Patent ID: 7664570

Claim:
A method of limiting the movement of a robot, said method comprising the steps of: constructing a physical safety barrier surrounding a movable robot including a base mounted on a floor; defining in a memory a virtual safety barrier including a trajectory of a work or a tool mounted on a wrist of an arm of the robot in operation, the virtual safety barrier having boundaries spaced inward from the physical safety barrier and surrounding the work or tool; defining in the memory a margin width of the virtual safety barrier, wherein a degree of freedom of a movement of the work or tool can be obtained; defining in the memory at least two three-dimensional spatial regions including parts of the arm of the robot including said work or tool, wherein each of the three-dimensional spatial regions has a substantially spherical shape with a predetermined radius, wherein the radius for each of the three-dimensional spatial regions is configured to maintain a space efficiency; calculating a movement trajectory of the work or tool included in the defined three-dimensional spatial regions; determining a predicted position of each of the defined three-dimensional spatial regions based on the trajectory calculation; matching the predicted position of each of the defined three-dimensional spatial regions with said virtual safety barrier; recognizing a forward position of at least one of the three-dimensional spatial regions spaced apart from the virtual safety barrier by a predetermined distance as a deceleration start position to safely stop the work or tool; and carrying out a control to start the deceleration of the work or tool when at least one of the three-dimensional spatial regions is at the predetermined distance ahead of the virtual safety barrier and stop the movement of the work or tool ahead of the virtual safety barrier.