Robot Arm Path Planning Using Precomputed Roadmaps
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Solution Overview
Problem
Robotic arms face challenges in navigating constrained environments without reaching joint limits or striking obstacles, requiring efficient and optimal path planning to maintain speed and accuracy.
Innovation Solution
A method for planning a path for an articulated robot arm that generates a graph of joint spaces, computes outer and inner domains, and simulates movements to determine direct travel possibilities, adjusting the path to avoid obstacles and joint limits by selecting candidate paths based on distance and domain overlap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the robotic arm follows a precomputed path through joint space nodes, then the path planning completeness is improved, but the movement time increases
Solution Approach 1:
The system precomputes a roadmap of valid joint configurations and collision-free paths in advance, storing them as a data structure. During actual operation, the robot queries this precomputed roadmap to find optimal paths between start and target poses, avoiding the need to recompute paths in real-time and thus reducing movement time while maintaining planning completeness
Solution Approach 2:
The patent replaces real-time mechanical path computation with a precomputed data structure (roadmap) that can be quickly queried. This substitution transforms the expensive real-time calculation problem into a faster lookup problem, reducing movement time while preserving the completeness of path planning
2Productivity
If the robotic arm moves at high speed, then productivity is improved, but the risk of reaching joint limits or striking obstacles increases
Solution Approach 1:
The system performs preliminary verification of path validity by checking whether intermediate joint configurations lie within safe domains (inner domains) that are guaranteed to avoid obstacles and joint limits. This advance verification allows the robot to move at high speed along the path without risking collisions, as the safety constraints were already satisfied during path planning
Solution Approach 2:
The patent introduces intermediate safety domains (inner domains) as mediators between the robot's high-speed movement requirement and the collision avoidance requirement. These domains act as buffers that guarantee the robot remains safe from obstacles and joint limits while allowing optimal-speed traversal along the planned path
3Manufacturing precision
If the path planning considers all possible joint configurations, then the optimality of the path is improved, but the computational complexity increases
Solution Approach 1:
The patent segments the continuous joint space into discrete nodes and edges, creating a roadmap where each node represents a valid joint configuration and each edge represents a collision-free path between configurations. This segmentation transforms the complex continuous optimization problem into a more manageable graph traversal problem, achieving optimal paths with reduced computational complexity
Solution Approach 2:
The system performs preliminary sampling and verification of joint configurations to build the roadmap structure before actual path planning is needed. By precomputing which configurations are valid and how they connect, the system avoids the need to evaluate all possible configurations during real-time operation, reducing computational complexity while maintaining path optimality
Data Source
AI summary
A method of planning a path for an articulated arm of robot includes generating a directed graph corresponding to a joint space of the articulated arm. The directed graph includes a plurality of nodes each corresponding to a joint pose of the articulated arm. The method also includes generating a planned path from a start node associated with a start pose of the articulated arm to an end node associated with a target pose of the articulated arm. The planned path includes a series of movements along the nodes between the start node and the end node. The method also includes determining when the articulated arm can travel to a subsequent node or the target pose, terminating a movement of the articulated arm towards a target node, and initiating a subsequent movement of the articulated arm to move directly to the target pose or the subsequent node.