Robot Path Segment Deformation for Collision-Aware RRT Planning
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Solution Overview
Problem
Traditional robot motion planning techniques, such as RRT, are inefficient in obstacle-intensive environments due to the discarding of sample points with minor interference conditions without considering the severity of robot-obstacle collisions, leading to slow tree growth or inefficient direction.
Innovation Solution
The use of swept volume deformation in robot interference checking motion planning, where the severity of collisions is evaluated, and virtual forces are applied to modify the path segment to alleviate minor interferences, allowing the inclusion of sample points that would otherwise be discarded, resulting in a revised motion plan that avoids collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional RRT technique is used to check for collision-free paths, then collision avoidance is achieved, but path planning efficiency deteriorates due to discarding sample points with minor interferences
Solution Approach 1:
The patent changes the parameter of interference evaluation from binary (collision-free or not) to a continuous severity metric based on swept volume intersection. This allows sample points with minor interferences to be retained and optimized rather than discarded, improving path planning efficiency while maintaining collision avoidance.
Solution Approach 2:
The patent dynamically adjusts the motion segment to resolve interferences by computing swept volumes and identifying critical postures. Instead of statically discarding sample points, the system dynamically modifies paths to alleviate minor interferences, transforming a rigid rejection process into a flexible optimization process.
2Reliability
If sample points with minor interferences are discarded to ensure collision-free paths, then safety is improved, but tree growth speed deteriorates
Solution Approach 1:
The patent introduces a swept volume-based interference severity parameter that quantifies the degree of intersection between robot motion and obstacles. By using this continuous parameter instead of a binary collision indicator, the system can distinguish between critical and minor interferences, retaining sample points with minor interferences for further optimization and thus accelerating tree growth while maintaining safety.
3Device complexity
If traditional interference checking is used without considering severity, then simplicity is maintained, but path planning effectiveness deteriorates in obstacle-intensive environments
Solution Approach 1:
The patent segments the path planning process into distinct phases: initial RRT sampling, swept volume computation, interference severity evaluation, and selective optimization. This segmentation allows the complex swept volume analysis to be applied only when necessary (when interferences are detected), maintaining overall algorithmic simplicity while improving effectiveness in obstacle-intensive environments.
Data Source
AI summary
A robot interference checking motion planning technique using swept volume deformation. A rapidly-exploring random tree (RRT) algorithm generates random sample nodes between a start point and a goal point. Each sample node is evaluated by checking for robot-obstacle interference along a path segment to the node. If an interference exists along the path segment, a swept volume of the segment is used to identify a critical posture where the interference is greatest, and obstacle interference points are used to define a virtual force applied to the robot links to modify the path segment to alleviate the interference condition. A swept volume of the modified path segment is computed and evaluated. If the modified swept volume is collision-free and the modified path segment motion plan meets robot joint range criteria, the modified path segment and the sample node are added to the overall robot motion program.