Method, robot system and computer readable medium for determining a safety zone and for path planning for robots

A robot system, comprising:

• at least one robot carrying out operations along a specified trajectory;
• a local controller situated on said at least one robot;
• and
• a central fail-safe controller determining a safety zone for a collision-free operation of said at least one robot by:
• a) dividing the specified trajectory into a plurality of subtrajectories;
• b) determining a plurality of envelope cuboids, referred to as fine-grained envelope cuboids in the following, around extreme points of each subtrajectory;
• c) determining a number of optimized envelope cuboids from an enlargement of individual ones of the fine-grained envelope cuboids based on a volume occupied by enlarged fine-grained envelope cuboids, wherein the optimized envelope cuboids determined in this way form the safety zone for the trajectory;
• d) determining a further safety zone for a further robot, for which a further trajectory is specified, wherein the further robot interacts with said at least one robot, by performing the further steps of:
• carrying out the steps a) to c) for the further trajectory, and the safety zone and the further safety zone determined for said specified trajectory and the further trajectory are overlaid, which produces an overlap zone;
• defining a cuboid-shaped semaphore zone contained in the overlap zone, the cuboid-shaped semaphore zone contains a crossing of the further trajectory and the specified trajectory and is minimized compared to the optimized envelope cuboids of the further safety zone and the safety zone;
• and
• e) recalculating a new trajectory based on the optimized envelope cuboids determined in step c), the first robot carrying out operations along the new trajectory when a blockage occurs along the specified trajectory in real time.

A non-transitory computer readable medium storing computer executable instructions to be executed on a computer system and/or on a central fail-safe controller of a robot system, the computer executable instructions carrying out a method for determining a safety zone for a first robot carrying out operations along a specified trajectory, the safety zone for a collision-free operation being determined by the following method steps of:

• a) dividing the specified trajectory into a plurality of subtrajectories;
• b) determining a plurality of envelope cuboids, referred to as fine-grained envelope cuboids in the following, around extreme points of each subtrajectory;
• and
• c) determining a number of optimized envelope cuboids from an enlargement of individual ones of the fine-grained envelope cuboids based on a volume occupied by enlarged fine-grained envelope cuboids, wherein the optimized envelope cuboids determined in this way form the safety zone for the trajectory;
• d) determining a further safety zone for a further robot, for which a further trajectory is specified, wherein the further robot interacts with the first robot, by performing the further steps of:
• carrying out the method steps a) to c) for the further trajectory, and the safety zone and the further safety zone determined for said specified trajectory and the further trajectory are overlaid, which produces an overlap zone;
• defining a cuboid-shaped semaphore zone contained in the overlap zone, the cuboid-shaped semaphore zone contains a crossing of the further trajectory and the specified trajectory and is minimized compared to the optimized envelope cuboids of the further safety zone and the safety zone;
• and
• e) recalculating a new trajectory based on the optimized envelope cuboids determined in step c), the first robot carrying out operations along the new trajectory when a blockage occurs along the specified trajectory in real time.