Swept volume deformation

A method for robot collision avoidance motion planning, said method comprising:

• running a sampling-based path planning algorithm, on a computer having a processor and memory, to find a collision-free path for a robot to move from a start point to a goal point;
• defining a random sample node in the path planning algorithm and computing a path segment from a feasible node to the random sample node;
• computing a swept volume of a motion plan for the path segment;
• determining if the swept volume interferes with any obstacles;
• determining a critical posture of interference from the swept volume when the swept volume interferes with any obstacles;
• computing a modified critical posture, including computing a virtual force repelling each robot link from obstacle penetration at the critical posture, including a virtual force vector applied normal to a centerline of each robot link having obstacle penetration at the critical posture, and computing the modified critical posture using the virtual force in a Jacobian matrix calculation;
• computing a deformed swept volume of a modified motion plan for the path segment including the modified critical posture;
• verifying that the deformed swept volume is collision-free and that the modified motion plan meets robot joint movement constraints;
• adding the sample node and the modified motion plan as feasible elements of the collision-free path;
• and
• defining a new random sample node in the path planning algorithm.

A robot system with collision avoidance motion planning, said system comprising:

• a robot configured to perform an operation on a workpiece;
• a controller, having a processor and memory, controlling the robot;
• and
• a motion planner software module running on the controller or on a separate computer, where the motion planner software module is configured to;
• compute a swept volume of a motion plan for the robot to move along a path segment;
• determine if the swept volume interferes with any obstacles;
• determine a critical posture of interference from the swept volume when the swept volume interferes with any obstacles;
• compute a modified critical posture, including computing a virtual force repelling each robot link from obstacle penetration at the critical posture, including a virtual force vector applied normal to a centerline of each robot link having obstacle penetration at the critical posture, and computing the modified critical posture using the virtual force in a Jacobian matrix calculation;
• compute a deformed swept volume of a modified motion plan for the path segment including the modified critical posture;
• and
• verify that the deformed swept volume is collision-free and that the modified motion plan meets robot joint movement constraints.