Robot Device 3D Sensor Position Correction
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Solution Overview
Problem
Errors in the position and orientation of a robot device due to backlash in reduction gears can lead to inaccuracies in the conversion of three-dimensional points from a sensor coordinate system to a robot coordinate system, affecting the accuracy of work performed by the robot.
Innovation Solution
A robot device equipped with a three-dimensional sensor and a control method that includes a position information generating unit, a face estimating unit, and a correction amount setting unit. The device changes the relative position between the workpiece and the three-dimensional sensor, setting a correction amount for driving the robot based on face information to ensure accurate matching of detected faces at different positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the robot device performs measurement at multiple positions to measure large workpieces or compensate for halation, then the measurement coverage is improved, but the position accuracy deteriorates due to error accumulation from robot movement and coordinate system conversions
Solution Approach 1:
The patent creates a virtual model (point cloud) of the workpiece from multiple measurement positions and synthesizes them into a unified coordinate system. This virtual copy allows the system to achieve complete coverage without the error accumulation that would occur in physical repeated measurements, as the synthesis process integrates data mathematically rather than physically repositioning the robot multiple times.
Solution Approach 2:
The patent introduces a coordinate system conversion mechanism as an intermediary between the sensor coordinate system and robot coordinate system. By using intermediate coordinate transformations and synthesis processing, the system bridges the gap between multiple measurement positions while maintaining position accuracy, preventing direct error propagation from robot movement to final measurement results.
2Loss of information
If the robot device converts three-dimensional points from sensor coordinate system to robot coordinate system based on robot position and orientation, then the position information is obtained, but errors due to robot position and orientation inaccuracies (such as backlash) are transferred to the three-dimensional points
Solution Approach 1:
The patent implements a feedback mechanism where the robot's actual position and orientation are detected and used to correct the coordinate system conversion. By continuously monitoring robot state and adjusting the transformation accordingly, the system compensates for position errors and prevents them from being transferred to the three-dimensional point data, maintaining measurement accuracy despite robot imperfections.
Data Source
AI summary
This robot device comprises: a positional information generation unit that generates three-dimensional positional information of a surface of a workpiece on the basis of an output from a visual sensor; and a face inference unit that infers face information related to a face including the surface of the workpiece on the basis of the three-dimensional positional information. The robot moves the visual sensor from a first position to a second position. A correction amount setting unit sets a correction amount for driving the robot in the second position so that a first face including the surface of the workpiece detected in the first position matches a second face including the surface of the workpiece detected in the second position.