Motion planning and task execution using potential occupancy envelopes
Spatial regions potentially occupied by a robot (or other machinery) or portion thereof and a human operator during performance of all or a defined portion of a task or an application are computationally estimated. These “potential occupancy envelopes” (POEs) may be based on the states (e.g., the current and expected positions, velocities, accelerations, geometry and/or kinematics) of the robot and the human operator. Once the POEs of human operators in the workspace are established, they can be used to guide or revise motion planning for task execution.
1. A safety system for enforcing safe operation of machinery performing an activity in a three-dimensional (3D) workspace, the system comprising:
a computer memory for storing (i) a model of machinery and its permitted movements, (ii) a plurality of different task specifications, and (iii) geometric representations of a plurality of restriction zones within a 3D spatial representation of the workspace, wherein each of the restriction zones is associated with one of the task specifications; and
a processor configured to:
computationally generate the 3D spatial representation of the workspace;
identify a 3D region of the workspace corresponding to space occupied or potentially occupied by a human within the workspace augmented by a 3D envelope around the human corresponding to anticipated movements of the human within the workspace during performance of the specified task, wherein the processor is configured so that the 3D envelope is bounded based on safety standards defining expected human motion in a hazardous setting, and either of
modified to include a workpiece carried by the human, or
truncated based on a physical boundary within the workspace;
computationally generate a constrained motion plan comprising a trajectory of the machinery to perform the specified task without entering the 3D region;
cause the machinery to execute the constrained motion plan and physically perform the specified task; and
during physical performance of the specified task, restrict operation of the machinery to remain within or outside a restriction zone associated with a task specification of the specified task, wherein restricting operation of the machinery does not preclude physical performance of the specified task.
2. The system of claim 1 , wherein the constrained motion plan implements a safety protocol specifying speed restrictions of the machinery in proximity to a human and a minimum separation distance between the machinery and a human.
3. The system of claim 2 , wherein the processor is configured to, during physical performance of the task, continuously compare an instantaneous measured distance between the machinery and the human to the minimum separation distance and adjust an operating speed of the machinery based at least in part on the comparison.
4. The system of claim 2 , wherein the processor is configured to, during physical performance of the task, govern an operating speed of the machinery to a set point at a distance larger than the minimum separation distance.
5. The system of claim 1 , wherein the motion plan comprises a plurality of trajectories of the machinery, the processor being further configured to:
assign a cost value to each of the trajectories;
select one of the trajectories based at least in part on the cost values assigned to the trajectories; and
cause the machinery to execute the selected trajectory to perform the task.
6. The system of claim 5 , wherein the processor is further configured to assign the corresponding cost value to each of the trajectories based at least in part on a length of the trajectory and/or an operation time of the machinery on the trajectory.
7. The system of claim 1 , wherein the processor is responsive to real-time monitoring of the workspace and is further configured to alter the motion plan in response to a change in the 3D region.
8. The system of claim 1 , wherein the processor is responsive to real-time monitoring of the workspace and is further configured to recompute the motion plan in response to a change in the 3D region.
9. The system of claim 8 , wherein the motion plan is recomputed by generating a plurality of candidate trajectories each capable of performing the task and selecting one of the candidate trajectories.
10. The system of claim 1 , wherein the restriction zone is a keep-out zone and the constrained motion plan comprises trajectories along which the machinery can perform the specified task without entering the keep-out zone.
11. The system of claim 1 , wherein the restriction zone is a keep-in zone and the constrained motion plan comprises trajectories along which the machinery can perform the specified task without leaving the keep-in zone.
12. The system of claim 1 , wherein one or more of the geometric representations of the restriction zones are each established by recording motion of the machinery as it performs the task associated therewith.
13. The system of claim 1 , wherein one or more of the geometric representations of the restriction zones are each established by a computational simulation defining performance of the task associated therewith.
14. A method of enforcing safe operation of machinery performing an activity in a three-dimensional (3D) workspace, the method comprising the steps of:
computationally generating a 3D spatial representation of the workspace;
storing geometric representations of a plurality of restriction zones within the 3D spatial representation of the workspace, each restriction zone being associated with a different task specification;
computationally identifying a 3D region of the workspace corresponding to space occupied or potentially occupied by a human within the workspace augmented by a 3D envelope around the human corresponding to anticipated movements of the human within the workspace during performance of a specified task, wherein the 3D envelope is bounded based on safety standards defining expected human motion in a hazardous setting, and either of
modified to include a workpiece carried by the human, or
truncated based on a physical boundary within the workspace;
computationally generating a constrained motion plan comprising a trajectory of the machinery to perform the task without entering the 3D region;
causing the machinery to execute the constrained motion plan and physically perform the specified task; and
during physical performance of the specified task, restricting operation of the machinery to remain within or outside the restriction zone associated with the task specification of the specified task, wherein restricting operation of the machinery does not preclude physical performance of the specified task.
15. The method of claim 14 , wherein the constrained motion plan implements a safety protocol specifying speed restrictions of the machinery in proximity to a human and a minimum separation distance between the machinery and a human.
16. The method of claim 15 , further comprising, during physical performance of the task, continuously comparing an instantaneous measured distance between the machinery and the human to the minimum separation distance and adjusting an operating speed of the machinery based at least in part on the comparison.
17. The method of claim 15 , further comprising, during physical performance of the task, governing an operating speed of the machinery to a set point at a distance larger than the minimum separation distance.
18. The method of claim 14 , wherein the motion plan comprises a plurality of trajectories of the machinery, and further comprising the steps of:
assigning a cost value to each of the trajectories;
computationally selecting one of the trajectories based at least in part on the cost values assigned to the trajectories; and
causing the machinery to execute the selected trajectory to perform the task.
19. The method of claim 18 , further comprising the step of assigning the corresponding cost value to each of the trajectories based at least in part on a length of the trajectory and/or an operation time of the machinery on the trajectory.
20. The method of claim 14 , further comprising the step of computationally altering the motion plan in response to a change in the 3D region.
21. The method of claim 14 , further comprising the step of recomputing the motion plan in response to a change in the 3D region.
22. The method of claim 21 , wherein the motion plan is recomputed by generating a plurality of candidate trajectories each capable of performing the task and selecting one of the candidate trajectories.
23. The method of claim 14 , wherein the restriction zone is a keep-out zone and the constrained motion plan comprises trajectories along which the machinery can perform the specified task without entering the keep-out zone.
24. The method of claim 14 , wherein the restriction zone is a keep-in zone and the constrained motion plan comprises trajectories along which the machinery can perform the specified task without leaving the keep-in zone.
25. The method of claim 14 , wherein one or more of the geometric representations of the restriction zones are each established by recording motion of the machinery as it performs the task associated therewith.
26. The method of claim 14 , wherein one or more of the geometric representations of the restriction zones are each established by a computational simulation defining performance of the task associated therewith.