Robot Controller Coordinate Transformation for Rotating Conveyor
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Solution Overview
Problem
Existing robot control systems face difficulties in accurately following a shelf on a conveyor that maintains a constant horizontal orientation during rotation, as they require complex calculations and considerations to maintain the robot's orientation in sync with the shelf's motion, making the teaching process burdensome.
Innovation Solution
A robot controller system that calculates a second coordinate system with a constant orientation for the shelf, allowing the robot to generate motion commands based on the shelf's rotation angle and position, simplifying the teaching process by decoupling the robot's motion from the rotating coordinate system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the robot is controlled based on a rotating coordinate system to follow the conveyor rotation, then the robot can track the rotating conveyor, but the shelf orientation becomes constantly changing relative to the robot, making teaching burdensome and difficult
Solution Approach 1:
The patent introduces an intermediate coordinate system (conveyor coordinate system) that rotates with the conveyor but maintains a fixed relationship with the shelf. This intermediary coordinate system acts as a bridge between the robot's reference coordinate system and the shelf's constant orientation, allowing the robot to track the rotating conveyor while the shelf appears stationary in the conveyor coordinate system, thus simplifying teaching operations
Solution Approach 2:
The patent transforms the control problem from a single rotating coordinate system to a multi-dimensional coordinate transformation system. By introducing the conveyor coordinate system as an intermediate layer and using transformation matrices, the system separates the conveyor rotation dynamics from the shelf orientation, enabling independent control and simplifying the teaching process
2Stability of the object's composition
If the shelf orientation is kept constant during conveyor rotation, then articles on the shelf remain stable, but the robot must perform complex coordinate transformations to account for both conveyor rotation and shelf orientation
Solution Approach 1:
The patent segments the coordinate transformation into multiple independent stages: first transforming from the robot reference coordinate system to the conveyor coordinate system (accounting for conveyor rotation), then from the conveyor coordinate system to the shelf coordinate system (accounting for shelf position and orientation). This segmentation allows each transformation to be handled independently, reducing overall computational complexity while maintaining article stability
3Productivity
If the robot follows the workpiece on a rotating conveyor using conventional techniques, then the robot can perform operations on the workpiece, but the orientation of the robot must be constantly adjusted relative to the rotating shelf, increasing control complexity
Solution Approach 1:
The conveyor coordinate system serves as an intermediary that decouples the robot motion control from the shelf rotation. The robot plans and controls its motion in the conveyor coordinate system where the shelf has constant orientation, then transforms the motion commands to the robot reference coordinate system. This intermediary approach maintains productivity while reducing motion control complexity
Data Source
AI summary
A robot system and a robot controller, by which teaching operation, etc., for a robot can be easily carried out, with respect to a shelf having an unchangeable orientation. The robot controller has: a rotation angle obtaining section configured to obtain a rotation angle of a first rotation axis; a coordinate system calculating section configured to calculate a second coordinate system based on a first coordinate system; a position/orientation calculating section configured to calculate a position and orientation of the robot on a reference coordinate system, based on the rotation angle of the first rotation axis obtained by the rotation angle obtaining section and the teaching position on the second coordinate system; and a motion command generating section configured to generate a motion command for controlling a motion of the operation of the robot, based on the position and orientation of the robot calculated by the position/orientation calculating section.