body's approach speed (mm/s)
T = Total system stopping performance (s)
C = Intrusion distance (mm)
Human-machine speed curve
In human-robot collaboration applications, where humans and robots are allowed to be in the same space simultaneously, the relative speed between the robot and the human needs to be taken into account when determining the safe distance.
In the human-robot speed curve above, there is a response delay between the system issuing a stop command and the robot receiving the command; similarly, there is also a considerable time interval between the robot starting to decelerate and stopping. Therefore, the robot system's response time and stopping distance (sr, ss), as well as the positional uncertainties of the operator and the robot system (zd, zr), should all be evaluated.
Pilz's newly developed course on human-machine collaboration and its safety applications based on ISO/TS 15066, launched in 2018, is now open for enrollment!
Through this course, participants will learn and understand the fundamentals of human-robot collaborative applications, including relevant standards and different collaboration methods. In particular, the course will cover how to mitigate and validate risks associated with collaborative robots.
Pilz China
Training business inquiries: [email protected]
Website: www.pilz.com.cn
