Robot Tool Coordinate Control for Marker-Visible Positioning
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Solution Overview
Problem
Robots with movable arms face challenges in positioning tools rotationally symmetrical about a specific axis, as rotations about this axis can cause markers to move out of detection regions, leading to unreliable tracking and positioning issues.
Innovation Solution
A method that calculates the orientation of a tool's coordinate system relative to a stationary reference system, minimizing rotations by determining the x- and y-axes of the target coordinate system, allowing for improved trackability and visibility of markers without additional hardware or computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the robot positions the tool in a target pose using conventional 6D positioning, then the positioning accuracy is improved, but the marker may move out of the detection region or be masked by the robot
Solution Approach 1:
The patent changes the parameter representation from full 6D pose to 5D pose by removing the irrelevant rotation angle about the tool's specified axis. This parameter reduction maintains positioning accuracy while minimizing unnecessary rotational movements that would cause markers to move out of detection regions or be masked by the robot body.
Solution Approach 2:
The patent extracts and removes the irrelevant rotation parameter from the 6D pose specification. By identifying that rotation about the tool's specified axis does not affect the functional outcome, this parameter is taken out of the control system, reducing the problem from 6D to 5D and eliminating the harmful effect of marker occlusion.
2Manufacturing precision
If the robot performs full 6D positioning movements, then the tool can be positioned precisely, but the computational complexity and movement time increase
Solution Approach 1:
The patent reduces the number of controlled parameters from 6 to 5 by eliminating the irrelevant rotation angle. This parameter reduction directly decreases computational complexity in the control system and reduces the total movement time required for positioning, while maintaining the necessary positioning precision through the remaining 5 parameters.
3Manufacturing precision
If the tool is rotated about its specified axis during positioning, then the 6D pose is achieved, but the marker visibility is lost
Solution Approach 1:
The patent identifies that the rotational degree of freedom about the tool's specified axis is functionally irrelevant to the tool's operational purpose. This irrelevance is converted into a benefit by using it as a parameter to be eliminated from control, thereby preventing marker occlusion while maintaining full functional capability of the tool.
Data Source
AI summary
The disclosure relates to a method for operating a robot, a data memory with a corresponding program code, the corresponding robot, and a corresponding robot system. Different coordinate system and their relationships to one another are used to position a tool in a target pose. A stationary reference coordinate system originating at a robot foot of the robot and a target coordinate system originating at the tool are specified. Herein, a z-axis of the target coordinate system corresponds to a specified axis of the tool. The orientations of an x-axis and a y-axis of the target coordinate system are calculated by a first cross product of the orientation of the specified axis and a direction vector, that is not parallel thereto, of coordinate axis of the reference coordinate system and by a second cross product of a result of the first cross product and the orientation of the specified axis.