Manipulator Collision Avoidance Using Priority-Based DOF Control
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Solution Overview
Problem
Industrial and intelligent service robots with multi-joint manipulators face challenges in avoiding collisions with obstacles, particularly when they have only 6 degrees of freedom, as they cannot effectively use redundant degrees of freedom to maintain operation continuity without stopping or altering their motion.
Innovation Solution
A control method for manipulators that prioritizes the use of operating degrees of freedom (DOFs) and redundant DOFs to avoid collisions, calculating the lowest priority DOF or DOFs with the highest collision avoidance contribution to safely navigate around obstacles while maintaining operation continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a manipulator has only 6 degrees of freedom, then the device complexity is reduced, but the ability to avoid collision with obstacles is compromised
Solution Approach 1:
The patent implements dynamic selection of degrees of freedom for collision avoidance based on real-time operational context. The control method dynamically determines which DOFs to use for avoiding obstacles while maintaining operational continuity, allowing the manipulator to adaptively switch between using only redundant DOFs and using operating DOFs when necessary. This dynamic approach resolves the contradiction by enabling collision avoidance capability without permanently increasing device complexity.
2Reliability
If a manipulator uses redundant DOF to avoid collision, then collision avoidance capability is improved, but operation continuity may be disrupted
Solution Approach 1:
The patent segments the degrees of freedom into operating DOFs and redundant DOFs, and further segments the collision avoidance strategy into multiple levels: first attempting to use only redundant DOFs to avoid obstacles, and if that proves insufficient, then selectively using operating DOFs. This segmentation allows the system to prioritize operation continuity while maintaining collision avoidance capability, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The control method performs preliminary assessment to determine whether redundant DOFs alone are sufficient for collision avoidance before executing the avoidance maneuver. By evaluating the situation in advance and only using operating DOFs when absolutely necessary, the system maintains operation continuity while ensuring collision avoidance when needed, thus resolving the contradiction between operation continuity and collision avoidance capability.
3Reliability
If a manipulator uses operating DOFs to avoid collision, then collision avoidance capability is improved, but the precision of the primary operation may deteriorate
Solution Approach 1:
The patent applies local quality by selectively using only the necessary operating DOFs for collision avoidance while keeping other operating DOFs focused on the primary task. The control method identifies which specific operating DOFs should be used for avoidance and which should maintain operational precision, allowing different parts of the manipulator system to have different functional priorities. This resolves the contradiction by enabling collision avoidance without compromising the precision of the primary operation.
Data Source
AI summary
A manipulator, and a control method thereof, calculates a degree of freedom (DOF) used to prevent collision with an obstacle in consideration of an order of priority of DOFs for an operation and collision avoidance contribution. The manipulator judges whether there is danger of collision of the manipulator with an obstacle, judges whether or not there is at least one operating DOF capable of avoiding collision with the obstacle among the plurality of operating DOFs, upon judging that there is danger of collision with the obstacle, and avoids collision with the obstacle using at least one operating DOF having the lowest priority while performing the operation among the at least one operating DOF capable of avoiding collision with the obstacle, upon judging that there is the at least one operating DOF capable of avoiding collision with the obstacle.