Robot End Effector Control for Moving Workpiece Positioning
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Solution Overview
Problem
Existing robot systems face challenges in accurately and efficiently controlling end effectors relative to movable workpieces due to delays in image processing and control responses, leading to instability and inaccuracies in positioning.
Innovation Solution
A robot system incorporating a vision sensor, target position generation circuit, estimation circuit, and control circuit that generates target positions and estimates change amounts in relative positions based on images and non-vision sensor information, allowing for real-time adjustments to ensure precise movement of the end effector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image processing and control response are performed at standard intervals, then system complexity is reduced, but positioning accuracy deteriorates due to delays
Solution Approach 1:
The estimation circuit performs preliminary estimation of workpiece position and posture changes at shorter intervals than target position generation. This preliminary action provides advance information about position changes, allowing the control system to compensate for processing delays and maintain positioning accuracy without increasing overall system complexity.
Solution Approach 2:
The system uses different time intervals for different functions: shorter intervals for estimation (high-frequency monitoring) and standard intervals for target position generation (lower-frequency control). This dynamic approach allows the system to adapt to changing conditions while maintaining stability, resolving the contradiction between responsiveness and processing load.
2Measurement precision
If estimation is performed at shorter intervals, then positioning accuracy is improved, but device complexity increases
Solution Approach 1:
The control system is segmented into distinct functional circuits: vision sensor for image capture, estimation circuit for position/posture estimation, target position generation circuit for control target determination, and control circuit for robot actuation. This segmentation allows high-frequency estimation without proportionally increasing overall system complexity, as each segment performs its specific function independently.
Solution Approach 2:
The estimation circuit acts as an intermediary between the vision sensor and the target position generation circuit. It processes raw image data and relative position information to estimate workpiece position changes, providing refined input to the target position generation without requiring the entire system to operate at high frequency, thus managing complexity while improving accuracy.
3Speed
If real-time image processing is performed, then responsiveness is improved, but processing time increases
Solution Approach 1:
The estimation circuit performs partial processing by estimating only the changes in position and posture of the workpiece relative to the end effector, rather than processing complete target positions. This partial action reduces processing time while maintaining responsiveness, as change detection requires fewer computational resources than full position generation.
Solution Approach 2:
Relative position information about the workpiece is acquired in advance and stored before estimation is performed. This preliminary acquisition of data allows the estimation circuit to work with pre-processed information, reducing real-time processing requirements and improving responsiveness without sacrificing accuracy.
Data Source
AI summary
A robot system includes a robot, a vision sensor, a target position generation circuit, an estimation circuit, and a control circuit. The robot includes an end effector and is configured to work via the end effector on a workpiece which is disposed at a relative position and which is relatively movable with respect to the end effector. The vision sensor is configured to take an image of the workpiece. The target position generation circuit is configured to, based on the image, generate a target position of the end effector at every generation interval. The estimation circuit is configured to, at least based on relative position information related to the relative position, estimate a change amount in the relative position at every estimation interval. The control circuit is configured to control the robot to move the end effector based on the target position and the change amount.