(Translation of German Websites)
Time is money. However, in many cases even space is money. Because at installation sites of industrial robot systems often less space is provided. Therefore, in many cases the maximum space of robot system exceeds the perimeter safeguarding. In order to avoid collision the application program is designed such that the movement of robot tools and work pieces takes place only within safeguarded space.
But what’s about a crash? Shall a crash still be assumed? Can the safety fence withstand a collision with the robot
The standard EN ISO 10218-2 divides:
- Maximum space: Whole space which can be reached by the robot system inclusive its tools and work pieces
- Restricted space: Portion of maximum space that is restricted by safeguards, e.g. safe hardware limit switches or safe software spaces
- Operating space: Portion of the restricted space determined by the task program
According to the present standards the robot task program unfortunately, does not satisfy general safety requirements. Because of Hard or Software failure a crash between robot system and safety fence cannot be excluded. What would happen if a person is standing close to such a crash?
Primarily, a robot safety fence provides only protection against access from outside. Therefore, the robot motion shall be restricted either by a sufficient strength of the fence (e.g. by mechanical enforcement) or by a restricted space. Restricted space is a safety function. The means for providing restricted space (e.g. safe hardware limit switches or safe software spaces) shall be independent from the task program.
According to the existing standard a difference between high and low person exposition can be made according to a risk assessment. Therefore, a restricted space e.g. near to simple routes or pallet stores can be eventually dispensable (see DGUV-Information 209-074). By the new Draft ISO 10218-2 this option probably will disappear. Therefore, in future, when moving parts of the robot system could exceed the perimeter safeguarding by their maximum space then generally a restricted space shall be provided (see figure). The new EN ISO 10218-2 probably will be published in 2024.
