Robot Tool Pose Planning With a Virtual Joint for 5D Positioning
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Solution Overview
Problem
Conventional methods for controlling robots to position rotationally symmetrical tools in 5D poses are limited by mechanical constraints, often resulting in the exclusion of potentially more efficient control sequences due to the inability to achieve specified 6D poses.
Innovation Solution
The method involves specifying 3D coordinates and an axis orientation for a 5D target pose, expanding the robot's kinematics with a virtual joint allowing unrestricted rotation around the symmetry axis, and using automatic path planning to determine a collision-free path, thereby overcoming mechanical limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixed 6D pose is specified for the tool to account for rotational symmetry, then the target pose is well-defined, but the robot cannot achieve the pose due to mechanical limitations and other valid control sequences are excluded
Solution Approach 1:
The patent reduces the pose specification from 6D to 5D by exploiting the rotational symmetry of the tool. Instead of specifying all six parameters (three position coordinates and three orientation angles), the method specifies only five parameters by omitting the redundant rotation angle about the tool's symmetry axis. This dimensional reduction allows the robot to achieve the same functional pose through multiple different 6D configurations, thereby increasing control sequence flexibility while maintaining pose specification accuracy.
2Ease of manufacture
If conventional methods are used to determine control sequences for 6D poses, then the control approach is straightforward, but potentially more efficient control sequences are automatically excluded due to mechanical constraints
Solution Approach 1:
The patent introduces dynamic reconfiguration of the control approach by allowing the robot to transition between different 6D poses that all map to the same 5D target pose. Instead of being constrained to a single fixed control sequence, the system can dynamically select from multiple valid sequences based on real-time considerations such as collision avoidance, path optimization, and mechanical constraints, thereby improving productivity while maintaining implementation feasibility.
3Manufacturing precision
If the robot arm is constrained to achieve a specific 6D pose, then the tool orientation is precisely controlled, but mechanical limitations prevent the robot from assuming the specified pose
Solution Approach 1:
The patent changes the parameter specification from 6D to 5D by recognizing that one parameter (the rotation angle about the tool's symmetry axis) is redundant for rotationally symmetrical tools. This parameter reduction transforms an unsolvable 6D positioning problem into a solvable 5D positioning problem, allowing the robot to reliably achieve the target pose within its mechanical capabilities while maintaining precise tool positioning accuracy through the reduced parameter set.
Data Source
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AI summary
The invention relates to a method (19) for controlling a robot (1) to automatically position a tool (7) in a predetermined target pose (16). The invention further relates to a corresponding data carrier and the robot (1). In the method (19), a 6D pose of a robot flange (5) corresponding to the target pose (16) is determined. In addition, extended kinematics of the robot (1) are generated by adding a virtual joint (17) arranged in the tool (7). The virtual joint (17) enables virtually unrestricted rotation about a predetermined axis (8) of the tool (7). Using an automatic path planning module, a path is then determined from the determined 6D pose of the robot flange (5) and the extended kinematics, according to which the determined 6D pose of the robot flange (5) can be approached from an initial pose of the robot (1).Any conflicts arising with the maximum physical range of motion of the robot (1) are resolved by a rotation (20) of the virtual joint (17).